2002-2013 Microchip Technology Inc. DS30487D-page 1
PIC16F87/88
Low-Power Features:
Power-Managed modes:
- Primary Run: RC oscillator, 76 A, 1 MHz, 2V
- RC_RUN: 7 A, 31.25 kHz, 2V
- SEC_RUN: 9 A, 32 kHz, 2V
- Sleep: 0.1 A, 2V
Timer1 Oscillator: 1.8 A, 32 kHz, 2V
Watchdog Timer: 2.2 A, 2V
Two-Speed Oscillator Start-up
Oscillators:
Three Crystal modes:
- LP, XT, HS: up to 20 MHz
Two External RC modes
One External Clock mode:
- ECIO: up to 20 MHz
Internal oscillator block:
- 8 user selectable frequencies: 31 kHz,
125 kHz, 250 kHz, 500 kHz, 1 MHz, 2 MHz,
4MHz, 8MHz
Peripheral Feat ures:
Capture, Compare, PWM (CCP) module:
- Capture is 16-bit, max. resolution is 12.5 ns
- Compare is 16-bit, max. resolution is 200 ns
- PWM max. resolution is 10-bit
10-bit, 7-channel Analog-to-Digital Converter
Synchronous Serial Port (SSP) with SPI
(Master/Slave) and I2C™ (Slave)
Addressable Universal Synchronous
Asynchronous Receiver Transmitter
(AUSART/SCI) with 9-bit address detection:
- RS-232 operation using internal oscillator
(no exter nal crystal required)
Dual Analog Comparator module:
- Programmable on-chip voltage reference
- Programmabl e input multi plexing fr om device
inputs and internal voltage reference
- Comparator outputs are externally accessible
Pin Diagram
S pecial Microcontroller Features:
100,000 eras e/w ri te cy cles Enhanced Flash
program memory typical
1,000,000 typical erase/write cycles EEPROM
data memory typical
EEPROM Data Retention: > 40 years
In-Circuit Serial Programming™ (ICSP™)
via two pins
Processor read/write access to program memory
Low-Voltage Programming
In-Circuit Debugging via two pins
Extended Watchdog Timer (WDT):
- Programmable period from 1 ms to 268s
Wide operating voltage range: 2.0V to 5.5V
RA1/AN1
RA0/AN0
RA7/OSC1/CLKI
RA6/OSC2/CLKO
VDD
RB7/AN6/PGD/
RB6/AN5/PGC/
RB5/SS/TX/CK
RB4/SCK/SCL
RA3/AN3/VREF+/
RA4/AN4/T0CKI/
RA5/MCLR/VPP
VSS
RB0/INT/CCP1(1)
RB1/SDI/SDA
RB2/SDO/RX/DT
RB3/PGM/CCP1(1)
1
2
3
4
5
6
7
8
9
18
17
16
15
14
13
12
11
10
PIC16F88
T1OSI
T1OSO/T1CKI
C2OUT
C1OUT
VREF-
RA2/AN2/CVREF/
18-Pin PDIP, SOIC
Note 1: The CCP1 pin is determined by the CCPMX bit in
Configuration Word 1 register .
Device
Prog ram Memory Data Memory I/O
Pins 10-bit
A/D (ch) CCP
(PWM) AUSART Comparators SSP Timers
8/16-bit
Flash
(bytes) # Single-W ord
Instructions SRAM
(bytes) EEPROM
(bytes)
PIC16F87 7168 4096 368 256 16 N/A 1 Y 2 Y 2/1
PIC16F88 7168 4096 368 256 16 1 1 Y 2 Y 2/1
18/20/ 28-Pin Enha nced Flash MCUs with nanoWatt Technolog y
PIC16F87/88
DS30487D-page 2 2002-2013 Microchip Technology Inc.
Pin Diagrams
RA1/AN1
RA0/AN0
RA7/OSC1/CLKI
RA6/OSC2/CLKO
VDD
RB7/PGD/T1OSI
RB6/PGC/T1OSO/T1CKI
RB5/SS/TX/CK
RB4/SCK/SCL
RA2/AN2/CVREF
RA3/AN3/C1OUT
RA4/T0CKI/C2OUT
RA5/MCLR/VPP
VSS
RB0/INT/CCP1(1)
RB1/SDI/SDA
RB2/SDO/RX/DT
RB3/PGM/CCP1(1)
1
2
3
4
5
6
7
8
9
18
17
16
15
14
13
12
11
10
PIC16F87
18-Pin PDIP, SOIC
RB7/AN6/PGD/T1OSI
RB6/AN5/PGC/T1OSO/T1CKI
RA7/OSC1/CLKI
RA6/OSC2/CLKO
VDD
RB5/SS/TX/CK
RB4/SCK/SCLRB3/PGM/CCP1(1)
RB2/SDO/RX/DT
RA0/AN0
RA1/AN1
RA4/AN4/T0CKI/C2OUT
RA5/MCLR1/VPP
VSS
RA2/AN2/CVREF/VREF-
RA3/AN3/VREF+/C1OUT
RB0/INT/CCP1(1)
RB1/SDI/SDA
1
2
3
4
5
6
7
8
9
20
19
18
17
16
15
14
13
12
VDDVSS
10 11
PIC16F88
20-Pin SSOP
20-Pin SSOP
18-Pin PDIP, SOIC
RA1/AN1
RA0/AN0
RA7/OSC1/CLKI
RA6/OSC2/CLKO
VDD
RB7/AN6/PGD/T1OSI
RB6/AN5/PGC/T1OSO/T1CKI
RB5/SS/TX/CK
RB4/SCK/SCL
RA2/AN2/CVREF/VREF-
RA3/AN3/VREF+/C1OUT
RA4/AN4/T0CKI/C2OUT
RA5/MCLR/VPP
VSS
RB0/INT/CCP1(1)
RB1/SDI/SDA
RB2/SDO/RX/DT
RB3/PGM/CCP1(1)
1
2
3
4
5
6
7
8
9
18
17
16
15
14
13
12
11
10
PIC16F88
RB7/PGD/T1OSI
RB6/PGC/T1OSO/T1CKI
RA7/OSC1/CLKI
RA6/OSC2/CLKO
VDD
RB5/SS/TX/CK
RB4/SCK/SCL
RB3/PGM/CCP1(1)
RB2/SDO/RX/DT
RA0/AN0
RA1/AN1
RA4/T0CKI/C2OUT
RA5/MCLR/VPP
VSS
RA2/AN2/CVREF
RA3/AN3/C1OUT
RB0/INT/CCP1(1)
RB1/SDI/SDA
1
2
3
4
5
6
7
8
9
20
19
18
17
16
15
14
13
12
VDDVSS
10 11
PIC16F87
Note 1: The CCP1 pin is determined by the CCPMX bit in Configuration Wo rd 1 register.
2002-2013 Microchip Technology Inc. DS30487D-page 3
PIC16F87/88
Pin Diagrams (Cont’d)
16
2
RA2/AN2/CVREF
RA0/AN0
RA4/T0CKI/C2OUT
RA5/MCLR/VPP
NC
VSS
NC
RB0/INT/CCP1(2)
RB1/SDI/SDA
RA3/AN3/C1OUT
RA7/OSC1/CLKI
RA6/OSC2/CLKO
VDD
NC
VDD
RB7/PGD/T1OSI
RB6/PGC/T1OSO/T1CKI
RB5/SS/TX/CK
RB4/SCK/SCL
7
PIC16F87
1
3
6
5
4
15
21
19
20
17
18
22
28
26
27
23
24
25
14
8
10
9
13
12
11
VSS
NC
NC
RA1/AN1
RB2/SDO/RX/DT
RB3/PGM/CCP1(2)
NC
NC NC
16
2
RA2/AN2/CVREF/VREF-
RA0/AN0
RA4/AN4/T0CKI/C2OUT
RA5/MCLR/VPP
NC
VSS
NC
RB0/INT/CCP1(2)
RB1/SDI/SDA
RA3/AN3/VREF+/C1OUT
RA7/OSC1/CLKI
RA6/OSC2/CLKO
VDD
NC
VDD
RB7/AN6/PGD/T1OSI
RB6/AN5/PGC/T1OSO/T1CKI
RB5/SS/TX/CK
RB4/SCK/SCL
7
PIC16F88
1
3
6
5
4
15
21
19
20
17
18
22
28
26
27
23
24
25
14
8
10
9
13
12
11
VSS
NC
NC
RA1/AN1
RB2/SDO/RX/DT
RB3/PGM/CCP1(2)
NC
NC NC
28-Pin QFN(1)
28-Pin QFN(1)
Note 1: For the QFN package, it is recommended that the bottom pad be connected to VSS.
2: The CCP1 pin is determined by the CCPMX bit in Configuration Wor d 1 register.
PIC16F87/88
DS30487D-page 4 2002-2013 Microchip Technology Inc.
Table of Contents
1.0 Device Overview .......................................................................................................................................................................... 5
2.0 Memory O rganization................................................................................................................................................................. 11
3.0 Data EEPROM and Flash Program Memory.............................................................................................................................. 27
4.0 Oscillator Configurations ........ .................................................................................................................................................... 35
5.0 I/O Ports ............... ........... .......... ........... .......... ........... ........................................ ......................................................................... 51
6.0 Timer0 Module ........................................................................................................................................................................... 67
7.0 Timer1 Module ........................................................................................................................................................................... 71
8.0 Timer2 Module ........................................................................................................................................................................... 79
9.0 Capture/Compare/PWM (CCP) Module ..................................................................................................................................... 81
10.0 Synchronous Serial Port (SSP) Module ..................................................................................................................................... 87
11.0 Addr essable Universal Synchronous Asynchr onous Receiv er Transmitter (AUS ART ) ............................................................. 97
12.0 Analog-t o-Digital Converter (A/D) Module................................................................................................................................ 113
13.0 Comparator Module.................................. .. .... .... ......... .. .... .... ......... .... .. .... .... ......... .... .. .... ......................................................... 121
14.0 Comparator Voltage Reference Module. .. .... .... .. ......... .... .. .... .. ......... .... .. .... ......... .. .... .... .. ......... .. ... ........................................... 127
15.0 Specia l Features of the CPU.................. .......... ........... .......... ........... .......... ..................... ......................................................... 129
16.0 Instruction Set Summary.......................................................................................................................................................... 149
17.0 Development Support............................................................................................................................................................... 157
18.0 Electrical Characteristics.......................................................................................................................................................... 161
19.0 DC and AC Characteristics Graphs and Tables....................................... .... ......... .... .... .... ........... .... ........................................ 191
20.0 Packagin g In fo rmation..... .......... ........... .......... ..................... ........... .......... ........... .......... ........................................................... 205
Appendix A: Revision History. ............................................................................................................................................................ 215
Appendix B: Device Differences......................................................................................................................................................... 215
INDEX................................................................................................................................................................................................ 217
The Micro chip Web Site...................... ........... .......... ........................................ .................................................................................. 225
Customer Change Notification Service ..................................................................................... ......................................................... 225
Customer Support............................................................................................................... ............................................................... 225
Reader Response.............................................................................................................................................................................. 226
PIC16F87/88 Product Identification System ...................................................................................................................................... 227
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2002-2013 Microchip Technology Inc. DS30487D-page 5
PIC16F87/88
1.0 DEVICE OVERVIEW
This document contains device specific information for
the operation of the PIC16F87/88 devices. Additional
information may be found in the “PIC® Mid-Range MCU
Family Reference Manual” (DS33023) which may be
downloaded from the Microchip web site. This
Reference Manual should be considered a comple-
mentary document to this data sheet and is highly
recommended reading for a better understanding of the
device architecture and operation of the peripheral
modules.
The PIC16F87/88 belongs to the Mid-Range family of
the PIC® devices. Block diagrams of the devices are
shown in Figure 1-1 and Figure 1-2. These devices
cont ain features that are new to the PIC16 produc t line:
Low-power modes: RC_RUN allows the core and
peripherals to be clocked from the INTRC, while
SEC_RUN allows the core and peripherals to be
clocked from the low-power Timer1. Refer to
Section 4.7 “Power-Managed Modes” for
further details.
Internal RC oscillator with eight selectable
frequencies, including 31.25 kHz, 125 kHz,
250 kHz, 500 kHz, 1 MHz, 2 MHz, 4 MHz and
8 MHz. The INTRC can be configured as a
primary or secondary clock source. Refer to
Section 4 .5 “Internal Oscillator Block” for
further details.
The Timer1 module current consumption has
been gre atly reduc ed from 20 A (previous PIC1 6
devi ces) to 1. 8 A typical (32 kHz at 2V), which is
ideal for real-time clock applications. Refer to
Section 7.0 “Timer1 Module” for further details.
Exten ded W atch dog T ime r (WDT) th at can h ave a
progra mmab le peri od from 1 ms to 268s. The
WDT has its own 16-bit prescaler. Refer to
Section 15.12 “Watchdog Timer (WDT)” for
further details.
Two-Speed Start-up: When the oscillator is
configured for LP, XT or HS Oscillator mode, this
featur e will cloc k t he devic e f rom the INTRC w hil e
the oscillator is warming up . This, in turn, will
enable almost immediate code execution. Refer
to Section 15.12.3 “Two-Speed Clock Start-up
Mode” for further details.
Fail-Safe Clock Monitor: This feature will allow the
device to continue operation if the primary or
secondary clock source fails by switching over to
the INTRC.
The A/D module has a new register for PIC16
devices named ANSEL. This register allows
easier configuration of analog or digital I/O pins.
TABLE 1-1: AVA ILABLE MEM O RY IN
PIC16F87/88 DEVICES
There are 16 I/O pins that are user configurable on a
pin-to-pin basis. Some pins are multiplexed with other
device functions. These functions include:
External Inte rrupt
Change on PORTB Interrupt
Timer0 Clock Input
Low-Power Timer1 Clock/Oscillator
Capture/Compare/PWM
10-bit, 7-channel A/D Converter (PIC16F88 on ly)
SPI/I2C™
Two Analog Comparators
AUSART
•MCLR
(RA5) can be configured as an input
Table 1-2 details the pinout of the devices with
descriptions and details for each pin.
Device Program
Flash Data
Memory Data
EEPROM
PIC16F87/88 4K x 14 368 x 8 256 x 8
PIC16F87/88
DS30487D-page 6 2002-2013 Microchip Technology Inc.
FIGURE 1-1: PIC16F87 DEVICE BLOCK DIAGRAM
Program
Memory
4K x 14
13 Data Bus 8
14
Program
Bus
Instruc ti on reg
Progr am Coun ter
8 Level Stack
(13-bit)
RAM
File
Registers
368 x 8
Direct Addr 7
RAM Addr(1) 9
Addr MUX
Indirect
Addr
FSR reg
STATUS reg
MUX
ALU
W reg
Power-up
Timer
Oscillator
Start-up Timer
Power-on
Reset
Watchdog
Timer
Instruction
Decode &
Control
Timing
Generation
OSC1/CLKI
OSC2/CLKO
RA5/MCLR VDD, VSS
8
8
Brown-out
Reset
Note 1: Higher order bits are from the STATUS register.
2: The CCP1 pin is determined by the CCPMX bit in Configuration Word 1 register.
8
3
Comparators
Timer0
Data EE
256 Bytes
Timer1
CCP1
Timer2
AUSART
PORTA
PORTB
RA4/T0CKI/C2OUT
RB0/INT/CCP1(2)
RA3/AN3/C1OUT
RA2/AN2/CVREF
RA1/AN1
RA0/AN0
RA5/MCLR/VPP
RA6/OSC2/CLKO
RB5/SS/TX/CK
RB4/SCK/SCL
RB3/PGM/CCP1(2)
RB2/SDO/RX/DT
RB1/SDI/SDA
RB6/PGC/T1OSO/T1CKI
RB7/PGD/T1OSI
RA7/OSC1/CLKI
SSP
Flash
2002-2013 Microchip Technology Inc. DS30487D-page 7
PIC16F87/88
FIGURE 1-2: PIC16F88 DEVICE BLOCK DIAGRAM
Flash
Program
Memory
4K x 14
13 Data Bus 8
14
Program
Bus
Instruction reg
Program Counter
8 Level Stack
(13-bit)
RAM
File
Registers
368 x 8
Direct Addr 7
RAM Addr(1) 9
Addr MUX
Indirect
Addr
FSR reg
STATUS reg
MUX
ALU
W reg
Power-up
Timer
Oscillator
Start-up Timer
Power-on
Reset
Watchdog
Timer
Instruction
Decode &
Control
Timing
Generation
OSC1/CLKI
OSC2/CLKO
RA5/MCLR VDD, VSS
8
8
Brown-out
Reset
Note 1: Higher order bits are from the STATUS register.
2: The CCP1 pin is determined by the CCPMX bit in Conf iguration Word 1 register.
8
3
Comparators
Timer0
Data EE
256 Bytes
Timer1
CCP1
Timer2
AUSART
PORTA
PORTB
RA4/AN4/T0CKI/C2OUT
RB0/INT/CCP1(2)
RA3/AN3/VREF+/C1OUT
RA2/AN2/CVREF/VREF-
RA1/AN1
RA0/AN0
RA5/MCLR/VPP
RA6/OSC2/CLKO
RB5/SS/TX/CK
RB4/SCK/SCL
RB3/PGM/CCP1(2)
RB2/SDO/RX/DT
RB1/SDI/SDA
RB6/AN5/PGC/T1OSO/T1CKI
RB7/AN6/PGD/T1OSI
RA7/OSC1/CLKI
10-bit A/D SSP
PIC16F87/88
DS30487D-page 8 2002-2013 Microchip Technology Inc.
TABLE 1-2: PIC16F87/88 PINOUT DESCRIPTION
Pin Na me PDIP/
SOIC
Pin#
SSOP
Pin# QFN
Pin# I/O/P
Type Buffer
Type Description
PORTA is a bidirectional I/O port.
RA0/AN0
RA0
AN0
17 19 23 I/O
ITTL
Analog Bidirectional I/O pin.
Analog input channel 0.
RA1/AN1
RA1
AN1
18 20 24 I/O
ITTL
Analog Bidirectional I/O pin.
Analog input channel 1.
RA2/AN2/CVREF/VREF-
RA2
AN2
CVREF
VREF-(4)
1126
I/O
I
O
I
TTL
Analog
Analog
Bidirectional I/O pin.
Analog input channel 2.
Comparator VREF output.
A/D reference voltage (Low) input.
RA3/AN3/VREF+/C1OUT
RA3
AN3
VREF+(4)
C1OUT
2227
I/O
I
I
O
TTL
Analog
Analog
Bidirectional I/O pin.
Analog input channel 3.
A/D reference voltage (High) input.
Comparator 1 output.
RA4/AN4/T0CKI/C2OUT
RA4
AN4(4)
T0CKI
C2OUT
3328
I/O
I
I
O
ST
Analog
ST
Bidirectional I/O pin.
Analog input channel 4.
Clock input to the TMR0 timer/counter.
Comparator 2 output.
RA5/MCLR/VPP
RA5
MCLR
VPP
441I
I
P
ST
ST
Input pin.
Master Clear (Reset). Input/programming voltage
input. This pin is an active-low Reset to the device.
Programming voltage input.
RA6/OSC2/CLKO
RA6
OSC2
CLKO
15 17 20 I/O
O
O
ST
Bidirectional I/O pin.
Oscillator crystal output. Connects to crystal or
resonator in Crystal Oscillator mode.
In RC mode, this pin outputs CLKO signal which has
1/4 the frequency of OSC1 and denotes the
instruction cycle rate.
RA7/OSC1/CLKI
RA7
OSC1
CLKI
16 18 21 I/O
I
I
ST
ST/CMOS(3)
Bidirectional I/O pin.
Oscillator crystal input.
External clock source input.
Legend: I = Input O = Output I/O = Input/Output P = Power
= N ot used TTL = TTL Input ST = Schmitt Trigger Input
Note 1: This buffer is a Schmitt Trigger input when configured as the external interrupt.
2: This buffer is a Schmitt Trigger input when used in Serial Programming mode.
3: This buffer is a Schmitt Trigger input when configured in RC Oscillator mode and a CMOS input otherwise.
4: PIC16F88 devices only.
5: The CCP1 pin is determined by the CCPMX bit in Configuration Word 1 register.
2002-2013 Microchip Technology Inc. DS30487D-page 9
PIC16F87/88
PORTB is a bidirectional I/O port. PORTB can be
software programmed for internal weak pull-up on all
inputs.
RB0/INT/CCP1(5)
RB0
INT
CCP1
677
I/O
I
I/O
TTL
ST(1)
ST
Bidirectional I/O pin.
External interrupt pin.
Capture input, Compare output, PWM output.
RB1/SDI/SDA
RB1
SDI
SDA
788
I/O
I
I/O
TTL
ST
ST
Bidirectional I/O pin.
SPI data in.
I2C™ data.
RB2/SDO/RX/DT
RB2
SDO
RX
DT
899
I/O
O
I
I/O
TTL
ST Bidirectional I/O pin.
SPI data out.
AUSART asynchronous receiv e.
AUSART synch ronous dete ct.
RB3/PGM/CCP1(5)
RB3
PGM
CCP1
91010
I/O
I/O
I
TTL
ST
ST
Bidirectional I/O pin.
Low-Voltage ICSP™ Programming enable pin.
Capture input, Compare output, PWM output.
RB4/SCK/SCL
RB4
SCK
SCL
10 11 12 I/O
I/O
I
TTL
ST
ST
Bidirectional I/O pin. Interrupt-on-change pin.
Synchronous serial clock input/output for SPI.
Synchronous serial clock Input for I2C.
RB5/SS/TX/CK
RB5
SS
TX
CK
11 12 13 I/O
I
O
I/O
TTL
TTL Bidirectional I/O pin. Interrupt-on-change pin.
Slave select for SPI in Slave mode.
AUSART asynchronous tr ansm it.
AUSART synch ronous clock .
RB6/AN5/PGC/T1OSO/
T1CKI
RB6
AN5(4)
PGC
T1OSO
T1CKI
12 13 15
I/O
I
I/O
O
I
TTL
ST(2)
ST
ST
Bidirectional I/O pin. Interrupt-on-change pin.
Analog input channel 5.
In-Circuit Debugger and programming clock pin.
Timer1 oscillator output.
Timer1 external clock input.
RB7/AN6/PGD/T1OSI
RB7
AN6(4)
PGD
T1OSI
13 14 16 I/O
I
I
I
TTL
ST(2)
ST
Bidirectional I/O pin. Interrupt-on-change pin.
Analog input channel 6.
In-Circuit Debugger and ICSP programming data pin.
Timer1 oscillator input.
VSS 5 5, 6 3, 5 P Ground reference for logic and I/O pins.
VDD 14 15, 16 17, 19 P Positive supply for logic and I/O pins.
TABLE 1-2: PIC16F87/88 PINOUT DESCRIPTION (CONTINUED)
Pin Na me PDIP/
SOIC
Pin#
SSOP
Pin# QFN
Pin# I/O/P
Type Buffer
Type Description
Legend: I = Input O = Output I/O = Input/Output P = Power
= N ot used TTL = TTL Input ST = Schmitt Trigger Input
Note 1: This buffer is a Schmitt Trigger input when configured as the external interrupt.
2: This buffer is a Schmitt Trigger input when used in Serial Programming mode.
3: This buffer is a Schmitt Trigger input when configured in RC Oscillator mode and a CMOS input otherwise.
4: PIC16F88 devices only.
5: The CCP1 pin is determined by the CCPMX bit in Configuration Word 1 register.
PIC16F87/88
DS30487D-page 10 2002-2013 Microchip Technology Inc.
NOTES:
2002-2013 Microchip Technology Inc. DS30487D-page 11
PIC16F87/88
2.0 MEMORY ORGANIZATION
There are two memory blocks in the PIC16F87/88
dev ices . Th ese a re th e pro gr am me mory and the d ata
memory. Each block has it s own bus, so access to each
block can occur during the same oscillator cycle.
The data memory can be further broken down into the
general purpose RAM and the Special Function
Registers (SFRs). The operation of the SFRs that
control the “core” are described here. The SFRs used
to control the peripheral modules are described in the
section discussing each individual peripheral module.
The data memory area also contains the data EEPROM
memory. This memory is not directly mapped into the
data memory but is indirectly mapped. That is, an indi-
rect address pointer specifies the address of the data
EEPROM memory to read/write. The PIC16F87/88
device’s 256 bytes of data EEPR OM memory have the
address range of 00h-FFh. More details on the
EEPROM memory can be found in Section 3.0 “Data
EEPROM and Flash Program Memory.
Addit ional informat ion on devi ce memory may be found
in th e “PIC® Mid-Range MCU Family Reference Man-
ual” (DS33023).
2.1 Program Memory Organization
The PIC1 6F87/88 devi ces have a 13- bit program cou n-
ter capable of address in g an 8K x 1 4 program memory
spac e. For the PIC16F87/88, the first 4K x 14 (0000h-
0FFFh) is physically implemented (see Figure 2-1).
Accessing a location above the physicall y implemented
address will cause a wraparound. For example, the
same instruction will be accessed at locations 020h,
420h, 820h, C20h, 1020h, 1420h, 1820h and 1C20h.
The Res et vector is at 000 0h and the interru pt vector is
at 0004h.
FIGURE 2-1: PROGRAM MEMORY MAP
AND ST ACK: PIC16F87/88
2.2 Data Memory Organization
The dat a memory is pa rtit ioned into m ultipl e ban ks th at
cont ain the G eneral Purpose Reg isters a nd the Specia l
Function Registers. Bits RP1 (STATUS<6>) and RP0
(STATUS<5>) are the bank select bits.
Each bank extends up to 7Fh (128 bytes). The lower
locations of each bank are reserved for the Special
Function Registers. Above the Special Function Regis-
ters are General Purpose Registers, implemented as
static RAM. All implemented banks contain SFRs.
Some “high use” SFRs from one bank may be mirrored
in another bank for code reduction and quicker access
(e.g., the STATUS register is in Banks 0-3).
RP1:RP0 Bank
00 0
01 1
10 2
11 3
Note: EEPROM dat a memory description can be
found in Section 3.0 “Dat a EEPROM and
Flash Program Memory” of this data
sheet.
PC<12:0>
13
0000h
0004h
0005h
Stack Level 1
Stack Lev el 8
Reset Vector
Interr upt Vector
On-Chip
CALL, RETURN
RETFIE, RETLW
1FFFh
Stack Lev el 2
Program
Memory
Page 0 07FFh
Wraps t o
0000h-03FFh
Page 1 0FFFh
1000h
0800h
PIC16F87/88
DS30487D-page 12 2002-2013 Microchip Technology Inc.
2.2.1 GENERAL PURPOSE REGISTER FILE
The register file can be accessed either directly, or
indirectly, through the File Select Register (FSR).
FIGURE 2-2: PIC16F87 REGISTER FILE MAP
Indirect add r.(*)
TMR0
PCL
STATUS
FSR
PORTA
PORTB
PCLATH
INTCON
PIR1
OPTION_REG
PCL
STATUS
FSR
TRISA
TRISB
PCLATH
INTCON
PIE1
PCON
00h
01h
02h
03h
04h
05h
06h
07h
08h
09h
0Ah
0Bh
0Ch
0Dh
0Eh
0Fh
10h
11h
12h
13h
14h
15h
16h
17h
18h
19h
1Ah
1Bh
1Ch
1Dh
1Eh
1Fh
80h
81h
82h
83h
84h
85h
86h
87h
88h
89h
8Ah
8Bh
8Ch
8Dh
8Eh
8Fh
90h
91h
92h
93h
94h
95h
96h
97h
98h
99h
9Ah
9Bh
9Ch
9Dh
9Eh
9Fh
20h A0h
7Fh FFh
Bank 0 Bank 1
Unimplemented data memory locations, read as ‘0’.
* Not a physical register.
Note 1: This register is reserved, maintain this register clear.
File
Address
Indirect addr.(*) Indirect addr.(*)
PCL
STATUS
FSR
PCLATH
INTCON
PCL
STATUS
FSR
PCLATH
INTCON
100h
101h
102h
103h
104h
105h
106h
107h
108h
109h
10Ah
10Bh
180h
181h
182h
183h
184h
185h
186h
187h
188h
189h
18Ah
18Bh
Indirect add r.(*)
CVRCON
TMR0 OPTION_REG
PIR2 PIE2
General
Purpose
Register
accesses
70h-7Fh
TRISB
PORTB
96 Bytes EFh
F0h
10Ch
10Dh
10Eh
10Fh
110h
18Ch
18Dh
18Eh
18Fh
190h
EEDATA
EEADR EECON1
EECON2
EEDATH
EEADRH
Reserved(1)
Reserved(1)
17Fh 1FFh
Bank 2 Bank 3
19Fh
1A0h
accesses
70h-7Fh
11Fh
120h
accesses
70h-7Fh
CMCON
OSCCON
General
Purpose
Register
80 Bytes
TMR1L
TMR1H
T1CON
TMR2
T2CON
CCPR1L
CCPR1H
CCP1CON
RCSTA
TXREG
RCREG
PR2
TXSTA
SPBRG
OSCTUNE
WDTCON
16Fh
170h
General
Purpose
Register
80 Bytes 1EFh
1F0h
General
Purpose
Register
80 Bytes
General
Purpose
Register
16 Bytes
General
Purpose
Register
16 Bytes
SSPBUF
SSPCON SSPADD
SSPSTAT
File
Address
File
Address
File
Address
STATUS
2002-2013 Microchip Technology Inc. DS30487D-page 13
PIC16F87/88
FIGURE 2-3: PIC16F88 REGISTER FILE MAP
Indirect addr.(*)
TMR0
PCL
STATUS
FSR
PORTA
PORTB
PCLATH
INTCON
PIR1
OPTION_REG
PCL
STATUS
FSR
TRISA
TRISB
PCLATH
INTCON
PIE1
PCON
00h
01h
02h
03h
04h
05h
06h
07h
08h
09h
0Ah
0Bh
0Ch
0Dh
0Eh
0Fh
10h
11h
12h
13h
14h
15h
16h
17h
18h
19h
1Ah
1Bh
1Ch
1Dh
1Eh
1Fh
80h
81h
82h
83h
84h
85h
86h
87h
88h
89h
8Ah
8Bh
8Ch
8Dh
8Eh
8Fh
90h
91h
92h
93h
94h
95h
96h
97h
98h
99h
9Ah
9Bh
9Ch
9Dh
9Eh
9Fh
20h A0h
7Fh FFh
Bank 0 Bank 1
File
Address
Indirect addr.(*) Indirect addr.(*)
PCL
STATUS
FSR
PCLATH
INTCON
PCL
STATUS
FSR
PCLATH
INTCON
100h
101h
102h
103h
104h
105h
106h
107h
108h
109h
10Ah
10Bh
180h
181h
182h
183h
184h
185h
186h
187h
188h
189h
18Ah
18Bh
Indirect addr.(*)
TMR0 OPTION_REG
PIR2 PIE2
ADRESH
ADCON0 ADCON1
General
Purpose
Register
accesses
70h-7Fh
TRISB
PORTB
96 Bytes
10Ch
10Dh
10Eh
10Fh
110h
18Ch
18Dh
18Eh
18Fh
190h
EEDATA
EEADR EECON1
EECON2
EEDATH
EEADRH
Reserved(1)
Reserved(1)
17Fh 1FFh
Bank 2 Bank 3
19Fh
1A0h
11Fh
120h
CVRCON
OSCCON
CMCON
ADRESL
TMR1L
TMR1H
T1CON
TMR2
CCPR1L
CCPR1H
CCP1CON
RCSTA
TXREG
RCREG
PR2
TXSTA
SPBRG
T2CON
OSCTUNE
WDTCON
EFh
F0h
General
Purpose
Register
80 Bytes 16Fh
170h
General
Purpose
Register
80 Bytes 1EFh
1F0h
General
Purpose
Register
80 Bytes
General
Purpose
Register
16 Bytes
General
Purpose
Register
16 Bytes
accesses
70h-7Fh
accesses
70h-7Fh
SSPBUF
SSPCON SSPADD
SSPSTAT
ANSEL
File
Address
File
Address
File
Address
Unimplemented data memory locations, read as ‘0’.
* Not a physical register.
Note 1: This register is reserved, maintain this register clear.
PIC16F87/88
DS30487D-page 14 2002-2013 Microchip Technology Inc.
2.2.2 SPECIAL FUNCTION REGISTERS
The Special Function Registers are registers used by
the CPU and peripheral modules for controlling the
desired operation of the device. These registers are
implemented as static RAM. A list of thes e registers is
given in Table 2-1.
The Special Function Registers can be classified into
two sets: core (CPU) and peripheral. Those registers
associated with the core functions are described in
detail in this section. Those related to the operation of
the peripheral features are described in detail in the
peripheral feature section.
TABLE 2-1: SPECIAL FUNCTION REGISTER SUMMARY
Ad d re s s Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on:
POR, BOR
Details
on
page
Bank 0
00h
(2)
INDF Addressing this location uses contents of FSR to address data memory (not a physical register) 0000 0000 26, 1 35
01h
TMR0 Timer0 Module Register xxxx xxxx 69
02h
(2)
PCL Program Counter (PC) Least Significant Byte 0000 0000
03h
(2)
STATUS IRP RP1 RP0 TO PD ZDCC0001 1xxx 17
04h
(2)
FSR Indirect Data Memory Addre ss Poi nter xxxx xxxx 135
05h
PORTA PORTA Data Latch when written; PORTA pins when read (PIC16F87)
PORTA Data Latch when written; PORTA pins when read (PIC16F88) xxxx 0000
xxx0 0000 52
06h
PORTB PORTB Data Latch when written; PORTB pins when read (PIC16F87)
PORTB Data Latch when writ ten; PORTB pins when read (PIC16F88) xxxx xxxx
00xx xxxx 58
07h
Unimplemented
08h
Unimplemented
09h
Unimplemented
0Ah
(1,2)
PCLATH Write Buffer for the Upper 5 bits of the Program Counter ---0 0000 135
0Bh
(2)
INTCON GIE PEIE TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 0000 000x 19, 69 ,
77
0Ch
PIR1 —ADIF
(4) RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF -000 0000 21, 77
0Dh
PIR2 OSFIF CMIF EEIF 00-0 ---- 23, 34
0Eh
TMR1L Holding Register for the Least Significant Byte of the 16-bit TMR1 Register xxxx xxxx 77, 83
0Fh
TMR1H Holding Register for the Most Significant Byte of the 16-bit TMR1 Register xxxx xxxx 77, 83
10h
T1CON T1RUN T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON -000 0000 72, 83
11h
TMR2 Timer2 Module Register 0000 0000 80, 85
12h
T2CON TOUTPS3 TOUTPS2 TOUTPS1 TOUTPS0 TMR2ON T2CKPS1 T2CKPS0 -000 0000 80, 85
13h
SSPBUF Synchronous Serial Port Receive Buffer/Tr ansmit Register xxxx xxxx 90, 95
14h
SSPCON WCOL SSPOV SSPEN CKP SSPM3 SSPM2 SSPM1 SSPM0 0000 0000 89, 95
15h
CCPR1L Capture/Compare/PWM Register 1 (LSB) xxxx xxxx 83, 85
16h
CCPR1H Capture/Compare/PWM Register 1 (MSB) xxxx xxxx 83, 85
17h
CCP1CON CCP1X CCP1Y CCP1M3 CCP1M2 CCP1M1 CCP1M0 --00 0000 81, 83
18h
RCSTA SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 0000 000x 98, 99
19h
TXREG AUSART Transmit Data Register 0000 0000 103
1Ah
RCREG AUSART Receive Data Register 0000 0000 105
1Bh
Unimplemented
1Ch
Unimplemented
1Dh
Unimplemented
1Eh
ADRESH(4) A/D Result Register High Byte xxxx xxxx 120
1Fh
ADCON0(4) ADCS1 ADCS0 CHS2 CHS1 CHS0 GO/DONE —ADON0000 00-0 114, 120
Legend: x = unk nown, u = unchanged, q = value depends on condition, - = unimplemented, read as ‘0’, r = reserved.
Shaded locations are unimplemented, read as0’.
Note 1: The upper byte of the program counter is not directly accessible. PCLATH is a holding register for PC<12:8>, whose
contents are transferred to the upper byte of the program counter.
2: These registers can be addressed from any bank.
3: RA5 is an input only; the state of the TRISA5 bit has no effect and will always read 1’.
4: PIC16F88 device only.
2002-2013 Microchip Technology Inc. DS30487D-page 15
PIC16F87/88
Bank 1
80h
(2)
INDF Addressing this location uses contents of FSR to address data memory (not a physical register) 0000 0000 26, 13 5
81h
OPTION_REG RBPU INTEDG T0CS T0SE PSA PS2 PS1 PS0 1111 1111 18, 69
82h
(2)
PCL Program Counter (PC) Least Significant Byte 0000 0000 135
83h
(2)
STATUS IRP RP1 RP0 TO PD ZDCC0001 1xxx 17
84h
(2)
FSR Indirect Data Memory Addre ss Poi nter xxxx xxxx 135
85h
TRISA TRISA7 TRISA6 TRISA5(3) PORTA Data Direction Register (TRISA<4:0>) 1111 1111 52, 12 6
86h
TRISB PORTB Data Direction Register 1111 1111 58, 85
87h
Unimplemented
88h
Unimplemented
89h
Unimplemented
8Ah
(1,2)
PCLATH Write Buffer for the Upper 5 bits of the Program Counter ---0 0000 135
8Bh
(2)
INTCON GIE PEIE TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 0000 000x 19, 69,
77
8Ch
PIE1 ADIE(4) RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE -000 0000 20, 80
8Dh
PIE2 OSFIE CMIE —EEIE 00-0 ---- 22, 34
8Eh
PCON —PORBOR ---- --0q 24
8Fh
OSCCON IRCF2 IRCF1 IRCF0 OSTS IOFS SCS1 SCS0 -000 0000 40
90h
OSCTUNE TUN5 TUN4 TUN3 TUN2 TUN1 TUN0 --00 0000 38
91h
Unimplemented
92h
PR2 T imer2 Period Register 1111 1111 80, 85
93h
SSPADD Synchronous Seria l Port (I2C™ mode) Address Register 0000 0000 95
94h
SSPSTAT SMP CKE D/A PSR/WUA BF 0000 0000 88, 95
95h
Unimplemented
96h
Unimplemented
97h
Unimplemented
98h
TXSTA CSRC TX9 TXEN SYNC BRGH TRMT TX9D 0000 -010 97, 99
99h
SPBRG Baud Rate Generator Register 0000 0000 99, 10 3
9Ah
Unimplemented
9Bh
ANSEL(4) ANS6 ANS5 ANS4 ANS3 ANS2 ANS1 ANS0 -111 1111 120
9Ch
CMCON C2OUT C1OUT C2INV C1INV CIS CM2 CM1 CM0 0000 0111 121,
126, 128
9Dh
CVRCON CVREN CVROE CVRR CVR3 CVR2 CVR1 CVR0 000- 0000 126, 128
9Eh
ADRESL(4) A/D Result Regist er Low By te xxxx xxxx 120
9Fh
ADCON1(4) ADFM ADCS2 VCFG1 VCFG0 0000 ---- 52, 1 15,
120
TABLE 2-1: SPECIAL FUNCTION REGISTER SUMMARY (CONTINUED)
Ad d re s s Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on:
POR, BOR
Details
on
page
Legend: x = unk nown, u = unchanged, q = value depends on condition, - = unimplemented, read as ‘0’, r = reserved.
Shaded locations are unimplemented, read as0’.
Note 1: The upper byte of the program counter is not directly accessible. PCLATH is a holding register for PC<12:8>, whose
contents are transferred to the upper byte of the program counter.
2: These registers can be addressed from any bank.
3: RA5 is an input only; the state of the TRISA5 bit has no effect and will always read 1’.
4: PIC16F88 device only.
PIC16F87/88
DS30487D-page 16 2002-2013 Microchip Technology Inc.
Bank 2
100h
(2)
INDF Addressing this location uses contents of FSR to address data memory (not a physical register) 0000 0000 26, 1 35
101h
TMR0 Timer0 Module Register xxxx xxxx 69
102h
(2)
PCL Program Counter’s (PC) Least Significant Byte 0000 0000 135
103h
(2)
STATUS IRP RP1 RP0 TO PD ZDCC0001 1xxx 17
104h
(2)
FSR Indirect Data Memory Addre ss Poi nter xxxx xxxx 135
105h
WDTCON WDTPS3 WDTPS2 WDTPS1 WDTPS0 SWDTEN ---0 1000 142
106h
PORTB PORTB Data Latch when written; PORTB pins when read (PIC16F87)
PORTB Data Latch when writ ten; PORTB pins when read (PIC16F88) xxxx xxxx
00xx xxxx 58
107h
Unimplemented
108h
Unimplemented
109h
Unimplemented
10Ah
(1,2)
PCLATH Write Buffer for the Upper 5 bits of the Program Counter ---0 0000 135
10Bh
(2)
INTCON GIE PEIE TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 0000 000x 19, 69,
77
10Ch
EEDATA EEPROM/Flash Data Register Low Byte xxxx xxxx 34
10Dh
EEADR EEPROM/Flash Address Register Low Byte xxxx xxxx 34
10Eh
EEDATH EEPROM/Flash Data Register High Byte --xx xxxx 34
10Fh
EEADRH EEPR OM /F lash Address Regi st er High Byt e ---- xxxx 34
Bank 3
180h
(2)
INDF Addressing this location uses contents of FSR to address data memory (not a physical register) 0000 0000 135
181h
OPTION_REG RBPU INTEDG T0CS T0SE PSA PS2 PS1 PS0 1111 1111 18, 69
182h
(2)
PCL Program Counter (PC) Least Significant Byte 0000 0000 135
183h
(2)
STATUS IRP RP1 RP0 TO PD ZDCC0001 1xxx 17
184h
(2)
FSR Indirect Data Memory Addre ss Poi nter xxxx xxxx 135
185h
Unimplemented
186h
TRISB PORTB Data Direction Register 1111 1111 58, 83
187h
Unimplemented
188h
Unimplemented
189h
Unimplemented
18Ah
(1,2)
PCLATH Write Buffer for the Upper 5 bits of the Program Counter ---0 0000 135
18Bh
(2)
INTCON GIE PEIE TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 0000 000x 19, 69,
77
18Ch
EECON1 EEPGD FREE WRERR WREN WR RD x--x x000 28, 34
18Dh
EECON2 EEPROM Control Register 2 (not a p hysical register) ---- ---- 34
18Eh Reserved, maintain clear
0000 0000
18Fh Reserved, maintain clear
0000 0000
TABLE 2-1: SPECIAL FUNCTION REGISTER SUMMARY (CONTINUED)
Ad d re s s Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on:
POR, BOR
Details
on
page
Legend: x = unk nown, u = unchanged, q = value depends on condition, - = unimplemented, read as ‘0’, r = reserved.
Shaded locations are unimplemented, read as0’.
Note 1: The upper byte of the program counter is not directly accessible. PCLATH is a holding register for PC<12:8>, whose
contents are transferred to the upper byte of the program counter.
2: These registers can be addressed from any bank.
3: RA5 is an input only; the state of the TRISA5 bit has no effect and will always read 1’.
4: PIC16F88 device only.
2002-2013 Microchip Technology Inc. DS30487D-page 17
PIC16F87/88
2.2.2.1 STATUS Register
The STATUS register, shown in Register 2-1, contains
the arithmetic status of the ALU , the R eset status and
the bank select bits for data memory.
The STATUS register can be the destination for any
instruction, as with any other register. If the STATUS
register is the destination for an instruction that affects
the Z, DC or C bits, then the write to these three bits is
disabl ed. These bit s are set or clea red according to the
device logic. Furthermore, the TO and PD bits are not
writable. Therefore, the result of an instruction with the
STATUS register as destination may be different than
intended.
For exam pl e, CLRF STATUS wil l clear the upper thre e
bits and set t he Z bit. T his leav es the STA T US regist er
as ‘000u u1uu’ (where u = unchanged).
It is recommended, therefore, that only BCF, BSF, SWAPF
and MOVWF instructions are used to alter the STATUS
register because these instructions do not affect the Z, C
or DC bits from the STATUS register. For other
instructions not affecting any Status bits, see
Section 16.0 “Instructio n Se t Su mm ary.
REGISTER 2-1: ST A TUS: ARITHMETIC STATUS REGISTER (ADDRESS 03h, 83h, 103h, 183h)
Note: The C and DC bits operate as a borrow
and digit borrow bit, respectively, in
subtraction. See the SUBLW and SUBWF
instructions for examples.
R/W-0 R/W-0 R/W-0 R-1 R-1 R/W-x R/W-x R/W-x
IRP RP1 RP0 TO PD ZDCC
bit 7 bit 0
bit 7 IRP: Register Bank Sele ct bit (us ed for indi rec t addre ssing )
1 = Bank 2, 3 (100h-1FFh )
0 = Bank 0, 1 (00h-FFh)
bit 6-5 RP<1:0>: Register Bank Select bits (used for direct addressing)
11 = Bank 3 (180h-1FFh)
10 = Bank 2 (100h-17Fh)
01 = Bank 1 (80h-FFh)
00 = Bank 0 (00h-7Fh)
Each bank is 128 bytes.
bit 4 TO: Time-out bit
1 = After power-u p, CLRWDT instruction or SLEEP instruction
0 = A WDT time-out occu rred
bit 3 PD: Power-Down bit
1 = After power-up or by the CLRWDT instru cti on
0 = By execution of the SLEEP instruction
bit 2 Z: Zero bit
1 = The result of an arithmetic or logic operation is zero
0 = The result of an arithmetic or logic operation is not zero
bit 1 DC: Digit carry/borrow bit (ADDWF, ADDLW, SUBLW and SUBWF instructions)(1)
1 = A carry- out from the 4t h low-ord er bit of the result o c curred
0 = No carry-out from the 4th low-order bit of the result
bit 0 C: Carry/borrow bit (ADDWF, ADDLW, SUBLW and SUBWF instructions)(1,2)
1 = A carry-out from the Most Significant bit of the result occurred
0 = No carry-out from the Most Significant bit of the result occurred
Note 1: For borrow, the polarity is reversed. A subtraction is executed by adding the two’s
complement of the second operand.
2: For rot ate (RRF, RLF) instructi ons, thi s bit is lo aded with either the high or low-or der
bit of the source register.
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
PIC16F87/88
DS30487D-page 18 2002-2013 Microchip Technology Inc.
2.2.2.2 OPTION_REG Register
The OPTION_REG register is a readable and writable
register that contains various control bits to configure
the TMR0 prescaler/WDT postscaler (single assign-
able register known also as the prescaler), the external
INT inte rrupt, TMR0 and the weak pull-u ps o n POR TB.
REGISTER 2-2: OPTION_REG: OPTION CONTROL REGISTER (ADDRESS 81h, 181h)
Note: To achieve a 1:1 prescaler assignment for
the TMR 0 re gis ter, assign the pres ca ler to
the Watchdog Timer. Although the pres-
caler can be assigned to either the WDT or
T i mer0, bu t not both, a new div ide co unter
is implemented in the WDT circuit to give
multiple WDT time-out selections. This
allows TMR0 and WDT to each have their
own scaler. Refer to Section 15.12
“Watchdog Timer (WDT)” for further
details.
R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1
RBPU INTEDG T0CS T0SE PSA PS2 PS1 PS0
bit 7 bit 0
bit 7 RBPU: PORTB Pull-up Enable bit
1 = PORTB pull-ups are disabled
0 = PORTB pull-ups are enabled by individual port latch values
bit 6 INTEDG: Interrupt Edge Select bit
1 = Interrupt on rising edge of RB0/INT pin
0 = Interrupt on fall ing edge of RB0/INT pin
bit 5 T0CS: TMR0 Clock Source Select bit
1 = Transition o n RA4/T0CKI/C2OUT pin
0 = Internal instruction cycle clock (CLKO)
bit 4 T0SE: TMR0 Source Edge Select bit
1 = Increment on high-to-low transition on RA4/T0CKI/C2OUT pin
0 = Increment on low-to-high transition on RA4/T0CKI/C2OUT pin
bit 3 PSA: Prescaler Assignment bit
1 = Prescaler is assigned to the WDT
0 = Prescaler is assigned to the Timer0 module
bit 2-0 PS<2:0>: Prescaler Rate Select bits
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
Bit Value TMR0 Rate WDT Rate
000 1 : 2 1 : 1
001 1 : 4 1 : 2
010 1 : 8 1 : 4
011 1 : 16 1 : 8
100 1 : 32 1 : 16
101 1 : 64 1 : 32
110 1 : 128 1 : 64
111 1 : 256 1 : 128
2002-2013 Microchip Technology Inc. DS30487D-page 19
PIC16F87/88
2.2.2.3 INTCON Register
The INTCON register is a readable and writable regis-
ter that contains various enable and flag bits for the
TMR0 register overflow, RB Port change and External
RB0/INT pin interrupts.
REGISTER 2-3: INTCON: INTERRUPT CONTROL REGISTER (ADDRESS 0Bh, 8Bh, 10Bh, 18Bh)
Note: Interru pt flag bit s get set when an interru pt
conditi on occ urs, regar dless o f the s tate of
its corresponding enable bit or the global
enable bit, GIE (INTCON<7>). User
software should ensure the appropriate
interrupt flag bits are clear prior to
enabling an interrupt.
R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-x
GIE PEIE TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF
bit 7 bit 0
bit 7 GIE: Global Interrupt Enable bit
1 = Enables all unmasked interrupts
0 = Disables all interrupts
bit 6 PEIE: Peripheral Interrupt Enable bit
1 = Enables all unmasked peripheral interrupts
0 = Disables all peripheral interrupts
bit 5 TMR0IE: TMR0 Overflow Interrupt Enable bit
1 = Enables the TMR0 interrupt
0 = Disables the TMR0 interrupt
bit 4 INT0IE: RB0/INT External Interrupt Enable bit
1 = Enables the RB0/INT external interrupt
0 = Disables the RB0/INT external interrupt
bit 3 RBIE: RB Port Change Interrupt Enable bit
1 = Enables the RB port change interrupt
0 = Disables the RB port change interrupt
bit 2 TMR0IF: TMR0 Overflow Interrupt Flag bit
1 = TMR0 register has overflowed (must be cleared in software)
0 = TMR0 register did not overflow
bit 1 INT0IF: RB0/INT External Interrupt Flag bit
1 = The RB0/INT external interrupt occurred (must be cleared in software)
0 = The RB0/INT external interrupt did not occur
bit 0 RBIF: RB Port Change Interrupt Flag bit
A misma tch cond ition will continu e to set flag bit RBIF. Read ing POR TB will end the mismatch
condition and allow flag bit RBIF to be cleared.
1 = At least one of the RB7:RB4 pins changed state (must be cleared in software)
0 = None of the RB7:RB4 pins have changed state
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
PIC16F87/88
DS30487D-page 20 2002-2013 Microchip Technology Inc.
2.2.2.4 PIE1 Regist er
This register contains the individual enable bits for the
peripheral interrupts.
REGISTER 2-4: PIE1: PERIPHERAL INTERRUPT ENABLE REGISTER 1 (ADDRESS 8Ch)
Note: Bit PEIE (INTCON<6>) must be set to
enable any peripheral interrupt.
U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0
—ADIE
(1) RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE
bit 7 bit 0
bit 7 Unimplemented: Read as ‘0
bit 6 ADIE: A/D Converter Interrupt Enable bit(1)
1 = Enabled
0 = Disabled
Note 1: This bit is only im plemented on the PIC16F 88. The bit will rea d ‘0’ on the PIC16F87.
bit 5 RCIE: AUSART Receive Interrupt Enable bit
1 = Enabled
0 = Disabled
bit 4 TXIE: AUSART Transmit Interrupt Enable bit
1 = Enabled
0 = Disabled
bit 3 SSPIE: Synchronous Serial Port (SSP) Interrupt Enable bit
1 = Enabled
0 = Disabled
bit 2 CCP1IE: CCP1 Interrupt Enable bit
1 = Enabled
0 = Disabled
bit 1 TMR2IE: TMR2 to PR2 Match Interrupt Enable bit
1 = Enabled
0 = Disabled
bit 0 TMR1IE: TMR1 Overflow Interrupt Enable bit
1 = Enabled
0 = Disabled
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
2002-2013 Microchip Technology Inc. DS30487D-page 21
PIC16F87/88
2.2.2.5 PIR1 Register
This register contains the individual flag bits for the
peripheral interrupts.
REGISTER 2-5: PIR1: PERIPHERAL INTERRUPT REQUEST (FLAG) REGISTER 1 (ADDRESS 0Ch)
Note: Interru pt flag bi ts are set when an interrupt
conditi on occ urs, regardle ss of the st ate of
its corresponding enable bit, or the global
enable bit, GIE (INTCON<7>). User
software should ensure the appropriate
interrupt flag bits are clear prior to
enabling an interrupt.
U-0 R/W-0 R-0 R-0 R-0 R/W-0 R/W-0 R/W-0
—ADIF
(1) RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF
bit 7 bit 0
bit 7 Unimplemented: Read as ‘0
bit 6 ADIF: A/D Converter Interrupt Flag bit (1)
1 = The A/D conversion completed (must be cleared in software)
0 = The A/D conversion is not complete
Note 1: This bit is only implement ed on the PIC16F8 8. The bit will read 0’ on the PIC16F87.
bit 5 RCIF: AUSART Receive Inte rrupt Flag bit
1 = The AUSART receive buffer is full (cleared by reading RCREG)
0 = The AUSART receive buffer is not full
bit 4 TXIF: AUSART Transmit Interrupt Flag bit
1 = The AUSART transmit buffer is empty (cleared by writing to TXR EG)
0 = The AUSART transmit buffer is full
bit 3 SSPIF: Synchronous Serial Port (SSP) Interrupt Flag bit
1 = The transmission/reception is complete (must be cleared in software)
0 = Waiting to transmit/rec eive
bit 2 CCP1IF: CCP1 Interrupt Flag bit
Capture mode:
1 = A TMR1 register capture occurred (must be cleared in software)
0 = No TMR1 register capture occurred
Compare mode:
1 = A TMR1 register compare match occurred (must be cleared in software)
0 = No TMR1 register compare match occurred
PWM mode:
Unused in this mode.
bit 1 TMR2IF: TMR2 to PR2 Interrupt Fl ag bit
1 = A TMR2 to PR2 match occurred (must be cleared in software)
0 = No TMR2 to PR2 match occurred
bit 0 TMR1IF: TMR1 Overflow Interrupt Flag bit
1 = The TMR1 regi ster overf lowe d (must be clear ed in software)
0 = The TMR1 register did not overflow
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
PIC16F87/88
DS30487D-page 22 2002-2013 Microchip Technology Inc.
2.2.2.6 PIE2 Regist er
The PIE2 register contains the individual enable bit for
the EEPROM write operation interrupt.
REGISTER 2-6: PIE2: PERIPHERAL INTERRUPT ENABLE REGISTER 2 (ADDRESS 8Dh)
R/W-0 R/W-0 U-0 R/W-0 U-0 U-0 U-0 U-0
OSFIE CMIE EEIE
bit 7 bit 0
bit 7 OSFIE: Oscillator Fail Interrupt Enable bit
1 = Enabled
0 = Disabled
bit 6 CMIE: Comparator Interrupt Enable bit
1 = Enabled
0 = Disabled
bit 5 Unimplemented: Read as ‘0
bit 4 EEIE: EEPROM Write Operation Interrupt Enable bit
1 = Enabled
0 = Disabled
bit 3-0 Unimplemented: Read as ‘0
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set 0’ = Bit is cleared x = Bit is unknown
2002-2013 Microchip Technology Inc. DS30487D-page 23
PIC16F87/88
2.2.2.7 PIR2 Register
The PIR2 regis ter contains the flag bit for the EEPROM
write operation interrupt.
.
REGISTER 2-7: PIR2: PERIPHERAL INTERRUPT REQUEST (FLAG) REGISTER 2 (ADDRESS 0Dh)
Note: Interru pt flag bi ts are set when an interrupt
conditi on occ urs, regardle ss of the st ate of
its corresponding enable bit, or the global
enable bit, GIE (INTCON<7>). User
software should ensure the appropriate
interrupt flag bits are clear prior to
enabling an interrupt.
R/W-0 R/W-0 U-0 R/W-0 U-0 U-0 U-0 U-0
OSFIF CMIF EEIF
bit 7 bit 0
bit 7 OSFIF: Oscillator Fail Interrupt Flag bit
1 = System oscillator failed, clock input has changed to INTRC (must be cleared in software)
0 = System clock operating
bit 6 CMIF: Comparator Interrupt Flag bit
1 = Comparator input has changed (must be cleared in software)
0 = Comparator input has not changed
bit 5 Unimplemented: Read as ‘0
bit 4 EEIF: EEPROM Write O peration Interrupt Flag bit
1 = The write operation completed (must be cleared in software)
0 = The write operation is not complete or has not been started
bit 3-0 Unimplemented: Re ad as ‘0
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR 1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
PIC16F87/88
DS30487D-page 24 2002-2013 Microchip Technology Inc.
2.2.2.8 PCON Register
The Power Control (PCON) register contains a flag bit
to allow differentiation between a Power-on Reset
(POR), a Brown-out Reset, an external MCLR Reset
and WDT Reset.
REGISTER 2-8: PCON: POWER CONTROL REGISTER (ADDRESS 8Eh)
Note: Interru pt flag bit s get set when an interru pt
conditi on occ urs, regardle ss of the st ate of
its corresponding enable bit, or the global
enable bit, GIE (INTCON<7>). User
software should ensure the appropriate
interrupt flag bits are clear prior to
enabling an interrupt.
Note: BOR is unknown on Power-on Reset. It
must the n be set b y th e us er an d c hec ke d
on subsequent Resets to see if BOR is
clear , indicating a brown-out has occurred.
The BOR status bit is a ‘don’t care’ and is
not necessarily predictable if the brown-
out circuit is disabled (by clearing the
BOREN bit in the Configuration Word
register).
U-0 U-0 U-0 U-0 U-0 U-0 R/W-0 R/W-x
—PORBOR
bit 7 bit 0
bit 7-2 Unimplemented: Read as ‘0
bit 1 POR: Power-o n Reset Status bit
1 = No Power-on Reset occurred
0 = A Power-on Reset occurred (must be set in software after a Power-on Reset occurs)
bit 0 BOR: Brown-out Reset Status bit
1 = No Brown-out Reset occurred
0 = A Brown-out Reset occurred (must be set in software after a Brown-out Reset occurs)
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR 1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
2002-2013 Microchip Technology Inc. DS30487D-page 25
PIC16F87/88
2.3 PCL and PCLATH
The Program Counter (PC) is 13 bits wide. The low
byte comes from the PCL register which is a readable
and writable register. The upper bits (PC<12:8>) are
not readable but are indirectly writable through the
PCLATH register. On any Reset, the upper bits of the
PC will b e clea red. Fig ure 2-4 sho ws th e two sit uat ions
for the loading of the PC. The upper example in the
figure shows how the PC is loaded on a write to PCL
(PCLATH<4:0> PCH). The lower example in the
figure shows how the PC is loaded during a CALL or
GOTO instructi on (PCLATH<4:3> PC H).
FIGU RE 2-4 : LOADING OF P C IN
DIFF ERENT SITUA TIO NS
2.3.1 COMPUT ED GO TO
A comput ed GOTO is a ccom pli shed by adding an offset
to the program counter (ADDWF PCL). When doing a
table read using a computed GOTO method, care
should be ex ercise d if th e t able loca tion c rosse s a PCL
memory boundary (each 256-byte block). Refer to the
applic ation note, AN55 6, “Implementing a Table Read”.
2.3.2 STACK
The PIC16F87/88 family has an 8-level deep x 13-bit
wide hardware stack. The stack space is not part of
either program or data space and the S tack Pointer is not
readable or writable. The PC is PUSHed onto the stack
when a CALL instruction is executed or an interrupt
causes a branch. The stack is POPed in the event of a
RETURN, RETLW or a RETFIE instruction execution.
PCLATH is not affected by a PUSH or POP operation.
The st ack operates as a circular buf fer . This means that
after the st ack h as be en PU SHed ei ght ti mes, th e nin th
push ov erwrit es the v alue tha t was stor ed fro m the first
push. The tenth push overw ri tes the second push (an d
so on).
2.4 Program Memory Paging
All PIC16F87/88 devices are capable of addressing a
continuous 8K word block of program memory. The
CALL and GOTO instructions provide only 11 bits of
address to allow branching within any 2K program
memory page. When doing a CALL or GOTO instruction,
the upper 2 bits of the address are provided by
PCLATH<4:3>. When doing a CALL or GOTO instruc-
tion, the us er must ensure that the p a ge s ele ct bi ts are
programmed so that the desired program memory
page is addressed. If a return from a CALL in struction
(or interrup t) is executed, the e ntire 13-bit PC is popped
off the stack. Therefore, manipulation of the
PCLATH<4:3> bits is not required for the RETURN
instructions (which POPs the address from the stack).
Example 2-1 shows the calling of a subroutine in
page 1 of the program memory. This exa mple assume s
that PCLATH is saved and restored by the Interrupt
Service Routi ne (if interrupts are used).
EXAMPLE 2-1: CALL OF A SUBROUTINE
IN PAGE 1 FROM PAGE 0
PC
12 8 7 0
5PCLATH<4:0>
PCLATH
Instruction with
ALU
GOTO,CALL
Opcode < 10: 0>
8
PC
12 11 10 0
11
PCLATH<4:3>
PCH
87
2
PCLATH
PCH PCL
PCL as
Destination
PCL
Note 1: There are no status bits to indicate stack
overflow or stack underflow conditions.
2: There are no instructions/mnemonics
called PUSH or POP. These are actions
that occur from the execution of the
CALL, RETURN, RETLW and RETFIE
instructions, or the vectoring to an
interr upt add res s.
Note: The contents of the PCLATH register are
unchanged after a RETURN or RETFIE
instruction is executed. The user must
rewrite the contents of the PCLATH regis-
ter for any subsequent subroutine calls or
GOTO instructions.
ORG 0x500
BCF PCLATH, 4
BSF PCLATH, 3 ;Select page 1
;(800h-FFFh)
CALL SUB1_P1 ;Call subroutine in
: ;page 1 (800h-FFFh)
:
ORG 0x900 ;page 1 (800h-FFFh)
SUB1_P1
: ;called subroutine
;page 1 (800h-FFFh)
:
RETURN ;return to
;Call subroutine
;in page 0
;(000h-7FFh)
PIC16F87/88
DS30487D-page 26 2002-2013 Microchip Technology Inc.
2.5 Indirect Addressing, INDF and
FSR Registers
The INDF register is no t a physica l register. Add ressing
the INDF register will cause indirect addressing.
Indirect addressing is possible by using the INDF reg-
ister. Any instruction using the INDF register actually
acces ses the register pointed to by the File Select R eg-
ister, FSR. Reading the INDF register itself, indirectly
(FSR = 0) will read 00h. Writing to the INDF register
indirec tly resu lts in a no operation (alth oug h status bit s
may be affec ted). An ef fectiv e 9-bit add ress is o btaine d
by conc atenat ing the 8 -bit F SR regi ster and the IRP bit
(STATUS <7>), as shown i n Figu re 2-5.
A simple program to clear RAM locations 20h-2Fh
using indirect addressing is shown in Example 2-2.
EXAMPLE 2-2: INDIRECT ADDRESSING
FIGURE 2-5: DIRECT/INDIRECT ADDRESSING
MOVLW 0x20 ;initialize pointer
MOVWF FSR ;to RAM
NEXT CLRF INDF ;clear INDF register
INCF FSR, F ;inc pointer
BTFSS FSR, 4 ;all done?
GOTO NEXT ;no clear next
CONTINUE
: ;yes continue
Note 1: For register file map detail, see Figure 2-2 or Figure 2-3.
Data
Memory(1)
Indirect AddressingDirect Addressing
Bank Select Location Select
RP1:RP0 6 0
From Opcode IRP FSR Register
70
Bank Select Location Select
00 01 10 11
Bank 0 Bank 1 Bank 2 Bank 3
FFh
80h
7Fh
00h
17Fh
100h
1FFh
180h
2002-2013 Microchip Technology Inc. DS30487D-page 27
PIC16F87/88
3.0 DATA EEPROM AND FLASH
PROGRAM MEMORY
The data EEPROM and Flash program memory are
readable and writable during normal operation (over
the full VDD range). Thi s memory is not directly mapped
in the register file space. Instead, it is indirectly
addressed through the Special Function Registers.
There are six SFRs used to read and write this
memory:
EECON1
EECON2
EEDATA
EEDATH
EEADR
EEADRH
This section focuses on reading and writing data
EEPROM and Flash program memory during normal
operation. Refer to the appropriate device program-
ming specification document for serial programming
information.
When interfacing the data memory block, EEDATA
holds the 8-bit data for read/write and EEADR holds the
address of the EEPROM locati on bein g access ed. The
PIC16F87/88 devices have 256 bytes of data
EEPROM with an address range from 00h to 0FFh.
When writing to unimplemented locations, the charge
pump will be turned off.
When inte rfacing the program me mory bloc k, the EED-
ATA and EEDATH r egiste rs for m a two -byt e word t hat
holds the 14-bit dat a for read/write and th e EEADR and
EEADRH registers form a two-byte word that holds the
13-bit address of the EEPROM location being
acces sed. The PIC16F87/88 devices have 4K w ords of
program Flash with an address range from 0000h to
0FFFh. Addresses above the range of the respective
device will wraparound to the beginning of program
memory.
The EEPROM data memory allows single byte read
and write. The Flash program memory allows single-
word reads and four-word block writes. Program
memory writes must first start with a 32-word block
erase, then write in 4-word blocks. A byte write in data
EEPROM memory automatically erases the location
and writes the ne w data (erase before write).
The write time is controlled by an on-chip timer. The
write/erase voltages are generated by an on-chip
charge pump, rated to operate over the voltage range
of the device for byte or word operations.
When the device is code-protected, the CPU may
continu e to rea d and wr ite th e data EEPROM memory.
Depending on the settings of the write-protect bits, the
device may or may not be able to write certain blocks
of the program memory; however , reads of the program
memory ar e allowed. Whe n code-prote cted, the dev ice
programmer can no longer access data or program
memory; thi s d oes NOT inh ib it in tern al re ad s or wri tes .
3.1 EEADR and EEADRH
The EEADRH:EEADR register pair can address up to
a maximum of 256 bytes of data EEPROM, or up to a
maximum of 8K words of program EEPROM. When
selecting a data address value, only the LSB of the
address is writte n to the EEADR regi st er. When se lect-
ing a program address value, the MSB of the address
is written to the EEADRH register and the LSB is
written to the EEADR register.
If the device co ntains less memory than the full add ress
reach of the address register pair, the Most Significant
bits of the reg isters are not im plem ented. F or exam ple,
if the de vi ce has 128 bytes of dat a EEPROM, th e M os t
Signific ant bit of EEADR i s not impl ement ed on a cces s
to data EEPROM.
3.2 EECON1 and EECON2 Registers
EECON1 is the control register for memory accesses.
Control bit EEPGD determines if the access will be a
program or data memory access. When clear, as it is
when reset, any sub seque nt operati ons will operate on
the data memory. When set, any subsequent
operations will operate on the program memory.
Control bits, RD and WR, initiate read and write,
resp ectivel y. These bi ts cannot be cl eared, o nly set in
software. They are cleared in hardware at completion
of the read or write operation. The inability to cl ear the
WR bit in software prevents the accidental, premature
termination of a write operation.
The WREN bit, when set, will allow a write or erase
operation. On power-up, the WREN bit is clear. The
WRERR bit is set when a write (or erase) operation is
interrupted by a MCLR, or a WDT Time-out Reset dur-
ing normal operation. In these situations, following
Reset, the user can check the WRERR bit and rewrite
the location. The data and address will be unchanged
in the EEDATA and EEADR registers.
Interrupt flag bit, EEIF in the PIR2 register, is set when
the write is complete. It must be cleared in software.
EECON2 is not a physical register. Reading EECON2
will read all ‘0’s. The EECON2 register is used
exclusively in the EEPROM write sequence.
PIC16F87/88
DS30487D-page 28 2002-2013 Microchip Technology Inc.
REGISTER 3-1: EECON1: EEPROM ACCESS CONTROL REGISTER 1 (ADDRESS 18Ch)
R/W-x U-0 U-0 R/W-x R/W-x R/W-0 R/S-0 R/S-0
EEPGD FREE WRERR WREN WR RD
bit 7 bit 0
bit 7 EEPGD: Program/Data EEPROM Select bit
1 = Accesses program memory
0 = Accesses data memory
bit 6-5 Unimplemented: Read as0
bit 4 FREE: EEPROM Forced Row Erase bit
1 = Erase t he program memory row a ddressed by EEADRH:EEADR on th e next WR command
0 = Perform write only
bit 3 WRERR: EEPROM Error Flag bit
1 = A write operation is prematurely terminated (any MCLR or any WDT Reset during normal
operation)
0 = The write operation completed
bit 2 WREN: EEPROM Write Enable bit
1 = Allows write cycles
0 = Inhibits write to the EEPROM
bit 1 WR: Write C ontr ol bit
1 = Initiates a write cycle. The bit is cleared by hardware once write is complete. The WR bit
can only be set (not cleared) in software.
0 = Write cycle to the EEPROM is complete
bit 0 RD: Read Control bit
1 = Initiates an EEPROM read, RD is cleared in hardware. The RD bit can only be set (not
cleared) in software.
0 = Does not initiate an EEPROM read
Legend:
R = Re ad able bit W = W ritable bi t U = Unimplemente d b it, read as ‘0 S = Set onl y
-n = Value at POR 1’ = Bit is s e t ‘0’ = Bit is cleared x = Bit i s unk n own
2002-2013 Microchip Technology Inc. DS30487D-page 29
PIC16F87/88
3.3 Reading Data EEPROM Memory
To read a data memory loca tion, the user must write the
address to the EEADR register, clear the EEPGD con-
trol bit (EECON1<7>) and then set control bit RD
(EECON1<0>). The data is available in the very next
cycle in the EEDATA register; therefore, it can be read
in the next instruction (see Example 3-1). EEDATA will
hold this value until another read or until it is written to
by the user (during a write operation).
The steps to reading the EEPROM data memory are:
1. Write the address to EEADR. Make sure that the
address is not larger than the memory size of
the device.
2. Clear the EEPGD bit to point to EEPROM data
memory.
3. Set the RD bit to start the read operation.
4. Read the data from the EEDATA register.
EXAMPLE 3-1: DAT A EEPROM READ
3.4 Writing to Data EEPROM Memory
To write an EEPROM data location, the user must first
write the address to the EEADR register and the data to
the EEDATA register. Then, the user must follow a
specific write sequen ce to initiate the write for each byte.
The write will not initiate if the write sequence is not
exactly followed (write 55h to EECON2, write AAh to
EECON2, then set WR bit) for each byte. We strongly
recommend that interrupts be disabled during this
code segment (see Example 3-2).
Additionally, the WREN bit in EECON1 must be set to
enable write. This mechanism prevents accidental
writes to data EEPROM due to errant (unexpected)
code execution (i.e., lost programs). The user should
keep the WREN bit clear at all times except when
updating EEPROM. The WREN bit is not cleared
by hardware
After a write sequence has been initiated, clearing the
WREN bit wil l not af fect this wri te cycle. T he WR bit will
be inhibited from being set unless the WREN bit is set.
At the completion of the write cycle, the WR bit is
cleared in hardware and the EE Write Complete
Interrupt Flag bit (EEIF) is set. The user can either
enable this interrupt or poll this bit. EEIF must be
clea red by soft ware .
The steps to write to EEPROM data memory are:
1. If step 10 is not implemented , check the WR bit
to see if a write is in progress.
2. Write the address to EEADR. Make sure that the
address is not larger than the memory size of
the device.
3. Write the 8-bit data value to be programmed in
the EEDATA register.
4. Clear the EEPGD bit to point to EEPROM data
memory.
5. Set the WREN bit to en able program operations.
6. Disable interrupts (if enabled).
7. Execute the special five instruction sequence:
Write 55h to EECON2 in two steps (first to W,
then to EECON2).
Write AAh to EECON2 in two steps (first to W,
then to EECON2).
Set the WR bit.
8. Enable interrupts (if using interrupts).
9. Clear the WREN bit to disable program
operations.
10. At the completion of the write cycle, the WR bit
is cleared and the EEIF interrupt flag bit is set
(EEIF must be cleared by firmware). If step 1 is
not implemented, then firmware should check
for EEIF to be set, or WR to clear, to i ndicate th e
end of the program cycle.
EXAMPLE 3-2: DAT A EEPROM WR ITE
BANKSEL EEADR ; Select Bank of EEADR
MOVF ADDR, W ;
MOVWF EEADR ; Data Memory Address
; to read
BANKSEL EECON1 ; Select Bank of EECON1
BCF EECON1, EEPGD; Point to Data memory
BSF EECON1, RD ; EE Read
BANKSEL EEDATA ; Select Bank of EEDATA
MOVF EEDATA, W ; W = EEDATA
BANKSEL EECON1 ; Select Bank of
; EECON1
BTFSC EECON1, WR ; Wait for write
GOTO $-1 ; to complete
BANKSEL EEADR ; Select Bank of
; EEADR
MOVF ADDR, W ;
MOVWF EEADR ; Data Memory
; Address to write
MOVF VALUE, W ;
MOVWF EEDATA ; Data Memory Value
; to write
BANKSEL EECON1 ; Select Bank of
; EECON1
BCF EECON1, EEPGD ; Point to DATA
; memory
BSF EECON1, WREN ; Enable writes
BCF INTCON, GIE ; Disable INTs.
MOVLW 55h ;
MOVWF EECON2 ; Write 55h
MOVLW AAh ;
MOVWF EECON2 ; Write AAh
BSF EECON1, WR ; Set WR bit to
; begin write
BSF INTCON, GIE ; Enable INTs.
BCF EECON1, WREN ; Disable writes
Required
Sequence
PIC16F87/88
DS30487D-page 30 2002-2013 Microchip Technology Inc.
3.5 Reading Flash Program Memory
To read a program memory location, the user must
write two bytes of the address to the EEADR and
EEADRH registers, set the EEPGD control bit
(EECON1<7>) and then set control bit RD
(EECON1<0>). Once the read control bit is set, the
program memory Flash controller will use the second
instruction cycle to read the data. This causes the
second instruction immediately following the “BSF
EECON1,RD” instruction to be ignored. The data is
available in the very next cycle in the EEDATA and
EEDATH registers; therefore, it can be read as two
bytes in the following instructions. EEDATA and EED-
ATH registers will hold this value until another read or
until it is written to by the user (during a write
operation).
EXAMPLE 3-3: FLASH PROGRAM READ
3.6 Erasing Flash Program Memory
The minimum erase block is 32 words. Only through
the use of an external programmer, or through ICSP
control, can larger blocks of program memory be bulk
erase d. Word erase in the Fla sh array is not supporte d.
When initiating an erase sequence from the micro-
controll er itself, a blo ck of 32 words of program memory
is erased. The Most Significant 11 bits of the
EEADRH:EEADR point to the block being erased.
EEADR< 4:0> are ignored.
The EECON1 register commands the erase operation.
The EEPGD bit must be set to point to the Flash
progra m memory. The WREN bit must be set to enable
write op erations. T he FREE bit is s et to select an e rase
operation.
For protec tio n, t he w ri te i nit iate sequence for EECO N2
must be used.
After th e BSF EECON1,WR” instruction, the processor
requires two cycles to setup the erase operation. The
user mus t place two NOP instructi ons after the WR bit i s
set. The processor will halt internal operations for the
typical 2 ms, only during the cycle in which the erase
takes plac e. This is not Sleep mode, as the clocks and
peripherals will continue to run. After the erase cycle,
the processor will resume operation with the third
instruction after the EECON1 write instruction.
3.6.1 FLASH PROGRAM MEMORY
ERASE SEQUENCE
The sequence of events for erasing a block of internal
program memory location is :
1. Load EEADRH:EEADR with address of row
being erased.
2. Set EEPGD bit to point to program memory, set
WREN bit to enable writes and set FREE bit to
enable the erase.
3. Disable int errup ts.
4. Write 55h to EECON2.
5. Write AAh to EECON2.
6. Set the WR bit. This will begin the row erase
cycle.
7. The CPU will stall for duration of the erase.
BANKSEL EEADRH ; Select Bank of EEADRH
MOVF ADDRH, W ;
MOVWF EEADRH ; MS Byte of Program
; Address to read
MOVF ADDRL, W ;
MOVWF EEADR ; LS Byte of Program
; Address to read
BANKSEL EECON1 ; Select Bank of EECON1
BSF EECON1, EEPGD ; Point to PROGRAM
; memory
BSF EECON1, RD ; EE Read
;
NOP ; Any instructions
; here are ignored as
NOP ; program memory is
; read in second cycle
; after BSF EECON1,RD
BANKSEL EEDATA ; Select Bank of EEDATA
MOVF EEDATA, W ; DATAL = EEDATA
MOVWF DATAL ;
MOVF EEDATH, W ; DATAH = EEDATH
MOVWF DATAH ;
2002-2013 Microchip Technology Inc. DS30487D-page 31
PIC16F87/88
EXAMPLE 3-4: ERASING A FLASH PROGRAM MEMORY ROW
BANKSEL EEADRH ; Select Bank of EEADRH
MOVF ADDRH, W ;
MOVWF EEADRH ; MS Byte of Program Address to Erase
MOVF ADDRL, W ;
MOVWF EEADR ; LS Byte of Program Address to Erase
ERASE_ROW
BANKSEL EECON1 ; Select Bank of EECON1
BSF EECON1, EEPGD ; Point to PROGRAM memory
BSF EECON1, WREN ; Enable Write to memory
BSF EECON1, FREE ; Enable Row Erase operation
;
BCF INTCON, GIE ; Disable interrupts (if using)
MOVLW 55h ;
MOVWF EECON2 ; Write 55h
MOVLW AAh ;
MOVWF EECON2 ; Write AAh
BSF EECON1, WR ; Start Erase (CPU stall)
NOP ; Any instructions here are ignored as processor
; halts to begin Erase sequence
NOP ; processor will stop here and wait for Erase complete
; after Erase processor continues with 3rd instruction
BCF EECON1, FREE ; Disable Row Erase operation
BCF EECON1, WREN ; Disable writes
BSF INTCON, GIE ; Enable interrupts (if using)
PIC16F87/88
DS30487D-page 32 2002-2013 Microchip Technology Inc.
3.7 Writing to Flash Program Memory
Flash program memory may only be written to if the
desti nati on addr ess i s in a se gment of me mory th at is
not write-protected, as defined in bits WRT1:WRT0 of
the device Configuration Word (Register 15-1). Flash
prog ram memor y must b e writte n in four -word bl ocks.
A block consists of four words with sequential
addresses, with a lower boundary defined by an
addr ess, wher e EE ADR< 1:0 > = 00. At the same time,
all bl ock w rit es t o prog ram me mor y are d one as wr ite-
only operations. The program memory must first be
erased. Th e write operation is edge-aligned and cannot
occur across boundaries.
To write to the program memory, the data must first be
loaded into the buffer registers. There are four 14-bit
buffer registers and they are addressed by the low
2 bits of EEADR.
The following sequence of events illustrate how to
perform a write to program memory:
Set the EEPGD and WREN bits in the EECON1
register
Clear the FREE bit in EECON1
Write address to EEADRH:EEADR
Write data to EEDATH:EEDATA
Write 55 to EECON2
Write AA to EECON2
Set WR bit in EECON1
The user must follow the same specific sequence to
initiate the write for each word in the program block
by writing each program word in sequence (00, 01,
10, 11).
There are 4 buffer register words and all four locations
MUST be written to with correct data.
After the “BSF EECON1, WR” instruction, if
EEADR xxxxxx11, then a short write will occur.
This short write only transfers the data to the buffer
register. The WR bit will be cleared in hardware after
1cycle.
After the “BSF EECON1, WR” instruction, if
EEADR = xxxxxx11, then a long write will occur. This
will simultaneously transfer the data from
EEDATH :EEDAT A to the buf fer registers and begin the
write of all four words. The processor will execute the
next instruction and then ignore the subsequent
inst ruction. The us er should pl ace NOP instru ctions in to
the seco nd wo rds . Th e pro ce ssor w il l th en h alt int erna l
operat io ns for typ ic all y 2 msec in which the wr ite ta ke s
place. This is not Sleep mode, as the clocks and
peripherals will continue to run. After the write cycle,
the processor will resume operation with the 3rd
instruction after the EECON1 write instruction.
Aft er each long writ e, the 4 buf fer registers will be reset
to 3FFF.
FIGURE 3-1: BLOCK WRITES TO FLASH PROGRAM MEMORY
14 14 14 14
Program Memory
Buffer Register
EEADR<1:0>
= 00
Buffer Register
EEADR<1:0>
= 01
Buffer Register
EEADR<1:0>
= 10
Buffer Register
EEADR<1:0>
= 11
EEDATAEEDATH
75 07 0
6 8
First word of block
to be written
to Flash
automatically
after this word
is written
transferred
All buffers are
2002-2013 Microchip Technology Inc. DS30487D-page 33
PIC16F87/88
An example of the complete four-word write sequence
is shown in Example 3-5. The initial address is loaded
into the EEADRH:EEADR register pair; the four words
of dat a a re load ed us ing in direct addres sing, assum ing
that a row erase sequence has already been
performed.
EXAMPLE 3-5: WRITING TO FLASH PROGRAM MEMORY
; This write routine assumes the following:
; 1. The 32 words in the erase block have already been erased.
; 2. A valid starting address (the least significant bits = '00') is loaded into EEADRH:EEADR
; 3. This example is starting at 0x100, this is an application dependent setting.
; 4. The 8 bytes (4 words) of data are loaded, starting at an address in RAM called ARRAY.
; 5. This is an example only, location of data to program is application dependent.
; 6. word_block is located in data memory.
BANKSEL EECON1 ;prepare for WRITE procedure
BSF EECON1, EEPGD ;point to program memory
BSF EECON1, WREN ;allow write cycles
BCF EECON1, FREE ;perform write only
BANKSEL word_block
MOVLW .4
MOVWF word_block ;prepare for 4 words to be written
BANKSEL EEADRH ;Start writing at 0x100
MOVLW 0x01
MOVWF EEADRH ;load HIGH address
MOVLW 0x00
MOVWF EEADR ;load LOW address
BANKSEL ARRAY
MOVLW ARRAY ;initialize FSR to start of data
MOVWF FSR
LOOP
BANKSEL EEDATA
MOVF INDF, W ;indirectly load EEDATA
MOVWF EEDATA
INCF FSR, F ;increment data pointer
MOVF INDF, W ;indirectly load EEDATH
MOVWF EEDATH
INCF FSR, F ;increment data pointer
BANKSEL EECON1
MOVLW 0x55 ;required sequence
MOVWF EECON2
MOVLW 0xAA
MOVWF EECON2
BSF EECON1, WR ;set WR bit to begin write
NOP ;instructions here are ignored as processor
NOP
BANKSEL EEADR
INCF EEADR, f ;load next word address
BANKSEL word_block
DECFSZ word_block, f ;have 4 words been written?
GOTO loop ;NO, continue with writing
BANKSEL EECON1
BCF EECON1, WREN ;YES, 4 words complete, disable writes
BSF INTCON,GIE ;enable interrupts
Required
Sequence
PIC16F87/88
DS30487D-page 34 2002-2013 Microchip Technology Inc.
3.8 Protect ion Against Spurious Wr ite
There are conditions when the device should not write
to the data EEPROM memory. To protect against
spurious EEPROM writes, various mechanisms have
been b uilt-in. O n power-u p, WREN is cleared. Also, th e
Power-up Timer (72 ms duration) prevents an
EEPROM write.
The wri te in iti ate sequence and the WR EN bi t together
help prevent an accidental write during brown-out,
power glitch or software malfunctio n.
3.9 Operation During Code-Protect
When the dat a EEPROM is code- prote ct ed, the micro-
controll er can read and writ e to th e EEPROM n ormally.
However, all external access to the EEPROM is
disabl ed. External write access to the progra m memory
is also disabled.
When program memory is code-protected, the micro-
controller can read and write to program memory
normall y, as well as e xe cu te i ns truc tio ns. W rites by the
device may be selectively inhibited to regions of the
memory depending on the setting of bits WRT1:WRT0
of the Configuration Word (see Section 15.1 “Config-
uration Bits” for additional information). External
access to the memory is also disabled.
TABLE 3-1: REGISTERS/BITS ASSOCIATED WITH DATA EEPROM AND
FLASH PROGRAM MEMORIES
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on
Power-on
Reset
Value on
all other
Resets
10Ch EEDATA EEPROM/Flash Data Register Low Byte xxxx xxxx uuuu uuuu
10Dh EEADR EEPROM/Flash Address Register Low Byte xxxx xxxx uuuu uuuu
10Eh EEDATH EEPROM /Flash Data Register High Byte --xx xxxx --uu uuuu
10Fh EEADRH EEPROM /Flash Address Register High Byte ---- xxxx ---- uuuu
18Ch EECON1 EEPGD FREE WRERR WREN WR RD x--x x000 x--x q000
18Dh EECON2 EEPROM Control Register 2 (not a physical register) ---- ---- ---- ----
0Dh PIR2 OSFIF CMIF —EEIF 00-0 ---- 00-0 ----
8Dh PIE2 OSFIE CMIE —EEIE 00-0 ---- 00-0 ----
Legend: x = unk nown, u = unchanged, - = unimplemented, read as ‘0’, q = value depends upon c ondition.
Shaded cells are not used by data EEPROM or Flash program memory.
2002-2013 Microchip Technology Inc. DS30487D-page 35
PIC16F87/88
4.0 OSCILLATOR
CONFIGURATIONS
4.1 Oscillator Types
The PIC16F87/88 can be operated in eight different
oscillator modes. The user can program three configu-
ration bits (FOSC2:FOSC0) to select one of these eight
modes (modes 5-8 are new PIC16 oscillator
configurations):
1. LP Lo w-Power Crystal
2. XT Crystal/Resonator
3. HS High-Speed Crystal/Resonator
4. RC External Resist or/C apacitor with
FOSC/4 output on RA6
5. RCIO Extern al R esi st or/C apacitor with
I/O on RA6
6. INTIO1 Internal Osci ll ator with FOSC/4
output on RA6 and I/O on RA7
7. INTIO2 Internal Oscillator with I/O on RA6
and RA7
8. ECIO External Cloc k with I/O on RA6
4.2 Crystal Oscillator/Ceramic
Resonators
In XT, LP or HS modes, a crystal or ceramic resonator
is connected to the OSC1/CLKI and OSC2/CLKO pins
to est abl ish osci llatio n (see Fi gure 4-1 and Figure 4-2).
The PIC16F87/88 oscillator design requires the use of
a parallel cut crystal. Use of a series cut crystal may
give a frequency out of the crystal manufacturer’s
specifications.
FIGURE 4-1: CRYSTAL OPERATION
(HS, XT, OR LP
OSCILLATOR
CONFIGURATION)
T ABLE 4-1: CAPACITOR SELECTION FOR
CRYSTAL OSCILLATOR (FOR
DESIGN GUIDANCE ONLY)
Note1: See Table 4-1 for typical values of C1 and C2.
2: A series resistor (RS) may be required for AT strip
cut crystals.
3: RF varies with the crystal chosen (typically
between 2 M to 10 M.
C1(1)
C2(1)
XTAL
OSC2
RS(2)
OSC1
RF(3) Sleep
To Internal
Logic
PIC16F87/88
Osc Type Crystal
Freq
Ty pical Cap acitor V alu es
Tested:
C1 C2
LP 32 kHz 33 pF 33 pF
XT 200 kHz 56 pF 56 pF
1 MHz 15 pF 15 pF
4 MHz 15 pF 15 pF
HS 4 MHz 15 pF 15 pF
8 MHz 15 pF 15 pF
20 MHz 15 pF 15 pF
Capacitor values are for design guidance only.
These capacito rs were tested with th e crystals listed
below for basic start-up and operation. These values
were not optimized.
Dif ferent capa citor values m ay be required to prod uce
acceptable oscillator operation. The user should test
the performance of the oscillator over the expected
VDD and temperature range for the application.
See the notes following this table for additional
information.
Note 1: Higher capacit ance inc reases the st abilit y
of oscillator but also increases the
start-up time.
2: Since each crystal has its own character-
istic s, th e use r shoul d cons ult th e crys tal
manufacturer for appropriate values of
external components.
3: Rs may be required in HS mode, as well
as XT mode, to av oid ove rdrivi ng cryst als
with low drive level specification.
4: Always veri fy os ci lla tor performance over
the VDD and temperature range that is
expected for the application.
PIC16F87/88
DS30487D-page 36 2002-2013 Microchip Technology Inc.
FIGURE 4-2: CER AMIC RES ONATOR
OPERATION (HS OR XT
OSC CONFIGURATION)
TABLE 4-2: CERAMIC RESONATORS
(FOR DESIGN GUIDANCE
ONLY)
4.3 External Clock Input
The ECIO Oscillator mode requires an external clock
source to be connected to the OSC1 pin. There is no
oscillator start-up time required after a Power-on
Reset, or after an exit from Sleep mode.
In the ECIO Oscillator mode, the OSC2 pin becomes
an additional general purpose I/O pin. The I/O pin
becomes bit 6 of PORTA (RA6). Figure 4-3 shows the
pin connections for the ECIO Oscillator mode.
FIGURE 4-3: EXTERNAL CLOCK INPUT
OPERATION
(ECIO CONFIGURATION)
Typical Capacitor Values Used:
Mode Freq OSC1 OSC2
XT 455 kHz
2.0 MHz
4.0 MHz
56 pF
47 pF
33 pF
56 pF
47 pF
33 pF
HS 8.0 M Hz
16.0 MHz 27 pF
22 pF 27 pF
22 pF
Capacitor values are for design guidance only.
These capacitors were tested with the resonators
listed below for basic start-up and operation. These
values were not optimized.
Dif ferent cap acitor values ma y be required to prod uce
acceptable oscillator operation. The user should test
the performance of the oscillator over the expected
VDD and temperature range for the application.
See the notes following this table for additional
information.
Note: When using resonators with frequencies
above 3.5 MHz, the use of HS mode,
rather than XT mode, is recommended.
HS mode may be used at any VDD for
which the controller is rated. If HS is
selected, it is possible that the gain of the
oscillator will overdrive the resonator.
Therefore, a series resistor should be
placed between the OSC2 pin and the
resonator. As a good starting point, the
recommended value of RS is 330
Note 1: See Table 4-2 for typical values of C1 and
C2.
2: A series resistor (RS) may be required.
3: RF varies with the resonator chosen
(typically between 2 M to 10 M.
C1(1)
C2(1)
RES
OSC2
RS(2)
OSC1
RF(3) Sleep
To Internal
Logic
PIC16F87/88
OSC1/CLKI
I/O (OSC2)
RA6
Clock from
Ext. System PIC16F87/88
2002-2013 Microchip Technology Inc. DS30487D-page 37
PIC16F87/88
4.4 RC Oscillator
For timing insensitive applications, the “RC” and
“RCIO” device options offer additional cost savings.
The RC oscillator frequency is a function of the supply
voltage, the resistor (REXT) and capacitor (CEXT) val-
ues and the operating temperature. In addition to this,
the oscil lator frequen cy will va ry from unit to unit due to
normal manufacturing variation. Furthermore, the dif-
ference in lead frame capacitance between package
types will also affect the oscillation frequency,
especi all y for lo w CEXT values. The user also needs to
take into account variation due to tolerance of external
R and C components used. Figure 4-4 shows how the
R/C combination is connected.
In the RC Oscillator mode, the oscillator frequency
divided by 4 is available on the OSC2 pin. This signal may
be used for test purposes or to synchronize other logic.
FIGURE 4-4: RC OSCILLATOR MODE
The RCIO Oscillator mode (Figure 4-5) functions like
the RC mode, except that the OSC2 pin becomes an
additional general purpose I/O pin. The I/O pin
becomes bit 6 of PORTA (RA6).
FIGURE 4-5: RCIO OSCILLATOR MODE
4.5 Internal Oscillator Block
The PIC1 6F87/88 devic es inclu de an intern al oscil lator
block which generates two different clock signals;
either can be used as the system s clock source. This
can eliminate the need for external oscillator circuits on
the OSC1 and/or OSC2 pins.
The main output (INTOSC) is an 8 MHz clock source
which can be used to directly drive the system clock. It
also driv es the INT OSC postscal er which can prov ide a
range of six clock frequencies from 125 kHz to 4 MHz.
The other clock source is the internal RC oscillator
(INTRC) which provides a 31.25 kHz (32 s nominal
period) output. The INTRC oscillator is enabled by
selecting the INTRC as the system clock source or
when any of the following are enabled:
Power-up Timer
Watchdog Timer
Two-Speed Start-up
Fail- Safe C loc k Mo nito r
These features are discussed in greater detail in
Section 15.0 “Spec ial Features of the CPU”.
The clock source frequency (INTOSC direct, INTRC
direct or INTOSC postscaler) is selected by configuring
the IRCF bits of the OSCCON register (p age 40).
OSC2/CLKO
CEXT
REXT
PIC16F87/88
OSC1
FOSC/4
Internal
Clock
VDD
VSS
Recommended values: 3 k REXT 100 k
CEXT > 20 pF
CEXT
REXT
PIC16F87/88
OSC1 Internal
Clock
VDD
VSS
Recommended values: 3 k REXT 100 k
CEXT > 20 pF
I/O (OSC2)
RA6
Note: Throughout this data sheet, when referring
specifically to a generic clock source, the
termINTRC may also be used to refer to
the clo ck modes usin g the internal osci llator
block. This is regardless of whether the
actu al f r eq uency us ed is I NTOSC (8 MHz) ,
the INTOSC postscaler or INTRC
(31.25 kHz).
PIC16F87/88
DS30487D-page 38 2002-2013 Microchip Technology Inc.
4.5.1 INTRC MODES
Using the internal oscillator as the clock source can
elimin ate the ne ed for up t o two extern al oscil lator pins ,
after which it can be used for digital I/O. Two distinct
configurations are available:
In INTIO1 mode, the OSC2 pin outputs FOSC/4,
while OSC1 fu nc tio ns as RA 7 fo r dig it a l input and
output.
In INTIO2 mode, OSC1 functi ons as RA7 and
OSC2 func tions as RA6, both for digital input and
output.
4.5.2 OSCTUNE REGISTER
The internal oscillator’s output has been calibrated at the
factory but can be adjusted in the application. This is
done by writing to the OSCTUNE register (Register 4-1).
The tuning sensitivity is constant throughout the tuning
range. The OSCTUNE register has a tuning range of
±12.5%.
When the OSCTUNE register is modified, the INTOSC
and INTRC frequencies will begin shif ting to the new fre-
quency. The INTRC clock will reach the new frequency
within 8 clock cycles (approximately 8 * 32 s = 256 s);
the INTOSC clock will stabilize within 1 ms. Code execu-
tion continues during this shift. There is no indication that
the shift has occurred. Operation of features that depend
on the 31.25 kHz INTRC clock source frequency, such
as the WDT, Fail-Safe Clock Monitor and peripherals,
will also be af fec ted by the cha nge in frequency.
REGISTER 4-1: OSCTUNE: OSCILLATOR TUNING REGISTER (ADDRESS 90h)
U-0 U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0
TUN5 TUN4 TUN3 TUN2 TUN1 TUN0
bit 7 bit 0
bit 7-6 Unimplemented: Read as ‘0
bit 5-0 TUN<5:0>: Frequency Tuning bits
011111 = Maximum frequency
011110 =
000001 =
000000 = Center frequency. Oscillator module is running at the calibrated frequency.
111111 =
100000 = Minimum frequency
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
2002-2013 Microchip Technology Inc. DS30487D-page 39
PIC16F87/88
4.6 Clock Sources and Oscillator
Switching
The P IC16F 87/88 devices incl ude a fea ture tha t allo ws
the system clock source to be switched from the main
oscillator to an alternate low-frequency clock source.
PIC16F87/88 devices offer three alternate clock
sources. When enabled, these give additional options
for switching to the various power-managed operating
modes.
Essentially, there are three clock sources for these
devices:
Primary oscillators
Second ary oscillators
Internal osc illator block (INTRC)
The primary oscillators include the External Crystal
and Resonator modes, the External RC modes, the
External Clock mode and the internal oscillator block.
The par ticula r mode is defin ed on POR by the content s
of Configuration Word 1. The details of these modes
are covered earlier in this chapter.
The seco ndary oscillators are those external sources
not connected to the OSC1 or OSC2 pins. These
sources may continue to operate even after the
controller is placed in a power-managed mode.
PIC16F87/88 devices offer the Timer1 oscillator as a
secondary oscillator. This oscillator continues to run
when a SLEEP instruction is executed and is often the
time base for functions such as a real-time clock.
Most often, a 32.768 kHz watch crystal is connected
between the RB6/T1OSO and RB7/T1OSI pins. Like
the LP mode oscillator circuit, loading capacitors are
also connected from each pin to ground. The Timer1
oscillator is discussed in greater detail in Section 7.6
“Timer1 Oscillator”.
In addi tion to be ing a prim ary clock s ource, the internal
oscillator block is available as a power-managed
mode clock source. The 31.25 kHz INTRC source is
also used as the clock source for several special
features, such as the WDT, Fail-Safe Clock Monitor,
Powe r-up Timer and Two- Speed Start-up.
The clock sources for the PIC16F87/88 devices are
shown in Figure 4-6. See Section 7.0 “Timer1 Mod-
ule” for further details of the Timer1 oscillator. See
Section 15.1 “Configuration Bits” for Configuration
register details.
4.6.1 O SCCON REGIS TER
The OSCCON register (Register 4-2) controls several
aspects of the system clock’s operation, both in full
power ope ratio n and in pow e r-ma nag ed mo des .
The System Clock Select bits, SCS1:SCS0, select the
clock source that is used when the device is operating
in power-managed modes. When the bits are
cleared (SCS<1:0> = 00), the system clock source
comes from the main oscillator that is selected by the
FOSC2:FOSC0 configuration bits in Configuration
Word 1 register. When the bits are set in any other
manner, the system clock source is provided by the
Timer1 oscillator (SCS1:SCS0 = 01) or from the
internal oscillator block (SCS1:SCS0 = 10). After a
Reset, SCS<1:0> are always set to ‘00’.
The Intern al Oscillator Select bi ts, IRCF2:IRCF0, select
the freque ncy o utput of the interna l oscill ator block th at
is use d to driv e th e syst em cl ock. T he choi ces ar e the
INTRC source (31.25 kHz), the INTOSC source
(8 MHz) or one of the six frequencies derived from the
INTOSC postsca ler (12 5 kHz to 4 MHz). Cha n gin g the
configu ration of these bit s has an i mmediate c hange on
the multiplexor’s frequency output.
The OSTS and IOFS bits indicate the status of the
primary oscillator and INTOSC source; these bits are
set when their respective oscillators are stable. In
particular, OSTS indicates that the Oscillator Start-up
Timer has timed out.
4.6.2 CLOCK SWITCHING
Clock switching will occur for the following reasons:
The FCMEN (CONFIG2<0>) bi t is set, the device
is running from the primary oscill ator and the
primary oscillator fails. The clock source will be
the internal RC oscillator.
The FCMEN bi t is set, the device is running from
the T1OSC and T1OSC fails. The clock source
will be the internal RC oscillator.
Following a wake-up due to a Reset or a POR,
when the device is configured for Two-Speed
Start-up mode, switching will occur between the
INTRC and the system clock defined by the
FOSC<2:0> bits.
A wake-up from Sleep occurs due to an interrupt or
WDT wake-up and T wo-S peed S tart-up is enabled.
If the primary clock is XT, HS or LP, the clock will
switch between th e INTRC and the primary system
clock after 1024 c lock s (OST) and 8 cloc ks of the
primary oscillator. This i s conditional upon the SCS
bits being set eq ual to ‘00’.
SCS bits are modified from their original value.
IRCF bi ts are mo dified from their origin al value.
Note: The instruction to immediately follow the
modification of SCS<1:0> will have an
instruction time (TCY) based on the previ-
ous clock source. This should be taken
into consideration when developing time
dependant code.
Note: Because the SCS bits are cleared on any
Reset, no clock switching will occur on a
Reset unless the Two-Speed Start-up is
enabled and the p rimary clock is XT, HS or
LP. The device will wait for the primary
clock to become stable before execution
begins (Two-Spe ed Start-u p disa ble d).
PIC16F87/88
DS30487D-page 40 2002-2013 Microchip Technology Inc.
4.6.3 CLOCK TRANSITION AND WDT
When clock switching is performed, the Watchdog
T ime r is disa bled bec ause the W atchdog ripple co unter
is used as the Oscillator Start-up Timer.
Once the clock transition is complete (i.e., new oscilla-
tor selec tion switc h has oc curred), the W atchdog c oun-
ter is re-en abled wit h the counte r reset. Th is allows th e
user to synchronize the Watchdog Timer to the start of
execution at the new clock frequency.
REGISTER 4-2: OSCCON: OSCILLATOR CONTROL REGISTER (ADDRESS 8Fh)
Note: The OST is only used when switching to
XT, HS and LP Oscillator modes.
U-0 R/W-0 R/W-0 R/W-0 R-0 R/W-0 R/W-0 R/W-0
IRCF2 IRCF1 IRCF0 OSTS(1) IOFS SCS1 SCS0
bit 7 bit 0
bit 7 Unimplemented: Read as ‘0
bit 6-4 IRCF<2:0>: Internal RC Oscillator Frequency Select bits
000 = 31.25 kHz
001 = 125 kHz
010 = 250 kHz
011 = 500 kHz
100 = 1 MHz
101 = 2 MHz
110 = 4 MHz
111 = 8 MHz
bit 3 OSTS: Oscillator Start-up Time-out Status bit(1)
1 = Device is running from the primary system clock
0 = Device is running from T1OSC or INTRC as a secondary system clock
Note 1: Bit resets to ‘0’ with Two-Speed Start-up mode and LP, XT or HS selected as the
oscillator mode.
bit 2 IOFS: INTOSC Frequency Stable bit
1 = Frequency is stable
0 = Frequency is not stable
bit 1-0 SCS<1:0>: Os ci ll ator Mode Sele ct bits
00 = Oscillator mode defined by FOSC<2:0>
01 = T1OSC is used for system clock
10 = Internal RC is used for system clock
11 = Reserved
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR 1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
2002-2013 Microchip Technology Inc. DS30487D-page 41
PIC16F87/88
FIGURE 4-6: PIC16F87/88 CLOCK DIAGRAM
4.6.4 MODIFYING THE IRCF BITS
The IRCF bits can be modified at any time regardless of
which clock source is currently being used as the
system clock. The internal oscillator allows users to
change the frequency during run time. Thi s is achieved
by modifying the IRCF bits in the OSCCON register.
The sequen ce of events tha t occur after the IRCF bits
are modified is dependent upon the initial value of the
IRCF bits before they are modified. If the INTRC
(31.25 kHz, IRCF<2:0> = 000) is running and the IRCF
bits are modified to any other va lue than ‘000’, a 4 ms
(approx. ) clock swit ch delay is turned o n. Code e xecu-
tion continues at a higher than expected frequency
while the new frequency stabilizes. T ime sensitive code
should wait for the IOFS bit in the OSCCON register to
become set before continuing. This bit can be moni-
tored to ensure that the frequency is stable before using
the system clock in time critical applications.
If th e IRCF b its a re modif ied wh ile the internal oscilla tor
is running at any other frequency than INTRC
(31.25 kHz, IRCF<2:0> 000), there is no need for a
4 ms (approx.) clock switch delay. The new INTOSC
frequenc y will be stable immediatel y after the eight fall-
ing edges. The IOFS bit will remain set after clock
switching occurs.
4.6.5 CLOCK TRANSITION SEQUENCE
Following are three different sequences for switching
the internal RC oscillator frequency.
Clock before switch: 31.25 kHz (IRCF<2:0> = 000)
1. IRCF bits are modified to an INTOSC/INTOSC
postscaler frequency.
2. The clock switching circuitry waits for a falling
edge o f the curr ent cloc k, at whic h point CL KO
is held low.
3. The clock swit ching circuitry the n waits for eight
falling edges of requested clock, after which it
switches CLKO to this new clock source.
4. The IOFS bit is cle ar to indicate that the cloc k i s
unstable and a 4 ms (approx.) delay is started.
Time dependent code should wait for IOFS to
become set.
5. Switchover is complete.
Clock before switch: One of INTOSC/INTOSC
postscaler (IRCF<2:0> 000)
1. IRCF bits are modified to INTRC
(IRCF<2:0> = 000).
2. The clock switching circuitry waits for a falling
edge o f the curr ent cloc k, at whic h point CL KO
is held low.
3. The clock swit ching circuitry the n waits for eight
falling edges of requested clock, after which it
switches CLKO to this new clock source.
4. Oscillator switchover is complete.
Secondary Oscillator
T1OSCEN
Enable
Oscillator
T1OSO
T1OSI
OSC1
OSC2
Sleep
Primary Oscillator
LP, XT, HS, RC, EC
T1OSC
CPU
Peripherals
Postscaler
MUX
MUX
8 MHz
4 MHz
2 MHz
1 MHz
500 kHz
125 kHz
250 kHz
OSCCON<6:4>
111
110
101
100
011
010
001
000
31.25 kHz
31.25 kHz
Source
Internal
Oscillator
Block
WDT, FSCM
31.25 kHz
8 MHz
Internal Oscillator
(INTRC)
(INTOSC)
Configuration Word 1 (FOSC2:FOSC0)
SCS<1:0> (T1OSC)
To Ti mer1
Note: Caution must be t aken when mod ifying the
IRCF bits using BCF or BSF instructions. It
is possible to modify the IRCF bits to a
frequency that may be out of the VDD spec-
ification range; for example, VDD = 2.0V
and IRCF = 111 (8 MHz).
PIC16F87/88
DS30487D-page 42 2002-2013 Microchip Technology Inc.
Clock before switch: One of INTOSC/INTOSC
postscaler (IRCF<2:0> 000)
1. IRCF bits are modified to a different INTOSC/
INTOSC postscaler frequency.
2. The clock switching circuitry waits for a falling
edge o f the curr ent clock, at which p oint CLKO
is held low.
3. The clock sw itc hi ng ci rcu itry then waits for eight
falling edges of requested clock, after which it
switches CLKO to this new clock source.
4. The IOFS bit is set.
5. Oscillator switchover is c omplete.
4.6.6 OSCILLATOR DELAY UPON
POWER-UP, W AKE-UP AND
CLOCK SWITCHING
Table 4-3 shows the different delays invoked for
various clock switching sequences. It also shows the
delays invoked for POR and wake-up.
TABLE 4-3: OSCILLATOR DELAY EXAMPLES
Clock Swit ch Frequency Oscillator Delay Comments
From To
Sleep/POR
INTRC
T1OSC 31.25 kHz
32.768 kHz CPU Start-up(1)
Following a wake-up from Sleep mode or
POR, CPU start-up is invoked to allow the
CPU to become ready for code execution.
INTOSC/
INTOSC
Postscaler 125 kHz-8 MHz 4 ms (approx.) and
CPU Start-up(1)
INTRC/Sleep EC, RC DC – 20 MHz
INTRC
(31.25 kHz) EC, RC DC – 20 MHz
Sleep LP, XT, HS 32.768 kHz-20 MHz 1024 Clock Cy cles
(OST) Following a change from INTRC, an OST
of 1024 cycles must occur.
INTRC
(31.25 kHz)
INTOSC/
INTOSC
Postscaler 125 kHz-8 MHz 4 ms (approx.) Refer to Section 4.6.4 “Modifying the
IRCF Bits” for further details.
Note 1: The 5 - 10 s start-up delay is based on a 1 MHz system clock.
2002-2013 Microchip Technology Inc. DS30487D-page 43
PIC16F87/88
4.7 Power-Managed Modes
4.7.1 RC_RUN MODE
When SCS bits are configured to run from the INTRC,
a clock transition is generated if the system clock is
not already using the INTRC. The event will clear the
OSTS bit, switch the system clock from the primary
system clock (if SCS<1:0> = 00) determined by the
value contained in the configuration bits, or from the
T1OSC (if SCS<1:0> = 01) to the INTRC clock option
and shut down the primary system clock to conserve
power. Clock switching will not occur if the primary
system clock is already configured as INTRC.
If the system clock does not come from the INTRC
(31.25 kHz) when the SCS bits are changed and the
IRCF bit s in the OSC CO N regi ster are configured for a
frequency other than INTRC, the frequency may not be
stable immediately. The IOFS bit (OSCCON<2>) will
be set when the INTOSC or postscaler frequency is
stable, after 4 ms (approx.).
After a clock swi tch has b een exec uted, th e OSTS bit
is cleared, indicating a low-power mode and the
device does not run from the primary system clock.
The internal Q clocks are held in the Q1 state until
eight falling edge clocks are counted on the INTRC
oscill ator. Af ter th e eigh t cloc k peri ods ha ve tran spire d,
the cl ock inpu t to th e Q clocks i s releas ed and oper a-
tion resumes (see Figure 4-7).
FIGURE 4-7: TIMING DIAGRAM FOR XT, HS, LP, EC AND EXTRC TO RC_RUN MODE
Q4Q3Q2
OSC1
SCS<1:0>
Program PC + 1PC
Note 1: TINP =32s typical.
2: TOSC = 50 ns minimum.
3: TSCS =8 TINP.
4: TDLY =1 TINP.
Q1
INTOSC
Q1
TSCS(3)
Counter
Q1
TDLY(4)
TINP(1)
System
Clock TOSC(2)
Q3Q2 Q4 Q1 Q2
PC + 3
Q3 Q4 Q1
PC + 2
PIC16F87/88
DS30487D-page 44 2002-2013 Microchip Technology Inc.
4.7.2 SEC_RUN MODE
The core and peripherals can be configured to be
clocked by T1OSC using a 32.768 kHz crystal. The
crystal must be connected to the T1OSO and T1OSI
pins. This is the same configuration as the low-power
timer circuit (see Section 7.6 “Timer1 Oscillator”).
When SCS bits are configured to run from T1OSC, a
clock transition is generated. It will clear the OSTS bit,
switch th e sys tem cl ock fro m eith er the pri mary sys tem
clock or INTRC, depending on the value of SCS<1:0>
and FOSC<2:0>, to the external low-power Timer1
oscillator input (T1OSC) and shut down the primary
system clock to conserve power.
After a cloc k swit ch has been ex ec uted , the in ter nal Q
clocks are held in the Q1 state until eight falling edge
clocks are counted on the T1OSC. After the eight
cloc k peri ods have t ransp ir ed, th e cl ock i nput t o th e Q
clocks is released and operation resumes (see
Figure 4-8). In addition, T1RUN (In T1CON) is set to
indicate that T1OSC is being used as the system
clock.
FIGURE 4-8: TIMING DIAGRAM FOR SWITCHING TO SEC_RUN MODE
Note 1: The T1OSC EN bit must be enabled and it
is the user’s responsibility to ensure
T1OSC is stabl e before cloc k switchin g to
the T 1OSC input clock can occur.
2: When T1OSCEN = 0, the following possible
effects result.
Original
SCS<1:0> Modified
SCS<1:0> Final
SCS<1:0>
00 01 00 – no change
00 11 10 – INTRC
10 11 10 – no change
10 01 00 – Oscillator
defined by
FOSC<2:0>
A clock switching event will occur if the
final state of the SCS bits is different from
the original.
Q4Q3Q2
OSC1
SCS<1:0>
Program PC +1PC
Note 1: TT1P = 30.52 s.
2: TOSC = 50 ns minimum.
3: TSCS = 8 TT1P
4: TDLY = 1 TT1P.
Q1
T1OSI
Q1
TSCS(3)
Counter
Q1
TDLY(4)
TT1P(1)
System
Clock
TOSC(2)
Q3Q2 Q4 Q1 Q2
PC + 3
Q3 Q4 Q1
PC + 2
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PIC16F87/88
4.7.3 SEC_RUN/RC_RUN TO PRIMARY
CLOCK SOURCE
When switching from a SEC_RUN or RC_RUN mode
back to the primary system clock, following a change
of SCS<1:0> to 00’, the s equen ce of ev ent s that t a kes
place will depend upon the value of the FOSC bits in
the Configuration register. If the primary clock source
is config ured as a cryst al (HS, XT or LP), the n the tra n-
sition will take place after 1024 clock cycles. This is
necessary because the crystal oscillator has been
powered down until the time of the transition. In order
to provide the system with a reliable clock when the
changeover has occurred, the clock will not be
released to the changeover circuit until the 1024 count
has expire d.
During the oscillator start-up time, the system clock
comes from the current system clock. Instruction
execution and/or peripheral operation continues using
the currently selected oscillator as the CPU clock
source, until the necessary clock count has expired, to
ensure that the primary system clock is stable.
To know when the OST has expired, the OSTS bit
should be monitored. OSTS = 1 indicates that the
Oscil la tor St art-u p Timer has time d out and the sys te m
cloc k comes from the primary clock source.
Following the oscillator start-up time, the internal Q
clocks are held in the Q1 state until eight falling edge
clock s are coun ted from the prima ry sys tem cloc k. The
clock input to the Q clocks is then released and opera-
tion resum es with the primary sy stem clock de termined
by the FOSC bits (see Figure 4-10).
When in SEC_RUN mode, the act of clearing the
T1OSCEN bit in the T1CON register will cause
SCS<0> to be cleared, which causes the SCS<1:0>
bits to revert to ‘00’ or ‘10’ depending on what SCS<1>
is. Althou gh the T1OSCEN bit was c leared, T1OSC will
be enabled and instru ct ion ex ec utio n w i ll c on tinue until
the OST time-out for the main system clock is com-
plete. At th at time, the system cloc k will switc h from the
T1OSC to the primary clock or the INTRC. Following
this, the T1 oscillator will be shut down.
4.7.3.1 Returning to Primary Clock Source
Sequence
Changing back to the primary oscillator from
SEC_RUN or RC_RUN can be accomplished by either
changing SCS<1:0> to ‘00, or clearing the T1OSCEN
bit in th e T1CON register (i f T1OSC wa s the sec ondary
clock).
The sequence of events that follows is the same for
both modes :
1. If the primary system cloc k is configured as EC,
RC or IN TRC, then t he OST time-ou t is skip ped.
Skip to step 3.
2. If t he prim ary s ystem c lock is confi gured as an
external oscillator (HS, XT, LP), then the OST
will be active, waiting for 1024 clocks of the
prim ary sy stem clock.
3. On the following Q1, the device holds the
system clock in Q1.
4. The device stays in Q1 while eight falling edges
of the primary system clock are counted.
5. Once the eight counts transpire, the device
begins to run from the primary os cillator.
6. If the secondary clock was INTRC and the
primary is not INTRC, the INTRC will be shut
down to save current providing that the INTRC
is not bei ng used for a ny othe r functi on, such a s
WDT or Fail-Safe Clock monitori ng.
7. If the secondary clock was T1OSC, the T1OSC
will continue to run if T1OSCEN is still set;
otherwise, the T1 oscillator will be shut down.
Note: If the p r im ary sy s tem c loc k is ei t he r R C or
EC, an internal delay timer (5-10 s) will
suspen d oper ation a fte r exiti ng Sec ondary
Clock mode to allow the CPU to become
ready for code execution.
PIC16F87/88
DS30487D-page 46 2002-2013 Microchip Technology Inc.
FIGURE 4-9: TIMING FOR TRANSITION BETWEEN SEC_RUN/RC_RUN AND PRIMARY CLOCK
Q4 Q1 Q3 Q4
OSC1
Program PC PC + 1
Secondary
Primary Clock
TOST
Q1
PC + 3
TDLY(5)
TT1P(1) or TINP(2)
TSCS(4)
Q2
OSC2
Q3 Q4 Q1
OSTS
System Clock
PC + 2
Counter
Q2 Q2 Q3 Q4
SCS<1:0>
Note 1: TT1P = 30.52 s.
2: TINP = 32 s typical.
3: TOSC = 50 ns minimum.
4: TSCS = 8 TINP OR 8TT1P.
5: TDLY = 1 TINP OR 1TT1P.
Oscillator
TOSC(3)
2002-2013 Microchip Technology Inc. DS30487D-page 47
PIC16F87/88
4.7.3.2 Returning to Primary Oscillator with
a Reset
A Reset will clear SCS<1:0> back to ‘00’. The
sequence for starting the primary oscillator following a
Reset is the same for all forms of Reset, including
POR. There is no transition sequence from the
alte rnat e syst em clo ck to th e pri mary s ystem clock on
a Reset condition. Instead, the device will reset the
state of the OSCCON register and default to the
primary system clock. The sequence of events that
takes place after this will depend upon the value of the
FOSC bits in t he Conf igur ation r egist er. I f the extern al
oscillator is configured as a crystal (HS, XT or LP), the
CPU wi ll be h eld in th e Q1 st at e until 1024 clock cyc les
have transpired on the primary clock. This is
necessary because the crystal oscillator has been
powered down until the time of the transition.
During the oscillator start-up time, instruction
execution and/or peripheral operation is suspended.
If the primary system clock is either RC, EC or INTRC,
the CPU will begin operating on the first Q1 cycle
following the wake-up event. This means that there is
no oscillator start-up time required because the
primary clock is already stable; however, there is a
delay between the wake-up event and the following
Q2. An internal delay timer of 5-10 s will suspend
operation after the Reset to allow the CPU to become
ready for code execution. The CPU and peripheral
clock will be held in the first Q1.
The sequence of events is as follows:
1. A device Reset is asserted from one of many
sources (WDT, BOR, MCLR, etc.).
2. The device resets and the CPU start-up timer is
enabled if in Sleep mode. The device is held in
Reset until the CPU start-up time-out is
complete.
3. If t he prim ary s ystem c lock is confi gured as an
external oscillator (HS, XT, LP), then the OST
will be active waiting for 1024 clocks of the
primary system clo ck. While wa iting for the OST,
the device will be held in Reset. The OST and
CPU start-up timers run in parallel.
4. After both the CPU start-up and OST timers
have ti med o ut, the de vice will wai t for o ne add i-
tional clock cycle and instruction execution will
begin.
FIGURE 4-10: PRIMARY SYSTEM CLOCK AFTER RESET (HS, XT, LP)
Note: If Two-Speed Clock Start-up mode is
enabled, the INTRC will act as the system
clock until the OST timer has timed out.
Q4 Q1 Q3 Q4 Q1 Q2
OSC1
Peripheral
Sleep
Program PC 0000h
T1OSI
TOST
Q3
TT1P(1)
Q4
OSC2
OSTS
System Clock
0001h
Q1 Q2 Q3 Q4 Q1 Q2
Clock
Counter 0004h 0005h
0003h
Q1 Q2 Q3 Q4
Reset
TCPU(3)
Note 1: TT1P = 30.52 s.
2: TOSC = 50 ns minimum.
3: TCPU = 5-10 s (1 MHz system clock).
CPU Start-up TOSC(2)
PIC16F87/88
DS30487D-page 48 2002-2013 Microchip Technology Inc.
FIGURE 4-11: PRIMARY SYSTEM CLOCK AFTER RESET (EC, RC, INTRC)
Q4 Q1 Q3 Q4 Q1 Q2
OSC1
Program PC 0000h
T1OSI
Q3
TT1P(1)
Q4
OSC2
OSTS
System Clock
0001h
Q1 Q2 Q3 Q4 Q1 Q2
Counter 0003h 0004h
0002h
Q1 Q2 Q3 Q4
MCLR
TCPU(2)
Note 1: TT1P = 30.52 s.
2: TCPU = 5-10 s (1 MHz system clo ck).
CPU Start-up
2002-2013 Microchip Technology Inc. DS30487D-page 49
PIC16F87/88
TABLE 4-4: CLOCK SWITCHING MODES
Current
System
Clock
SCS Bits <1:0>
Modified to: Delay OSTS
Bit IOFS
Bit T1RUN
Bit
New
System
Clock Comments
LP, XT, HS,
T1OSC,
EC, RC
10
(INTRC)
FOSC<2:0> = LP,
XT or HS
8 Clocks of
INTRC 01
(1) 0INTRC
or
INTOSC
or
INTOSC
Postscaler
The internal RC osc il la tor
frequency is dependant upon
the IRCF bits.
LP, XT, HS,
INTRC,
EC, RC
01
(T1OSC)
FOSC<2:0> = LP,
XT or HS
8 Clocks of
T1OSC 0N/A 1T1OSC T1OSCEN bit must be
enabled.
INTRC
T1OSC 00
FOS C<2: 0> = EC
or
FOSC<2:0> = RC
8 Clocks of
EC
or
RC
1N/A 0EC
or
RC
INTRC
T1OSC 00
FOSC<2:0> = LP,
XT, HS
1024 Clocks
(OST)
+
8 Clocks of
LP, XT, HS
1N/A 0LP, XT, HS During the 1024 clocks,
program execution is clo c ked
from the secondary oscillator
until the primary oscillator
becomes stable.
LP, XT, HS 00
(Due to Reset)
LP, XT, HS
1024 Clocks
(OST) 1N/A 0LP, XT, HS When a Res et o cc ur s, th ere i s
no clock transition sequence.
Instruction execution and/or
peripheral operation is
suspended unless Two-Speed
Start-up mode is enabled, after
which the INT RC will act as th e
system clock until the OST
timer has expired.
Note 1: If the new clock source is the INTOSC or INTO SC postscaler, then the IOFS bit will be set 4 ms (approx.)
af ter the cl ock change.
PIC16F87/88
DS30487D-page 50 2002-2013 Microchip Technology Inc.
4.7.4 EXITING SLEEP WITH AN
INTERRUPT
Any interru pt, such as WDT or INT0 , will cause the part
to leave the Sleep mode.
The SCS bits are unaffected by a SLEEP command and
are the same before and after entering and leaving
Sleep. The clock source used after an exit from Sleep
is determined by the SCS bits.
4.7.4.1 Sequence of Events
If SCS<1:0> = 00:
1. The device is held in Sleep until the CPU start-up
time-out is complete.
2. If the primary system clock is configured as an
external oscillator (HS, XT, LP), then the OST will
be active waiting for 1024 clocks of the primary
system clock. While waiting for the OST, the
device will be held in Sleep unless Two-Speed
Start-up is enabled. The OST and CPU start-up
timers run in parallel. Refer to Section 15.12.3
“Two-Speed Clock Start-up Mode” for details
on Two-Speed S t art-up.
3. After both the CPU start-up and OST timers
have timed out, the device will exit Sleep and
begin instruction execution with the primary
clock defined by the FOSC bits.
If SCS<1:0> = 01 or 10:
1. The device is held in Sleep until the CPU start-up
time-out is complete.
2. After the CPU start-up timer has timed out, the
device will exit Sleep and begin instruction
execution with the selected oscillator mode.
Note: If a user changes SCS<1:0> just before
entering Sleep mode, the system clock
used when exiting Sleep mode could be
different than the system clock used when
entering Sleep mode.
As an example, if SCS<1:0> = 01 and
T1OSC is the system clock and the
following instructions are executed:
BCF OSCCON, SCS0
SLEEP
then a clock change event is executed. If
the primary oscillator is XT, LP or HS, the
core will continue to run off T1OSC and
execute the SLEEP comm and .
When Sleep is exited, the part will resume
operation with the primary oscillator after
the OST has expired.
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PIC16F87/88
5.0 I/O PORTS
Some pins for these I/O ports are multiplexed with an
alternate function for the peripheral features on the
device. In general, when a peripheral is enabled, that
pin may not be used as a general purpose I/O pin.
Additional information on I/O ports may be f ound in the
PIC® Mid-Range MCU Family Reference Manual
(DS33023).
5.1 PORTA and the TRISA Register
PORTA is an 8-bit wide, bidirectional port. The corre-
sponding data direction register is TRISA. Setting a
TRISA bit (= 1) will make the corresponding PORTA
pin an input (i.e., put the corresponding output driver in
a high-impedance mode). Clearing a TRISA bit (= 0)
will mak e the correspond ing PORTA pin an output (i.e .,
put the contents of the output latch on the selected pin).
Reading the PORTA register, reads the status of the
pins, where as writin g to it, will write to the po rt latch. All
write operations are read-modify-write operations.
Therefore , a write to a port implies that the port pins are
read, this value is modified and then written to the port
data l atch.
Pin RA4 is multiplexed with the Timer0 module clock
input. On PIC16F88 devices, it is also multiplexed with
an analog input to become the RA4/AN4/T0CKI/
C2OUT pin. The RA4/AN4/T0CKI/C2OUT pin is a
Schmitt Trigger input and full CMOS output driver.
Pin RA5 is multiplexed with the Master Clear module
input. The RA5/MCLR/VPP pin is a Schmitt Trigger
input.
Pin RA6 is mul tiplexed with th e oscillator module input
and external oscillator output. Pin RA7 is multiplexed
with the oscillator module input and external oscillator
input. Pin RA6/OSC2/CLKO and pin RA7/OSC1/CLKI
are Schmitt Trigger inputs and full CMOS output drivers.
Pins RA<1:0> are multiplexed with analog inputs. Pins
RA<3:2> are multiplexed with analog inputs and com-
parator outputs. On PIC16F88 devices, pins RA<3:2>
are also m ultiplexed with the VREF input s. Pins RA<3:0>
have TTL inputs an d full CM OS output driv ers.
EXAMPLE 5-1: INITIALIZI NG PORTA
TABLE 5-1: PORTA FUNCTIONS
Note: On a Power-on Reset, the pins
PORTA<4:0> are configured as analog
inputs and read as ‘0’.
BANKSEL PORTA ; select bank of PORTA
CLRF PORTA ; Initialize PORTA by
; clearing output
; data latches
BANKSEL ANSEL ; Select Bank of ANSEL
MOVLW 0x00 ; Configure all pins
MOVWF ANSEL ; as digital inputs
MOVLW 0xFF ; Value used to
; initialize data
; direction
MOVWF TRISA ; Set RA<7:0> as inputs
Name Bit# Buffer Function
RA0/AN0 bit 0 TTL Input/output or analog input.
RA1/AN1 bit 1 TTL Input/output or analog input.
RA2/AN2/CVREF/VREF-(2) bit 2 TTL Input/output, analog input, VREF- or comparator VREF
output.
RA3/AN3/VREF+(2)/C1OUT bit 3 TTL Input/outpu t, analog input, VREF+ or comparator output.
RA4/AN4(2)/T0CKI/C2OUT bit 4 ST Input/output, analog input, TMR0 external input or
comparator output.
RA5/MCLR/VPP bit 5 ST Input, Master Clear (Reset) or programming voltage input.
RA6/OSC2/CLKO bit 6 ST Input/output, connects to crystal or resonator, oscillator
output or 1/4 the frequency of OSC1 and denotes the
instruction cycle in RC mode.
RA7/OSC1/CLKI bit 7 ST/CMOS(1) Input/output, connects to crystal or resonator or oscillator
input.
Legend: TTL = TTL input, ST = Schmitt Trigger input
Note 1: This bu ffer is a Schmitt Tri gge r i nput when config ure d in RC Oscill ato r m ode a nd a C M O S i npu t o therwise.
2: PIC 16F88 only.
PIC16F87/88
DS30487D-page 52 2002-2013 Microchip Technology Inc.
TABLE 5-2: SUMMARY OF REGISTERS ASSOCIATED WITH PORTA
FIGURE 5-1: BLOCK DIAGRAM OF RA0/AN0:RA1/AN1 PINS
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on
POR, BOR
Value on
all other
Resets
05h PORTA RA7 RA6 RA5 RA4 RA3 RA2 RA1 RA0 xxxx 0000(1)
xxx0 0000(2) uuuu 0000(1)
uuu0 0000(2)
85h TRISA TRISA7 TRISA6 TRISA5(3) PORTA Data Direction Register 1111 1111 1111 1111
9Fh ADCON1 ADFM ADCS2 VCFG1 VCFG0 0000 ---- 0000 ----
9Bh ANSEL(4) ANS6 ANS5 ANS4 ANS3 ANS2 ANS1 ANS0 -111 1111 -111 1111
Legend: x = unk nown, u = unchanged, - = unimplemented locations read as ‘0’. Shaded cells are not used by PORTA.
Note 1: This value applies only to the PIC16F87.
2: This value applies only to the PIC16F88.
3: Pin 5 is an input only; the state of the TRISA5 bit has no effect and will always read 1’.
4: PIC16F88 device only.
Data
Bus QD
Q
CK P
N
WR
PORTA
WR
TRISA
Data Latch
TRIS Latch
RD TRISA
RD PORTA
Analog VSS
VDD
I/O pin
QD
Q
CK
Input Mode
DQ
EN
To Comparator
TTL
Input Buffer
VDD
To A/D Module Channel Input (PIC16F88 only)
2002-2013 Microchip Technology Inc. DS30487D-page 53
PIC16F87/88
FIGURE 5-2: BLOCK DIAGRAM OF RA3/AN3/VREF+/C1OUT PIN
FIGURE 5-3: BLOCK DIAGRAM OF RA2/AN2/CVREF/VREF- PIN
Data
Bus QD
Q
CK
N
WR
PORTA
WR
TRISA
Data Latch
TRIS Latch
RD TRISA
RD PORTA
VSS
RA3 pin
QD
Q
CK
DQ
EN
To A/D Module Channel Input (PIC16F88 only)
Comparator 1 Output
Comparator Mode = 110
VDD
Analog
Input Mode
To A/D Module Channel VREF+ Input (PIC16F88 only)
P
VDD
To Comparator
VSS
Input Buffer
TTL
Data
Bus QD
Q
CK P
N
WR
PORTA
WR
TRISA
Data Latch
TRIS Latch
RD TRISA
RD PORTA
Analog
VSS
VDD
RA2 pin
QD
Q
CK
DQ
EN
To Comparator
TTL
Inpu t Bu ffe r
Input Mode
VDD
To A/D Module Channel Input (PIC16F88 only)
CVROE
CVREF
To A/D Module VREF- (PIC16F88 only)
PIC16F87/88
DS30487D-page 54 2002-2013 Microchip Technology Inc.
FIGURE 5-4: BLOCK DIAGRAM OF RA4/AN4/T0CKI/C2OUT PIN
FIGURE 5-5: BLOCK DIAGRAM OF RA5/MCLR/VPP PIN
Data
Bus QD
Q
CK
N
WR
PORTA
WR
TRISA
Data Latch
TRIS Latch
RD TRISA
RD PORTA
VSS
RA4 pin
DQ
EN
TMR0 Clock Input
Schmitt Trigger
Input Buffer
Comparator 2 Output
Comparator Mode = 011, 101, 110
1
0
VDD
Analog
Input Mode
To A/D Module Channel Input (PIC16F88 only)
P
VDD
QD
Q
CK
DQ
EN
MCLR Filter
RA5/MCLR/VPP pin
RD Port
MCLR Circuit
MCLRE
MCLRE
Data Bus
RD TRIS
Schmitt Trigger
Buffer
VSS
VSS Schmitt Trigger
Inpu t Bu ffe r
2002-2013 Microchip Technology Inc. DS30487D-page 55
PIC16F87/88
FIGURE 5-6: BLOCK DIAGRAM OF RA6/OSC2/CLKO PIN
Data
Bus QD
Q
CK
P
N
WR
PORTA
WR
TRISA
Data Latch
TRIS Latch
RD TRISA
RD PORTA
VSS
VDD
RA6/OSC2/CLKO pin
Q
D
Q
CK
DQ
EN
Oscillator
Circuit
From OSC1
(FOSC = 1x0, 011)
P
N
VSS
VDD
CLKO (FOSC/4)
VDD
Note 1: I/O pins have protection diodes to VDD and V SS.
2: CLKO signal is 1/4 of the FOSC frequency.
(FOSC = 1x0, 011)
(FOSC = 1x1)VSS
Schmitt Trigger
Input Buffer
PIC16F87/88
DS30487D-page 56 2002-2013 Microchip Technology Inc.
FIGURE 5-7: BLOCK DIAGRAM OF RA7/OSC1/CLKI PIN
Data
Bus QD
Q
CK
WR
PORTA
WR
TRISA
Data Latch
TRIS Latch
RD TRISA
RD PORTA
DQ
EN
Oscillator
Circuit
RA7/OSC1/CLKI pin(1)
P
N
VSS
VDD
FOSC = 10x
VDD
Note 1: I/O pins have protection diodes to VDD and VSS.
(FOSC = 011)
FOSC = 10x
From OSC2
VSS
Schmitt Trigger
Input Buffer
Q
D
Q
CK
2002-2013 Microchip Technology Inc. DS30487D-page 57
PIC16F87/88
5.2 PORTB and the TRISB Register
PORTB is an 8-bit wide, bidirectional port. The corre-
sponding data direction register is TRISB. Setting a
TRISB bit (= 1) will make the corresponding PORTB
pin an input (i.e., put the corresponding output driver in
a high-impedance mode). Clearing a TRISB bit (= 0)
will make th e corresp onding POR TB pi n an out put (i.e .,
put the contents of the output latch on the select ed pin).
Each of th e POR TB pins has a we ak inte rnal pul l-up. A
single control bit can turn on all the pull-ups. This is
performed by clearing bit RBPU (OPTION_REG<7>).
The weak pull-up is automatically turned off when the
port pin is configured as an output. The pull-ups are
disabled on a Power-on Reset.
Four of POR TB’s pi ns, RB7:RB4, hav e an interrupt-o n-
change feature. Only pins configured as inputs can
cause this interrupt to occur (i.e., any RB7:RB4 pin
configured as an output is excluded from the interrupt-
on-change comparison). The input pins (of RB7:RB4)
are compared with the old value latched on the last
read of PORTB. The “mismatch” outputs of RB7:RB4
are OR’ed together to generate the RB Port Change
Interrupt with Flag bit RBIF (INTCON<0>).
This interrupt can wake the device from Sleep. The
user, in the Interrupt Service Routine, can clear the
inter rupt in the fol lowi ng man ne r :
a) Any read or write of PORTB. This will end the
mismatch condition.
b) Clear flag bit RBIF.
A mism at c h c ond it i on wi ll cont i n ue to s et f lag bi t RB IF.
Reading PORTB will end the mismatch condition and
allow flag bit RBIF to be cleared.
The interrupt-on-change feature is recommended for
wake-up on key depression operation and operations
where PORTB is only used for the interrupt-on-change
feature. Polling of PORTB is not recommended while
using the interrupt-on-change feature.
RB0/INT is an external interrupt input pin and is
configured using the INTEDG bit (OPTION_REG<6>).
PORTB i s multiplexed w ith several pe ripheral function s
(see Table 5-3). PORTB pins have Schmitt Trigger
input buffers.
When enabling peripheral functions, care should be
taken in defining TRIS bits for each PORTB pin. Some
peripherals override the TRIS bit to make a pin an
output, w hile other peripherals override the TRIS bit to
make a pin an input. Since the TRIS bit override is in
effect while the peripheral is enabled, read-modify-
write instructions (BSF, BCF, XORWF) with TRISB as
the destination should be avoided. The user should
refer to the corresponding peripheral section for the
correct TRIS bit settings.
PIC16F87/88
DS30487D-page 58 2002-2013 Microchip Technology Inc.
TABLE 5-3: PORTB FUNCTIONS
TABLE 5-4: SUMMARY OF REGISTERS ASSOCIATED WITH PORTB
Name Bit# Buffer Function
RB0/INT/CCP1(7) bit 0 TTL/ST(1) Input/output pin or external interrupt input.
Capture input/Compare output/PWM output pin.
Internal software programmable weak pull-up.
RB1/SDI/SDA bit 1 TTL/ST(5) Input/output pin, SPI data input pin or I2C™ data I/O pin.
Internal software programmable weak pull-up.
RB2/SDO/RX/DT bit 2 TTL/ST(4) Input/output pin, SPI data output pin.
AUSART asynchronous receive or synchronous data.
Internal software programmable weak pull-up.
RB3/PGM/CCP1(3,7) bit 3 TTL/ST(2) Inpu t/ou tpu t pin, prog ram mi ng in LVP mode or Captur e inpu t/Com p a r e
output/PWM output pin. Internal software programmab le weak pull-up.
RB4/SCK/SCL bit 4 TTL/ST(5) Input/output pin or SPI and I2C clock pin (with interrupt-on-change).
Internal software programmable weak pull-up.
RB5/SS/TX/CK bit 5 TTL Input/output pin or SPI slave select pin (with interrupt-on-change).
AUSART asynchronous transmit or synchronous clock.
Internal software programmable weak pull-up.
RB6/AN5(6)/PGC/
T1OSO/T1CKI bit 6 TTL/ST(2) Input/output pin, analog input(6), serial programming clock
(with interrupt-on-change), Timer1 oscillator outp ut pin or Timer1 clock
input pin. Internal software programmable weak pull-up.
RB7/AN6(6)/PGD/
T1OSI bit 7 TTL/ST(2) Input/output pin, analog input(6), serial programming data (with
interrupt-on-change) or Timer1 oscillator input pin.
Internal software programmable weak pull-up.
Legend: TTL = TTL input, ST = Schmitt Trigger input
Note 1: This buffer is a Schmitt Trigger i nput when configured as the external interru pt.
2: This buffer is a Schmitt Trigger input when used in Serial Programming mo de.
3: Low-Voltage ICSP™ Programming (LVP) is enabled by defaul t, which disables the RB3 I/O function. LVP
must be disabled to enable RB3 as an I/O pin and allow maximum compatibility to the other 18-pin
mid-range dev ic es .
4: This buffer is a Schmitt Trigger input when configured for CCP or SSP mode.
5: This buffer is a Schmitt Trigger input when config ured for SPI or I2C mode.
6: PIC16F88 onl y.
7: The CCP1 pin is determined by the CCPMX bit in Configuration Word 1 register.
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on
POR, BOR
Value on
all other
Resets
06h, 106h PORTB RB7 RB 6 RB5 RB4 RB3 R B2 RB1 RB0 xxxx xxxx(1)
00xx xxxx(2) uuuu uuuu(1)
00uu uuuu(2)
86h, 186h TRISB PORTB Data Dir ect ion Register 1111 1111 1111 1111
81h, 181h OPTION_RE G RBPU INTEDG T0CS T0SE PSA PS2 PS1 PS0 1111 1111 1111 1111
9Bh ANSEL(2) ANS6 ANS5 ANS4 ANS3 ANS2 ANS1 ANS0 -111 1111 -111 1111
Legend: x = unknown, u = unchanged, - = unimplemented, read as ‘0’. Shaded cells are not used by PORTB.
Note 1: This value applies only to the PIC16F87.
2: This value applies only to the PIC16F88.
2002-2013 Microchip Technology Inc. DS30487D-page 59
PIC16F87/88
FIGURE 5-8: BLOCK DIAGRAM OF RB0/INT/CCP1(3) PIN
Note 1: I /O pins have diode protection to VDD and VSS.
2: To enable weak pull-ups, set the appropriate TRIS bit(s) and clear the RBPU bit.
3: The CCP1 pin is determined by the CCPMX bit in Configuration Word 1 register.
Data Latch
RBPU(2) P
VDD
QD
CK
QD
CK
QD
EN
Data Bus
WR PORTB
WR TRISB
RD TRISB
RD PORTB
Weak
Pull-up
RD PORTB
I/O pin(1)
TTL
Input
Buffer
TRIS Latch
0
1
CCP
CCP1M<3:0> = 1000, 1001, 11xx and CCPMX = 1
To INT0 or CCP
CCP1M<3:0> = 000
PIC16F87/88
DS30487D-page 60 2002-2013 Microchip Technology Inc.
FIGURE 5-9: BLOCK DIAGRAM OF RB1/SDI/SDA PIN
Data Latch
RBPU(2)
P
VDD
Q
D
CK
QD
CK
QD
EN
Data Bus
WR
WR
RD TRISB
RD PORTB
Weak
Pull-up
RD PORTB
SDA(3)
I/O pin(1)
TTL
Input
Buffer
Schmitt Trigger
Buffer
TRIS Latch
Note 1: I/O pins have diode protection to VDD and VSS.
2: To enable weak pull-ups, set the appropriate TRIS bit(s) and clear the RBPU bit.
3: The SDA Schmi t t confor ms to the I2C specification.
1
0
SDA Output
P
N
VSS
VDD
Q
SDA Drive
Port/SSPEN Se lect
I2C™ Mode
SDI
PORTB
TRISB
2002-2013 Microchip Technology Inc. DS30487D-page 61
PIC16F87/88
FIGURE 5-10: BLOCK DIAGRA M OF RB2/SDO/RX/DT PIN
DT
SDO
Data Latch
RBPU(2) P
VDD
Q
D
CK
QD
CK
QD
EN
Data Bus
WR PORTB
WR TRISB
RD TRISB
RD PORTB
Weak
Pull-up
RD PORTB
RX/DT
I/O pin(1)
TTL
Input
Buffer
Schmitt Trigger
Buffer
TRIS Latch
1
0
P
N
VSS
VDD
Q
DT Drive
SPEN
1
0
SSPEN
Note 1: I/O pins have diode protection to VDD and VSS.
2: To enable weak pull-ups, set the appropriate TRIS bit(s) and clear the RBPU bi t.
SSPEN + SPEN
PIC16F87/88
DS30487D-page 62 2002-2013 Microchip Technology Inc.
FIGURE 5-11: BLOCK DIAGRAM OF RB3/PGM/CCP1(3) PIN
Data Latch
RBPU(2) P
VDD
QD
CK
QD
CK
QD
EN
Data Bus
WR
WR
RD TRISB
RD PORTB
Weak
Pull-up
RD PORTB
I/O pin(1)
TTL
Input
Buffer
TRIS Latch
PORTB
Note 1: I/O pins have diode protection to VDD and VSS.
2: To enable weak pull-ups, set the appropriate TRIS bit(s) and clear the RBPU bit.
3: The CCP1 pin is determined by the CCPMX bit in Configuration Wo rd 1 register.
0
1
CCP
To PGM or CCP
CCP1M<3:0> = 1000, 1001, 11xx and CCPMX = 0
CCP1M<3:0> = 0100, 0101, 0110, 0111 and CCPMX = 0
or LVP = 1
TRISB
2002-2013 Microchip Technology Inc. DS30487D-page 63
PIC16F87/88
FIGURE 5-12: BLOCK DIAGRA M OF RB4/SCK/SCL PIN
Data Latch
From other
RBPU(2)
P
VDD
I/O pin(1)
QD
CK
QD
CK
QD
EN
QD
EN
Data Bus
WR
WR
Set RBIF
TRIS Latch
RD TRISB
RD PORTB
RB7:RB4 pins
Weak
Pull-up
RD PORTB
Latch
TTL
Input
Buffer
Q3
Q1
PORTB
Note 1: I/O pins have diode protection to VDD and VSS.
2: To ena ble weak pull- ups, set the appropriate TRIS bit(s) and clear the RBPU bit.
3: The SC L Schmit t conforms to the I2C™ specification.
SCK
SCK/SCL 1
0
Port/SSPEN
SCL(3)
P
N
VSS
VDD
SCL Drive
TRISB
PIC16F87/88
DS30487D-page 64 2002-2013 Microchip Technology Inc.
FIGURE 5-13: BLOCK DIAGRAM OF RB5/SS/TX/CK PIN
Data Latch
From other
RBPU(2)
P
VDD
I/O pin(1)
QD
CK
QD
CK
QD
EN
QD
EN
Data Bus
WR
WR
Set RBIF
TRIS Latch
RD TRISB
RD PORTB
RB7:RB4 pins
Weak
Pull-up
RD PORTB
Latch
Q3
Q1
PORTB
Peripheral Input
Port/SSPEN
Note 1: I/O pins have diode protection to VDD and VSS.
2: To enable weak pull-ups, set the appropriate TRIS bit(s) and clear the RBPU bit.
TRISB
TTL
Input
Buffer
2002-2013 Microchip Technology Inc. DS30487D-page 65
PIC16F87/88
FIGURE 5-14: BLOCK DIAGRAM OF RB6/AN5(3)/PGC/T1OSO/T1CKI PIN
Data Latch
From other
RBPU(2)
P
VDD
I/O pin(1)
QD
CK
QD
CK
QD
EN
QD
EN
Data Bus
WR PORTB
WR TRISB
Set RBIF
TRIS Latch
RD TRISB
RD PORTB
RB7:RB4 pins
Weak
Pull-up
RD PORTB
Latch
Q3
Q1
Note 1: I/O pins have diode protection to VDD and VSS.
2: To enable weak pull-ups, set the appropriate TRIS bit(s) and clear the RBPU bit.
3: PIC16F88 devices only.
PGC/T1CKI
Analog
TTL
Input Buffer
Input Mode
T1OSCEN/ICD/PROG
From T1OSCO Output
To A/D Module Channel Input (PIC16F88 only)
Analog
Input Mode
Mode
PIC16F87/88
DS30487D-page 66 2002-2013 Microchip Technology Inc.
FIGURE 5-15: BLOCK DIAGRAM OF RB7/AN6(3)/PGD/T1OSI PIN
Data Latch
From other
RBPU(2) P
VDD
I/O pin(1)
QD
CK
QD
CK
QD
EN
QD
EN
Data Bus
WR
T1OSCEN
Set RBIF
TRIS Latch
RD TRISB
RD PORTB
RB7:RB4 pins
Weak
Pull-up
RD PORTB
Latch
Q3
Q1
PORTB
Note 1: I/O pins have diode pro tect ion to VDD and VSS.
2: To enable weak pull-ups, set the appropriate TRIS bit(s) and clear the RBPU bit.
3: PIC16F88 devices only.
PGD
PGD
Port/Program Mode/ICD
Analog
TTL
Input Buffer
Input Mode
To T1OSCI Input
1
0
PGD DRVEN
T1OSCEN
WR
TRISB
To A/D Module Channel Input (PIC16F88 only)
1
0
Analog Input Mode
2002-2013 Microchip Technology Inc. DS30487D-page 67
PIC16F87/88
6.0 TIMER0 MODULE
The Timer0 module timer/counter has the following
features:
8-bit timer/counter
Readable and writable
8-bit software programmable prescaler
Internal or external clock select
Interrupt-on-overflow from FFh to 00h
Edge select for external clock
Additional information on the Timer0 module is
available in the “PIC® Mid-Range MCU Family Refer-
ence Manual” (D S330 23) .
Figure 6-1 is a bloc k diagram o f the T imer0 mod ule and
the prescaler shared with the WDT.
6.1 Timer0 Operation
Timer0 operation is controlled through the
OPTION_REG register (se e Register 2-2). T imer mod e
is selected by clearing bit T0CS (OPTION_REG<5>).
In T imer m ode, the T ime r0 module w ill incr ement eve ry
instruc tion cy cle (with out pr escal er). If the TMR0 regis-
ter is w ritten , the i ncrem ent is inhi bited f or the follow ing
two instruction cycles. The user can work around this
by writing an adjusted value to the TMR0 register.
Counter mode is selected by setting bit T0CS
(OPTION_REG<5>). In Count er mode, T imer0 will incre-
ment, either on every rising or falling edge of pin RA4/
T0CKI/C2O U T. The in crementing edge is determ in ed by
the Timer0 Source Edge Select bit, T0SE
(OPTION_REG< 4>). Clearing bit T0SE selects the rising
edge. Restrictions on the external clock input are
discussed in detail in Section 6.3 “Using Timer0 with
an External Clock”.
The prescaler is mutually, exclusively shared between
the Timer0 module and the Watchdog Timer. The
prescaler is not readable or writable. Section 6.4
“Prescaler” details the operation of the prescaler.
6.2 Timer0 Interrupt
The TMR0 interrupt is generated when the TMR0 reg-
ister overflows from FFh to 00h. This overflow sets bit
TMR0IF (INTCON<2>). The interrupt can be masked
by clearing bit TMR0IE (INTCON<5>). Bit TMR0IF
must be cleared in software by the Timer0 module
Interrupt Service Routine before re-enabling this inter-
rupt. The TM R0 interrupt c annot awake n the proce ssor
from Sleep, sin ce the timer is sh ut off duri ng Slee p.
FIGURE 6-1: BLOCK DIAGRAM OF THE TIMER0/WDT PRESCALER
RA4/T0CKI/C2OUT
T0SE
pin
M
U
X
CLKO (= FOSC/4)
Sync
2
Cycles TMR0 reg
8-bit Prescaler
8-to-1 MUX
M
U
X
M U X
PSA
01
0
1
WDT
Time-out
PS2:PS0
8
Note: T0CS, T0SE, PSA and PS2:PS0 bits are (OPTION_REG<5:0>).
PSA
M
U
X
0
10
1
Data Bus
Set Flag bit TMR0IF
on Overflow
8
PSA
T0CS
Prescaler
31.25 kHz
WDT Timer
WDT Enable bit
16-bit
Prescaler
PIC16F87/88
DS30487D-page 68 2002-2013 Microchip Technology Inc.
6.3 Using Timer0 with an External
Clock
When no pr escal er is used, t he ex ternal clo ck inp ut is
the same as the pre sc al er outp ut. Th e sy nch ron iz atio n
of T0CKI, with the internal phase clocks, is accom-
plishe d by sampling the prescale r output on the Q2 and
Q4 cycles of the internal phase clocks. Therefore, it is
necessary for T0CKI to be high for at least 2 TOSC (and
a small RC delay of 20 ns) and low for at least 2 TOSC
(and a small RC delay of 20 ns). Refer to the electrical
specification of the desired device.
6.4 Prescaler
There i s only one pres caler a vailable , whic h is mutu ally
exclus ively shar ed between th e T imer0 mod ule and the
Watchdog Timer. A prescaler assignment for the
Timer0 module means that the prescaler cannot be
used by the Watchdog Timer and vice versa. This
prescaler is not readable or writable (see Figure 6-1).
The PSA and PS2:PS0 bits (OPTION_REG<3:0>)
determine the prescaler assignment and prescale ratio.
When assigned to the Timer0 module, all instructions
writing to the TMR0 register (e.g., CLRF 1, MOVWF 1,
BSF 1, x.... etc.) will clear the prescaler . W hen assigned
to WDT, a CLRWDT instruction will clear the prescaler
along with the Watchdog Timer. The prescaler is not
readable or writable.
REGISTER 6-1: OPTION_REG: OPTION CONTROL REGISTER (ADDRESS 81h, 181h)
Note: Althou gh the presca ler can be assi gned to
either the WDT or Timer0, but not both, a
new divide counter is implemented in the
WDT circui t to giv e m ul tipl e WDT tim e-o ut
selecti on s. T his al low s TM R0 an d WD T to
each have their own scaler. Refer to
Section 15.12 “Watch dog Timer (WDT)”
for further details.
Note: Writing to TMR0, when the prescaler is
assigned to Timer0, will clear the
prescaler count but will not change the
prescaler assignment.
R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1
RBPU INTEDG T0CS T0SE PSA PS2 PS1 PS0
bit 7 bit 0
bit 7 RBPU: PORTB Pull-up Enable bit
bit 6 INTEDG: Interrupt Edge Select bit
bit 5 T0CS: TMR0 Clock Source Select bit
1 = Transition on T0CKI pin
0 = Internal instruction cycle clock (CLKO)
bit 4 T0SE: TMR0 Source Edge Select bit
1 = Increm ent on high-to-low transition on T0CKI pin
0 = Increm ent on low-to-high transition on T0CKI pin
bit 3 PSA: Prescaler Assignment bit
1 = Prescaler is assigned to the WDT
0 = Prescaler is assigned to the Timer0 modu le
bit 2-0 PS<2:0>: Prescaler Rate Select bits
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
Note: To avoid an uninten ded device Reset , the ins tru ction sequence sho wn in the ”PIC®
Mid-Range MCU Family Reference Manual” (DS33023) must be executed when
changing the prescaler assignment from Timer0 to the WDT. This sequence must
be followed even if the WDT is disabled.
000
001
010
011
100
101
110
111
1 : 2
1 : 4
1 : 8
1 : 16
1 : 32
1 : 64
1 : 128
1 : 256
1 : 1
1 : 2
1 : 4
1 : 8
1 : 16
1 : 32
1 : 64
1 : 128
Bit Value TMR0 Rate WDT Rate
2002-2013 Microchip Technology Inc. DS30487D-page 69
PIC16F87/88
EXAMPLE 6-1: CHANGING THE PRESCALER ASSIGNMENT FROM WDT TO TIMER0
TABLE 6-1: REGISTERS ASSOCIATED WITH TIMER0
CLRWDT ; Clear WDT and prescaler
BANKSEL OPTION_REG ; Select Bank of OPTION_REG
MOVLW b'xxxx0xxx' ; Select TMR0, new prescale
MOVWF OPTION_REG ; value and clock source
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on
POR, BOR
Value on
all other
Resets
01h,101h TMR0 Ti mer0 M odule Register xxxx xxxx uuuu uuuu
0Bh,8Bh,
10Bh,18Bh INTCON GIE PEIE TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 0000 000x 0000 000u
81h,181h OPTION_REG RBPU INTEDG T0CS T0SE PSA PS2 PS1 PS0 1111 1111 1111 1111
Legend: x = unk nown, u = unchanged. Shaded cells are not used by Timer0.
PIC16F87/88
DS30487D-page 70 2002-2013 Microchip Technology Inc.
NOTES:
2002-2013 Microchip Technology Inc. DS30487D-page 71
PIC16F87/88
7.0 TIMER1 MODULE
The Timer1 module is a 16 -bi t tim er/c ou nter cons is tin g
of two 8-bit registers (TMR1H and TMR1L) which are
readable and writable. The TMR1 register pair
(TMR1H:TMR1L) increments from 0000h to FFFFh
and rol ls over to 0000h. Th e TMR1 inter rupt, if e nabled,
is generated on overflow which is latched in interrupt
flag bit, TMR1IF (PIR1<0>). This interrupt can be
enabled/disabled by setting/clearing TMR1 interrupt
enable bit, TMR1IE (PIE1<0>).
The T imer1 oscil lator can be used as a secondary clock
source in low-power modes . When the T1R UN bit i s set
along with SCS<1:0> = 01, the Timer1 oscillator is pro-
viding the system c lock. If the Fail-Safe Clock Monitor is
enabled and the Timer1 oscillator fails while providing
the system clock, polling the T1RUN bit will indicate
whether the clock is being provided by the Timer1
oscillator or another source.
Timer1 can also be used to provide Real-Time Clock
(RTC) functionality to applications with only a minimal
addition of external components and code overhead.
7.1 Timer1 Operation
Timer1 can operate in one of three modes:
•as a Timer
as a Sync hronous Counter
as an Asynchronous Counter
The operating mode is determined by the clock select
bit, TMR1CS (T1CON<1>).
In Timer mode, Timer1 increments every instruction
cycle. In Counter mode, it increments on every rising
edge of the external clock input.
Timer1 can be enabled/disabled by setting/clearing
control bit, TMR1ON (T1CON<0>).
Timer1 also has an internal “Reset input”. This Reset
can be generated by the CCP1 module as the special
event trigger (see Section 9.1 “Capture Mode”).
Register 7-1 shows the Timer1 Control register.
When the Timer1 oscillator is enabled (T1OSCEN is
set), the RB6/PGC/T1OSO/T1CKI and RB7/PGD/
T1OSI pins become inputs. That is, the TRISB<7:6>
value is ignored and these pins read as ‘0’.
Additional information on timer modules is available in
the “PIC® Mid-Range MCU Family Reference Manual”
(DS33023).
PIC16F87/88
DS30487D-page 72 2002-2013 Microchip Technology Inc.
REGISTER 7-1: T1CON: TIMER1 CONTROL REGISTER (ADDRESS 10h)
U-0 R-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0
T1RUN T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON
bit 7 bit 0
bit 7 Unimplemented: Read as ‘0
bit 6 T1RUN: Timer1 System Clock Status bit
1 = System clock is derived from Timer1 oscillator
0 = System clock is derived from another source
bit 5-4 T1CKPS<1:0>: Timer1 Input Clock Prescale Select bi ts
11 =1:8 Prescale value
10 =1:4 Prescale value
01 =1:2 Prescale value
00 =1:1 Prescale value
bit 3 T1OSCEN: Timer1 Oscillator Enable Control bit
1 = Oscillator is enabled
0 = Oscillator is shut off (the oscillator inverter is turned off to eliminate power drain)
bit 2 T1SYNC: Timer1 External Clock Input Synchronization Control bit
TMR1CS = 1:
1 = Do not synchronize external clock input
0 = Synchronize external clock input
TMR1CS = 0:
This bit is ignored. Timer1 uses the in ternal clock when TMR1CS = 0.
bit 1 TMR1CS: Timer1 Clo ck Sour ce Select bit
1 = External clock from pin RB6/AN5(1)/PGC/T1OSO/T1CKI (on the rising edge)
0 = Internal clock (FOSC/4)
Note 1: Available on PIC16F88 devices only.
bit 0 TMR1ON: Timer1 On bit
1 = Enables Timer1
0 = Stops Timer1
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR 1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
2002-2013 Microchip Technology Inc. DS30487D-page 73
PIC16F87/88
7.2 Timer1 Operation in Timer Mode
Timer mode is selected by clearing the TMR1CS
(T1CON<1>) bit. In this mode, the input clock to the
timer is FOSC/4. The synchronize control bit, T1SYNC
(T1CON<2>), has no effect since the internal clock is
always in sync.
7.3 Timer1 Counter Operation
Timer1 may operate in Asynchronous or Synchronous
mode, depending on the setting of the TMR1CS bit.
When Timer1 is being incremented via an external
source, increments occur on a rising edge. Af ter Timer1
is enab led in Coun ter mode, the module must first have
a falling edge before the counter begins to increment.
7.4 Timer1 Operation in Synchr onized
Counter Mode
Counter mode is selected by setting bit TMR1CS. In
this mode, the timer increments on every rising edge of
clock input on pin RB7/PGD/T1OSI when bit
T1OSCEN is set, or on pin RB6/PGC/T1OSO/T1CKI
when bit T1OSCEN is cleared.
If T1SYNC is cleared, then the external clock input is
synchronized with internal phase clocks. The synch-
ronization is done after the prescaler stage. The
prescaler stage is an asynchronous ripple counter.
In this configuration, during Sleep mode, T imer1 will not
increment even if the external clock is presen t since the
synchronization circuit is shut off. The prescaler,
however, will continue to increment.
FIGURE 7-1: TIMER1 INCREMENTING EDGE
FIGURE 7-2: TIMER1 BLOCK DIAGRAM
T1CKI
(Default High)
T1CKI
(Default Low)
Note: Arrows indicate counter increments.
TMR1H TMR1L
T1OSC T1SYNC
TMR1CS
T1CKPS1:T1CKPS0 Q Clock
T1OSCEN
Enable
Oscillator(1)
FOSC/4
Internal
Clock
TMR1ON
On/Off
Prescaler
1, 2, 4, 8 Synchronize
det
1
0
0
1
Synchronized
Clock Input
2
T1OSI
T1OSO/T1CKI
Note 1: When the T1OSCEN bit is cleared, the inverter is turned off. This eliminates power drain.
Set Flag bit
TMR1IF on
Overflow TMR1
PIC16F87/88
DS30487D-page 74 2002-2013 Microchip Technology Inc.
7.5 Timer1 Operation in
Asynchronous Counter Mode
If control bit T1SYNC (T1CON<2>) is set, the external
clock input is not synchronized. The timer continues to
increment asynchronous to the internal phase clocks.
The timer will continue to run during Sleep and can
generate an interrupt-on-overflow t hat w ill wak e-u p th e
processor. However, special precautions in software
are needed to read/write the timer (see Section 7.5.1
“Reading and Writing Timer1 in Asynchronous
Counter Mode”).
In Asynchronous Counter mode, Timer1 cannot be
used as a time base for capture or compare operations.
7.5.1 READING AND WRITING TIMER1 IN
ASYNCHRONOUS COUNTER
MODE
Reading TMR1H or TMR1L while the timer is running
from an e xternal asyn chronous cl ock will ens ure a valid
read (taken care of in hardware). However, the user
should keep i n mind that rea ding t he 16-bi t ti mer in two
8-bit values itself, poses certain problems, since the
timer ma y overflow between the reads.
For writes , it is re commend ed that th e user s imply sto p
the timer and write the desired values. A write conten-
tion may occur by writing to the timer registers while the
register is incrementing. This may produce an
unpredi c table valu e in the timer register.
Reading the 16-bit value requires some care. The
example codes provided in Example 7-1 and
Example 7-2 demonstrate how to write to and read
Timer1 while it is running in Asynchronous mo de.
EXAMPLE 7-1: WRITING A 16-BIT FREE RUNNING TIMER
EXAMPLE 7-2: READING A 16-BIT FREE RUNNING TIMER
; All interrupts are disabled
CLRF TMR1L ; Clear Low byte, Ensures no rollover into TMR1H
MOVLW HI_BYTE ; Value to load into TMR1H
MOVWF TMR1H, F ; Write High byte
MOVLW LO_BYTE ; Value to load into TMR1L
MOVWF TMR1H, F ; Write Low byte
; Re-enable the Interrupt (if required)
CONTINUE ; Continue with your code
; All interrupts are disabled
MOVF TMR1H, W ; Read high byte
MOVWF TMPH
MOVF TMR1L, W ; Read low byte
MOVWF TMPL
MOVF TMR1H, W ; Read high byte
SUBWF TMPH, W ; Sub 1st read with 2nd read
BTFSC STATUS, Z ; Is result = 0
GOTO CONTINUE ; Good 16-bit read
; TMR1L may have rolled over between the read of the high and low bytes.
; Reading the high and low bytes now will read a good value.
MOVF TMR1H, W ; Read high byte
MOVWF TMPH
MOVF TMR1L, W ; Read low byte
MOVWF TMPL ; Re-enable the Interrupt (if required)
CONTINUE ; Continue with your code
2002-2013 Microchip Technology Inc. DS30487D-page 75
PIC16F87/88
7.6 Timer1 Oscillator
A crystal oscillator circuit is built between pins T1OSI
(input) and T1OSO (amplifier output). It is enabled by
setting control b it T1OSCEN (T1CON<3>). The o scilla-
tor is a low-power oscillator, rated up to 32.768 kHz. It
will continue to run during all power-managed modes.
It is primarily intended for a 32 kHz crystal. The circuit
for a typical LP oscillator is shown in Figure 7-3.
Table 7-1 shows the capacitor selection for the Timer1
oscillator.
The user m us t prov id e a so ftware time delay to en su re
proper oscillator start-up.
FIGURE 7-3: EX TER NAL
COMPONENTS FOR THE
TIMER1 LP OSCILLATOR
T ABLE 7-1: CAPACITOR SELECTION FOR
THE TIMER1 OSCILLATOR
7.7 Timer1 Oscillator Layout
Considerations
The Timer1 oscillator circuit draws very little power
during operation. Due to the low-power nature of the
oscillator, it may also be sensitive to rapidly changing
signals in close proximity.
The oscillator circuit, shown in Figure 7-3, should be
located as close as possible to the microcontroller.
There should be no circuits passing within the oscillator
circuit boundaries other than VSS or VDD.
If a high-speed circui t mus t b e l oc ate d n ear the oscilla-
tor, a grounded guard ring around the oscillator circuit,
as shown in Figure 7-4, may be helpful when used on
a single-sided PCB or in addition to a ground plane.
FIGURE 7-4: OSCILLATOR CIRCUIT
WITH GROUNDED
GUARD RING
Note: The Timer1 oscillator shares the T1OSI
and T1OSO pins with the PGD and PGC
pins used for programming and
debugging.
When using the Timer1 osc illator, In-Circuit
Serial Programming™ (ICSP™) may not
function correctly (high voltage or low
voltage), or the In-Circuit Debugger (ICD)
may not communicate with the controller.
As a result of using either ICSP or ICD, the
Timer1 crystal m ay be dam aged.
If ICSP or ICD operatio ns are requi red, the
crystal should be disconnected from the
circuit (disconnect either lead) or installed
after programming. The oscillator loading
capacitors may remain in-circuit during
ICSP or ICD operation.
PIC16F87/88
T1OSI
T1OSO
C2
33 pF
C1
33 pF
XTAL
32.768 kHz
Note: See the Notes with Table 7-1 for additional
information about capacitor selection.
Osc Type Freq C1 C2
LP 32 kHz 33 pF 33 pF
Note 1: Microchip suggests this value as a starting
point in validating the oscillator circuit.
2: Higher capacit ance inc reases the st abilit y
of the oscillator but also increases the
start-up time.
3: Since each resonator/crystal has its own
characteristics, the user should consult
the resonator/crystal manufacturer for
appropriate values of external
components.
4: Capacitor values are for design guidance
only.
OSC1
VSS
OSC2
RB7
RB6
RB5
PIC16F87/88
DS30487D-page 76 2002-2013 Microchip Technology Inc.
7.8 Resetting Timer1 Using a CCP
Trigger Output
If the CCP1 module is configured in Compare mode to
generate a “special event trigger” signal
(CCP1M3:CCP1M0 = 1011), the signal will reset
Timer1 and start an A/D conversion (if the A/D module
is enabled).
T ime r1 must be c onfigured fo r either T ime r or Synchr o-
nized Counter mode to take advantage of this feature.
If Timer1 is running in Asynchronous Counter mode,
this Reset operation may not work.
In the event that a write to Timer1 coincides with a
special event trigger from CCP1, the write will take
precedence.
In this mode of operation, the CCPR1H:CCPR1L
register pair e ffectively bec om es th e pe riod regi ste r for
Timer1.
7.9 Resetting Timer1 Register Pair
(TMR1H, TMR1L)
TMR1H an d TMR1L reg isters are not rese t to 00h on a
POR, or any other Reset, except by the CCP1 special
event triggers.
T1CON re gister is re set to 00h o n a Power-on Re set or
a Brown-out Reset, which shuts off the timer and
leaves a 1:1 prescale. In all other Resets, the register
is unaffected.
7.10 Timer1 Prescaler
The prescaler counter is cleared on writes to the
TMR1H or TMR1L registers.
7.11 Using Tim er1 as a Real-Time
Clock
Adding an extern al LP os cilla tor to Timer1 (such a s the
one described in Section 7.6 “Timer1 Oscillator”)
gives users the option to include RTC functionality to
their applications. This is accomplished with an inex-
pensive watch crystal to provide an accurate time base
and several lines of application code to calculate the
time. When operating in Sleep mode and using a
battery or supercapacitor as a power source, it can
completely eliminate the need for a separate RTC
device and battery backup.
The application code routine, RTCisr, shown in
Example 7-3, demonstrates a simple method to
increment a counter at one-second intervals using an
Interrupt Service Routine. Incrementing the TMR1
register pair to overflow triggers the interrupt and calls
the routine, which increments the seconds counter by
one; additional counters for minutes and hours are
inc remented as the previous coun ter overflows.
Since the register pair is 16 bits wide, counting up to
overflow the register directly from a 32.768 kHz clock
would take 2 seconds. To force the overflow at the
required one-second intervals, it is necessary to pre-
load it; the simplest m ethod is to set the MSb of TMR1H
with a BSF instruction. Note that the TMR1L register is
never preloaded or altered; doing so may introduce
cumulative error over many cycles.
For this m ethod to be a ccurate, T imer 1 must o perate in
Asynchronous mode and the Timer1 overflow interrupt
must be enabled (PIE1<0> = 1), as shown in the
routine, RTCinit. The Timer1 oscillator must also be
enabled and running at all times.
Note: The special event triggers from the CCP1
module will not set interrupt flag bit,
TMR1IF (PIR1<0>).
2002-2013 Microchip Technology Inc. DS30487D-page 77
PIC16F87/88
EXAMPLE 7-3: IMPLEMENTING A REAL-TIME CLOCK USING A TIMER1 INTERRUPT SERVICE
TABLE 7-2: REGISTERS ASSOCIATED WITH TIMER1 AS A TIMER/COUNTER
RTCinit BANKSEL TMR1H
MOVLW 0x80 ; Preload TMR1 register pair
MOVWF TMR1H ; for 1 second overflow
CLRF TMR1L
MOVLW b’00001111’ ; Configure for external clock,
MOVWF T1CON ; Asynchronous operation, external oscillator
CLRF secs ; Initialize timekeeping registers
CLRF mins
MOVLW .12
MOVWF hours
BANKSEL PIE1
BSF PIE1, TMR1IE ; Enable Timer1 interrupt
RETURN
RTCisr BANKSEL TMR1H
BSF TMR1H, 7 ; Preload for 1 sec overflow
BCF PIR1, TMR1IF ; Clear interrupt flag
INCF secs, F ; Increment seconds
MOVF secs, w
SUBLW .60
BTFSS STATUS, Z ; 60 seconds elapsed?
RETURN ; No, done
CLRF seconds ; Clear seconds
INCF mins, f ; Increment minutes
MOVF mins, w
SUBLW .60
BTFSS STATUS, Z ; 60 seconds elapsed?
RETURN ; No, done
CLRF mins ; Clear minutes
INCF hours, f ; Increment hours
MOVF hours, w
SUBLW .24
BTFSS STATUS, Z ; 24 hours elapsed?
RETURN ; No, done
CLRF hours ; Clear hours
RETURN ; Done
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on
POR, BOR
Value on
all other
Resets
0Bh, 8Bh,
10Bh, 18Bh INTCON GIE PEIE TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 0000 000x 0000 000u
0Ch PIR1 ADIF(1) RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF -000 0000 -000 0000
8Ch PIE1 ADIE(1) RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE -000 0000 -000 0000
0Eh TMR1L Holding Register for the Least Significant Byte of the 16-bit TMR1 Register xxxx xxxx uuuu uuuu
0Fh TMR1H Holding Register for the Most Significant Byte of the 16-bit TMR1 Register xxxx xxxx uuuu uuuu
10h T1CON T1RUN T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON -000 0000 -uuu uuuu
Legend: x = unk nown, u = unchanged, - = unimplemented, read as ‘0’. Shaded cells are not used by the Timer1 module.
Note 1: This bit is only implemented on the PIC16F88. The bit will read ‘0’ on the PIC16F87.
PIC16F87/88
DS30487D-page 78 2002-2013 Microchip Technology Inc.
NOTES:
2002-2013 Microchip Technology Inc. DS30487D-page 79
PIC16F87/88
8.0 TIMER2 MODULE
Timer2 is an 8-bit timer with a prescaler and a post-
scaler. It can be used as the PWM time base for the
PWM mod e of the C CP1 modul e. The TMR 2 regist er is
readable and writable and is cleared on any device
Reset.
The in put cloc k (FOSC/4) has a prescale option of 1:1,
1:4 or 1:16, selected by control bits
T2CKPS1:T2CKPS0 (T2CON<1: 0>).
The Timer2 module has an 8-bit period register, PR2.
Timer2 increments from 00h until it matches PR2 and
then resets to 00h on the next increment cycle. PR2 is
a readable and writable register. The PR2 register is
initialized to FFh upon Reset.
The matc h output of TMR2 goes through a 4-bit post-
scaler (which gives a 1:1 to 1:16 scaling inclusive) to
generate a TMR2 interrupt (latched in flag bit TMR2IF
(PIR1<1>)).
Timer2 can be sh ut off by clearing control bit TMR2ON
(T2CON<2>) to minimize power consumption.
Register 8-1 shows the Timer2 Control register.
Additional information on timer modules is available in
the “PIC® Mid-Range MCU Family Reference Manual”
(DS33023).
8.1 Timer2 Prescaler and Postscaler
The prescaler and postscaler counters are cleared
when any of the following occurs:
A write to the TMR2 register
A write to the T2CON register
Any devic e R ese t (P ower-o n Re se t, MCL R, WDT
Reset or Brown-out Reset)
TMR2 is not cleared when T2CON is written.
8.2 Output of TMR2
The output of TMR2 (before the pos t scale r) is fed to the
Synchronous Serial Port module (SSP) which optionally
uses it to generate a shif t clock .
FIGURE 8-1: TIMER2 BLOCK DIAGRAM
Comparator
TMR2
Sets Flag
TMR2 reg
Output(1)
Reset
Postscaler
Prescaler
PR2 reg
2
FOSC/4
1:1 1:16
1:1, 1:4, 1:16
EQ
4
bit TMR2IF
Note 1: TMR2 register output can be software selected by the
SSP module as a baud clock.
to
PIC16F87/88
DS30487D-page 80 2002-2013 Microchip Technology Inc.
REGISTER 8-1: T2CON: TIMER2 CONTROL REGISTER (ADDRESS 12h)
TABLE 8-1: REGISTERS ASSOCIATED WITH TIMER2 AS A TIMER/COUNTER
U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0
TOUTPS3 TOUTPS2 TOUTPS1 TOUTPS0 TMR2ON T2CKPS1 T2CKPS0
bit 7 bit 0
bit 7 Unimplemented: Read as0
bit 6-3 TOUTPS<3:0>: Timer2 Output Postscale Select bits
0000 =1:1 Postscale
0001 =1:2 Postscale
0010 =1:3 Postscale
1111 =1:16 Postscale
bit 2 TMR2ON: Timer2 On bit
1 = Timer2 is on
0 = Timer2 is off
bit 1-0 T2CKPS<1:0>: Timer2 Clock Prescale Select bits
00 = Prescaler is 1
01 = Prescaler is 4
1x = Prescaler is 16
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on
POR, BOR
Value on
all other
Resets
0Bh, 8Bh,
10Bh, 18Bh INTCON GIE PEIE TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 0000 000x 0000 000u
0Ch PIR1 ADIF(1) RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF -000 0000 -000 0000
8Ch PIE1 ADIE(1) RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE -000 0000 -000 0000
11h TMR2 Timer2 Module Register 0000 0000 0000 0000
12h T2CON TOUTPS3 TOUTPS2 TOUTPS1 TOUTPS0 TMR2ON T2CKPS1 T2CKPS0 -000 0000 -000 0000
92h PR2 Timer2 Period Register 1111 1111 1111 1111
Legend: x = unk nown, u = unchanged, - = unimplemented, read as ‘0’. Shaded cells are not used by the Timer2 module.
Note 1: This bit is only implemented on the PIC16F88. The bit will read ‘0’ on the PIC16F87.
2002-2013 Microchip Technology Inc. DS30487D-page 81
PIC16F87/88
9.0 CAPTURE/COMPARE/PWM
(CCP) MODULE
The Cap ture /C ompare/PWM (CCP) m od ule co nt ains a
16-bit register that can operate as a:
16-bit Capture re giste r
16-bit Compare register
PWM Master/Slave Duty Cycle register.
Table 9-1 shows the timer resources of the CCP
module modes.
Capture/Compare/PWM Register 1 (CCPR1) is com-
prised of two 8-bit registers: CCPR1L (low byte) and
CCPR1H (high byte). The CCP1CON register controls
the operation of CCP1. The special event trigger is
generate d by a comp are match w hich will reset T i mer1
and start an A/D conversion (if the A/D module is
enabled).
The CCP module’s input/output pin (CCP1) can be
configu red as RB0 or RB3. T his selec tion is s et in bit 1 2
(CCPMX) of the Configuration Word.
Additional information on the CCP module is available
in th e “PIC® Mid-Range MCU Family Reference Man-
ual” (DS3 302 3) a nd in Ap pl ica tio n N ot e AN594, Using
the CCP Module(s)” (DS00594).
TABLE 9-1: CCP MODE – TIMER
RESOURCE
REGISTER 9-1: CCP1CON: CAPTURE/COMPARE/PWM CONTROL REGISTER 1 (ADDRESS 17h)
CCP Mode Ti mer Re source
Capture
Compare
PWM
Timer1
Timer1
Timer2
U-0 U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0
CCP1X CCP1Y CCP1M3 CCP1M2 CCP1M1 CCP1M0
bit 7 bit 0
bit 7-6 Unimplemented: Read as0
bit 5-4 CCP1X:CCP1Y: PWM Leas t Sign ificant bits
Capture mode:
Unused.
Compare mode:
Unused.
PWM mode:
These bits are the two LSbs of the PWM duty cycle. The eight MSbs are found in CCPR1L.
bit 3-0 CCP1M<3:0>: CCP1 Mode Select bits
0000 = Capture/Compare/PWM disabled (resets CCP1 module)
0100 = Capture mode, every falling edge
0101 = Capture mode, every rising edge
0110 = Capture mode, every 4th rising edge
0111 = Captur e mode, every 16th rising edge
1000 = Compare mode, set output on match (CCP1IF bi t is set)
1001 = Compare mode, clear output on match (CCP1IF bit is set)
1010 = Compare mode, generate software interrupt on match (CCP1IF bit is set, CCP1 pin is
unaffected)
1011 = Compare mo de, trigger spec ial event (CCP1 IF bit is set, C CP1 pin is unaf fected); CCP1
resets TMR1 and starts an A/D conversion (if A/D module is enabled)
11xx =PWM mode
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
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DS30487D-page 82 2002-2013 Microchip Technology Inc.
9.1 Capture Mode
In Capture mode, CCPR1H:CCPR1L captures the
16-bit val ue of the TMR1 register when an event occurs
on the CCP1 pin. An event is defined as:
Every falling edge
Every rising edge
Every 4th rising edge
Every 16th rising edge
An event is selected by control bits CCP1M3:CCP1M0
(CCP1CON<3:0>). When a capture is made, the inter-
rupt request flag bit, CCP1IF (PIR1<2>), is set. It must
be cle ared in so ftware. If a nother captu re occurs b efore
the value in register CCPR1 is read, the old captured
value is overwritten by the new captured value.
9.1.1 CCP PIN CONFIGURATION
In Capture mode, the CCP1 pin should be configured
as an input by setting the TRISB<x> bit.
FIGURE 9-1: CAPTURE MODE
OPER ATI ON BLO CK
DIAGRAM
9.1.2 TIMER1 MOD E SELECTION
Timer1 must be running in Timer mode or Synchro-
nized Counter mode for the CCP module to use the
capture feature. In Asynchronous Counter mode, the
capture operation may not work.
9.1.3 SOFTWARE INTERRUPT
When the Capture mode is changed, a false capture
interrupt may be generated. The user should keep bit
CCP1IE (PIE1<2>) clear to avoid false interrupts and
should clear the flag bit, CCP1IF, following any such
change in ope rati ng mod e.
9.1.4 CCP PRESCALER
There are four prescaler settings, specified by bits
CCP1M3:CCP1M0. Whenever the CCP module is
turned off, or the CCP module is not in Capture mode,
the prescaler counter is cleared. This means that any
Reset will clear the prescaler counter.
Switching from one capture prescaler to another may
generate an interrupt. Also, the prescaler counter will
not be cleare d, therefore , the first cap ture may be from
a non-zero prescaler. Example 9-1 shows the recom-
mended method for switching between capture
prescalers. This example also clears the prescaler
counter and will not generate the “false” interrupt.
EXAMPLE 9-1: CHANGING BETWEEN
CAPTURE PRESCALERS
Note 1: If the CCP1 pin is configured as an
output, a write to the port can cause a
capture co ndition.
2: The TR ISB b it (0 o r 3 ) is d ependent upon
the setting of configuration bit 12
(CCPMX).
CCPR1H CCPR1L
TMR1H TMR1L
Set Flag bit CCP1IF
(PIR1<2>)
Capture
Enable
Qs CCP1CON<3:0>
CCP 1 p i n
Prescaler
1, 4, 16
and
Edge Detect
CLRF CCP1CON ;Turn CCP module off
MOVLW NEW_CAPT_PS ;Load the W reg with
;the new prescaler
;move value and CCP ON
MOVWF CCP1CON ;Load CCP1CON with this
;value
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PIC16F87/88
9.2 Compare Mode
In C ompare mo de, t he 16 -bit CC PR1 r egist er va lue is
constantly compared against the TMR1 register pair
value. When a match occurs, the CCP1 pin is:
Driven high
•Driven low
Remains unchanged
The action on the pin is based on the value of control
bits CCP1M3:CCP1M0 (CCP1CON<3:0>). At the
same time, interrupt flag bit, CCP1IF, is set.
FIGURE 9-2: COMPARE MODE
OPER ATI ON BLO CK
DIAGRAM
9.2.1 CCP PIN CONFIGURATION
The user m us t co nfig ure t he CC P1 p in a s an outp ut b y
clearing the TRISB<x> bit.
9.2.2 TIMER1 MOD E SELECTION
Timer1 must be running in Timer mode or Synchro-
nized Counter mode if the CCP module is using the
compare feature. In Asynchronous Counter mode, the
compare operation may not work.
9.2.3 SOFTWARE INTERRUPT MODE
When gen erat e sof tware i nte rrupt is chosen, the CCP1
pin is not af fected. On ly a CCP interrupt is generated (if
enabled).
9.2.4 SPECIAL EVENT TRIGGER
In this mode, an internal hardware trigger is generated
that may be used to initiate an action.
The special event trigger output of CCP1 resets the
TMR1 re gist e r p ai r and starts an A/D conversion (if the
A/D module is enabled). This allows the CCPR1
register to effectivel y be a 16-bit programmable period
register for Timer1.
TABLE 9-2: REGISTERS ASSOCIATED WITH CAPTURE, COMPARE AND TIMER1
CCPR1H CCPR1L
TMR1H TMR1L
Comparator
QS
ROutput
Logic
Special Event Trigger
Set Flag bit CCP1IF
(PIR1<2>)
Match
CCP1 pin
TRISB<x> CCP1CON<3:0>
Mode Selec t
Output Enab le
Special Event T rigger will:
Reset Timer1 but not set interrupt flag bit, TMR1IF
(PIR1<0>)
Set bit GO/DONE (ADCON0<2>) which starts an A/D
conversion
Note 1: Clearing th e CCP1CO N register w ill force
the CCP1 compare output latch to the
default low level. This is not the data
latch.
2: The TR ISB b it (0 o r 3) is dependent upo n
the setting of configuration bit 12
(CCPMX).
Note: The special event trigger from the CCP1
module will not set interrupt flag bit
TMR1IF (PIR1<0>).
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on
POR, BOR
Value on
all other
Resets
0Bh,8Bh
10BH,18Bh INTCON GIE PEIE TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 0000 000x 0000 000u
0Ch PIR1 ADIF(1) RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF -000 0000 -000 0000
8Ch PIE1 ADIE(1) RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE -000 0000 -000 0000
86h TRISB PORTB Data Direction Register 1111 1111 1111 1111
0Eh TMR1L Holding Register for the Least Significant Byte of the 16-bit TMR1 Register xxxx xxxx uuuu uuuu
0Fh TMR1H Holding Register for the Most Significant Byte of the 16-bit TMR1 Register xxxx xxxx uuuu uuuu
10h T1CON T1RUN T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON -000 0000 -uuu uuuu
15h CCPR1L Capture/Compare/PWM Register 1 (LSB) xxxx xxxx uuuu uuuu
16h CCPR1H Capture/Compare/PWM Register 1 (MSB) xxxx xxxx uuuu uuuu
17h CCP1CON CCP1X CCP1Y CCP1M3 CCP1M2 CCP1M1 CCP1M0 --00 0000 --00 0000
Legend: x = unknown, u = unchanged, - = unimplemented, read as ‘0’. Shaded cells are not used by Capture and Timer1.
Note 1: This bit is only implemented on the PIC16F88. The bit will read ‘0’ on the PIC16F87.
PIC16F87/88
DS30487D-page 84 2002-2013 Microchip Technology Inc.
9.3 PWM Mode
In Pulse -Width Modulati on (PWM) m ode, the CCP1 pin
produces up to a 10-bit resolution PWM output. Since
the CCP1 pin is multiplexed with the PORTB data latch,
the TRISB<x> bit must be cleared to make the CCP1
pin an output.
Figure 9-3 shows a simplified block diagram of the
CCP module in PWM mode.
For a ste p-by-step proc edure on how t o set up the CC P
module for PWM operation, see Section 9.3.3 “Setup
for PWM Operatio n”.
FIGURE 9-3: SIMPLIFIED PWM BLOCK
DIAGRAM
A PWM output (Figure 9-4) has a time base (period)
and a time that the output stays high (duty cycle). The
frequency of the PWM is the inverse of the period
(1/period).
FIGURE 9-4: PWM OUTPUT
9.3.1 PWM PE RIOD
The PWM period is specified by writing to the PR2
register. The PWM period can be calculated using the
following formula.
EQUATION 9-1:
PWM frequency is defined as 1/[PWM period ].
When TM R2 is equal to PR2, t he following three event s
occur on the next increment cycle:
•TMR2 is cleared
The CCP1 pin is set (exception: if PWM duty
cycle = 0%, the CCP1 pin will not be set)
The PWM duty cycle is latched from C CPR1L into
CCPR1H
9.3.2 PW M DUTY CYCLE
The PWM duty cycle is specified by writing to the
CCPR1L register and to the CCP1CON<5:4> bits. Up
to 10- b i t re so l uti on is av ai l ab le. T he CC PR 1L c on tai ns
the eight MSbs and the CCP1CON<5:4> bits contain
the two LSbs. This 10-bit value is represented by
CCPR1L:CCP1CON<5:4>. The following equation is
used to calculate the PWM duty cycle in time.
EQUATION 9-2:
CCPR1L and CCP1CON<5:4> can be written to a t any
time, but the duty cycle value is not latched into
CCPR1H until after a match between PR2 and TMR2
occurs (i.e., the period is complete). In PWM mode,
CCPR1H is a read-only register.
The CCPR1H register and a 2-bit internal latch
are used to double-buffer the PWM duty cycle. This
double-buffering is essential for glitchless PWM
operation.
When the CCPR1H and 2-bit latch match TMR2,
concatenated with an internal 2-bit Q clock or 2 bits of
the TMR2 prescaler, the CCP1 pin is cleared.
Note: Clearing the CCP1CON register will force
the CCP1 PWM o utpu t la tch to th e de fau lt
low l evel. T his is not t he PO RTB I /O data
latch.
CCPR1L
CCPR1H (S lav e)
Comparator
TMR2
Comparator
PR2
(Note 1)
RQ
S
Duty Cycle Registers CCP1CON<5:4>
Clear Timer,
CCP1 pin and
latch D.C.
TRISB<x>
CCP1 pin
Note 1: 8-bit timer is concatenated with 2-bit internal Q
clock, or 2 bi ts of the prescaler, t o create 10-bit
time base.
Period
Duty Cycle
TMR2 = PR2
TMR2 = Duty Cycle
TMR2 = PR2
Note: The Timer2 postscaler (see Section 8.0
“Timer2 Module”) is not used in the deter-
mination of the PWM frequency. The post-
scaler could be used to have a servo
update rate at a different frequency than
the PWM output.
PWM Period = [(PR2) + 1] • 4 • TOSC
(TMR2 Prescal e Value)
PWM Duty Cycle = (CCPR1L:CCP1CON<5:4>) •
TOSC • (TMR2 Prescal e Value)
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The ma ximum P WM res olut ion (b its) fo r a giv en PWM
frequenc y is given b y the following formula.
EQUATION 9-3:
9.3.3 SETUP FOR PWM OPERATION
The following steps should be taken when configuring
the CCP module for PWM operation:
1. Set the PWM period by writing to the PR2
register.
2. Set the PWM duty cycle by writing to the
CCPR1L register and CCP1CON<5:4> bits.
3. Make the CCP1 pin an output by clearing the
TRISB<x> bit.
4. Set the TMR2 prescale value and enable T imer2
by writing to T2CON.
5. Configure th e CCP1 module for PWM operation.
TABLE 9-3: EXAMPLE PWM FREQUENCIES AND RESOLUTIONS AT 20 MHz
TABLE 9-4: REGISTERS ASSOCIATED WITH PWM AND TIMER2
Note: If the PWM duty cycle value is longer than
the PWM period, the CCP1 pin will not be
cleared.
log(FPWM
log(2)
FOSC )bits
=
Resolution
Note: The TR ISB bit (0 or 3) is dependant upon
the setting of configuration bit 12
(CCPMX).
PWM Frequency 1.22 kHz 4.88 kHz 19.53 kHz 78.12 kHz 156.3 kHz 208.3 kHz
Timer Prescaler (1, 4, 16) 16 4 1 1 1 1
PR2 Value 0xFF 0xFF 0xFF 0x3F 0x1F 0x17
Maximum Resolution (bits) 10 10 10 8 7 6.6
Addr e s s Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on
POR, BOR
Value on
all other
Resets
0Bh,8Bh
10Bh,18Bh INTCON GIE PEIE TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 0000 000x 0000 000u
0Ch PIR1 ADIF(1) RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF -000 0000 -000 0000
8Ch PIE1 ADIE(1) RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE -000 0000 -000 0000
86h TRISB PORTB Data Direction Register 1111 1111 1111 1111
11h TMR2 Timer2 Module Register 0000 0000 0000 0000
92h PR2 Tim er2 P eri od Regis ter 1111 1111 1111 1111
12h T2CON TOUTPS3 TOUTPS2 TOUTPS1 TOUTPS0 TMR2ON T2CKPS1 T2CKPS0 -000 0000 -000 0000
15h CCPR1L Capture/Compare /PWM Register 1 (LSB) xxxx xxxx uuuu uuuu
16h CCPR1H Capture/Comp are/PWM R egister 1 ( MSB) xxxx xxxx uuuu uuuu
17h CCP1CON CCP1X CCP1Y CCP1M3 CCP1M2 CCP1M1 CCP1M0 --00 0000 --00 0000
Legend: x = unknown, u = unchanged, - = unimplemented, read as ‘0’. Shaded cells are not used by PWM and Timer2.
Note 1: This bit is only implemented on the PIC16F88. The bit will read0’ on the PIC16F87.
PIC16F87/88
DS30487D-page 86 2002-2013 Microchip Technology Inc.
NOTES:
2002-2013 Microchip Technology Inc. DS30487D-page 87
PIC16F87/88
10.0 SYNCHRONOUS SERIAL PORT
(SSP) MODULE
10.1 SSP Module Overview
The Synchronous Serial Port (SSP) module is a serial
interface useful for communicating with other periph-
eral or microcontroller devices. These peripheral
devices may be serial EEPROMs, shift registers,
display drivers, A/D converters, etc. The SSP module
can operate in one of two modes:
Serial Peripheral Interface (SPI)
Inter-Integrated Circuit (I2C™)
An overview of I2C operations and additional informa-
tion on t he SSP module c an be fo und in the “PIC® Mid-
Range MCU Family Reference Manual” (DS33023).
Refer to Application Note AN578, “Use of the SSP
Module in the I 2C™ Multi-Master Environment”
(DS00578).
10.2 SPI Mode
This section contains register definitions and
operational characteristics of the SPI module.
SPI mode allows 8 bits of data to be synchronously
transmitted and received simultaneously. To
accomplish communication, typically three pins are
used:
Serial Data Out (SDO) RB2/SDO/RX/DT
Serial Data In (SDI) RB1/SDI/SDA
Serial Clock (SCK) RB4/SCK/SCL
Additionally, a fourth pin may be used when in a Slave
mode of operation:
Slave Select (SS) RB5/SS/TX/CK
When initializing the SPI, several options need to be
specified. This is done by programming the appropriate
control bits in the SSPCON register (SSPCON<5:0>)
and the SSPSTAT register (SSPSTAT<7:6>). These
control bits allow the foll owing to be specified:
Master mode (SCK is the clock output)
Slave mode (SCK is the clock input)
Clock Polarity (Idle state of SCK)
Clock Edge (output data on rising/falling
edge of SCK)
Clock Rate (Master mode only)
Slave Select mode (Slave mode only)
Note: Before enabling the module in SPI Slave
mode, the state of the clock line (SCK)
must match the polarity selected for the
Idle state. The clock line can be observed
by read ing the SCK pin. The pola rity of th e
Idle state is determined by the CKP bit
(SSPCON<4>).
PIC16F87/88
DS30487D-page 88 2002-2013 Microchip Technology Inc.
REGISTER 10-1: SSPSTAT: SYNCHRONOUS SERIAL PORT STATUS REGISTER (ADDRESS 94h)
R/W-0 R/W-0 R-0 R-0 R-0 R-0 R-0 R-0
SMP CKE D/A P(1) S(1) R/W UA BF
bit 7 bit 0
bit 7 SMP: SPI Data Input Sample Phase bit
SPI Master mode:
1 = Input data sampled at end of data output time
0 = Input data sampled at middle of data output time (Microwire)
SPI Slave mode:
This bit must be cleared when SPI is used in Slave mode.
I2 C mode:
This bit must be maintained clear.
bit 6 CKE: SPI Clock Edge Select bit
1 = Transmit occurs on transition from active to Idle clock state
0 = Transmit occurs on transition from Idle to active clock state
Note: Polarity of clock state is set by the CKP bit (SSPCON<4>).
bit 5 D/A: Data /Addr ess bit (I2C mode only)
In I2 C Slave mode:
1 = Indicates that the last byte received was data
0 = Indicates that the last byte received was address
bit 4 P: Stop bit(1) (I2C mode onl y )
1 = Indicates that a Stop bit has been detected last
0 = Stop bit was not detected last
bit 3 S: Start bit(1) (I2C mode only)
1 = Indicates that a Start bit has been detected last (this bit is ‘0’ on Reset)
0 = Start bit was not detected last
bit 2 R/W: Read/Write Information bit (I2C mode only)
Holds the R/W bit inform ation fol lowing th e last add ress matc h and is on ly vali d from add ress
match to the next Start bit, Stop bit or ACK bit.
1 =Read
0 = Write
bit 1 UA: Update Address bit (10-bit I2C mode onl y)
1 = Indicates that the user needs to update the address in the SSPADD register
0 = Address does not need to be updated
bit 0 BF: Buffer Full Status bit
Receive (SPI and I2 C modes):
1 = Receive complete, SSPBUF is full
0 = Receive not complete, SSPBUF is empty
Transmit (in I2 C mode only) :
1 = Transmit in progress, SSPBUF is full (8 bits)
0 = Transmit complete, SSPBUF is empty
Note 1: This bit is cleared when the SSP module is disabled (i.e., the SSPEN bit is cleared).
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
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PIC16F87/88
REGISTER 10-2: SSPCON: SYNCHRONOUS SERIAL PORT CONTROL REGISTER (ADDRESS 14h)
R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0
WCOL SSPOV SSPEN(1) CKP SSPM3 SSPM2 SSPM1 SSPM0
bit 7 bit 0
bit 7 WCOL: Write Collision Detect bit
1 = An attempt to write the SSPBUF register failed because the SSP module is busy
(must be cleared in software)
0 = No collision
bit 6 SSPOV: Receive Overflow Indicator bit
In SPI mode:
1 = A new byte is rec eived whil e the SSPBUF regist er is still holding th e previou s data. In c ase
of overfl ow, the data in SSPSR is lost. Overflow can only occur in Slave mode. The user
must read the SSPBUF, even if only trans mittin g data, to avoid setting ov erfl ow. In Mast er
mode, the overflow bit is not set since each new reception (and transmission) is initiated
by writing to the SSPBUF register.
0 = No overflow
In I2 C mode:
1 = A byte is received while the SSPBUF register is still holding the previous byte. SSPOV is
a “don’t care” in Transmit mode. SSPOV must be cleared in software in either mode.
0 = No overflow
bit 5 SSPEN: Synchronous Serial Port Enable bit(1)
In SPI mode:
1 = Enables serial port and configures SCK, SDO and SDI as serial port pins
0 = Disables serial port and configures these pins as I/O port pins
In I2 C mode:
1 = Enables the serial port and configures the SDA and SCL pins as serial port pins
0 = Disables serial port and configures these pins as I/O port pins
Note 1: In both modes, when enabled, these pins must be properly configured as input or
output.
bit 4 CKP: Clock Polarity Select bit
In SPI mode:
1 = T ransm it happens on falling edg e, receive on ris ing edge. Idl e state for c lock is a hi gh level.
0 = Transmit h app ens on ris ing edg e, re ce iv e on falling edge. Idl e s t ate for c lo ck is a l ow le vel.
In I2 C Slave mode:
SCK release control
1 = Enable clock
0 = Holds clock low (clock stretch). (Used to ensure data setup time.)
bit 3-0 SSPM<3:0>: Synchronous Serial Port Mode Select bits
0000 = SPI Master mode, clock = OSC/4
0001 = SPI Master mode, clock = OSC/16
0010 = SPI Master mode, clock = OSC/64
0011 = SPI Master mode, clock = TMR2 ou tput/2
0100 = SPI Slave mode, clock = SCK pin. SS pin control enabled.
0101 = SPI Slave mode, clock = SCK pin. SS pin control dis ab led . SS can be used as I/O pin.
0110 = I2C Slave mode, 7-bit address
0111 = I2C Slave mode, 10-bit address
1011 = I2C Firmware Controlled Master mode (Slave Idle)
1110 = I2C Slave mode, 7-bit address with Start and Stop bit interrupts enabled
1111 = I2C Slave mode, 10-bit address with Start and Stop bit interrupts enabled
1000, 1001, 1010, 1100, 1101 = Reserved
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
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DS30487D-page 90 2002-2013 Microchip Technology Inc.
FIGURE 10-1: SS P BLOC K DIAGRAM
(SPI MODE) To enable the serial port, SSP Enable bit, SSPEN
(SSPCON<5>), must be set. To reset or reconfigure
SPI mode, clear bit SSPEN, reinitialize the SSPCON
register and then set bit SSPEN. This configures the
SDI, SDO, SCK and SS pins as serial port pins. Fo r the
pins to behave as the serial port function, they must
have their data direction bits (in the TRISB register)
appropriately programmed. That is:
SDI must have TRISB<1> set
SDO must have TRISB<2> cleared
SCK (Master mode) must have TRISB<4>
cleared
SCK (Slave mode) must have TRISB<4> set
•SS
must have TRISB<5> set
TABLE 10-1: REGISTERS ASSOCIATED WITH SPI OPERATION
Read Write
Internal
Data Bus
RB1/SDI/SDA
RB2/SDO/RX/DT
RB5/SS/
RB4/SCK/
SSPSR reg
SSPBUF reg
SSPM3:SSPM0
bit0 Shift
Clock
SS Control
Enable
Edge
Select
Clock Select
TMR2 Output
TCY
Prescaler
4, 16, 64
TRISB<4>
2
Edge
Select
2
4
SCL
TX/CK
Note 1: When the SPI is in Slave mode with SS pin
control enabled (SSPCON<3:0> = 0100),
the SPI module will reset if the SS pin is
set to VDD.
2: If the SPI is used in Slave mode with
CKE = 1, then the SS pin control must be
enabled.
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on
POR, BOR
Value on
all other
Resets
0Bh,8Bh
10Bh,18Bh INTCON GIE PEIE TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 0000 000x 0000 000u
0Ch PIR1 ADIF(1) RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF -000 0000 -000 0000
8Ch PIE1 ADIE(1) RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE -000 0000 -000 0000
86h TRISB PO RTB Data Direction Register 1111 1111 1111 1111
13h SSPB UF Synchronous Serial Port Receive Buffer/Transmit Register xxxx xxxx uuuu uuuu
14h SSPCON WCOL SSPOV SSPEN CKP SSPM3 SSPM2 SSPM1 SSPM0 0000 0000 0000 0000
94h SSPSTAT SMP CKE D/A P S R/W UA BF 0000 0000 0000 0000
Legend: x = unk nown, u = unchanged, - = unimplemented, read as ‘0’. Shaded cells are not used by the SSP in SPI mode.
Note 1: This bit is only implemented on the PIC16F88. The bit will read ‘0’ on the PIC16F87.
2002-2013 Microchip Technology Inc. DS30487D-page 91
PIC16F87/88
FIGURE 10-2: SPI MODE TIMING (MASTER MODE)
FIGURE 10-3: SPI MODE TIMING (SLAVE MODE WITH CKE = 0)
FIGURE 10-4: SPI MODE TIMING (SLAVE MODE WITH CKE = 1)
SCK (CKP = 0,
SDI (SMP = 0)
SSPIF
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
SDI (SMP = 1)
SCK (CKP = 0,
SCK (CKP = 1,
SCK (CKP = 1,
SDO
bit 7
bit 7 bit 0
bit 0
CKE = 0)
CKE = 1)
CKE = 0)
CKE = 1)
SCK (CKP = 0)
SDI (SMP = 0)
SSPIF
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
SCK (CKP = 1)
SDO
bit 7 bit 0
SS (Optional)
SCK ( CKP = 0)
SDI (SMP = 0)
SSPIF
bit 7 bi t 6 bi t 5 bit 4 bit 3 bit 2 bit 1 bit 0
SCK ( CKP = 1)
SDO
bit 7 bit 0
SS
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10.3 SSP I 2C Mode Operation
The SSP m odule in I2C mode full y implement s all slave
functions, except general call support and provides
inter rupts on S ta rt and S top bit s in hardware to fac ilitate
firmwa re im ple me nt a tion s of the master func tio ns . The
SSP module implements the standard mode
specifications, as well as 7-bit and 10-bit addressing.
T wo pins are used for da ta transfer . These are the RB4/
SCK/SCL pin, which is the clock (SCL) and the RB1/
SDI/S DA pin, which i s the data ( SDA). T he user mu st
configure these pins as inputs or outputs through the
TRIS B<4,1> bits.
To ensure proper communication of the I2C Slave mode,
the TRIS bits (TRISx [SDA, SCL]) corresponding to the
I2C pin s must be set to ‘1’. If any TRIS bits (TRISx<7:0>)
of the port containing the I2C pins (PORTx [SDA, SCL])
are changed in software during I2C communication
using a Read-Modify-Write instruction (BSF, BCF) , then
the I2C mode may stop functioning properly and I2C
communication m ay suspend . Do not chan ge any of the
TRISx bits (TRIS bits of the port cont aining the I2C pins)
using the instruction BSF or BCF during I2C comm unica-
tion. If it is absolutely necessary to change the TRISx
bits during communication, the following m ethod ca n be
used:
EXAMPL E 10-1:
The SSP mod ule fun ctions a re enabl ed by settin g SSP
Enable bit, SSPEN (SSPCON<5>).
FIGURE 10-5: SS P BLOC K DIAGRAM
(I2C™ MODE)
The SSP module has five registers for I2C operation:
SSP Control register (SSPCON)
SSP Status register (SSPSTAT)
Serial Rece iv e/Transmit Buf f er regi st er (SSPBUF)
SSP Shift register (SSPSR) – Not directly
accessible
SSP Address register (SSPADD)
The SSPCON register al lows control of the I 2C opera-
tion. Four mode selection bits (SSPCON<3:0>) allow
one of the following I2C modes to be selected:
•I
2C Slave mode (7-bit address)
•I
2C Slave mode (10-bit address)
•I
2C Slave mode (7-bit address) with Start and
Stop bit interrupts enabled to support Firmware
Controlled Master mode
•I
2C Slave mode (10-bit address) with Start and
Stop bit interrupts enabled to support Firmware
Controlled Master mode
•I
2C Firmware Controlled Master mode operation
with Start and S top bit in terru pts enabled; sla ve i s
Idle
Selection of any I2C mode, with the SSPEN bit set,
forces the SCL and SDA pins to be open-drain, pro-
vided these pins are programmed to inputs by setting
the appropriate TRISB bits. Pull-up resistors must be
provide d external ly to the SCL and SD A pins for proper
operation of the I2C module.
Additional information on SSP I2C operation may be
found in the “PIC® Mid-Range MCU Family Re ference
Manual” (DS33023).
MOVF TRISC, W ; Example for an 18-pin part such as the PIC16F818/819
IORLW 0x18 ; Ensures <4:3> bits are ‘11’
ANDLW B’11111001’ ; Sets <2:1> as output, but will not alter other bits
; User can use their own logic here, such as IORLW, XORLW and ANDLW
MOVWF TRISC
Read Write
SSPSR Reg
Match Detect
SSPADD Reg
Start and
Stop Bit Detect
SSPBUF Reg
Internal
Data Bus
Addr Match
Set, Reset
S, P Bits
(SSPSTAT Reg)
RB4/SCK/
RB1/
Shift
Clock
MSb
SDI/ LSb
SDA
SCL
2002-2013 Microchip Technology Inc. DS30487D-page 93
PIC16F87/88
10.3.1 SLAVE MODE
In Slave mod e, the SCL and SDA pins mu st be co nfi g-
ured as in puts (TRISB<4,1> set). The SSP mo du le wil l
override the input state with the output data when
required (sl ave-tra nsmit ter).
When an add ress is matched, or the data transfer af ter
an add res s mat ch i s rece ived , th e ha rdw are au tom ati -
cally will generate the Acknowledge (ACK) pulse and
then loa d the SSPBUF re gis ter with the received value
currently in the SSPSR register.
Either or both of the following conditions will cause the
SSP module not to give this ACK pul se :
a) The Buffer Full bit, BF (SSPSTAT<0>), was set
before the transfer was received.
b) The Overflow bit, SSPOV (SSPCON<6>), was
set before the transfer was received.
In this case, the SSPSR register value is not loaded
into the SSPBUF, but bit SSPIF (PIR1<3>) is set.
Table 10-2 shows what happens when a data transfer
byte is received, given the status of bits BF and
SSPOV. The shaded cells show the condition where
user s oftw are d id no t prope rly c lear th e ove rflow cond i-
tion. Flag bit, BF, is cleared by reading the SSPBUF
register while bit, SSPOV, is cleared through software.
The SCL clock input must have a minimum high and
low fo r pro per op eration. The high an d l ow ti me s of the
I2C specification, as well as the requirement of the SSP
module, are shown in timing parameter #100 and
parameter #101.
10.3.1.1 Addressing
Once the SSP module has been enabled, it waits for a
Start condition to occur. Following the Start condition,
the eight bits are shifted into the SSPSR register. All
incoming bits are sampled with the rising edge of the
clock (SCL) line. The value of register SSPSR<7:1> is
compared to the value of the SSPADD register. The
address is compared on the falling edge of the eighth
clock (SCL) pulse. If the addresses match and the BF
and SSPOV bits are clear, the following events occur:
a) The SSPSR register value is loaded into the
SSPBUF register.
b) The Buffer Full bit, BF, is set.
c) An ACK pulse is generated.
d) SSP Interrupt Flag bit, SSPIF (PIR1<3>), is set
(interrupt is generated if enabled) – on the falling
edge of the ninth SCL pulse.
In 10-bit Address mode, two address bytes need to be
received by the slave device. The five Most Significant
bits (MSbs) of the first address byte specify if this is a
10-bit address. Bit R/W (SSPSTAT<2>) must specify a
write so the slave device will receive the second
address by te. Fo r a 10 -bi t add res s, t he fi rst byt e woul d
equal ‘1111 0 A9 A8 0’, where A9 and A8 are the
two MSbs of the address.
The sequence of events for 10-bit Address mode is as
follows, with ste p s 7-9 for slave transm it ter:
1. Receive first (high) byte of address (bits SSPIF,
BF and UA (SSPSTAT<1>) are set).
2. Update the SSPADD register with second (low)
byte of address (clears bit UA and releases the
SCL line).
3. Read the SSPBUF register (clears bit BF) and
clear flag bit SSPIF.
4. Receive second (low) byte of address (bits
SSPIF, BF and UA are set).
5. Update t he SSPADD registe r with the f irst (high)
byte of a ddre ss ; if match releases SCL li ne, this
will clear bit U A.
6. Read the SSPBUF register (clears bit BF) and
clear flag bit SSPIF.
7. Receive Repeated Start condition.
8. Receive first (high) byte of address (bits SSPIF
and BF are set).
9. Read the SSPBUF register (clears bit BF) and
clear flag bit SSPIF.
10.3.1.2 Reception
When the R/W bi t of the addres s byte i s clear and an
address match occurs, the R/W bit of the SSPSTAT
register i s cleared . Th e receive d addre ss is loa ded in to
the SSPBUF register.
When the address byte overflow condition exis ts, then
a no Acknowledge (ACK) pulse is given. An overflow
conditi on is in dicated if ei ther bit, BF (SSPSTAT<0>), is
set or bit, SSPOV (SSPCON<6>), is set.
An SSP interrupt is generated for each data transfer
byte. Flag bit, SSPIF (PIR1<3>), must be cleared in
software. The SSPSTAT register is used to determine
the status of the byte.
10.3.1.3 Transmission
When the R/W bit of the incoming address byte is set
and an address match occurs, the R/W bit of the
SSPSTAT register is set. The received address is
loaded into the SSPBUF register. The ACK pulse will
be sent on the ninth bit and pin RB4/SCK/SCL is held
low. The transmit data must be loaded into the
SSPBUF registe r which also load s the SSPSR register .
Then, pin RB4/SCK/SCL should be enabled by setting
bit CKP (SSPCON<4>). The master device must m on-
itor the SCL pin prio r to asserting another clock pulse.
The slave devices may be holding of f the master device
by stretching the clock. The eight data bits are shifted
out on the falling edge of the SCL input. This ensures
that the SDA signal is valid during the SCL high time
(Figure 10-7).
PIC16F87/88
DS30487D-page 94 2002-2013 Microchip Technology Inc.
An SSP interrupt is generated for each data transfer
byte. Flag bit, SSPIF, must be cleared in software and
the SSPSTAT register is used to determine the status
of the byte . Flag bit , SSPIF, is set on the fall ing edge of
the ninth clock pulse.
As a slave transmitter, the ACK pulse from the master
receiver is latched on the rising edge of the ninth SCL
input pulse. If the SDA line was high (not ACK), then
the dat a tran sfer is com plete. When th e ACK is latched
by the slave device, the slave logic is reset (resets
SSPSTAT register) and the s lave de vi ce then mon itor s
for another occurrence of the Start bit. If the SDA line
was low (ACK), the transmit data must be loaded into
the SSPBUF register which also loads the SSPSR
register. Then, pin RB4/SCK/SCL should be enabled
by setting bit CKP.
TABLE 10-2: DATA TRANSFER RECEIVED BYTE ACTIONS
FIGURE 10-6: I2C™ WAVEFORMS FOR RECEPTION (7-BIT ADDRESS)
FIGURE 10-7: I2C™ WAVEFORMS FOR TRANSMISSION (7-BIT ADDRESS)
Status Bits as Data
Transfer is Received SSPSR  SSPBUF Generate ACK Pulse Set SSPIF Bit
(SSP Interrupt Occurs if Enabled)
BF SSPOV
00 Yes Yes Yes
10 No No Yes
11 No No Yes
0 1 No No Yes
Note 1: Shaded cells show the conditions where the user software did not properly clear the overflow condition.
P
9
8
7
6
5
D0
D1
D2
D3D4
D5
D6D7
S
A7 A6 A5 A4 A3 A2 A1SDA
SCL 123456789123456789123
4
Bus master
terminates
transfer
Bit SSPOV is set because the SSPBUF register is still full
Cleared in software
SSPBUF register is read
ACK Receiving Data
Receiving Data D0
D1
D2
D3D4
D5
D6D7
ACK
R/W = 0
Receiving Address
SSPIF (PIR1<3>)
BF (SSPSTAT<0>)
SSPOV (SSPC ON<6>)
ACK
ACK is not sent
SDA
SCL
SSPIF (PIR1<3>)
BF (SSPSTAT<0>)
CKP (SSPCON<4>)
A7 A6 A5 A4 A3 A2 A1 ACK D7 D6 D5 D4 D3 D2 D1 D0 ACK
Transmitting DataR/W = 1Receiving Address
123456789 123456789 P
Cleared in software
SSPBUF is written in software From SSP Interrupt
Service Routine
Set bit after writing to SSPBUF
SData is
sampled SCL held low
while CPU
responds to SSPIF
(the SSPBUF must be written to
before the CKP bit can be set)
2002-2013 Microchip Technology Inc. DS30487D-page 95
PIC16F87/88
10.3.2 MASTER MODE OPERATION
Master mode operation is supported in firmware using
interrupt generation on the detection of the Start and
Stop conditions. The Stop (P) and Start (S) bits are
cleared from a Reset, or when the SSP module is dis-
abled. The Stop (P) and Start (S) bits will toggle based
on the Start and S top conditions. Control of the I2C bus
may be taken when the P bit is set, or the bus is Idle
and both the S and P bits are clear.
In Master mode operation, the SCL and SDA lines are
manipulated in firmware by clearing the corresponding
TRISB<4,1> bit(s). The output level is always low, irre-
spective of the value(s) in PORTB<4,1>. So, when
transmitting data, a ‘1’ data bit must have the
TRISB<1> bit set (input) and a ‘0’ data bit must have
the TRISB<1> bit cleared (output). The same scenario
is tru e for the S CL line wit h the TRISB <4> bit . Pull-up
resistors must be provided externally to the SCL and
SDA pins for proper operation of the I2C modul e.
The following events will cause the SSP Interrupt Flag
bit, SSPIF, to be set (SSP Interrupt if enabled):
Start condition
Stop condition
Data transfer byte transmitted/received
Master mode operation can be done with either the
Slave mode Idle (SSPM3:SSPM0 = 1011), or with the
Slave m ode ac tiv e. W he n bo th M as ter mode operation
and Slave modes are used, the software needs to
differentiate the source(s) of the interrupt.
For more information on Master mode operation, see
Application Note AN554, “Software Implementation of
I2C™ Bus Master”.
10.3.3 MULTI-MASTER MODE OPERATION
In Multi-Master mode operation, the interrupt genera-
tion on the detection of the Start and Stop conditions
allows the determination of when the bus is free. The
Stop (P) and Start (S) bits are cleared from a Reset, or
when the SSP module is disabled. The Stop (P) and
Start (S) bits will toggle based on the Start and Stop
conditions. Control of the I2C bus may be take n when
bit P (SSPSTAT<4>) is set, or the bus is Idle and both
the S and P b its cl ear. When th e bu s is b us y, en a bl i ng
the SSP interrupt will generate the interrupt when the
Stop condition occurs.
In Mul ti -Mast er mode o per atio n, t he SD A li ne m ust be
monitore d to see if the signal level is the e xpe ct ed ou t-
put level. This check only needs to be done when a
high lev el is output. If a high lev el is expec ted and a low
level is present, the device needs to release the SDA
and SCL l ines (set T RISB<4, 1>). There are two sta ges
where this arbitration can be lost:
Address Transfer
Data Transfer
When the slave logic is enabled, the slave device
continues to receive. If arbitration was lost during the
address transfer stage, communication to the device
may be in progr ess. If addres sed, a n ACK puls e wi ll be
generated. If arbitration was lost during the data
transfer stage, the device will need to retransfer the
data at a later time.
For mo re in for m ati on on Mu l ti -Ma st er mo de o pe rat i on,
see Applic ation Note AN578, “Use of the SSP Module
in the of I2C™ Multi-Master Environment”.
TABLE 10-3: REGISTERS ASSOCIATED WITH I2C™ OPERATION
Add r e s s Name Bit 7 Bi t 6 B it 5 Bit 4 Bit 3 B it 2 Bit 1 B i t 0 Value on
POR, BOR
Value on
all other
Resets
0Bh, 8Bh,
10Bh,18Bh INTCON GIE PEIE TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 0000 000x 0000 000u
0Ch PIR1 ADIF(1) RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF -000 0000 -000 0000
8Ch PIE1 ADIE(1) RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE -000 0000 -000 0000
13h SSPBUF Synchronous Serial Port Receive Buffer/Transmit Register xxxx xxxx uuuu uuuu
93h SSPADD Synchronous Serial Port (I2C mode) Address Register 0000 0000 0000 0000
14h SSPCON WCOL SSPOV SSPEN CKP SSPM3 SSPM2 SSPM1 SSPM0 0000 0000 0000 0000
94h SSPSTAT SMP(2) CKE(2) D/A PSR/WUA BF 0000 0000 0000 0000
86h TRISB PORTB Data Direction Register 1111 1111 1111 1111
Legend: x = unk nown, u = unchanged, - = unimplemented locations read as ‘0’.
Shaded cells are not used by SSP module in SPI mode.
Note 1: This bit is only implemented on the PIC16F88. The bit will read ‘0’ on the PIC16F87.
2: Maintain these bits clear in I2C™ mode.
PIC16F87/88
DS30487D-page 96 2002-2013 Microchip Technology Inc.
NOTES:
2002-2013 Microchip Technology Inc. DS30487D-page 97
PIC16F87/88
11.0 ADDRESSABLE UNIVERSAL
SYNCHRONOUS
ASYNCHRONOUS RECEIVER
TRANSMITTER (AUSART)
The Addressable Universal Synchronous Asynchronous
Receiver Transmitter (AUSART) module is one of the
two serial I/O modules. (AUSART is also known as a
Serial Communications Interface or SCI.) The AUSART
can be configured as a full-duplex asynchronous system
that can communicate with peripheral devices, such as
CRT terminals and personal computers, or it can be
configured as a half-duplex synchronous system that
can communicate with peripheral devices, such as A/D
or D/A integrated circuit s , serial EEPROMs, etc.
The AUSART can be configured in the following
modes:
Asynchronous (full-duplex)
Synchronous – Master (h alf-duple x )
Synchronous – Slav e (half-duplex)
Bit SPEN (RCSTA<7>) and bits TRISB<5,2> have to
be set in order to configure pins, RB5/SS/TX/CK and
RB2/SDO/RX/DT, as the Addressable Universal
Synchronous Asynchronous Receiver Transmitter.
The AUSART module also has a multi-processor
communication capability, using 9-bit address
detection.
REGISTER 1 1-1: TXSTA: TRANSMIT STATUS AND CONTROL REGISTER (ADDRESS 98h)
R/W-0 R/W-0 R/W-0 R/W-0 U-0 R/W-0 R-1 R/W-0
CSRC TX9 TXEN SYNC BRGH TRMT TX9D
bit 7 bit 0
bit 7 CSRC: Clock Source Select bit
Asynchronous mode:
Don’t care.
Synchronous mode:
1 = Master mode (clock generated internally from BRG)
0 = Slave mode (clock from external source)
bit 6 TX9: 9-bit Transmit Enable bit
1 = Selects 9-bit transmission
0 = Selects 8-bit transmission
bit 5 TXEN: Transmit Enable bit
1 = Transmit enabled
0 = Transmit disabled
Note: SREN/CREN overrides TXEN in Sync mode.
bit 4 SYNC: AUSART Mode Select bit
1 = Synchronous mode
0 = Asynchronous mode
bit 3 Unimplemented: Read as0
bit 2 BRGH: High Baud Rate Select bit
Asynchronous mode:
1 = High speed
0 = Low speed
Synchronous mode:
Unused in this mode.
bit 1 TRMT: Tran smit Shift Register Status bit
1 = TSR empty
0 = TSR full
bit 0 TX9D: 9th bit of Transmit Data, can be Parity bit
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
PIC16F87/88
DS30487D-page 98 2002-2013 Microchip Technology Inc.
REGISTER 1 1-2: RCST A: RECEIVE STATUS AND CONTROL REGISTER (ADDRESS 18h)
R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R-0 R-0 R-x
SPEN RX9 SREN CREN ADDEN FERR OERR RX9D
bit 7 bit 0
bit 7 SPEN: Serial Port Enable bit
1 = Serial port enabled (configures RB2/SDO/RX/DT and RB5/SS/TX/CK pins as serial port pins)
0 = Serial port disabled
bit 6 RX9: 9-bit Receive Enable bit
1 = Selects 9-bit reception
0 = Selects 8-bit reception
bit 5 SREN: Single Receive Enable bit
Asynchronous mode:
Don’t care.
Synchronous mode – Master:
1 = Enables single receive
0 = Disables single rece ive
This bit is cleared after reception is complete.
Synchronous mode – Slave:
Don’t care.
bit 4 CREN: Continuous Receive Enable bit
Asynchronous mode:
1 = Enables continuous receive
0 = Disables continuous rec eive
Synchronous mode:
1 = Enables continuous receive until enable bit CREN is cleared (CREN overrides SREN)
0 = Disables continuous rec eive
bit 3 ADDEN: Address Detect Enable bit
Asynchronous mode 9-bit (RX9 = 1):
1 = Enables address de tection, en ables inte rrupt and loa d of the receive bu ffe r when RSR<8 >
is set
0 = Disables address detection, all bytes are received and ninth bit can be used as parity bit
bit 2 FERR: Framing Error bit
1 = Framing error (can be updated by reading RCREG register and receive next valid byte)
0 = No framing error
bit 1 OERR: Overrun Error bit
1 = Overrun error (can be cleared by clearing bit CREN)
0 = No overrun erro r
bit 0 RX9D: 9th bit of Received Data (can be Parity bit, but must be calculated by user firmware)
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
2002-2013 Microchip Technology Inc. DS30487D-page 99
PIC16F87/88
11.1 AUSART Baud Rate Generator
(BRG)
The BRG supports both the Asynchronous and
Synchronous modes of the AUSART. It is a dedicated
8-bit Baud Rate Generator. The SPBRG register
controls the period of a free r unning 8-bit time r. In Asyn-
chronous mode, bit BRGH (TXSTA<2>) also controls
the baud rate. In Synchronous mode, bit BRGH is
ignored. Table 11-1 shows the formula for computation
of the baud rate for different AUSART modes which
only apply in Master mode (internal clock).
Given the desired baud rate and FOSC, the nearest
integer value for the SPBRG register can be calculate d
using the formula in Table 11-1. From this, the error in
baud rate can be determined.
It may be advantageous to use the high baud rate
(BRGH = 1) even for slower baud clocks. This is
beca us e t he FOSC/(16(X + 1 )) eq ua tion c an red uc e th e
baud rate error in some cases.
Writing a new value to the SPBRG register causes the
BRG timer to be reset (or cleared). This ensures the
BRG does not wait for a timer overflow before
outputting the new baud rate.
11.1.1 AUSART AND INTRC OPERATION
The PIC16F87/88 has an 8 MHz INTRC that can be
used as the system clock , thereby eliminat ing the need
for external components to provide the clock source.
When the INTRC provides the system clock, the AUS-
ART module will also use the INTRC as its system
clock. Table 11-1 shows some of the INTRC
frequenc ies t hat can be use d to g en erate th e AUS ART
module’s baud rate.
11.1.2 LOW-POWER MODE OPERATION
The sys tem cl ock is used to generate the des ired bau d
rate; however, when a low-power mode is entered, the
low-po wer cl ock sourc e may be opera ting at a d if ferent
frequenc y tha n in ful l pow e r exec uti on . In Sleep mod e,
no clocks are present. This may require the value in
SPBRG to be adjusted.
11.1.3 SAMPLING
The dat a on the RB2/SDO/RX /DT pin is s am pl ed thre e
times by a majority detect circuit to determine if a high
or a low level is present at the RX pin.
TABLE 11-1: BAUD RATE FORMULA
TABLE 11-2: REGISTERS ASSOCIATED WITH BAUD RATE GENERATOR
SYNC BRGH = 0 (Low Speed) BRGH = 1 (High Speed)
0
1
(Asynchronous) Baud Rate = FOSC/(64(X + 1))
(Synchronous) Baud Rate = FOSC/(4(X + 1)) Baud Rate = FOSC/( 16(X + 1))
N/A
Legend: X = v alue in SPBRG (0 to 255)
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Va lue on:
POR, BOR
Value on
all other
Resets
98h TXSTA CSRC TX9 TXEN SYNC —BRGHTRMT TX9D 0000 -010 0000 -010
18h RCSTA SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 0000 000x 0000 000x
99h SPBRG Baud Rate Generator Register 0000 0000 0000 0000
Legend: x = unknown, - = unimplemented, read as ‘0’. Shaded cells are not used by the BRG.
PIC16F87/88
DS30487D-page 100 2002-2013 Microchip Technology Inc.
TABLE 11-3: BAUD RATES FOR ASYNCHRONOUS MODE (BRGH = 0)
BAUD
RATE
(K)
FOSC = 20 MHz FOSC = 16 MHz FOSC = 10 MHz
KBAUD %
ERROR
SPBRG
value
(decimal) KBAUD %
ERROR
SPBRG
value
(decimal) KBAUD %
ERROR
SPBRG
value
(decimal)
0.3———————
1.2 1.221 +1.75 255 1.202 +0.17 207 1.202 +0.17 129
2.4 2.404 +0.17 129 2.404 +0.17 103 2.404 +0.17 64
9.6 9.766 +1.73 31 9.615 +0.16 25 9.766 +1.73 15
19.2 19.531 + 1.72 15 19.231 +0.16 12 19.531 +1.72 7
28.8 31.250 +8.51 9 27.778 -3.55 8 31.250 +8.51 4
33.6 34.722 +3.34 8 35.714 +6.29 6 31.250 -6.99 4
57.6 62.500 +8.51 4 62.500 +8.51 3 52.083 -9.58 2
HIGH 1.221 255 0.977 255 0.610 255
LOW 312.500 0 250.000 0 156.250 0
BAUD
RATE
(K)
FOSC = 4 MHz FOSC = 3.6864 MHz
KBAUD
%
ERROR
SPBRG
value
(decimal) KBAUD
%
ERROR
SPBRG
value
(decimal)
0.3 0.300 0 207 0.3 0 191
1.2 1.202 +0.17 51 1.2 0 47
2.4 2.404 +0.17 25 2.4 0 23
9.6 8.929 +6.99 6 9.6 0 5
19.2 20.833 +8.51 2 19.2 0 2
28.8 31.250 +8.51 1 28.8 0 1
33.6
57.6 62.500 +8.51 0 57.6 0 0
HIGH 0.244 255 0.225 255
LOW 62.500 0 57.6 0
TABLE 11-4: BAUD RATES FOR ASYNCHRONOUS MODE (BRGH = 1)
BAUD
RATE
(K)
FOSC = 20 MHz FOSC = 16 MHz FOSC = 10 MHz
KBAUD %
ERROR
SPBRG
value
(decimal) KBAUD %
ERROR
SPBRG
value
(decimal) KBAUD %
ERROR
SPBRG
value
(decimal)
0.3————
1.2————
2.4 2.441 +1.71 255
9.6 9.615 +0.16 129 9.615 +0.16 103 9.615 +0.16 64
19.2 19.231 +0.16 64 19.231 +0.16 51 19.531 +1.72 31
28.8 29.070 +0.94 42 29.412 +2.13 33 28.409 -1.36 21
33.6 33.784 +0.55 36 33.333 -0.79 29 32.895 -2.10 18
57.6 59.524 +3.34 20 58.824 +2.13 16 56.818 -1.36 10
HIGH 4.883 255 3.906 255 2.441 255
LOW 1250.000 0 1000.000 0 625.000 0
BAUD
RATE
(K)
FOSC = 4 MHz FOSC = 3.6864 MHz
KBAUD
%
ERROR
SPBRG
value
(decimal) KBAUD
%
ERROR
SPBRG
value
(decimal)
0.3———
1.2 1.202 +0.17 207 1.2 0 191
2.4 2.404 +0.17 103 2.4 0 95
9.6 9.615 +0.16 25 9.6 0 23
19.2 19.231 +0.16 12 19.2 0 11
28.8 27.798 -3.55 8 28.8 0 7
33.6 35.714 +6.29 6 32.9 -2.04 6
57.6 62.500 +8.51 3 57.6 0 3
HIGH 0.977 255 0.9 255
LOW 250.000 0 230.4 0
2002-2013 Microchip Technology Inc. DS30487D-page 101
PIC16F87/88
TABLE 11-5: INTRC BAUD RATES FOR ASYNCHRONOUS MODE (BRGH = 0)
BAUD
RATE
(K)
FOSC = 8 MHz FOSC = 4 MHz FOSC = 2 MHz FOSC = 1 MHz
KBAUD %
ERROR
SPBRG
value
(decimal) KBAUD %
ERROR
SPBRG
value
(decimal) KBAUD %
ERROR
SPBRG
value
(decimal) KBAUD %
ERROR
SPBRG
value
(decimal)
0.3 NA 0.300 0 207 0.300 0 103 0.300 0 51
1.2 1.202 +0.16 103 1.202 +0.16 51 1.202 +0.16 25 1.202 +0.16 12
2.4 2.404 +0.16 51 2.404 +0.16 25 2.404 +0.16 12 2.232 -6.99 6
9.6 9.615 +0.16 12 8.929 -6.99 6 10.417 +8.51 2 NA
19.2 17.857 -6.99 6 20.833 +8.51 2 NA NA
28.8 31.250 +8.51 3 31.250 +8.51 1 31.250 +8.51 0 NA
38.4 41.667 +8.51 2 NA NA NA
57.6 62.500 +8.51 1 62.500 8.51 0 NA NA
TABLE 11-6: INTRC BAUD RATES FOR ASYNCHRONOUS MODE (BRGH = 1)
BAUD
RATE
(K)
FOSC = 8 MHz FOSC = 4 MHz FOSC = 2 MHz FOSC = 1 MHz
KBAUD %
ERROR
SPBRG
value
(decimal) KBAUD %
ERROR
SPBRG
value
(decimal) KBAUD %
ERROR
SPBRG
value
(decimal) KBAUD %
ERROR
SPBRG
value
(decimal)
0.3 NA NA NA 0.300 0 207
1.2 NA 1.202 +0.16 207 1.202 +0.16 103 1.202 +0.16 51
2.4 2.404 +0.16 207 2.404 +0.16 103 2.404 +0.16 51 2.404 +0.16 25
9.6 9.615 +0.16 51 9.615 +0.16 25 9.615 +0.16 12 8.929 -6.99 6
19.2 19.231 +0.16 25 19.231 +0.16 12 17.857 -6.99 6 20.833 +8.51 2
28.8 29.412 +2.12 16 27.778 -3.55 8 31.250 +8.51 3 31.250 +8.51 1
38.4 38.462 +0.16 12 35.714 -6.99 6 41.667 +8.51 2 NA
57.6 55.556 -3.55 8 62.500 +8.51 3 62.500 +8.51 1 62.500 +8.51 0
PIC16F87/88
DS30487D-page 102 2002-2013 Microchip Technology Inc.
11.2 AUSART Asynchronous Mode
In this mode, the AUSART uses standard Non-Return-
to-Zero (NRZ) format (one Start bit, eight or nine data
bits and one Stop bit). The most common data format
is 8 bits. An on-chip, dedicated, 8-bit Baud Rate
Generator can be used to derive standard baud rate
frequenc ies fr om the osci llator. The AUSART transm it s
and rece ives the LSb first. Th e transmitter a nd receiv er
are functionally independent, but use the same data
format and baud rate. The Baud Rate Generator
produces a clock, either x16 or x64 of the bit shift rate,
depending on bit BRGH (TXSTA<2>). Parity is not
supporte d by the hard ware, but can be imple mente d in
software (and stored as the ninth data bit).
Asynchronous mode is stopped during Sleep.
Asynchronous mode is selected by clearing bit SYNC
(TXSTA<4>).
The AUSART Asynchronous module consists of the
following important elements:
Baud Rate Generator
Sampling Circuit
Asynchronous Transmitter
Asynchronous Receiver
11.2.1 AUSART ASYNCHRONOUS
TRANSMITTER
The AUSART transmitter block diagram is shown in
Figure 11-1. The heart of the transmitter is the T ransmit
(Serial) Shift Regis ter (TSR). The Shi f t regi st er obtains
its data from the Read/Write Transmit Buffer register,
TXREG. The TXREG register is loaded with data in
softw are . Th e TSR re gi st e r is not lo ad e d un ti l t he Stop
bit has been transmitted from the previous load. As
soon as the Stop bit is transmitted, the TSR is loaded
with new data from the TXREG register (if available).
Once the TXR EG register trans fers the dat a to the TSR
register (occurs in one TCY), the TXREG register is
empty and flag bit, TXIF (PIR1<4>), is set. This
interrupt can be enabled/disabled by setting/clearing
enable bit, TXIE (PIE1<4>). Flag bit TXIF will be set,
regardless of the state of enable bit TXIE and cannot b e
cleared in software. It will reset only when new data is
loaded into the TXREG register. While flag bit TXIF
indica tes th e s t atus of the TXREG regi ste r, ano the r bi t,
TRMT (TXSTA<1>), shows the status of the TSR
register. Status bit TRMT is a read- onl y bit w hic h is set
when the TSR register is empty. No interrupt logic is
tied to thi s b it, s o th e us er h as to po ll t his bi t in o rder to
determine if the TSR register is empty.
Transmission is enabled by setting enable bit TXEN
(TXSTA<5>). The actual transmission will not occur
until the TXREG register has been loaded with data
and the Baud Rate Generator (BRG) has produced a
shift clock (Figure 11-2). The transmission can also be
started by first loading the TXREG register and then
setting enable bit TXEN. Normally, when transmission
is first started, the TSR register is empty. At that point,
transfer to the TXREG register will result in an immedi-
ate transfer to TSR, resulting in an empty TXREG. A
back-to-back transfer is thus possible (Figure 11-3).
Clearing enable bit TXEN during a transmission will
cause the tra nsm is s ion to be ab orte d and will rese t th e
transmitter. As a result, the RB5/SS/TX/CK pin will
revert to high-impedance.
In order to select 9-bit transmission, transmit bit, TX9
(TXSTA<6>), should be set and the ninth bit should be
written to TX9D (TXSTA<0>). The ninth bit must be
written before writing the 8-bit data to the TXREG
register. This is because a data write to the TXREG
register can result in an immediate transfer of the data
to the TSR register (if the TSR is empty). In such a
case, an incorrect ninth data bit may be loaded in the
TSR registe r.
FIGURE 11-1: AUSART TRANSMIT BLOCK DIAGRAM
Note 1: The TSR register is not mapped in data
memory, so it is not available to the user.
2: Flag bit T XIF is set whe n enable bit TXEN
is set. TXIF is cle ared by loadi ng TXRE G.
TXIF
TXIE
Interrupt
TXEN Baud Rate CLK
SPBRG
Baud Rate Generator TX9D
MSb LSb
Data Bus
TXREG Register
TSR Register
(8) 0
TX9
TRMT SPEN
RB5/SS/TX/CK pin
Pin Buffer
and Control
8

2002-2013 Microchip Technology Inc. DS30487D-page 103
PIC16F87/88
When se ttin g u p a n asynchronous t r ans m issio n, follow
these steps:
1. Initialize th e SPBRG re gis te r for the ap propriate
baud rate. If a high-speed baud rate is desired,
set bit BRGH (Section 11.1 “AUSART Baud
Rate Generator (BRG)”).
2. Enable the asynchronous serial port by clearing
bit SYNC and setting bit SPEN.
3. If interrupts are desired, then set enable bit
TXIE.
4. If 9-bit transmission is desired, then set transmit
bit TX9.
5. Enable the transmission by setting bit TXEN
which will also set bit TXIF.
6. If 9-bit transmission is selected, the ninth bit
should be loaded in bit TX9D.
7. Load data to the TXREG register (starts
transmission).
8. If using interrupts, ensure that GIE and PEIE
(bits 7 and 6) of the INTCON register are set.
FIGURE 11-2: ASYNCHRONOUS MASTER TRANSMISSION
FIGURE 11-3: ASYNCHRONOUS MASTER TRANSMISSION (BACK TO BACK)
TABLE 11-7: REGISTERS ASSOCIATED WITH ASYNCHRONOUS TRANSMISSION
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on:
POR, BOR
Value on
all other
Resets
0Bh, 8Bh,
10Bh,18Bh INTCON GIE PEIE TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 0000 000x 0000 000u
0Ch PIR1 ADIF(1) RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF -000 0000 -000 0000
18h RCSTA SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 0000 000x 0000 000x
19h TXREG A USA RT Transmit Data Register 0000 0000 0000 0000
8Ch PIE1 ADIE(1) RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE -000 0000 -000 0000
98h TXSTA CSRC TX9 TXEN SYNC BRGH TRMT TX9D 0000 -010 0000 -010
99h SPBRG Baud Rate Generator Register 0000 0000 0000 0000
Legend: x = unk nown, - = unimplemented locations read as ‘0’. Shaded cells are not used for asynchronous transmission.
Note 1: This bit is only implemented on the PIC16F88. The bit will read ‘0’ on the PIC16F87.
Word 1 Stop Bit
Word 1
Transmit Shi ft R e g
Start Bit Bit 0 Bit 1 Bit 7/8
Write to TXREG
BRG Output
(Shift Clock)
RB5/SS/TX/CK pin
TXIF bit
(Transmit Buffer
Reg. Empty Flag)
TRMT bit
(Transmit Shift
Reg. Empty Flag)
Word 1
Transmit Shift Reg.
Wr i te to TX RE G
BRG Output
(Shift C l o c k)
RB5/SS/TX/CK pin
TXIF b i t
(Interrupt Reg. Flag)
TRMT bit
(Transmit Shift
Reg. Empty Flag)
Word 1 Word 2
Word 1 Word 2
Start Bit Stop Bit Start Bit
Transmit Shift Reg.
Word 1 Word 2
Bit 0 Bit 1 Bit 7/8 Bit 0
Note: This timing diagram shows two consecutive transmissions.
PIC16F87/88
DS30487D-page 104 2002-2013 Microchip Technology Inc.
11.2.2 AUSART ASYNCHRONOUS
RECEIVER
The receiver block diagram is shown in Figure 11-4.
The data is received on the RB2/SDO/RX/DT pin and
drives the data recovery block. The data recovery block
is actually a high-speed shifter, operating at x16 times
the baud rate; whereas, the main receive serial shifter
operates at the bit rate or at FOSC.
Once Asynchronous mode is selected, reception is
enabled by setti ng bit CRE N (RCSTA<4>).
The heart of the receiver is the Receive (Serial) Shift
Register (RSR). After sampling the Stop bit, the
received data in the RSR is transferred to the RC REG
register (if it is empty). If the transfer is complete, flag
bit, R CIF (PIR1<5>), is se t. T he ac tual i nterrupt can be
enabled/disabled by setting/clearing enable bit RCIE
(PIE1<5>). Flag bit RCIF is a read-only bit which is
cleared by the hardware. It is cleared when the RCREG
register has been read and is empty. The RCREG is a
double-buffered register (i.e., it is a two-deep FIFO). It
is possible for two bytes of data to be received and
transferred to the RCREG FIFO and a third byte to
begin shifting to the RSR register. On the detection of
the Stop bit of the third byte, if the RCREG register is
still full, the Overrun Error bit, OERR (RCSTA<1>), will
be set. The word in the RSR will be lost. The RCREG
register can be read twice to retrieve the two bytes in
the FIFO. Overrun bit OERR has to be cleared in soft-
ware. Th is is done by re setting the re ceive logi c (CREN
is cleared and then set). If bit OERR is set, transfers
from the RSR register to the RCREG register are inhib-
ited and no further dat a will be rec eived. It is , therefore,
essential to clear error bit OERR if it is set. Framing
Error bit, FERR (RCSTA<2>), is set if a Stop bit is
detected as cle ar. Bit FER R and the 9th re cei ve bit a re
buffered the same way as the receive data. Reading
the RCREG will load bits RX9D and FERR with new
values ; the refo r e, it is ess ent ial for the us er to re ad th e
RCSTA register , before rea ding the RCREG r egister, in
order not to lose the old FERR and RX9D inform ation .
FIGURE 11-4: AUSART RECEIVE BLOCK DIAGRAM
FIGURE 11-5: ASYNCHRONOUS RECE PTION
x64 Baud Rate CLK
SPBRG
Baud Rate Generator
RB2/SDO/RX/DT Pin Buffer
and Control
SPEN
Data
Recovery
CREN OERR FERR
RSR Register
MSb LSb
RX9D RCREG Register FIFO
Interrupt RCIF
RCIE Data Bus
8
64
16
or Stop Start
(8) 710
RX9

FOSC
Start
bit bit 7/8bit 1bit 0 bit 7/8 bit 0Stop
bit
Start
bit Start
bit
bit 7/8 Stop
bit
RX pin
Reg
Rcv Buffer Reg
Rcv Shift
Read Rcv
Buff er Reg
RCREG
RCIF
(Interrupt Flag)
OERR bit
CREN
Word 1
RCREG Word 2
RCREG
Stop
bit
Note: This timing diagram shows three words appearing on the RX input. The RCREG (Receive Buffer) is read after the third word,
causing the OERR (Overrun) bit to be set.
2002-2013 Microchip Technology Inc. DS30487D-page 105
PIC16F87/88
When setting up an asynchronous reception, follow
these steps:
1. Initialize th e SPBRG re gis te r for the ap propriate
baud rate. If a high-speed baud rate is desired,
set bit BRGH (Section 11.1 “AUSART Baud
Rate Generator (BRG)”).
2. Enable the asynchronous serial port by clearing
bit SYNC and setting bit SPEN.
3. If interrupts are desired, then set enable bit
RCIE.
4. If 9-bit reception is desired, then set bit RX9.
5. Enable the reception by setting bit CREN.
6. Flag bit RC IF wi ll b e set when reception is com -
plete an d an interru pt will be generate d if enabl e
bit RCIE is set.
7. Read the RCSTA register to get the ninth bit (if
enabled) and determine if any error occurred
during rec e ption.
8. Read the 8-bit received data by reading the
RCREG register.
9. If any error occurred, clear the error by clearing
enable bit CREN.
10. If using interrupts, ensure that GIE and PEIE
(bits 7 and 6) of the INTCON register are set.
TABLE 11-8: REGISTERS ASSOCIATED WITH ASYNCHRONOUS RECEPTION
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on:
POR, BOR
Value on
all other
Resets
0Bh, 8Bh,
10Bh,18Bh INTCON GIE PEIE TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 0000 000x 0000 000u
0Ch PIR1 ADIF(1) RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF -000 0000 -000 0000
18h RCSTA SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 0000 000x 0000 000x
1Ah RCREG AUSART Receive Data Register 0000 0000 0000 0000
8Ch PIE1 ADIE(1) RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE -000 0000 -000 0000
98h TXSTA CSRC TX9 TXEN SYNC —BRGHTRMT TX9D 0000 -010 0000 -010
99h SPBRG Baud Rate Generator Register 0000 0000 0000 0000
Legend: x = unk nown, - = unimplemented locations read as ‘0’. Shaded cells are not used for asynchronous reception.
Note 1: This bit is only implemented on the PIC16F88. The bit will read ‘0’ on the PIC16F87.
PIC16F87/88
DS30487D-page 106 2002-2013 Microchip Technology Inc.
11.2.3 SETTING UP 9-BIT MODE WITH
ADDRES S DETE CT
When setting up an asynchronous reception with
address detect enabled:
Initialize the SPBRG register for the appropriate
baud rate. If a high-speed baud rate is desired,
set bit BRGH.
Enable the asynchronous serial port by clearing
bit SYNC and setting bit SPEN.
If interrupts are desired, then set enable bit RCIE.
Set bit RX9 to enable 9-bit reception.
Set ADDEN to enable address detect.
Enable the reception by setting enable bit CREN.
Flag bit RCIF will be set when reception is
complete and an interrupt will be generated if
enable bit RCIE was set.
Read the RCSTA register to get the ninth bit and
determine if any error occurred during reception.
Read the 8-bit received data by reading the
RCREG register to determine if the device is
being addressed.
If any error occurred, clear the error by clearing
enable bit CREN.
If the device has been addressed, clear the
ADDEN bi t to al low da t a b yte s and address bytes
to be read into the receive buffer and interru pt the
CPU.
FIGURE 11-6: AUSART RECEIVE BLOCK DIAGRAM
x64 Baud Rate CLK
SPBRG
Baud Rate Gener ato r
RB2/SDO/RX/DT
Pin Buffer
and Control
SPEN
Data
Recovery
CREN OERR FERR
RSR Register
MSb LSb
RX9D RCREG Register FIFO
Interrupt RCIF
RCIE Data Bus
8
64
16
or Stop Start
(8) 710
RX9

RX9
ADDEN
RX9
ADDEN
RSR<8>
Enable
Load of
Receive
Buffer
8
8
FOSC
2002-2013 Microchip Technology Inc. DS30487D-page 107
PIC16F87/88
FIGURE 11-7: ASYNCHRONOUS RECEPTION WITH ADDRESS DETECT
FIGURE 11-8: ASYNCHRONOUS RECEPTION WITH ADDRESS BYTE FIRST
TABLE 11-9: REGISTERS ASSOCIATED WITH ASYNCHRONOUS RECEPTION
Start
bit bit 1bit 0 bit 8 bit 0Stop
bit
Start
bit bit 8
RB2/SDO/RX/DT pin
Load RSR
Read
RCIF
Word 1
RCREG
Bit 8 = 0, Data Byte Bit 8 = 1, Address Byte
Note: This timing diagram shows a da ta byte followed by an ad dress byte . The data byt e is not r ead into the RCREG (Receive Buffer)
because ADDEN = 1.
Stop
bit
Start
bit bit 1bit 0 bit 8 bit 0Stop
bit
Start
bit bit 8
RB2/SDO/RX/DT pin
Load RSR
RCIF
Word 1
RCREG
Bit 8 = 1, Address Byte Bit 8 = 0, Data Byte
Note: This timing diagram shows a data byte followed by an address byte. The data byte is not read into the RCREG (Receive Buffer)
because ADDEN was not updated and still = 0.
Read
Stop
bit
Add r e s s Name Bi t 7 Bit 6 B it 5 B it 4 Bit 3 B it 2 Bit 1 B i t 0 Value on:
POR, BOR
Value on
all other
Resets
0Bh, 8Bh,
10Bh,18Bh INTCON GIE PEIE TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 0000 000x 0000 000u
0Ch PIR1 ADIF(1) RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF -000 0000 -000 0000
18h RCSTA SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 0000 000x 0000 000x
1Ah RCREG AUS ART Receive Data Register 0000 0000 0000 0000
8Ch PIE1 ADIE(1) RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE -000 0000 -000 0000
98h TXSTA CSRC TX9 TXEN SYNC —BRGHTRMT TX9D 0000 -010 0000 -010
99h SPBRG Baud Rate Generator Register 0000 0000 0000 0000
Legend: x = unknown, - = unimplemented locations read as ‘0’. Shaded cells are not used for asynchronous reception.
Note 1: This bit is only implemented on the PIC16F88. The bit will read ‘0’ on the PIC16F87.
PIC16F87/88
DS30487D-page 108 2002-2013 Microchip Technology Inc.
11.3 AUSART Synchronous
Master Mode
In Sync hronous Ma ster mode, the data is trans mitted in
a half-duplex manner (i.e., transmission and reception
do not occur at the same tim e). When transmitt ing data,
the reception is inhibited and vice versa. Synchronous
mode is entered by setting bit SYNC (TXSTA<4>). In
addition , enable bit SPEN (RCSTA<7>) is set in order
to configure the RB5/SS/TX/CK a nd RB2/SDO/RX/DT
I/O p ins to CK ( clock ) and D T (dat a) lin es, res pecti vely.
The Master mode indicates that the processor trans-
mits the maste r c lock on th e CK lin e. The M aster mod e
is entered by setting bit CSRC (TXSTA<7>).
11.3.1 AUSART SYNCHRONOUS MASTER
TRANSMISSION
The AUSART transmitter block diagram is shown in
Figure 11-6. The heart of the transmitter is the T ransmit
(Serial) Shift Regis ter (TSR). The Shi f t regi st er obtains
its data from the Read/Write Transmit Buffer register,
TXREG. The TXREG register is loaded with data in
softw are. The TSR register is not loaded until the last
bit has been transmitted from the previous load. As
soon as the last bit is transmitted, the TSR is loaded
with new data from the TXREG (if available). Once the
TXREG register transfers the data to the TSR register
(occurs in one TCYCLE), the TXREG is empty and
interrupt bit TXIF (PIR1<4>) is set. The inte rrupt can be
enabled/disabled by setting/clearing enable bit TXIE
(PIE1<4>). Flag bit TXIF will be set, regardless of the
state of enable bit TXIE and cannot be cleared in
soft ware. It wi ll res et onl y when new data is loaded into
the TXREG register. While flag bit TXIF indicates the
status of the TXREG register, another bit, TRMT
(TXSTA<1>), shows the status of the TSR register.
TRMT is a read-only bit which is set when the TSR is
empty. No interrupt logic is tied to this bit, so the user
has to poll this bit in order to determine if the TSR reg-
ister is empty. The TSR is n ot mapped in dat a memory,
so it is not available to the user.
Transmission is enabled by setting enable bit TXEN
(TXSTA<5>). The actual transmission will not occur
until the TXREG register has been loaded with data.
The first dat a bit will be shif ted out on the next av ailable
rising edge of the clock on the CK line. Data out is
stab le around the fal ling edge of the sync hronous cloc k
(Figure 11-9). The transmission can also be started by
first loading the TXREG register and then setting bit
TXEN (Figure 11-10). This is adv ant ageous when slow
baud rate s are selec ted, since th e BRG is kept in Reset
when bits TXEN, CREN and SREN are clear. Setting
enable bit TXEN will start the BRG, creating a shift
clock immediately. Normally, when transmission is first
started, the TSR register is empty, so a transfer to the
TXREG register will result in an immediate transfer to
TSR, resulting in an empty TXREG. Back-to-back
transfers are possible.
Clearing enable bit TXEN during a transmission will
cause the tra nsm is s ion to be ab orte d and will rese t th e
transmitter. The DT and CK pins will revert to high-
impeda nce. If ei ther bit C REN or bi t SREN is set durin g
a transmis sion , the transm issi on is abor ted and the DT
pin reverts to a high-impedance state (for a reception).
The CK pin will remain an output if bit CSRC is set
(internal clock). The transmitter logic, however, is not
reset, although it is disconnected from the pins. In order
to reset the tran sm itte r, th e us er ha s to cle ar bi t TXEN.
If bit SR EN is set (t o interrupt an on-goin g trans mission
and r eceive a single wo rd), then af ter the singl e word is
received, bit SREN will be cleared and the serial port
will revert back to transmitting, since bit TXEN is still
set. The DT line will immediately switch from High-
Impedan ce Rec eive mod e to transmit and st art dr iving.
To avoid this, bit TXEN should be cleared.
In order to select 9-bit transmission, the TX9
(TXSTA<6>) bit should be set and the ninth bit should
be written to bit TX9D (TXSTA<0>). The ninth bit must
be written before writing the 8-bit data to the TXREG
register. This is because a dat a write to the TXREG can
result in an immediate transfer of the data to the TSR
register (if the TSR is empty). If the TSR was empty and
the TXREG was writt en befo re writ ing the “new” T X9D,
the “present” value of bit TX9D is loaded.
Steps to follow when setting up a synchronous master
transmission:
1. Initialize the SPBRG re gister for the appropria te
baud rate (Sec tion 11.1 “AUSART Baud Rate
Generator (BRG)”).
2. Enable the synchronous master serial port by
setting bits SYNC, SPEN and CSRC.
3. If interrupts are desired, set enable bit TXIE.
4. If 9-bit transmission is desired, set bit TX9.
5. Enable the tr ansmission by setting bit TXEN.
6. If 9-bit transmission is selected, the ninth bit
should be loaded in bit TX9D.
7. S tart transmission by loading dat a to the TXREG
register.
8. If using interrupts, ensure that GIE and PEIE
(bits 7 and 6) of the INTCON register are set.
2002-2013 Microchip Technology Inc. DS30487D-page 109
PIC16F87/88
TABLE 11-10: REGISTERS ASSOCIATED WITH SYNCHRONOUS MASTER TRANSMISSION
FIGURE 11-9: SYNCHRONOUS TRANSMISSION
FIGURE 11-10: SY NCHRONOUS TRANSMISSION (THROUGH TXEN)
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on:
POR, BOR
Value on
all other
Resets
0Bh, 8Bh,
10Bh,18Bh INTCON GIE PEIE TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 0000 000x 0000 000u
0Ch PIR1 ADIF(1) RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF -000 0000 -000 0000
18h RCSTA SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 0000 000x 0000 000x
19h TXR EG AUSA RT Transmit Data Register 0000 0000 0000 0000
8Ch PIE1 ADIE(1) RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE -000 0000 -000 0000
98h TXSTA CSRC TX9 TXEN SYNC BRGH TRMT TX9D 0000 -010 0000 -010
99h SPBRG Baud Rate Generator Register 0000 0000 0000 0000
Legend: x = unknown, - = unimplemented, read as ‘0’. Shaded cells are not used for synchronous master transmission.
Note 1: This bit is only implemented on the PIC16F88. The bit will read ‘0’ on the PIC16F87.
bit 0 bit 1 bit 7
Word 1
Q1Q2 Q3 Q4 Q1Q2 Q3Q4Q1Q2Q3 Q4Q1Q2 Q3 Q4Q1 Q2 Q3 Q4 Q3Q4 Q1Q2 Q3Q4 Q1Q2 Q3Q4 Q1 Q2Q3 Q4Q1 Q2Q3 Q4Q1Q2 Q3Q4 Q1Q2Q3 Q4
bit 2 bit 0 bit 1 bit 7
RB2/SDO/
RB5/SS/TX/
Write to
TXREG R eg
TXIF bit
(Interrupt Flag)
TXEN bit 1 1
Wo rd 2
TRMT b it
Write Word 1 Write Word 2
Note: Sync Master mode; SPBRG = 0. Continuous transmission of two 8-bit words.
RX/DT pin
CK pin
RB2/SDO/RX/DT pin
RB5/SS/TX/CK pi n
Write to
TXREG Reg
TXIF bit
TRMT bit
bit 0 bit 1 bit 2 bit 6 bit 7
TXEN bi t
PIC16F87/88
DS30487D-page 110 2002-2013 Microchip Technology Inc.
11.3.2 AUSART SYNCHRONOUS MASTER
RECEPTION
Once Synchronous mode is selected, reception is
enabled by setting either enable bit SREN
(RCST A<5>), or enable bit CREN (RCSTA<4>). Data is
sampled on the RB2/SDO/RX/DT pin on the falling
edge of th e clo ck. If e nable bit SR EN is set, then only a
single word is received. If enable bi t C REN is set, the
reception is continuous until CREN is cleared. If both
bits are set, CREN takes precedence.
After clocking the last bit, the received data in the
Receive Shift Register (RSR) is transferred to the
RCREG register (if it is empty). When the transfer is
complete, interrupt flag b it, RCIF (PIR1<5>), is set. The
actual interrupt can be enabled/disabled by setting/
clearing enable bit RCIE (PIE1<5>).
Flag bit RCIF is a read-only bit which is reset by the
hardware. In this case, it is reset when the RCREG
register has been read and is empty. T he R CREG is a
double-buffered re gister (i.e., it is a two-deep FIFO). It is
possible for two bytes of data to be received and
transferred to the RCR EG FIFO an d a third byte to begin
shifting into th e RSR register. On the clocking of the last
bit of the third by te, if the RCREG register i s still full, then
Overrun Error bit, OERR (RCSTA<1>), is set. The word
in the RSR will be lost. The RCREG register can be read
twice to retrieve the two bytes in the FIFO. Bit OERR has
to be cleared in software (by clearing bit CREN). If bit
OERR is set, transfers from the RSR to the RCREG are
inhibited, so it is essential to clear bit OERR if it is set.
The ninth receive bit is buffered the same way as the
receive data. Reading the RCREG register will load bit
RX9D with a new value, therefore, it is essential for the
user to read the RCSTA register, before reading
RCREG, in order not to lose the old RX9D information.
When setting up a synchronous master reception:
1. Initialize the SPBRG re gister for the appropria te
baud rate (Sec tion 11.1 “AUSART Baud Rate
Generator (BRG)”).
2. Enable the synchronous master serial port by
setting bits SYNC, SPEN and CSRC.
3. Ensure bits CREN and SREN are clear.
4. If interrupts are desired, then set enable bit
RCIE.
5. If 9-bit reception is desired, then set bit RX9.
6. If a single reception is required, set bit SREN.
For continuous reception, set bit CREN.
7. Interrupt flag bit, RCIF, will be set when
reception is complete and an interrupt will be
generated if enable bit, RCIE, was set.
8. Read the RCSTA register to get the ninth bit (if
enabled) and determine if any error occurred
during rec e ption.
9. Read the 8-bit received data by reading the
RCREG register.
10. If any error occurred, clear the error by clearing
bit CREN.
11. If using interrupts, ensure that GIE and PEIE
(bits 7 and 6) of the INTCON register are set.
TABLE 11-11: REGISTERS ASSOCIATED WITH SYNCHRONOUS MASTER RECEPTION
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on:
POR, BOR
Value on
all other
Resets
0Bh, 8Bh,
10Bh,18Bh INTCON GIE PEIE TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 0000 000x 0000 000u
0Ch PIR1 ADIF(1) RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF -000 0000 -000 0000
18h RCSTA SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 0000 000x 0000 000x
1Ah RCREG AUSART Receive Data Register 0000 0000 0000 0000
8Ch PIE1 ADIE(1) RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE -000 0000 -000 0000
98h TXSTA CSRC TX9 TXEN SYNC BRGH TRMT TX9D 0000 -010 0000 -010
99h SP BRG Baud Rate Generator Register 0000 0000 0000 0000
Legend: x = unknown, - = unimplemented, read as ‘0’. Shaded cells are not used for synchronous master reception.
Note 1: This bit is only implemented on the PIC16F88. The bit will read ‘0’ on the PIC16F87.
2002-2013 Microchip Technology Inc. DS30487D-page 111
PIC16F87/88
FIGURE 11-11: SYNCHRONOUS RECEPTION (MASTER MODE, SREN)
11.4 AUSART Synchronous Slave Mode
Synchronous Slave mode dif fers from the Master mode
in the fact that the shift clock is supplied externally at
the RB5/SS/TX/CK pin (inst ead of bein g supplie d inter-
nally in Master mode). This allows the device to trans-
fer or receiv e da t a w hi le i n Slee p mo de . Slav e mo de i s
entered by clearing bit CSRC (TXSTA<7>).
11.4.1 AUSART SYNCHRONOUS SLAVE
TRANSMIT
The operation of the Synchronous Master and Slave
modes is identica l, except in the cas e of the Slee p mode.
If two words are written to the TXREG and then the
SLEEP instruction is executed, the following will occur:
a) The first word will immediately transfer to the
TSR register and transmit.
b) The second word will remain in the TXREG register.
c) Flag bit TXIF will not be set.
d) When the first word has been sh ifted out of TSR,
the TXREG register will transfer the second word
to the TSR and flag bit TXIF will now be set.
e) If enable bit TXIE is set, the interrupt will wake
the chip from Sleep and if the global interrupt is
enabled , the p rog ram wil l branc h to the in terrupt
vector (0004h).
When setting up a synchronous slave transmission,
follow these steps:
1. Enable the synchronous slave serial port by
setting bits SYNC and SPEN and clearing bit
CSRC.
2. Clear bits CREN and SREN.
3. If interrupts are desired, then set enable bit
TXIE.
4. If 9-bit transmis si on is des ired , then set bi t TX9.
5. Enable the transmission by setting enable bit
TXEN.
6. If 9-bit transmission is selected, the ninth bit
should be loaded in bit TX9D.
7. S tart transmission by loading dat a to the TXREG
register.
8. If using interrupts, ensure that GIE and PEIE
(bits 7 and 6) of the INTCON register are set.
TABLE 11-12: REGISTERS ASSOCIATED WITH SYNCHRONOUS SLAVE TRANSMISSION
CREN bit
RB2/SDO/RX/DT
RB5/SS/TX/CK
Write to
bit SREN
SREN bit
RCIF bit
(Interrupt)
Read
RXREG
Note: Timing diagram demonstrates Sync Master mode with bit SREN = 1 and bit BRG = 0.
Q3Q4 Q1Q2Q3 Q4Q1 Q2Q3 Q4Q2 Q1Q2 Q3Q4Q1 Q2Q3 Q4 Q1Q2 Q3Q4Q1 Q2Q3 Q4 Q1Q2 Q3Q4Q1Q2Q3 Q4 Q1Q2Q3 Q4
0
bit 0 bit 1 bit 2 bit 3 bit 4 bit 5 bit 6 bit 7
0
Q1Q2Q3Q4
pin
pin
Address Name Bit 7 B it 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Va lue on:
POR, BOR
Value on
all other
Resets
0Bh, 8Bh,
10Bh,18Bh INTCON GIE PEIE TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 0000 000x 0000 000u
0Ch PIR1 ADIF(1) RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF -000 0000 -000 0000
18h RCSTA SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 0000 000x 0000 000x
19h TXREG AUSART T ransmit Data Register 0000 0000 0000 0000
8Ch PIE1 ADIE(1) RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE -000 0000 -000 0000
98h TXSTA CSRC TX9 TXEN SYNC BRGH TRMT TX9D 0000 -010 0000 -010
99h SP BRG Baud Rate Generator Register 0000 0000 0000 0000
Legend: x = unknown, - = unimplemented, read as ‘0’. Shaded cells are not used for synchronous slave transmission.
Note 1: This bit is only implemented on the PIC16F88. The bit will read ‘0’ on the PIC16F87.
PIC16F87/88
DS30487D-page 112 2002-2013 Microchip Technology Inc.
11.4.2 AUSART SYNCHRONOUS SLAVE
RECEPTION
The operation of the Synchronous Master and Slave
modes is identical, except in the case of the Sleep
mode. Bit SREN is a “don’t care” in Slave mode.
If receive is enabled by setting bit CREN prior to the
SLEEP inst ruction , then a wor d m ay be receiv ed d urin g
Sleep. On completely receiv ing the word, the R SR reg-
ister will trans fer th e data to the RCREG regis ter an d if
enable bit RCIE bit is set, the interrupt generated will
wake the chip from Sleep. If the global interrupt is
enabled , the pro gram w ill branc h to the interru pt vec tor
(0004h).
When setting up a synch ronous slave rece ptio n, follow
these steps:
1. Enable the synchronous master serial port by
setting bits SYNC and SPEN and clearing bit
CSRC.
2. If interrupts are desired, set enable bit RCIE.
3. If 9-bit reception is desired, set bit RX9.
4. To enable reception, set enable bit CREN.
5. Flag bit RCIF will be set when reception is
complete and an interrupt will be generated if
enable bit RCIE was set.
6. Read the RCSTA register to get the ninth bit (if
enabled) and determine if any error occurred
during rec e ption.
7. Read the 8-bit received data by reading the
RCREG register.
8. If any error occurred, clear the error by clearing
bit CREN.
9. If using interrupts, ensure that GIE and PEIE
(bits 7 and 6) of the INTCON register are set.
TABLE 11-13: REGISTERS ASSOCIATED WITH SYNCHRONOUS SLAVE RECEPTION
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on:
POR, BOR
Value on
all other
Resets
0Bh, 8Bh,
10Bh,18Bh INTCON GIE PEIE TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 0000 000x 0000 000u
0Ch PIR1 ADIF(1) RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF -000 0000 -000 0000
18h RCSTA SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 0000 000x 0000 000x
1Ah RCREG A USA RT Receive Data Register 0000 0000 0000 0000
8Ch PIE1 ADIE(1) RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE -000 0000 -000 0000
98h TXSTA CSRC TX9 TXEN SYNC BRGH TRMT TX9D 0000 -010 0000 -010
99h SPBRG Baud Rate Generator Register 0000 0000 0000 0000
Legend: x = unknown, - = unimplemented, read as ‘0’. Shaded cells are not used for synchronous slave reception.
Note 1: This bit is only implemented on the PIC16F88. The bit will read ‘0’ on the PIC16F87.
2002-2013 Microchip Technology Inc. DS30487D-page 113
PIC16F87/88
12.0 ANALOG-TO-DIGITAL
CONVERTER (A/D) MODULE
The Analog-to-Digital (A/D) converter module has
seven inputs for 18/20 pin devices (PIC16F88 devices
only).
The conversion of an analog input signal results in a
corresponding 10-bit digital number. The A/D module
has a high and low-voltage reference input that is
softw are se lec table to so me c ombi nati on o f VDD, VSS,
VREF- (RA2) or VREF+ (RA3).
The A/D converter has a unique feature of being able
to operate while the de vice is in Sleep mode. To oper-
ate in Sleep, th e A/D conv ersion clock mu st b e derive d
from the A/D’s internal RC oscillator.
The A/D module has five registers:
A/D Result High Register (ADRESH)
A/D Result Low Register (ADRESL)
A/D Control Register 0 (ADCON0)
A/D Control Register 1 (ADCON1)
Analog Select Register (ANSEL)
The ADCON0 register, shown in Register 12-2,
controls the operation of the A/D module. The ANSEL
register, shown in Register 12-1 and the ADCON1
register, shown in Register 12-3, configure the func-
tions of the port pins. The port pins can be configured
as analog inputs (RA3/RA2 can also be voltage
references) or as di gital I/O.
Addition al information on usi ng the A/D module can b e
found in the “PIC® Mid-Range MCU Family R eference
Manual” (DS33023).
REGISTER 12-1: ANSEL: ANALOG SELECT REGISTER (ADDRESS 9Bh) PIC16F88 DEVICES ONLY
U-0 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1
ANS6 ANS5 ANS4 ANS3 ANS2 ANS1 ANS0
bit 7 bit 0
bit 7 Unimplemented: Read as ‘0
bit 6-0 ANS<6:0>: Analog Input Select bits
Bits select input function on corresponding AN<6:0> pins.
1 = Analog I/O(1,2)
0 = Digital I/O
Note 1: Setting a pin to an analog input disables the digital input buffer. The corresponding
TRIS bi t shoul d be se t to inpu t mode when using pin s as a nalog i nput s. O nly AN2 i s
an analog I/O, all other ANx pins are analog inputs.
2: See the b lock diagram s for t he ana log I/O pi ns to s ee how A NSEL in teract s w ith th e
CHS bits of the ADCO N0 register.
Legend:
R = Readable bit W = Writable bit U = Unimplem ented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
PIC16F87/88
DS30487D-page 114 2002-2013 Microchip Technology Inc.
REGISTER 12-2: ADCON0: A/D CONTROL REGISTER (ADDRESS 1Fh) PIC16F88 DEVICES ONLY
R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 U-0 R/W-0
ADCS1 ADCS0 CHS2 CHS1 CHS0 GO/DONE —ADON
bit 7 bit 0
bit 7-6 ADCS<1:0>: A/D Conversion Clock Select bits
If ADCS2 = 0:
00 = FOSC/2
01 = FOSC/8
10 = FOSC/32
11 = FRC (clock derived from the int ernal A/D module RC oscillat or)
If ADCS2 = 1:
00 = FOSC/4
01 = FOSC/16
10 = FOSC/64
11 = FRC (clock derived from the int ernal A/D module RC oscillat or)
bit 5-3 CHS<2:0>: Analog Channel Select bits
000 = Channel 0 (RA0/AN0)
001 = Channel 1 (RA1/AN1)
010 = Channel 2 (RA2/AN2)
011 = Channel 3 (RA3/AN3)
100 = Channel 4 (RA4/AN4)
101 = Channel 5 (RB6/AN5)
110 = Channel 6 (RB7/AN6)
bit 2 GO/DONE: A/D Conversion Status bit
If ADON = 1:
1 = A/D conversion in progress (setting this bit starts the A/D conversion)
0 = A/D conversion not in progress (this bit is automatically cleared by hardware when the A/D
conversion is compl ete)
bit 1 Unimplemented: Read as0
bit 0 ADON: A/D On bit
1 = A/D conve rter mo dule is operatin g
0 = A/D converter module is shut off and consumes no operating curre nt
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
2002-2013 Microchip Technology Inc. DS30487D-page 115
PIC16F87/88
REGISTER 12-3: ADCON1: A/D CONTROL REGISTER 1 (ADDRESS 9Fh) PIC16F88 DEVICES ONLY
R/W-0 R/W-0 R/W-0 R/W-0 U-0 U-0 U-0 U-0
ADFM ADCS2 VCFG1 VCFG0
bit 7 bit 0
bit 7 ADFM: A/D Result Format Select bit
1 = Right justified. Six Most Significant bits of ADRESH are read as ‘0’.
0 = Left justified. Six Least Significant bits of ADRESL are read as ‘0’.
bit 6 ADCS2: A/D Clock Di vide by 2 Select bit
1 = A/D clock source is divided by 2 when system clock is used
0 =Disabled
bit 5-4 VCFG<1:0>: A/D Voltage Reference Configuration bits
Note: The AN SEL bits for AN 3 and AN2 inp uts must be configure d as analog inputs for the
VREF+ and VREF- external pins to be used.
bit 3-0 Unimplemented: Read as ‘0
Legend:
R = Readable bit W = Writable bi t U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
Logic S tate VREF+VREF-
00 AVDD AVSS
01 AVDD VREF-
10 VREF+ AVSS
11 VREF+ VREF-
PIC16F87/88
DS30487D-page 116 2002-2013 Microchip Technology Inc.
The ADRESH:ADRESL registers contain the result of
the A/D conversion. When the A/D conversion is
complete, the result is loaded into the A/D Result register
pair, the GO/DONE bi t (ADCON0<2>) is cleared and
A/D Interrupt Flag bit, ADIF, is set. The block diagram of
the A/D module is shown in Figu re 12-1.
After the A/D module has been configured as desired,
the selected channel must be acquired before the
conversion is started. The analog input channels must
have their corresponding TRIS bits selected as inputs.
To determine sample time, see Section 12.1 “A/D
Acquisition Requirements”. After this sample time
has elapsed, the A/D conversi on can be started.
These steps should be followed for doing an A/D
conversion:
1. Configure the A/D module:
Configure analog/digital I/O (ANSEL)
Configure voltage reference (ADCON1)
Select A/D input channel (ADCON0)
Select A/D con ve rsi on clock (ADCON0)
Turn on A/D module (ADCON0)
2. Configure A/D interrupt (if desired):
Clear ADIF bit
Set ADIE bit
SET PEIE bit
Set GIE bit
3. Wait the required acquisition time.
4. Start conversion:
Set GO/D ONE bit (ADCON0)
5. Wait for A/D conversion to complete, by either:
Polling for the GO/DONE bit to be cleared
(with interrupts disabled); OR
Waiting for the A/D interrupt
6. Read A/D Result register pair
(ADRESH:ADRESL), clear bit ADIF if required.
7. For next conversion, go to step 1 or step 2 as
required. The A/D conversion time per bit is
defined as TAD. A minimum wait of 2 TAD is
required before the next acquisition starts.
FIGURE 12-1: A/D BLOCK DIAGRAM
(Input Voltage)
VIN
VREF+
(Reference
Voltage)
AVDD
VCFG1:VCFG0
CHS2:CHS0
RA3/AN3/VREF+/C1OUT
RA2/AN2/CVREF/VREF-
RA1/AN1
RA0/AN0
011
010
001
000
A/D
Converter
VREF-
(Reference
Voltage) AVSS
VCFG1:VCFG0
RB6/AN5/PGC/T1OSO/T1CKI
RB7/AN6/PGD/T1OSI
RA4/AN4/T0CKI/C2OUT
110
101
100
2002-2013 Microchip Technology Inc. DS30487D-page 117
PIC16F87/88
12.1 A/D Acquisition Requirements
For the A/D converter to meet its specified accurac y , the
charge holding capacitor (CHOLD) must be allowed to
fully charge to the input channel voltage level. The ana-
log input model is shown in Figure 12-2. The source
impedance (RS) and the internal sampling switch (RSS)
impedance directly affect the time required to charge the
capacitor CHOLD. The sampling switch (RSS) impedance
varies over the device voltage (VDD), see Figure 12-2.
The maximum recommended impedance for analog
sources is 10 k. As the impedance is decreased, the
acquisition time may be decreased. After the analog
input channel is selected (changed), this acquisition
must be done before the conversi on can be s tarted.
To calculate the minimum acquisition time,
Equation 12-1 may be used. This equation assumes
that 1/2 LSb error is used (1024 st eps for the A/D). The
1/2 LSb err or is the ma ximu m error allo wed for the A/D
to meet its specified resolution.
To calculate the minimum acquisition time, TACQ, see
the “PIC® Mid-Range MCU Family Reference Manual”
(DS33023).
EQUATION 12-1: ACQUISITION TIME
FIGURE 12-2: ANALOG INPUT MODEL
TACQ
TC
TACQ
=
=
=
=
=
=
=
=
Amplifier Settling Time + Hold Capacitor Charging Time + Temperature Coefficient
TAMP + TC + TCOFF
2 s + TC + [(Temperature -25°C)(0.05 s/°C)]
CHOLD (RIC + RSS + RS) In(1/2047)
-120 pF (1 k + 7 k + 10 k) In(0.0004885)
16.47 s
2 s + 16.47 s + [(50°C – 25C)(0.05 s/C)
19.72 s
Note 1: The reference voltage (VREF) has no effect on the equation, since it cancels itself out.
2: The charge holding capacitor (CHOLD) is not discharged after each conversion.
3: The maximum recommended impedance for analog sources is 10 k. This is required to meet the pin
leakage specification.
4: After a conversion has completed, a 2.0 TAD delay must complete before acquisition can begin again.
During this time, the holding capacitor is not connected to the selected A/D input channel.
CPIN
VA
RSANx
5 pF
VDD
VT = 0.6V
VT = 0.6V ILEAKAGE
RIC 1K
Sampling
Switch
SS RSS
CHOLD
= DAC Capacitance
VSS
6V
Sampling Switch
5V
4V
3V
2V
567891011
(k)
VDD
= 120 pF
±500 nA
Legend: CPIN
VT
ILEAKAGE
RIC
SS
CHOLD
= Input Capacitance
= Threshold Voltage
= Leakage Current at the pin due to
= Interconnect Resistance
= Sampling Switch
= Sample/Hold Capacitance (from DAC)
various junctions
PIC16F87/88
DS30487D-page 118 2002-2013 Microchip Technology Inc.
12.2 Selecting the A/D Conversion
Clock
The A/D conversion time per bit is define d as TAD. The
A/D conversion requires 9.0 TAD per 10-bit conv ers io n.
The source of the A/D conversion clock is software
selectable. The seven possible options for TAD are:
•2T
OSC
•4TOSC
•8TOSC
•16TOSC
•32TOSC
•64TOSC
Internal A/D module RC osc il lat or (2-6 s)
For correct A/D conversions, the A/D conversion clock
(TAD) must be selected to ensure a minimum TAD time
as small as possible, but no less than 1.6 s and not
greater than 6.4 s.
Table 12-1 shows the resultant TAD tim es de ri v ed f r om
the device operating frequencies and the A/D clock
sour ce se lec ted .
12.3 Operation in Power-Managed
Modes
The selection of the automatic acquisition time and
A/D conversion clock is determined in part by the clock
source and frequency while in a power-managed
mode.
If the A/D is expected to operate while the device is in
a power-managed mode, the ADCS2:ADCS0 bits in
ADCON0 and ADCON1 should be updated in accor-
dance w ith the power-manag ed mode cloc k that will be
used. After the power-managed mode is entered
(either of the power-managed Run modes), an A/D
acquisition or conversion may be started. Once an
acquisition or conversion is started, the device should
continue to be clocked by the same power-managed
mode clock source until the conversion has been
completed.
If the power-managed mode clock frequency is less
than 1 MHz, the A/D RC clock source should be
selected.
TABLE 12-1: TAD vs. MAXIMUM DEVICE OPERATING FREQUENCIES – STANDARD DEVICES (C)
AD Clock Source (TAD) Maximum Device Frequency
Operation ADCS<2> ADCS<1:0> Max.
2 TOSC 0001.25 MHz
4 TOSC 1002.5 MHz
8 TOSC 001 5 MHz
16 TOSC 101 10 MHz
32 TOSC 010 20 MHz
64 TOSC 110 20 MHz
RC(1,2,3) x11(Note 1)
Note 1: The R C source has a typical TAD time of 4 s, but can vary between 2-6 s.
2: When the device frequencies are greater than 1 MHz, the RC A/D conversion clock source is only
recommended for Sleep operation.
3: For extend ed voltage devices (LF), please refer to Section 18.0 “Electrical Characteristics”.
2002-2013 Microchip Technology Inc. DS30487D-page 119
PIC16F87/88
12.4 Configuring Analog Port Pins
The ADCON1, ANSEL, TRISA and TRISB registers
control th e operation of the A/D port pins. The port pins
that are desired as analog inputs must have their
corresponding TRIS bits set (input). If the TRIS bit is
cleared (output), the digital output level (VOH or VOL)
will be converted.
The A/D operation is independent of the state of the
CHS<2:0> bits and the TRIS bits.
12.5 A/D Conversions
Clearing the GO/DONE bit during a conversion will
abort the current conversion. The A/D Result register
pair will NOT be updated with the partially completed
A/D conversion sample. That is, the ADRESH:ADRESL
registers will continue to contain the value of the last
completed conversion (or the last value written to the
ADRESH:ADRESL registers). Af ter the A/D conversion
is aborted, a 2 TAD wait is required before the next
acquisition is started. After this 2 TAD wait, acquisition
on the selected channel is automatically started. The
GO/DONE bit can then be set to start the conversion.
In Figure 12-3, after the GO/DONE bit is set, the first
time se gment has a minimum of TCY and a maxi mum of
TAD.
12.5.1 A/D RESULT REGISTERS
The ADRESH:ADRESL register pair is the location
where the 10-bit A/D result is loaded at the completion
of the A/D co nversion . This register p air is 16 bit s wide.
The A/D mod ule gives the flexi bility to lef t or righ t justify
the 10-bit result in the 16-bit result register. The A/D
Format Select bit (ADFM) controls this justification.
Figure 12-4 shows the operation of the A/D result
justification. The extra bits are loaded with ‘0’s. W he n
an A/D result will not overwrite these locations (A/D
disable), these registers may be used as two general
purpose 8-bit registers.
FIGURE 12-3: A/D CONVE RSION TAD CYCLES
FIGURE 12-4: A/D RESULT JUSTIFICATION
Note 1: When reading the Port register, all pins
configured as analog input channels will
read as c le ared (a l ow l ev el). Pins config-
ured as digital inputs will convert an
analog input. Analog levels on a digitally
configured input will not affect the
conversion accuracy.
2: Analog le vels on any pin that is defined a s
a digit al input (including the RA4:RA0 and
RB7:RB6 pins), may cause the input
buffer to consume current out of the
device specification.
Note: The GO/DONE bit should NOT be set in
the sam e inst ructio n that tu rns on the A/D.
TAD1TAD2 TAD3 TAD4 TAD5TAD6
T
AD
7 T
AD
8
TAD9
Set GO/DONE bit
Holding capacitor is disconnected from analog input (typically 100 ns)
b9 b8 b7 b6 b5 b4 b3 b2
TAD10 TAD11
b1 b0
TCY to TAD
Conversion starts
ADRES is loaded,
GO/DONE bit is cleared,
ADIF bit is set,
holding capacitor is connected to analog input
10-bit Result
ADRESH ADRESL
0000 00
ADFM = 0
0
2 1 0 77
10-bit Result
ADRESH ADRESL
10-bit Result
0000 00
70 7 6 5 0
ADFM = 1
Right Justified Left Justified
PIC16F87/88
DS30487D-page 120 2002-2013 Microchip Technology Inc.
12.6 A/D Operation During Sleep
The A/D module can operate during Sleep mode. This
requires that the A/D clock source be set to RC
(ADCS1:ADCS0 = 11). When the RC clock source is
selected, the A/D module waits one instruction cycle
before starting the conversion. This allows the SLEEP
instruction to be executed which eliminates all digital
switchi ng noise fro m the conv ersion. Whe n the conver-
sion i s comple ted, the GO /DONE bit will be cleared and
the result loaded into the ADRES registers. If the A/D
interrupt is enabled, the device will wake-up from
Sleep. If the A/D interrupt is not enabled, the A/D
modul e wil l then be t urned off, alt hough the A DON bi t
will remain set.
When the A/D clock sour ce is anoth er clock optio n (not
RC), a SLEEP instructi on will cause the present conver-
sion t o be aborte d and the A/D mod ule to be turned of f,
though the ADON bit will remain set.
Turning of f the A/D plac es the A/D m odu le in it s lowes t
current consumption state.
12.7 Effects of a Reset
A device Reset forces all registers to their Reset state.
The A/D module is disabled and any conversion in
progress is aborted. All A/D input pins are configured
as analog inputs.
The value that is in the ADRESH:ADRESL registers
is not modified for a Power-on Reset. The
ADRESH:ADRESL registers w ill cont ain unkno wn data
after a Power-on Reset.
12.8 Use of the CCP Trigger
An A/D convers ion can be st arted by th e “special event
trigger” of the CCP module. This requires that the
CCP1M3:CCP1M0 bits (CCP1CON<3:0>) be pro-
grammed as ‘1011’ and that the A/D module is enabled
(ADON bit is set). When the trigger occurs, the GO/
DONE bit will be set, s tarting the A/D conversion and
the T imer1 counter will be res et to zero. T imer1 is reset
to automatically repeat the A/D acquisition period with
minimal software overhead (moving the
ADRESH:ADRESL to the de sired loc ation). Th e appro-
priate analog input channel must be selected and the
minimum acquisition done before the “special event
trigger” sets the GO/DONE bit (starts a conve rsion).
If the A/D module is not enabled (ADON is cleared), then
the “special event trigger” will be ignored by the A/D
module, but will still reset the Timer1 counter.
Note: For the A/D module to operate in Sleep,
the A/D clock source must be set to RC
(ADCS1:ADCS0 = 11). To perform an A/D
conversion in Sleep, ensure the SLEEP
instruction immediately follows the
instruction that sets the GO/DONE bit.
TABLE 12-2: REGISTERS/BITS ASSOCIATED WITH A/D
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on
POR, BOR
Value on
all other
Resets
0Bh, 8Bh
10Bh,
18Bh
INTCON GIE PEIE TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 0000 000x 0000 000u
0Ch PIR1 —ADIF
(1) RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF -000 0000 -000 0000
8Ch PIE1 —ADIE
(1) RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE -000 0000 -000 0000
1Eh ADRESH(2) A/D Result Register High Byte xxxx xxxx uuuu uuuu
9Eh ADRESL(2) A/D Result Register Low Byte xxxx xxxx uuuu uuuu
1Fh ADCON0(2) ADCS1 ADCS0 CHS2 CHS1 CHS0 GO/DONE —ADON0000 00-0 0000 00-0
9Fh ADCON1(2) ADFM ADCS2 VCFG1 VCFG0 0000 ---- 0000 ----
9Bh ANSEL(2 ANS6 ANS5 ANS4 ANS3 ANS2 ANS1 ANS0 -111 1111 -111 1111
05h PORTA
(PIC16F87)
(PIC16F88)
RA7 RA6 RA5 RA4 RA3 RA2 RA1 RA0
xxxx 0000
xxx0 0000
uuuu 0000
uuu0 0000
05h, 106h PORTB
(PIC16F87)
(PIC16F88)
RB7 RB6 RB5 RB4 RB3 RB2 RB1 RB0
xxxx xxxx
00xx xxxx
uuuu uuuu
00uu uuuu
85h TRISA TRISA7 TRISA6 TRISA5(3) PORTA Data Direction Register (TRISA<4:0>) 1111 1111 1111 1111
86h, 186h TRISB TRISB7 TRISB6 TRISB5 TRISB4 TRISB3 TRISB2 TRISB1 TRISB0 1111 1111 1111 1111
Legend: x = unk nown, u = unchanged, - = unimplemented, read as ‘0’. Shaded cells are not used for A/D conversion.
Note 1: This bit is only implemented on the PIC16F88. The bit will read ‘0’ on the PIC16F87.
2: PIC16F88 only.
3: Pin 5 is an input only; the state of the TRISA5 bit has no effect and will always read 1’.
2002-2013 Microchip Technology Inc. DS30487D-page 121
PIC16F87/88
13.0 COMPARATOR MODULE
The comparator module contains two analog
comparators. The inputs to the comparators are
multiple xed with I/O port pins RA0 through RA3, while
the outputs are multiplexed to pins RA3 and RA4. The
on-chip Voltage Reference (Section 14.0 “Comparator
Voltage Reference Module”) can also be an input to
the comparators.
The CMCON register (Register 13-1) controls the
comparator input and output multiplexors. A block
diagram of the various comparator configurations is
shown in Figure 13-1.
REGISTER 13-1: CMCON: COMPARATOR MODULE CONTROL REGISTER (ADDRESS 9Ch)
R-0 R-0 R/W-0 R/W-0 R/W-0 R/W-1 R/W-1 R/W-1
C2OUT C1OUT C2INV C1INV CIS CM2 CM1 CM0
bit 7 bit 0
bit 7 C2OUT: Comparator 2 Output bit
When C2INV = 0:
1 = C2 VIN+ > C2 VIN-
0 = C2 VIN+ < C2 VIN-
When C2INV = 1:
1 = C2 VIN+ < C2 VIN-
0 = C2 VIN+ > C2 VIN-
bit 6 C1OUT: Comparator 1 Output bit
When C1INV = 0:
1 = C1 VIN+ > C1 VIN-
0 = C1 VIN+ < C1 VIN-
When C1INV = 1:
1 = C1 VIN+ < C1 VIN-
0 = C1 VIN+ > C1 VIN-
bit 5 C2INV: Comparator 2 Output Inversion bit
1 = C2 output inverted
0 = C2 output not inverted
bit 4 C1INV: Comparator 1 Output Inversion bit
1 = C1 output inverted
0 = C1 output not inverted
bit 3 CIS: Comparator Input Switch bit
When CM2:CM0 = 001:
1 =C1 VIN- connects to RA3
0 =C1 V
IN- connects to RA0
When CM2:CM0 = 010:
1 =C1 VIN- connects to RA3
C2 VIN- connects to RA2
0 =C1 V
IN- connects to RA0
C2 VIN- connects to RA1
bit 2-0 CM<2:0>: Comparator Mode bits
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
PIC16F87/88
DS30487D-page 122 2002-2013 Microchip Technology Inc.
13.1 Comparator Configuration
There are eight modes of operation for the compara-
tors. The CMCON register is used to select these
modes. Figure 13-1 shows the eight possible modes.
The TRISA register controls the data direction of the
comparator pins for each mode. If the Comparator
mode is changed, the com p ara tor o utput level may n ot
be valid for the specified mode change delay shown in
Section 18.0 “Electrical Characteristics”.
FIGURE 13-1: COMPARATOR I/O OPERATING MODES
Note: Compara tor in terr upts sh ould be disab led
during a Comparator mode change;
otherwi se , a false inte rrup t may oc cur.
C1
RA0/AN0 VIN-
VIN+
RA3/AN3/ Off (Read as0’)
Comparators Reset
A
A
CM2:CM0 = 000
C2
RA1/AN1 VIN-
VIN+
RA2/AN2/ Off (Read as0’)
A
A
C1
RA0/AN0 VIN-
VIN+
RA3/AN3/ C1OUT
Two Independent Comparators
A
A
CM2:CM0 = 100
C2
RA1/AN1 VIN-
VIN+
RA2/AN2/ C2OUT
A
A
C1
RA0/AN0 VIN-
VIN+
RA3/AN3/ C1OUT
Two Common Reference Comparators
A
D
CM2:CM0 = 011
C2
RA1/AN1 VIN-
VIN+
RA2/AN2/ C2OUT
A
A
C1
RA0/AN0 VIN-
VIN+
RA3/AN3/ Off (Read as0’)
One Independent Comparator
D
D
CM2:CM0 = 101
C2
RA1/AN1 VIN-
VIN+
RA2/AN2/ C2OUT
A
A
C1
RA0/AN0 VIN-
VIN+
RA3/AN3/ Off (Read as ‘0’)
Comparators Off (POR Default Value)
D
D
CM2:CM0 = 111
C2
RA1/AN1 VIN-
VIN+
RA2/AN2/ Off (Read as ‘0’)
D
D
C1
RA0/AN0 VIN-
VIN+
RA3/AN3/ C1OUT
Four Inputs Multiplexed to Two Comparators
A
A
CM2:CM0 = 010
C2
RA1/AN1 VIN-
VIN+
RA2/AN2/ C2OUT
A
A
From VREF Module
CIS = 0
CIS = 1
CIS = 0
CIS = 1
C1
RA0/AN0 VIN-
VIN+
RA3/AN3/ C1OUT
Two Common Reference Comparators with Outputs
A
D
CM2:CM0 = 110
C2
RA1/AN1 VIN-
VIN+
RA2/AN2/ C2OUT
A
A
A = Analog Input, port reads zeros always.
D = Digital I nput.
CIS (CMCON<3>) is the Comparator Input Switch.
RA4/T0CKI/C2OUT
C1
RA0/AN0 VIN-
VIN+
RA3/AN3/ C1OUT
Three Inputs Multiplexed to Two Comparato rs
A
A
CM2:CM0 = 001
C2
RA1/AN1 VIN-
VIN+
RA2/AN2/ C2OUT
A
A
CIS = 0
CIS = 1
C1OUT
C1OUT
C1OUT
C1OUT C1OUT
C1OUT
C1OUT
C1OUT
CVREF
CVREF
CVREF
CVREF
CVREF
CVREF
CVREF
CVREF
2002-2013 Microchip Technology Inc. DS30487D-page 123
PIC16F87/88
13.2 Comparator Operation
A single comparator is shown in Figure 13-2, along with
the relationship between the analog input levels and
the digit al ou tput. When the an alog input a t VIN+ is les s
than the analog input VIN-, the o utput of the co mparator
is a digital low level. When the analog input at VIN+ is
greater than the analog input VIN-, the output of the
comparator is a digital high level. The shaded areas of
the output of the comparator in Figure 13-2 represent
the unce rtainty due to input offsets and response time.
13.3 Comparator Reference
An external or internal reference signal may be used
depending on the comparator operating mode. The
analog signal present at VIN- is comp ar ed to the si gna l
at VIN+ and the digital output of the comparator is
adjusted accordingly (Figure 13-2).
FIGURE 13-2: SINGLE COMPARATOR
13.3.1 EXTERN AL REFE REN C E SIGNA L
When external voltage references are used, the
comparator module can be configu red to have the com-
parators operate from the same, or different reference
sour ces. How ever , th resho ld detecto r applica tions ma y
require th e s am e re fere nc e. Th e re fere nc e s ignal m us t
be between VSS and VDD and can be app lie d to eit her
pin of the comparator(s).
13.3.2 INTERNAL REFERENCE SIGNAL
The com p arator module al so allows the sel ec tion of an
internally generated voltage reference for the
comparators. Section 14.0 “Comparator Voltage
Reference Module” contains a detailed description of
the Comparator Voltage Reference module that
provides this signal. The internal reference signal is
used when comparators are in mode CM<2:0> = 010
(Figure 13-1). In this mode, the internal voltage
reference is applied to the VIN+ pin of both
comparators.
13.4 Comparator Response Time
Response time is the minimum time, after selecting a
new reference voltage or input source, before the
comparator output has a valid level. If the internal
reference is changed, the maximum delay of the inter-
nal voltage reference must be considered when using
the comparator outputs. Otherwise, the maximum
delay of the comparators should be used (Section 18.0
“Electrical Characteristics”).
13.5 Comparator Outputs
The comparator outputs are read through the CMCON
register. These bits are read-only. The comparator
output s may al so be dire ctly output to the RA3 and RA4
I/O pins . When enab led, multipl exors in th e output p ath
of the RA3 and RA4 pins will switch and the output of
each pin will be the unsy nc hro niz ed output of the com-
parator. The uncertainty of each of the comparators is
related t o the input of fset voltage and the response time
given in the specifications. Figure 13-3 shows the
comp ara tor outp ut blo ck diagra m.
The TRISA bits will still function as an output enable/
disable for the RA3 and RA4 pins while in this mode.
The polarity of the comparator outputs can be changed
using the C2INV and C1INV bits (CMCON<5:4 >).
+
VIN+
VIN-Output
VIN–
VIN+
Output
Output
VIN+
VIN-
Note 1: When reading the Port register, all pins
configured as analog inputs will read as
0’. Pins configured as digital inputs will
convert an analog input, according to the
Schmitt Trigger input specification.
2: Analog levels, on any pin defined as a
digit al input, may ca use the input buff er to
consume more current than is specified.
PIC16F87/88
DS30487D-page 124 2002-2013 Microchip Technology Inc.
FIGURE 13-3: COMPARATOR OUTPUT BLOCK DIAGRAM
13.6 Comparator Interrupts
The comparator interrupt flag is set whenever there is
a change in the output value of either comparator.
Software will need to maintain information about the
stat us of the output b its, as rea d from CMCON<7:6> , to
determine the actual change that occurred. The CMIF
bit (PIR2 register) is the Comparator Interrupt Flag. The
CMIF bit must be reset by clearing it (‘0’). Since it is
also possible to write a ‘1’ to this register, a simulated
interrupt may be initiated.
The CMIE bit (PIE2 register) and the PEIE bit (INTCON
register ) must be set to ena ble the interrupt. In addition,
the GIE bit must also be set. If any of these bits are
clear, the interrupt is not enabled, though the CMIF bit
will still be set if an interrupt condition occurs.
The user , in the Interrupt Service Routine, can clear the
interrupt in the following manner:
a) Any read or write of CMCON will end the
mismatch condition.
b) Clear flag bit CMIF.
A mismatc h co ndi tio n will co nti nue to set fla g bit CMIF.
Reading CMCON will end the mismatch condition and
allow flag bit CMIF to be cleared.
DQ
EN
RD_CMCON
Set C M I F bit
MULTIPLEX
DQ
EN
CL
Port Pins
Q3 * RD_CMCON
RESET
From other Comparator
To D a ta Bu s
Q1
CnINV
Note: If a change in the CMCON register
(C1OUT or C2OUT) should occur when a
read operation is being executed (start of
the Q2 cycle), then the CMIF (PIR2
register) interrupt flag may not get set.
2002-2013 Microchip Technology Inc. DS30487D-page 125
PIC16F87/88
13.7 Comparator Operation During
Sleep
When a comparator is active and the device is placed
in Sleep mode, the comparator remains active and the
interrupt is functional, if enabled. This interrupt will
wake-up the device from Sleep mode when enabled.
While the comparator is powered up, higher Sleep
currents than shown in the power-down current
specification will occur. Each operational comparator
will consume additional current, as shown in the com-
parat or specifi cations. To minimiz e power co nsumptio n
while in Sleep mode, turn off the comparators,
CM<2:0> = 111, before entering Sleep. If the device
wakes up from Sleep, the contents of the CMCON
register are not affected.
13.8 Effects of a Reset
A device Reset forces the CMCON register to its Reset
state, causing the comparator module to be in the
Comparator Off mode, CM<2:0> = 111.
13.9 Analog Input Connection
Considerations
A simplified circuit for an analog input is shown in
Figure 13-4. Since the analog pins are connected to a
digital output, they have reverse biased diodes to V DD
and VSS. Th e analog input, th erefore, must be betw een
VSS and VDD. If the input voltage deviates from this
range by more than 0.6V in either direction, one of the
diodes is forward biased and a latch-up condition may
occur. A maximum source impedance of 10 k is
recommended for the analog sources. Any external
component connected to an analog input pin, such as
a capacitor or a Zener diode, should have very little
leakage current.
FIGURE 13-4: ANALOG INPUT MODEL
VA
RS < 10K
AIN CPIN
5 pF
VDD
VT = 0.6V
VT = 0.6V
RIC
ILEAKAGE
±500 nA
VSS
Legend: CPIN = Input Capaci tance
VT= Threshold Voltage
ILEAKAGE = Leakage Current at the pin due to various junctions
RIC = Interconnect Resistance
RS= Source Impedance
VA = Analog Voltage
PIC16F87/88
DS30487D-page 126 2002-2013 Microchip Technology Inc.
TABLE 13-1: REGISTERS ASSOCIATED WITH THE COMPARATOR MODULE
Add re ss N a m e B i t 7 Bit 6 B it 5 Bit 4 Bit 3 B i t 2 Bit 1 Bit 0 Value on
POR
Value on
all other
Resets
9Ch CMCON C2OUT C1OUT C2INV C1INV CIS CM2 CM1 CM0 0000 0111 0000 0111
9Dh CVRCON CVREN CVROE CVRR CVR3 CVR2 CVR1 CVR0 000- 0000 000- 0000
0Bh, 8Bh,
10Bh, 18Bh INTCON GIE PEIE TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 0000 000x 0000 000u
0Dh PIR2 OSFIF CMIF EEIF 00-0 ---- 00-0 ----
8Dh PIE2 OSFIE CMIE EEIE 00-0 ---- 00-0 ----
05h PORTA
(PIC16F87)
(PIC16F88)
RA7 RA6 RA5 RA4 RA3 RA2 RA1 RA0
xxxx 0000
xxx0 0000
uuuu 0000
uuu0 0000
85h TRISA TRISA7 TRISA6 TRISA5(1) TRISA4 TRISA3 TRISA2 TRISA1 TRISA0 1111 1111 1111 1111
Legend: x = unk nown, u = unchanged, - = unimplemented, read as 0’. Shaded cells are not used by the comparator module.
Note 1: Pin 5 is an input only; the state of the TRISA5 bit has no effect and will always read ‘1’.
2002-2013 Microchip Technology Inc. DS30487D-page 127
PIC16F87/88
14.0 COMPARATOR VOLTAGE
REFERENC E MODULE
The comparator voltage reference generator is a 16-tap
resistor ladder network that provides a fixed voltage
reference when the comparators are in mode ‘010’. A
programmable register c ontrols the function of the refer-
ence generator. Register 14-1 lists the bit functions of
the CVRCON register.
As shown in Figure 14-1, the resistor ladder is seg-
mented to provide tw o ranges of C VREF values and has
a power-down function to conserve power when the
reference is not bein g used. The comp arat or refer ence
supply voltage (also referred to as CVRSRC) comes
directly from VDD. It should be noted, however, that th e
voltage at the top of the ladder is CVRSRC – VSAT,
where VSAT is the saturation voltage of the power
switch transistor. This reference will only be as
accurate as the values of CVRSRC and VSAT.
The output of the reference generator may be
connected to the RA2/AN2/CVREF/VREF- pin (VREF- is
available on the PIC16F88 device only). This can be
used as a simple D/A function by the user if a very high-
impedance load is used. The primary purpose of this
function is to provide a test path for testing the
reference generator function.
REGISTER 14-1: CVR CON: COMPARATOR VO LTAGE REFERENCE CONTROL REGISTER
(ADDRESS 9Dh)
R/W-0 R/W-0 R/W-0 U-0 R/W-0 R/W-0 R/W-0 R/W-0
CVREN CVROE CVRR CVR3 CVR2 CVR1 CVR0
bit 7 bit 0
bit 7 CVREN: Comparator Voltage Reference Enable bit
1 = CVREF circuit powered on
0 = CVREF circuit powered down
bit 6 CVROE: Comparator VREF Output Enable bit
1 = CVREF voltage level is output on the RA2/AN2/CVREF/VREF- pin(1)
0 = CVREF voltage level is disconnected from the RA2/AN2/CVREF/VREF- pin(1)
bit 5 CVRR: Compara tor VREF Range Selection bit(1)
1 = 0.00 CVRSRC to 0.625 CVRSRC with CV RSRC/24 step size
0 = 0.25 CVRSRC to 0.72 CVRSRC with CVRSRC/32 step size
bit 4 Unimplemented: Read as0
bit 3-0 CVR<3:0>: Comparator VREF Value Selection 0 VR3:VR0 15 bits(1)
When CVRR = 1:
CVREF = (VR<3:0>/24) (CVRSRC)
When CVRR = 0:
CVREF = 1/4 (CVRSRC) + (VR3:VR0/32) (CVRSRC)
Note 1: VREF is available on the PIC16F88 device only.
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
PIC16F87/88
DS30487D-page 128 2002-2013 Microchip Technology Inc.
FIGURE 14-1: COMPARATOR VOLTAGE REFERENCE BLOCK DIAGRAM
TABLE 14-1: REGISTERS ASSOCIATED WITH COMPARATOR VOLTAGE REFERENCE
CVRR
8R
CVR3
CVR0
16-to-1 Analog MUX
8R RRRR
CVREN
CVREF
16 S tages
Input to
Comparator
CVROE
RA2/AN2/CVREF/VREF- pin(1)
VDD
CVR2
CVR1
Note 1: VREF is available on the PIC16F88 device only.
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 B it 1 Bit 0 Value on
POR
Value on
all other
Resets
9Dh CVRCON CVREN CVROE CVRR CVR3 CVR2 CVR1 CVR0 000- 0000 000- 0000
9Ch CMCON C2OUT C1OUT C2INV C1INV CIS CM2 CM1 CM0 0000 0111 0000 0111
Legend: x = unknown, u = unchanged, - = unimplement ed, read as ‘0 . Shaded cel ls are not used with the compara tor volt age reference.
2002-2013 Microchip Technology Inc. DS30487D-page 129
PIC16F87/88
15.0 SPECIAL FEATURES OF THE
CPU
These d evices have a host of features intended to max-
imize system reliability, minimize cost through elimina-
tion of external components, provide power-saving
operating modes and offer code protection:
Reset
- Power-o n Rese t (POR)
- Power-up Timer (PWRT)
- Oscillator Start-up Timer (OST)
- Brown-out Reset (BOR)
Interrupts
Watchdog Timer (WDT)
Two-Speed Start-up
Fail-Safe Clock Monitor
Sleep
Code Protection
ID Locations
In-Circuit Serial Programming™ (ICSP™)
There are two timers that offer necessary delays on
power-up. One is the Oscillator Start-up Timer (OST),
intended to keep the chip in Reset until the crystal
oscillator is stable. The other is the Power-up Timer
(PWRT), which provides a fixed dela y of 72 ms (nomi-
nal) on pow er-up on ly. It is designed to ke ep the p ar t in
Reset w hi le the po w er s up ply s t a bilizes and i s enabled
or disabled using a configuration bit. With these two
timers on-chip, most applications need no external
Reset circuitry.
Sleep mode is designed to offer a very low-current
Power-down mode. The user can wake-up from Sleep
through external Reset, Watchdog Timer wake-up or
through an interrupt.
Additional information on special features is available
in th e “PIC® Mid-Range MCU Family Reference Man-
ual” (DS33023).
15.1 Configuration Bits
The configuration bits can be programmed (read as
0’), or left unprogrammed (read as1’), to select
various device configurations. These bits are mapped
in program memory locations 2007h and 2008h.
The user will note that address 2007h is beyond the
user program memory space which can be accessed
only during programming.
PIC16F87/88
DS30487D-page 130 2002-2013 Microchip Technology Inc.
REGISTER 15-1: CONFIG1: CONFIGURATION WORD 1 REGISTER (ADDRESS 2007h)
R/P-1 R/P-1 R/P-1 R/P-1 R/P-1 R/P-1 R/P-1 R/P-1 R/P-1 R/P-1 R/P-1 R/P-1 R/P-1 R/P-1
CP CCPMX DEBUG WRT1 WRT0 CPD LVP BOREN MCLRE FOSC2 PWRTEN WDTEN FOSC1 FOSC0
bit 13 bit 0
bit 13 CP: Flash Program Memo ry Code Protection bits
1 = Code protection off
0 = 0000h to 0FFFh code-protected (all protected)
bit 12 CCPMX: CCP1 Pin Selection bit
1 = CCP1 function on RB0
0 = CCP1 function on RB3
bit 11 DEBUG: In-Circuit Debugger Mode bit
1 = In-Circuit Debugger disabled, RB6 and RB7 are general purpose I/O pins
0 = In-Circuit Debugger enabled, RB6 and RB7 are dedicated to the debugger
bit 10-9 WRT<1:0>: Flash Program Memory Write Enable bits
11 = Write protection off
10 = 0000h to 00FFh write-protected, 0100h to 0FFFh may be modified by EECON control
01 = 0000h to 07FFh write-protected, 0800h to 0FFFh may be modified by EECON control
00 = 0000h to 0FFFh write-protected
bit 8 CPD: Data EE Memory Code Protection bit
1 = Code protection off
0 = Data EE memory code-protected
bit 7 LVP: Low-Voltage Programming Enable bit
1 = RB3/PGM pin has PGM function, Low-Voltage Programming enabled
0 = RB3 is digital I/O, HV on MCLR must be used for programming
bit 6 BOREN: Brown-out Reset Enable bit
1 = BOR enabled
0 = BOR disabled
bit 5 MCLRE: RA5 /MCLR/VPP Pin Function Select bit
1 = RA5/MCLR/VPP pin fu nction is MCLR
0 = RA5/MCLR/VPP pin function is digital I/O, MCLR internally tied to VDD
bit 3 PWRTEN: Power-up Timer Enable bit
1 = PWRT disabled
0 = PWRT enabled
bit 2 WDTEN: Watchdog Timer Enable bit
1 = WDT enabled
0 = WDT disabled
bit 4, 1-0 FOSC<2:0>: Oscillator Selection bits
111 = EXTRC oscillator; CLKO function on RA6/OSC2/CLKO
110 = EXTRC oscillator; port I/O function on RA6/OSC2/CLKO
101 = INTRC oscillator; CLKO function on RA6/OSC2/CLKO pin and port I/O function on RA7/OSC1/CLKI pin
100 = INTRC oscillator; port I/O function on both RA6/OSC2/CLKO pin and RA7/OSC1/CLKI pin
011 = ECIO; port I/O function on RA6/OSC2/CLKO
010 = HS oscillator
001 = XT oscillator
000 = LP oscillator
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set 0’ = Bit is cleared x = Bit is unknown
2002-2013 Microchip Technology Inc. DS30487D-page 131
PIC16F87/88
REGISTER 15-2: CONFIG2: CONFIGURATION WORD 2 REGISTER (ADDRESS 2008h)
U-1 U-1 U-1 U-1 U-1 U-1 U-1 U-1 U-1 U-1 U-1 U-1 R/P-1 R/P-1
IESO FCMEN
bit 13 bit 0
bit 13-2 Unimplemented: Read as ‘1
bit 1 IESO: Internal External Switchover bit
1 = Internal External Switchover mode enabled
0 = Internal External Switchover mode disabled
bit 0 FCMEN: Fail-Safe Clock Monitor Enable bit
1 = Fail-Safe Clock Monitor enabled
0 = Fail-Safe Clock Monitor disabled
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
PIC16F87/88
DS30487D-page 132 2002-2013 Microchip Technology Inc.
15.2 Reset
The PIC16F 87/ 88 differentiate s bet we en vario us kind s
of Reset:
Power- on Re set (POR)
•MCLR
Reset during normal operation
•MCLR
Reset during Sleep
WDT Reset during normal operation
WDT wake-up during Sleep
Brown-out Reset (BOR)
Some regi sters a re not af fected in any Rese t condit ion.
Their statu s is unknown on POR and unchange d in any
other Reset. Most other registers are reset to a “Reset
state” on Power-on Reset (POR), on the MCLR and
WDT Reset, on MCL R R ese t du ring Sle ep a nd Bro w n-
out Reset (BOR). They are not affected by a WDT
wake-up which is viewed as the resumption of normal
operation. The TO and PD bits are set or cleared
differently in different Reset situations, as indicated in
Table 15-3. These bits are used in software to deter-
mine the nature of the Reset. Upon a POR, BOR or
wake-up from Sleep, the CPU requires approximately
5-10 s to become ready for code execution. This
delay runs in parallel with any other timers. See
Table 15-4 for a full description of Reset states of all
registers.
A simp lified block diagram of the On -Chip Reset C ircuit
is sh own in Figu re 15-1.
FIGURE 15-1: SI MPLIFI ED BLOCK DIAGRAM OF ON-CHIP RESET CIRCUIT
S
RQ
External
Reset
MCLR
VDD
OSC1
WDT
Module
VDD Rise
Detect
OST/PWRT
INTRC
WDT
Time-out
Power-on Reset
OST
10-bit Ripple Counter
PWRT
Chip_Reset
11-bit Ripple Counter
Reset
Enable OST
Enable PWRT
Sleep
Brown-out
Reset BOREN
31.25 kHz
2002-2013 Microchip Technology Inc. DS30487D-page 133
PIC16F87/88
15.3 MCLR
PIC16F87/88 devices have a noise filter in the MCLR
Reset path. The filter will detect and ignore small
pulses.
It should be noted that a WDT Reset does not drive
MCLR pin low.
The behavior of the ESD protection on the MCLR pin
has been altered from previous devices of this family.
Volta ges app lied to the p in that ex ceed i ts s pecif icatio n
can resul t in both MCLR an d excessi ve current beyon d
the device specification during the ESD event. The
circuit, as shown in Figure 15-2, is suggested.
The RA5/MCLR/VPP pin can be configured for MCLR
(default), or as an I/O pin (RA5). This is configured
through the MCLRE bit in Configuration Word 1.
FIGURE 15-2: EXT ERNAL POWER-ON
RESET CIRCUIT (FOR
SLOW VDD POWER-UP)
15.4 Power-on Reset (POR)
A Power-on Reset pulse is generated on-chip when
VDD rise is detected (in the ran ge of 1.2V -1.7V). To take
advantage of the POR, tie the MCLR pin to VDD, as
described in Section 15.3 “MCLR. A maximum rise
time fo r VDD is specif ied. See Section 18.0 “Ele ctrical
Characteristics for details.
When the device starts normal operation (exits the
Reset condition), device operating parameters (volt-
age, freque ncy, temperature ,...) must be met to ensu re
operation. If these conditions are not met, the device
must be held in Reset u ntil the o perating c ondition s are
met. For more information, see Application Note,
AN607 “Power-up Trouble Shooting” (DS00607).
15.5 Power-up Timer (PWRT)
The Power-up Timer (PWRT) of the PIC16F87/88 is a
counter that uses the INTRC oscillator as the clock
input. This yields a count of 72 ms. While the PWRT is
counting , the device is held in Reset.
The power-up time delay depends on the INTRC and
will vary from chip-to-chip due to temperature and
process variation. See DC parameter #33 for details.
The PWRT is enabled by clearing configuration bit
PWRTEN.
15.6 Oscillator Start- up Timer (OST)
The Oscillator Start-up Timer (OST) provides a 1024
oscillator cycle (from OSC1 input) delay after the
PWRT delay is over (if enabled). This helps to ensure
that the crystal oscillator or resonator has started and
stabilized.
The OST time-out is invoked only for XT, LP and HS
modes and only on Power-on Reset or wake-up from
Sleep.
15.7 Brown-out Reset (BOR)
The configuration bit, BOREN, can enable or disable
the Brown-out Reset circuit. If VDD falls below VBOR
(parameter D005, about 4V) for longer than TBOR
(param eter #3 5, abou t 100 s), the brown-ou t situatio n
will reset the device. If VDD falls below VBOR for less
than TBOR, a Reset may not occur.
Once the brown-out occurs, the device will remain in
Brown-out Reset until VDD rises above VBOR. The
Power-up Timer (if enabled) will keep the device in
Rese t fo r TPWRT (parameter #33, about 72 ms). If VDD
should fall below VBOR during TPWRT, the Brown-out
Reset process will restart when VDD rises above VBOR
with the Power-up Timer Reset. Unlike previous PIC16
devices, the PWRT is no longer automatically enabled
when the Brown-out Reset circuit is enabled. The
PWRTEN and BOREN configuration bits are
independent of each other.
Note: For this reason, Microchip recommends
that the MCLR pin no longer be tied
directly to VDD.
Note 1: External Power-on Reset circuit is required
only if the VDD power-up slope is too slow.
The diode D helps discharge the capacitor
quickly when VDD powers down.
2: R < 40 k is recommended to make sure that
the voltage drop across R does not violate
the device’s electrical specification.
3: R1 = 1 k to 10 k will limit any current flow-
ing into MCLR from external capacitor C
(0.1 F), in the event of RA5/MCLR/VPP pin
breakdown due to Electrostatic Discharge
(ESD) or Electrical Overstress (EOS).
C
R1
R
D
VDD
MCLR
PIC16F87/88
PIC16F87/88
DS30487D-page 134 2002-2013 Microchip Technology Inc.
15.8 Time-out Sequence
On power-up, the time-out sequence is as follows: the
PWRT delay starts (if enabled) when a POR occurs.
Then, OST starts countin g 10 24 os c ill ato r cy cle s when
PWRT ends (LP, XT, HS). When the OST ends, the
devi ce come s out of Re se t.
If MCLR is kept low long enough, all delays will expire.
Bringing MCLR high will beg in exec ution imme diatel y.
This is useful for testing purposes, or to synchronize
more than one PIC16F87/88 device operating in
parallel.
Table 15-3 shows the Reset conditions for the
STATUS, PCON and PC registers, while Table 15-4
shows the Reset conditions for all the registers.
15.9 Power Control/Status Register
(PCON)
The Power Control/Status Register, PCON, has two
bits to indicate the type of Rese t that last occurred.
Bit 0 is Brown-out Reset Status bit, BOR. Bit BOR is
unknown on a Power-on Reset. It must then be set by
the user and checked on subsequent Resets to see if
bit BOR cleared, indicating a Brown-out Reset
occurred. When the Brown-out Reset is disabled, the
state of the BOR bit is unpredictable.
Bit 1 is POR (Power-on Reset Status bit). It is cleared
on a Power-on Reset and unaffected otherwise. The
user must set this bit following a Power-on Reset.
TABLE 15-1: TIME-OUT IN VARIOUS SITUATIONS
TABLE 15-2: STATUS BITS AND THEIR SIGNIFICANCE
Oscillator
Configuration Pow er-up Brown-out Reset Wake-up from
Sleep
PWRTE = 0PWRTE = 1PWRTE = 0PWRTE = 1
XT, HS, LP TPWRT + 1024 • TOSC 1024 • TOSC TPWRT + 1024 • TOSC 1024 • TOSC 1024 • TOSC
EXTRC, INTRC TPWRT 5-10 s(1) TPWRT 5-10 s(1) 5-10 s(1)
T1OSC ———5-10s(1)
Note 1: CPU start-up is always invoked on POR, BOR and wake-up from Sleep. The 5-10 s delay is based on a
1 MHz system clock.
POR BOR TO PD
0x11Power-on Reset
0x0xIllegal, TO is set on POR
0xx0Illegal, PD is set on POR
1011Brown-out Rese t
1101WDT Reset
1100WDT Wake-up
11uuMCLR Reset duri ng Normal Operation
1110MCLR Reset during Sleep or Interrupt Wake-up from Sleep
Legend: u = unchanged, x = unknown
2002-2013 Microchip Technology Inc. DS30487D-page 135
PIC16F87/88
TABLE 15-3: RESET CONDITION FOR SPECIAL REGISTERS
Condition Program
Counter STATUS
Register PCON
Register
Power-on Reset 000h 0001 1xxx ---- --0x
MCLR Reset during normal operation 000h 000u uuuu ---- --uu
MCLR Reset during Sleep 000h 0001 0uuu ---- --uu
WDT Reset 000h 0000 1uuu ---- --uu
WDT Wake- up PC + 1 uuu0 0uuu ---- --uu
Brown-out Reset 000h 0001 1uuu ---- --u0
Interrupt Wake-up from Sleep PC + 1(1) uuu1 0uuu ---- --uu
Legend: u = unchanged, x = unknown, - = unimplemented bit, read as ‘0
Note 1: When the wake-up is due to an interrupt and the GIE bit is set, the PC is loaded with the interrupt vector
(0004h).
TABLE 15-4: INITIALIZATION CONDITIONS FOR ALL REGISTERS
Register Power-on Reset,
Brown-out Reset MCLR Reset,
WDT Reset Wake-up via WDT or
Interrupt
Wxxxx xxxx uuuu uuuu uuuu uuuu
INDF N/A N/A N/A
TMR0 xxxx xxxx uuuu uuuu uuuu uuuu
PCL 0000h 0000h PC + 1(2)
STATUS 0001 1xxx 000q quuu(3) uuuq quuu(3)
FSR xxxx xxxx uuuu uuuu uuuu uuuu
PORTA (PIC16F87)
PORTA (PIC16F88) xxxx 0000
xxx0 0000
uuuu 0000
uuu0 0000
uuuu uuuu
uuuu uuuu
PORTB (PIC16F87)
PORTB (PIC16F87) xxxx xxxx
00xx xxxx
uuuu uuuu
00uu uuuu
uuuu uuuu
uuuu uuuu
PCLATH ---0 0000 ---0 0000 ---u uuuu
INTCON 0000 000x 0000 000u uuuu uuuu(1)
PIR1 -000 0000 -000 0000 -uuu uuuu(1)
PIR2 00-0 ---- 00-0 ---- uu-u ----(1)
TMR1L xxxx xxxx uuuu uuuu uuuu uuuu
TMR1H xxxx xxxx uuuu uuuu uuuu uuuu
T1CON -000 0000 -uuu uuuu -uuu uuuu
TMR2 0000 0000 0000 0000 uuuu uuuu
T2CON -000 0000 -000 0000 -uuu uuuu
SSPBUF xxxx xxxx uuuu uuuu uuuu uuuu
SSPCON 0000 0000 0000 0000 uuuu uuuu
CCPR1L xxxx xxxx uuuu uuuu uuuu uuuu
CCPR1H xxxx xxxx uuuu uuuu uuuu uuuu
CCP1CON --00 0000 --00 0000 --uu uuuu
RCSTA 0000 000x 0000 000x uuuu uuuu
Legend: u = unchanged, x = unknown, - = unimplemented bit, read as ‘0’, q = value depends on condition
Note 1: One or more bits in INTCON, PIR1 and PR2 will be affected (to cause wake-up).
2: When the wake-up is due to an interrupt and the GIE bit is set, the PC is loaded with the interrupt vector
(0004h).
3: See Table 15-3 for Reset value for specific condition.
PIC16F87/88
DS30487D-page 136 2002-2013 Microchip Technology Inc.
TXREG 0000 0000 0000 0000 uuuu uuuu
RCREG 0000 0000 0000 0000 uuuu uuuu
ADRESH xxxx xxxx uuuu uuuu uuuu uuuu
ADCON0 0000 00-0 0000 00-0 uuuu uu-u
OPTION_REG 1111 1111 1111 1111 uuuu uuuu
TRISA 1111 1111 1111 1111 uuuu uuuu
TRISB 1111 1111 1111 1111 uuuu uuuu
PIE1 -000 0000 -000 0000 -uuu uuuu
PIE2 00-0 ---- 00-0 ---- uu-u ----
PCON ---- --0q ---- --uu ---- --uu
OSCCON -000 0000 -000 0000 -uuu uuuu
OSCTUNE --00 0000 --00 0000 --uu uuuu
PR2 1111 1111 1111 1111 1111 1111
SSPADD 0000 0000 0000 0000 uuuu uuuu
SSPSTAT 0000 0000 0000 0000 uuuu uuuu
TXSTA 0000 -010 0000 -010 uuuu -u1u
SPBRG 0000 0000 0000 0000 uuuu uuuu
ANSEL -111 1111 -111 1111 -111 1111
CMCON 0000 0111 0000 0111 uuuu u111
CVRCON 000- 0000 000- 0000 uuu- uuuu
WDTCON ---0 1000 ---0 1000 ---u uuuu
ADRESL xxxx xxxx uuuu uuuu uuuu uuuu
ADCON1 0000 ---- 0000 ---- uuuu ----
EEDATA xxxx xxxx uuuu uuuu uuuu uuuu
EEADR xxxx xxxx uuuu uuuu uuuu uuuu
EEDATH --xx xxxx --uu uuuu --uu uuuu
EEADRH ---- -xxx ---- -uuu ---- -uuu
EECON1 x--x x000 u--x u000 u--u uuuu
EECON2 ---- ---- ---- ---- ---- ----
TABLE 15-4: INITIALIZATION CONDITIONS FOR ALL REGISTERS (CONTINUED)
Register Power-on Reset,
Brown-out Reset MCLR Reset,
WDT Reset Wake-up via WDT or
Interrupt
Legend: u = unchanged, x = unknown, - = unimplemented bit, read as ‘0’, q = value depends on condition
Note 1: One or more bits in INTCON, PIR1 and PR2 will be affected (to cause wake-up).
2: When the wake-up is due to an interrupt and the GIE bit is set, the PC is loaded with the interrupt vector
(0004h).
3: See Table 15-3 for Reset value for specific condition.
2002-2013 Microchip Technology Inc. DS30487D-page 137
PIC16F87/88
FIGURE 15-3: TIME-OUT SEQUENCE ON POWER-UP (MCLR TIED TO VDD THROUGH
PULL-UP RESISTOR)
FIGURE 15-4: TIME-OUT SEQUENCE ON POWER-UP (MCLR TIED TO VDD THROUGH
RC NETWORK): CASE 1
FIGURE 15-5: TIME-OUT SEQUENCE ON POWER-UP (MCLR TIED TO VDD THROUGH
RC NETWORK): CASE 2
TPWRT
TOST
VDD
MCLR
INTERNAL POR
PWRT TIME-OUT
OST TIME-OUT
INTERNAL RESET
TPWRT
TOST
VDD
MCLR
INTERNAL POR
PWRT TIME-OUT
OST TIME-OUT
INTERNAL RESET
VDD
MCLR
INTERNAL POR
PWRT TIME-OUT
OST TIME-OUT
INTERNAL RESET
TPWRT
TOST
PIC16F87/88
DS30487D-page 138 2002-2013 Microchip Technology Inc.
FIGURE 15-6: SLOW RISE TIME (MCLR TIED TO VDD THROUGH RC NETWORK)
15.10 Interrupts
The PIC16F87/88 has up to 12 sources of interrupt.
The Interrupt Control register (INTCON) records
individual interrupt requests in flag bits. It also has
individual and global interrupt enable bits.
A global interrupt enable bit, GIE (INTCON<7>),
enables (if set) all unmasked interrupts, or disables (if
cleared) all i nterrupts. When bit GIE is enabled and an
inter rupt’s flag bit and mask bit are s et, the int errupt will
vector immediately. Individual interrupts can be
disabled through their corresponding enable bits in
various registers. Individual interrupt bits are set
regardless of the status of the GIE bit. The GIE bit is
cleared on Reset.
The “return from interrupt” instruction, RETFIE, exits
the interrupt routine, as well as sets the GIE bit which
re-enabl es inte rrupts.
The RB0/INT pin interrupt, the RB port change interru pt
and the TMR 0 over flo w interru pt f lag s are co nt a ine d in
the INTCON register.
The peripheral interrupt flags are contained in the
Special Function Register, PIR1. The corresponding
interrupt enable bits are contained in Special Function
Register, PIE1 and the periphe ral interrupt en able bit is
contained in S p ecial Function Registe r, INTC ON.
When an interrupt is serviced, the GIE bit is cleared to
disable any further interrupt, the return address is
pushed onto the stack and the PC is loa ded with 0004h.
Once in the Interrupt Service Routine, the source(s) of
the interrupt can be determined by polling the interrupt
flag bits. The interrupt flag bit(s) must be cleared in
software before re-enabling interrupts to avoid
recursive interrupts.
For external interrupt events, such as the INT pin or
PORTB change interrupt, the interrupt latency will be
three or four instruction cycles. The exact latency
depends on when the interrupt e vent occ urs, relative to
the current Q cycle. The latency is the same for one or
two cycle instructions. Individual interrupt flag bits are
set regardless of the status of their corresponding
mask bit, PEIE bit or the GIE bit.
VDD
MCLR
INTERNAL POR
PWRT TIME-O UT
OST TIME-OUT
INTERNAL RESET
0V 1V
5V
TPWRT
TOST
Note: Individual interrupt flag bits are set
regardless of the status of their
corresponding mask bit or the GIE bit.
2002-2013 Microchip Technology Inc. DS30487D-page 139
PIC16F87/88
FIGURE 15-7: INTE RRUP T LOGIC
OSFIF
OSFIE
ADIF
ADIE
RCIF
RCIE
TXIF
TXIE
SSPIF
SSPIE
TMR2IF
TMR2IE
TMR1IF
TMR1IE
TMR0IF
TMR0IE
INT0IF
INT0IE
RBIF
RBIE
GIE
PEIE
Wake-up (if in Sleep mode)
Interrupt to CPU
EEIF
EEIE
CCP1IF
CCP1IE
CMIE
CMIF
PIC16F87/88
DS30487D-page 140 2002-2013 Microchip Technology Inc.
15.10.1 INT INTERRUPT
External interrupt on the RB0/INT pin is edge-triggered,
either rising if bit INTEDG (OPTION_REG<6>) is set,
or falling if the INTEDG bit is clear. When a valid edge
appears on the RB0/INT pin, flag bit, INT0IF
(INTCON<1 >), i s s et. T his in terru pt c an b e d isa bl ed b y
clearing enable bit INT0IE (INTCON<4>). Flag bit
INT0IF must be cleared in software in the Interrupt
Service Routine before re-enabling this interrupt. The
INT interrupt can wake-up the processor from Sleep, if
bit INT0I E w a s s et prio r to goi ng into Sleep. The status
of global interrupt enable bit GIE decides whether or
not the processor branches to the interrupt vector,
following wake-up. See Section 15.13 “Power-Down
Mode (Sleep)” for details on Sleep mode.
15.10.2 TMR0 INTERRUPT
An overflow (FFh 00h) in the TMR0 register will set
flag bit TMR0IF (INTCON<2>). The interrupt can be
enabled/disabled by setting/clearing enable bit TMR0IE
(IN T CO N< 5>), se e Section 6.0 “Timer0 Module”.
15.10.3 PORTB INTCON CHANGE
An input change on PORTB<7:4> sets flag bit RBIF
(INTCON<0>). The interrupt can be enabled/disabled
by setting/clearing enable bit RBIE (INTCON<4>), see
Section 3.2 “EECON1 and EECON 2 Register s”.
15.11 Context Saving During Interrupts
During an interrupt, only the return PC value is saved on
the stack. T ypically , users may wish to save key registers
during an interrupt (i.e., W, STATUS registers).
Since the upper 16 bytes of each bank are common in
the PIC16F87/88 devices, temporary holding registers
W_TEMP, STATUS_TEMP and PCLATH_TEMP
should be placed in here. These 16 locations don’t
require banking and therefore, make it easier for
context save and restore. The same code shown in
Example 15-1 can be used.
EXAMPLE 15-1: SAVING STATUS, W AND PCLATH REGISTERS IN RAM
MOVWF W_TEMP ;Copy W to TEMP register
SWAPF STATUS, W ;Swap status to be saved into W
CLRF STATUS ;bank 0, regardless of current bank, Clears IRP,RP1,RP0
MOVWF STATUS_TEMP ;Save status to bank zero STATUS_TEMP register
MOVF PCLATH, W ;Only required if using page 1
MOVWF PCLATH_TEMP ;Save PCLATH into W
CLRF PCLATH ;Page zero, regardless of current page
:
:(ISR) ;(Insert user code here)
:
MOVF PCLATH_TEMP, W ;Restore PCLATH
MOVWF PCLATH ;Move W into PCLATH
SWAPF STATUS_TEMP, W ;Swap STATUS_TEMP register into W
;(sets bank to original state)
MOVWF STATUS ;Move W into STATUS register
SWAPF W_TEMP, F ;Swap W_TEMP
SWAPF W_TEMP, W ;Swap W_TEMP into W
2002-2013 Microchip Technology Inc. DS30487D-page 141
PIC16F87/88
15.12 Watchdog Timer (WDT)
For PIC16 F87/88 dev ices, the WD T has been mod ified
from previous PIC16 devices. The new WDT is code
and functionally backward compatible with previous
PIC16 WDT modules and allows the user to have a
scaler value for the WDT and TMR0 at the same time.
In additio n, the WDT time-out valu e can be extende d to
268 seconds, using the prescaler with the postscaler
when PSA is set to1’.
15.12.1 WDT OSCIL LAT O R
The WDT derives its time base from the 31.25 kHz
INTR C. The value of WDTCO N is ‘---0 1000’ on all
Resets. This gives a nominal time base of 16.38 ms,
which is compatible with the time base generated with
previous PIC16 microcontroller versions.
A new presca ler ha s been added t o the pat h betw een
the internal RC and the multiplexors used to select the
path for the WDT. This prescaler is 16 bits and can be
programmed to divide the internal R C by 32 to 65536,
giving the time base used for the WDT a n ominal range
of 1 ms to 2.097s.
15.12.2 WDT CONTROL
The WDTEN bi t is loca ted in Confi gur ation W ord 1 an d
when this bit is set, the WDT runs continuously.
The SWDTEN bit is in the WDTCON register . When the
WDTEN bit in the Configuration Word 1 register is set,
the SWDTE N bit has n o ef fect. I f WDTEN is cl ear, then
the SWDTEN bi t can be used to en able and disab le the
WDT. Setting the bit will enable it and clearing the bit
will disable it.
The PSA and PS<2:0> bits (OPTION_REG register)
have the same function as in previous versions of the
PIC16 family of microcontrollers.
FIGURE 15-8: WATCHDOG TIMER BLOCK DIAGRAM
TABLE 15-5: PRESCALER/POST SCALER BIT STATUS
Note: When the OST is invo ked, the WDT is held
in Reset because the WDT ripple counter
is us ed by the OS T to perf orm the osc ill a-
tor de lay coun t. When the OST co unt has
expired, the WDT will begin counting (if
enabled).
Condition s Prescaler Postscaler (PSA = 1)
WDTEN = 0
Cleared Cleared
CLRWDT command
Oscillator fail detected
Exit Sleep + System Clock = T1OSC, EXTRC, INTRC, ECIO
Exit Sleep + System Clock = XT, HS, LP Cleared at end of OST Cleared at end of OST
31.25 kHz
PSA
16-bit Programmable Prescaler WDT
From TMR0 Clock Source
Postscaler
8
PS<2:0>
PSA
WDT Time-out
To TMR0
WDTPS<3:0>
WDTEN from Configuration Word 1
1
1
0
0
SWDTEN from WDTCON
INTRC Clock
PIC16F87/88
DS30487D-page 142 2002-2013 Microchip Technology Inc.
REGISTER 15-3: WDTCON: WATCHDOG CONTROL REGISTER (ADDRESS 105h)
TABLE 15-6: SUMMARY OF WATCHDOG TIMER REGISTERS
U-0 U-0 U-0 R/W-0 R/W-1 R/W-0 R/W-0 R/W-0
WDTPS3 WDTPS2 WDTPS1 WDTPS0 SWDTEN(1)
bit 7 bit 0
bit 7-5 Unimplemented: Read as ‘0
bit 4-1 WDTPS<3:0>: Watchdog Timer Period Select bits
Bit Prescale
Value Rate
0000 =1:32
0001 =1:64
0010 =1:128
0011 =1:256
0100 =1:512
0101 = 1:1024
0110 = 1:2048
0111 = 1:4096
1000 = 1:8192
1001 = 1:16394
1010 = 1:32768
1011 = 1:65536
bit 0 SWDTEN: Software Enable/Disable for Watchdog Timer bit(1)
1 = WDT is turned on
0 = WDT is turned off
Note 1: If WDTEN configuration bit = 1, then WDT is always enabled, irrespective of this
control bit . If WDTEN confi guratio n bit = 0, then it is pos sible to t urn WDT on/of f wi th
this control bit.
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
81h,181h OPTION_REG RBPU INTEDG T0CS T0SE PSA PS2 PS1 PS0
2007h Configuration bits LVP BOREN MCLRE FOSC2 PWRTEN WDTEN FOSC1 FOSC0
105h WDTCON WDTPS3 WDTPS2 WSTPS1 WDTPS0 SWDTEN
Legend: Shaded cells are not used by the Watchdog Timer.
Note 1: See Register 15-1 for operation of these bits.
2002-2013 Microchip Technology Inc. DS30487D-page 143
PIC16F87/88
15.12.3 TWO-SPEED CLOCK START-UP
MODE
Two-Speed Start-up mode minimizes the latency
between oscillator start-up and code execution that
may be selected with the IESO (Internal/External Swi-
tchover) bit in Configuration Word 2. This mode is
achieved by initially using the INTRC for code
execution until the primary oscillator is stable.
If this mode is enabled and any of the following condi-
tions exist, the system will begin execution with the
INTRC oscillator. This results in almost immediate
code exec uti on with a min im um of dela y.
POR and aft er the Power-u p T im er has expired (if
PWRTEN = 0);
or following a wake-up from Sleep;
or a Reset when running from T1OSC or INTRC
(after a Reset, SCS<1:0> are always set to ‘00’).
If the primary oscillator is configured to be anything
other than XT, LP or HS, then Two-Speed Start-up
mode is di sabled becau se the primary osc illator will not
require a ny time to become stabl e after PO R, or an exit
from Sleep.
If the IRCF bits of the OSCCON register are configured
to a non-zero value prior to entering Sleep mode, the
system clock frequency will come from the output of
the I N TOSC. The IO FS bit i n th e OSCCON regis t er will
be clear until the INTOSC is stable. This will allow the
user to determine when the internal oscillator can be
used for time critical applications.
Checking the state of the OSTS bit will confirm
whether the primary clock configuration is engaged. If
not, the OSTS bit will rema in clear.
When the device is auto-configured in INTRC mode
following a POR or wake-up from Sleep, the rules for
entering other oscillator modes still apply, meaning the
SCS<1:0> bit s in OSC CON ca n be modif ied before the
OST time-out has occurred. This would allow the
application to wake-up from Sleep, perform a few
instructions using the INTRC as the clock source and
go back to Sleep without waiting for the primary
oscillator to become stable.
15.12.3.1 Two-Speed Start-up Mode
Sequence
1. Wake-up from Sleep, Reset or POR.
2. OSCCON bits configured to run from INTRC
(31.25 kHz).
3. Instructions begin execution by INTRC
(31.25 kHz).
4. OST enabled to count 1024 clock cycles.
5. OST timed out, wait for falling edge of INTRC.
6. OSTS is set.
7. System clock held low for eight falling edges of
new clock (LP, XT or HS).
8. System cloc k is sw i tch ed to prim ary sour ce (LP,
XT or HS).
The software may read the OSTS bit to determine
when the switchover takes place so that any software
timing edges can be adjusted.
FIGURE 15-9: TWO-SPEED START-UP MODE
Note: Following any Reset, the IRCF bits are
zeroed and the frequency selection is
forced to 31.25 kHz. The user can modi fy
the IRCF bits to select a higher internal
oscillator frequency.
Note: Executing a SLEEP instruction will abort
the oscillator start-up time and will cause
the OSTS bit to remain clear.
Q4Q1 Q3 Q4 Q1 Q2
OSC1
Sleep
Program PC 0000h
INTRC
TOST
Q3 Q4
OSC2
OSTS
System Clock
0001h
Q1 Q2 Q3 Q4 Q1 Q2
Counter 0004h 0005h
0003h
Q1 Q2 Q3 Q4
CPU Start-up
PIC16F87/88
DS30487D-page 144 2002-2013 Microchip Technology Inc.
15.12.4 FAIL-SAFE OPTION
The Fail-Safe Clock Monitor (FSCM) is designed to
allow the device to continue to operate even in the
event of an oscillator failure.
FIGURE 15-10: FSCM BLOCK DIAGRAM
The FSCM function is enabled by setting the FCMEN
bit in Configuration Word 2.
In the event of an oscillator failure, the FSCM will
generate an oscillator fail interrupt and will switch the
system clock over to the internal oscillator. The system
will continue to come from the internal oscillator until
the fail-safe condition is exited. The fail-safe condition
is exited with either a Reset, the execution of a SLEEP
instruction or a write to the OSCCON register.
The frequency of the internal oscillator will depend
upon the value contained in the IRCF bits. Another
clock source can be selected via the IRCF and the
SCS bits of the OSCCON register.
The FSCM sample clock is generated by dividing the
INTRC clock by 64. This will allow enough time
between FSCM sample clocks for a system clock edge
to occur.
On the rising edge of the postscaled clock, the
monitoring latch (CM = 0) will be cleared. On a falling
edge of the primary or secondary system clock, the
monitoring latch will be set (CM = 1). In the event that
a falling edge of the postscaled clock occurs and the
monitoring latch is not set, a clock failure has been
detected.
While in Fail-Safe mode, a Reset will exit the fail-safe
condition. If the primary clock source is configured for
a crystal, the OST timer will wait for the 1024 clock
cycles for the OST time-out and the device will
continue running from the internal oscillator until the
OST is complete. A SLEEP instruction, or a write to the
SCS bits (where SCS bits do not = 00), can be
performed to put the device into a low-power mode.
If Reset occurs while in Fail-Safe mode and the pri-
mary clock source is EC or RC, then the device will
immediately switch back to EC or RC mode.
15.12.4.1 Fail-Safe in Low-Power Mode
A write to the OSCCON register, or SLEEP instruct i on,
will end the fail-safe condition. The system clock will
default to the source selected by the SCS bits, which
is either T1OSC, INTRC or none (Sleep mode). How-
ever, the FSCM will continue to monitor the system
clock. If the secondary clock fails, the device will
immediately switch to the internal oscillator clock. If
OSFIE is set, an interru pt wi ll be gen erat ed.
FIGURE 15-11: FSCM TIMING DIAGRAM
Peripheral
INTRC ÷ 64
S
C
Q
31.25 kHz
(32 s) 488 Hz
(2.048 ms)
Clock Monitor
Latc h ( C M)
(edge-triggered)
Clock
Failure
Detected
Oscillator
Clock
Q
Note: T w o-S p eed S t art-up mode is automati cally
enabled when the fail-safe option is
enabled.
OSFIF
CM Output
System
Clock
Output
Sample Clock
Failure
Detected
Oscillator
Failure
Note: The system clock is normally at a much higher frequency than the sample clock. The relative frequencies in
this example have been chosen for clarity.
(Q)
CM Test CM Test CM Test
(488 Hz)
2002-2013 Microchip Technology Inc. DS30487D-page 145
PIC16F87/88
15.12.4.2 FSCM and the Watchdog Timer
When a clock failure is detected, SCS<1:0> will be
forced to10’ which will reset the WDT (if enabled).
15.12.4. 3 POR or Wake Fro m Slee p
The FS CM is designed to detect osc illator failu re at any
point after the device has exited Power-on Reset
(POR) or low-power Sleep mode. When the primary
system clock is EC, RC or INTRC modes, monitoring
can begin immediately following these events.
For Oscillator modes involving a crystal or resonator
(HS, LP or XT), the situation is somewhat different.
Since the osc il lat or ma y re quire a start-up ti me con si d-
erabl y longer than the FSCM samp le clock ti me, a false
clock failure may be detected. To prevent this, the
internal oscillator block is automatically configured as
the system clock and functions until the primary clock
is st able (the OST timer ha s timed out). This is ident ical
to T wo -S peed S tart-u p mode. Onc e the primary cl ock is
stable, the INTRC returns to its role as the FSCM
source.
15.12.4.4 Example Fail-Safe Conditions
1. CONDITIONS:
The device is clocked from a crystal, crystal
operatio n fa ils and th en S leep m ode is entere d.
OSTS = 0
SCS = 00
OSFIF = 1
USER ACTION:
Sleep mode will exit the fail-safe condition.
Therefore, if the user code did not handle the
detected fail-safe prior to the SLEEP command,
then upon wake-up, the device will try to start
the crystal that failed and a fail-safe condition
will not be detected. Monitoring the OSTS bit will
determine if the crystal is operating. The user
should not enter Sleep mode without handling
the fail-safe condition first.
2. CONDITIONS:
After a POR (Power-on Reset), the device is
running in Two-Speed Start-up mode. The crys-
tal fails before the OST has expired. If a crystal
fails duri ng the OST pe riod, a fail-sa f e co ndi tio n
will not be detected (OSFIF will not get set).
OSTS = 0
SCS = 00
OSFIF = 0
USER ACTION:
Check the OSTS bit. If it’s clear and the OST
should have expired at this point, then the user
can assume the crystal has failed. The user
should change the SCS bit to cause a clock
switch which will also release the 10-bit ripple
counter for WDT operation (if enabled).
3. CONDITIONS:
The device is clocked from a crystal during
normal operation and it fails.
OSTS = 0
SCS = 00
OSFIF = 1
USER ACTION:
Clear the OSFIF bit. Configure the SCS bits for
a clock switch and the fail-safe condition will be
cleared. Later, if the user decides to, the crystal
can be retried for operation. If this is done, the
OSTS bit should be monitored to determine if
the crystal operates.
15.13 Power-Down Mode (Sleep)
Power-Down mode is entered by executing a SLEEP
instruction.
If enabled, the Watchdog Timer will be cleared but
keep s runnin g, the PD bi t (STATUS<3>) is cleared, the
TO (STATUS<4>) bit is set and the oscillator driver is
turned off. The I/O ports maintain the status they had
before the SLEEP instruction was executed (driving
high, low or high-impedance).
For lo west curr ent cons umpti on in thi s mode , plac e all
I/O pins at either VDD or VSS, ensure no external cir-
cuitr y is dr awing c urre nt from the I/O pin, pow er-d own
the A/D and disable external clocks. Pull all I/O pins
that are high-im pedance inputs, high or low externally,
to avoid switching currents caused by floating inputs.
The T0CKI input should also be at VDD or V SS for low-
est current consumption. The contribution from on-chip
pull-ups on PORTB should also be con s ider ed.
The MCLR pin must be at a lo gic high level (VIHMC).
Note: The sa me logi c tha t prevents false oscill a-
tor failure interrupts on port or wake from
Sleep, will also prevent the detection of
the oscillator’s failure to start at all follow-
ing these events. This can be avoided by
monitoring the OSTS bit and using a
timing routine to determine if the oscillator
is taking too long to start. Even so, no
oscillator failure interrupt will be flagged.
PIC16F87/88
DS30487D-page 146 2002-2013 Microchip Technology Inc.
15.13.1 WA KE - UP FR OM SLEE P
The devi ce can wa ke-up from Sleep through on e of the
following events:
1. External Reset input on MCLR pin.
2. Watchdog T imer w ake-up (if WDT wa s enable d).
3. Interrupt from INT pin, RB port change or a
peripheral interrupt.
External MCLR Reset will cause a device Reset. All
other events are considered a continuation of program
execut ion and c aus e a “wak e-u p”. The TO and PD bits
in the STATUS register can be used to determine the
cause of the device Reset. The PD bit, wh ic h i s se t on
power-up, is cleared when Sleep is invoked. The TO bit
is cleared if a WDT time-out occurred and caused
wake-up.
The follo wing periph eral interrupt s can wake the device
from Sleep:
1. TMR1 interrup t. T imer1 m ust be ope rating as a n
asynchronous counter.
2. CCP Capture mode interrupt.
3. Special event trigger (Timer1 in Asynchronous
mode using an external clock).
4. SSP (Start/Stop) bit detect interrupt.
5. SSP transmit or receiv e in Slave m ode (SPI/I2C).
6. A/D conversion (when A/D clock source is RC).
7. EEPROM write operation completi on.
8. Comparator output changes state.
9. AUSART RX or TX (Synchronous Slave mode).
Other peripherals cannot generate interrupts, since
during Sleep, no on-chip clocks are present.
When the SLEEP instruction i s being executed, the nex t
instruction (PC + 1) is prefetched. For the device to
wake-u p thro ugh an int errup t ev ent, the co rres pon ding
interrupt enable bit must be set (enabled). Wake-up
occurs regardless of the state of the GIE bit. If the GIE
bit is clear (disabled), the device continues execution at
the inst ruction af ter the SLEEP ins truction. If the GIE b it
is set (enabled), the device executes the instruction
after the SLEEP instruction and then branches to the
interrupt address (0004h). In cases where the execu-
tion of the instruction following SLEEP is not desirable,
the user should have a NOP after the SLEEP instruction.
15.13.2 WAKE-UP USING INTERRUPTS
When global interrupts are disabled (GIE cleared) and
any interrupt source has both its interrupt enable bit
and inte rrupt fla g bit s et, one of the fo llow ing wil l occu r:
If the interrupt occurs before the ex ecution of a
SLEEP instruction, the SLEEP instruction will
comple te as a NOP. Therefore, th e WDT and WDT
prescaler and postscaler (if enabled) will not be
cleared, the TO bit will not be set and the PD bit
will not be clea red.
If the interrupt occurs during or after the
execution of a SLEEP ins truc tio n, the dev ic e wi ll
immediately wake-up from Sleep. The SLEEP
instruction will be completely executed before the
wake-up. The refore, the WDT and WDT pres caler
and pos tsc aler (if enable d) wi ll be c leared , the T O
bit will be set and the PD bit wi ll be cleared.
Even if the flag bits were checked before executing a
SLEEP instruction, it may be possible for flag bits to
become set before the SLEEP instruction completes. To
determine whether a SLEEP instruction executed, test
the PD bit. If the PD bit is set, the SLEEP instruction
was executed as a NOP.
To ensure that the WDT is cleared, a CLRWDT instruction
should be executed before a SLEEP instruction.
FIGURE 15-12: WAKE-UP FROM SLEEP THROUGH INTERRUPT(1)
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
OSC1
CLKO(4)
INT pin
INT0IF Flag
(INTCON<1>)
GIE bit(3)
(INTCON<7>)
INSTRUCTION FLOW
PC
Instruction
Fetched
Instruction
Executed
PC PC + 1 PC + 2
Inst(PC) = Sleep
Inst(PC – 1)
Inst(PC + 1)
Sleep
Processor in
Sleep
Interrupt Latency
(Note 2)
Inst(PC + 2)
Inst(PC + 1)
Inst(0004h) Inst(0005h)
Inst(0004h)
Dummy Cycle
PC + 2 0004h 0005h
Dummy Cycle
TOST(2)
PC + 2
Note 1: XT, HS or LP Oscillator mode assume d.
2: TOST = 1024 TOSC (drawing not to scale). This delay will not be there for RC Oscillator mode.
3: GIE = 1 assumed. In this case, after wake-up, the processor jumps to the interrupt routine.
If GIE = 0, execution will continue in-line.
4: CLKO is not available in these oscillator modes, but shown here for timing reference.
2002-2013 Microchip Technology Inc. DS30487D-page 147
PIC16F87/88
15.14 In-Circuit Debugger
When the DEBUG bit in the Configuration Word is
progra mmed to a 0’, the In-Circuit De bugger function-
ality is enabled . This function allows simple debuggin g
functions when used with MPLAB® ICD. When the
microcontroller has this feature enabled, some of the
resources ar e no t avai labl e for ge ner al use . Tab le 15- 7
shows which features are consumed by the background
debugger.
TABLE 15-7: DEBUGGER RESOURCES
To use the In-Circuit Debugger function of the micro-
controller, the design must implement In-Circuit Serial
Programming connections to RA5/MCLR/VPP, VDD,
GND, RB 7 an d RB 6 . Th is w il l inte rfac e to the In-C i rcu it
Debugger module available from Microchip, or one of
the third party development tool companies.
15.15 Program Verification/Code
Protection
If the code protection bit(s) have not been
programmed, the on-chip program memory can be
read out for verificati on purp os es .
15.16 ID Locations
Four memory locations (2000h-2003h) are designated
as ID locations, where the user can store checksum or
other code identification numbers. These locations are
not accessible during normal execution but are
readable and writable during program/verify. It is
recommended that only the four Least Significant bits
of the ID location are used.
15.17 In-Circuit Seri al Programming
PIC16F87/88 microcontrollers can be serially pro-
grammed while in the end application circuit. This is
simply done with tw o lines for cl ock and dat a and thre e
other lines for power, ground and the programming
volt age (see Figure 15-13 for an ex amp le ) . Thi s a llo ws
customers to manufacture boards with unprogrammed
devices and then program the microcontroller just
before shipping the product. This also allows the most
recent firmware or a custom firmware to be
programmed.
For more information on serial programming, please
refer to the “PIC16F87/ 88 Fla sh Mem ory Programm ing
Specification” (DS39607).
FIGURE 15-13: TYPICAL IN-CIRCUIT
SERIAL PROGRAMMING
CONNECTION
I/O pins RB6 , RB7
Stack 1 level
Program Memory Address 0000h must be NOP
Last 100h wor ds
Data Memory 0x070 (0x0F0, 0x170, 0x1F0)
0x1EB-0x1EF
Note: The Timer1 oscillator shares the T1OSI
and T1OSO pins with the PGD and PGC
pins used for programming and
debugging.
When using the Timer1 oscillator, In-
Circuit Serial Programming™ (ICSP™)
may not fu nc tio n co rrec tly (hi gh v oltage or
low voltage), or the In-Circuit Debugger
(ICD) may not communicate with the
controll er. As a resu lt of usi ng either ICSP
or ICD, the Timer1 crystal may be
damaged.
If ICSP or ICD operatio ns are required, the
crystal should be disconnected from the
circuit (disconne ct either lead), or ins talle d
after programming. The oscillator loading
capacitors may remain in-circuit during
ICS P or ICD operation.
External
Connector
Signals
To Norma l
Connections
To Normal
Connections
PIC16F87/88
VDD
VSS
RA5/MCLR/VPP
RB6
RB7
+5V
0V
VPP
CLK
Data I/O
VDD
* * *
*
* Isolation devices (as required).
RB3 only used in LVP mode.
RB3
RB3/PGM
PIC16F87/88
DS30487D-page 148 2002-2013 Microchip Technology Inc.
15.18 Low-Voltage ICSP Programming
The LVP bit of the Configuration Word enables Low-
Voltage ICSP Programming. This mode allows the
microcontroller to be programmed via ICSP using a
VDD source in the operating voltage range. This only
means that VPP does not have to be brought to VIHH,
but can instead be left at the no rm al op erating voltage.
In this mode, the RB3/PGM pin is dedicated to the
programming function and ceases to be a general
purpose I/O pin.
If Low-V oltage Pro gramming mode is not used, the L VP
bit can be programmed to a ‘0’ and RB3/PGM be comes
a digital I/O pin. However, the LVP bit may only be
programm ed whe n Pro gram m ing m ode is en tere d wi th
VIHH on MCLR. The LVP bit ca n only be c hanged whe n
using high voltage on MCLR.
It should be noted that once the LVP b it is programme d
to ‘0’, only the High-Voltage Programming mode is
available and only this mode can be used to program
the device.
When using Low-Voltage ICSP, the part must be
supplied at 4.5V to 5.5V if a bulk eras e will be ex ecuted.
This includes reprogramming of the code-protect bits
from an ON state to an OFF state. For all other cases of
Low-Voltage ICSP, the part may be programmed at the
normal operating voltage. This means calibration values,
unique user IDs or user code can be reprogrammed or
added.
The following LVP step s assume the LVP bit is set in the
Configuration register.
1. Appl y VDD to the VDD pin.
2. Drive MCLR low .
3. Appl y VDD to the RB3/PGM pin.
4. Appl y VDD to the MCLR pin.
5. Follow with the associated programming steps.
Note 1: The High-Voltage Programming mode is
always available, regardless of the state
of the LVP bit, by applying VIHH to the
MCLR pin.
2: While in Low-Voltage ICSP mode
(LVP = 1), the RB3 pin can no longer be
used as a general purpose I/O pin.
3: When using Low-Voltage ICSP Program-
ming (LVP) and the pull-ups on PORTB
are enabled, bit 3 in the TRISB register
must be cleared to disable the pull-up on
RB3 and ensure the proper operation of
the device.
4: RB3 should not be allowed to float if LVP
is enabled. An external pull-down device
should be used to default the device to
normal operating mode. If RB3 floats
high, the PIC16F87/88 devices will enter
Programming mode.
5: LVP mode is enabled by default on all
device s shi pped from Microchi p. It can b e
disabled by clearing the LVP bit in the
CONFIG1 register.
6: Disabling LVP will provide maximum
compatibility to other PIC16CXXX
devices.
2002-2013 Microchip Technology Inc. DS30487D-page 149
PIC16F87/88
16.0 INSTRUCTION SET SUMMARY
The PIC16 instruction set is highly orthogonal and is
comprised of three basic categories:
Byte-oriented operations
Bit-oriented operations
Literal and control operations
Each PIC16 instruction is a 14-bit word divided into an
opcode, which specifies the in struction type and one or
more operands, which further specify the operation of
the instruction. The formats for each of the categories
are presen ted in Fig ure 16-1, while the vari ous op code
fields are sum m ariz ed in Table 16-1.
Table 16-2 lists the instructions recognized by the
MPASMTM assembler. A complete description of each
instruction is also available in the “PIC® Mid-Range
MCU Family Re ference Man ual” (DS33023).
For byte-oriented instructions, ‘f’ represents a file
register designator and ‘d’ represents a destination
designator. The file register designator specifies which
file register is to be used by the instruction.
The desti nation designator specifies where the result of
the operation is to be placed. If ‘d’ is zero, the result is
placed in the W regis ter . If ‘d’ is one, the res ult is place d
in the file register specified in the instruction.
For bit-oriented instructions, ‘b’ represents a bit field
design ator, which select s the bi t affected by th e ope ra-
tion, w hi le ‘f’ represents the a ddress of the file in which
the bit is located.
For literal and control operations, ‘k’ represents an
eight or eleven-bit constant or literal value
One instr uction cycle co nsists of four os cillator periods .
For an oscillator frequency of 4 MHz, this gives a
normal instruction execution time of 1 s. All instruc-
tions are executed within a single instruction cycle,
unless a condi tional test is t rue, or the program co unter
is changed as a result of an instruction. When this
occurs , t he ex ec uti on takes two i ns truc tio n cy cl es , w i th
the second cycle executed as a NOP.
All inst ruction ex amples use the fo rmat ‘0xhh’ to repre-
sent a hexadecimal number, where ‘h’ signifies a
hexadecimal digit.
16.1 Read-Modify-Write Operations
Any instruction that specifies a file register as part of
the instruction performs a Read-Modify-Write (RMW)
operatio n. The register is read, the data is modi fied and
the resu lt is stored accordi ng to either the instruction, or
the destination designator ‘d’. A read operation is
perfor me d on a regi st er ev en if the instruction wri tes to
that register.
For example, a “CLRF PORTB” instruction will read
PORTB, clear all the data bits, then write the result
back to PORTB. This example would have the
unintended result that the condition that sets the RBIF
flag would be cl eared.
TABLE 16-1: OPCODE FIELD
DESCRIPTIONS
FIGURE 16-1: GENERAL FORMAT FOR
INSTRUCTIONS
Note: To maintain upward compatibility with
future PIC16F87/88 products, do not use
the OPTION and TRIS instru ctions.
Field Description
fRegister file address (0x00 to 0x7F)
WWorking register (accumulator)
bBit addres s within an 8-bit file register
kLiteral field, constant data or label
xDon't care loc ati on (= 0 or 1).
The assembler will generate code with x = 0.
It is the recommended form of use for
compatibility with all Microchip software tools.
dDestination select; d = 0: stor e result in W,
d = 1: store result in file register f.
Default is d = 1.
PC Program Counter
TO Time-out bit
PD Power-Down bit
Byte-oriented file regi ster oper a tions
13 8 7 6 0
d = 0 for destination W
OPCODE d f (FILE #)
d = 1 for destination f
f = 7-bit file register address
Bit-oriente d file register operations
13 10 9 7 6 0
OPCODE b (BIT # ) f (FIL E #)
b = 3-bit bit address
f = 7-bit file register address
Literal and control operations
13 8 7 0
OPCODE k (liter a l )
k = 8-bit immediate value
13 11 10 0
OPCODE k (lite ral)
k = 11-bit immediate value
General
CALL and GOTO instructions only
PIC16F87/88
DS30487D-page 150 2002-2013 Microchip Technology Inc.
TABLE 16-2: PIC16F87/88 INSTRUCTION SET
Mnemonic,
Operands Description Cycles 14-Bit Opcode Status
Affected Notes
MSb LSb
BYTE-ORIENTED FILE REGISTER OPERATIONS
ADDWF
ANDWF
CLRF
CLRW
COMF
DECF
DECFSZ
INCF
INCFSZ
IORWF
MOVF
MOVWF
NOP
RLF
RRF
SUBWF
SWAPF
XORWF
f, d
f, d
f
-
f, d
f, d
f, d
f, d
f, d
f, d
f, d
f
-
f, d
f, d
f, d
f, d
f, d
Add W and f
AND W with f
Clear f
Clear W
Complement f
Decrement f
Decrement f, Skip if 0
Increment f
Increment f, Skip if 0
Inclusive OR W with f
Move f
Mov e W to f
No Operation
Rotate Left f through Carry
Rotate Right f through Carry
Subtract W from f
Swap nibbles in f
Exclusive OR W with f
1
1
1
1
1
1
1(2)
1
1(2)
1
1
1
1
1
1
1
1
1
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
0111
0101
0001
0001
1001
0011
1011
1010
1111
0100
1000
0000
0000
1101
1100
0010
1110
0110
dfff
dfff
lfff
0xxx
dfff
dfff
dfff
dfff
dfff
dfff
dfff
lfff
0xx0
dfff
dfff
dfff
dfff
dfff
ffff
ffff
ffff
xxxx
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
0000
ffff
ffff
ffff
ffff
ffff
C,DC,Z
Z
Z
Z
Z
Z
Z
Z
Z
C
C
C,DC,Z
Z
1,2
1,2
2
1,2
1,2
1,2,3
1,2
1,2,3
1,2
1,2
1,2
1,2
1,2
1,2
1,2
BIT-ORIENTED FILE REGISTER OPERATIONS
BCF
BSF
BTFSC
BTFSS
f, b
f, b
f, b
f, b
Bit Clear f
Bit Se t f
Bit Test f, Skip if Clear
Bit Test f, Skip if Set
1
1
1 (2)
1 (2)
01
01
01
01
00bb
01bb
10bb
11bb
bfff
bfff
bfff
bfff
ffff
ffff
ffff
ffff
1,2
1,2
3
3
LITERAL AND CONTROL OPERATIONS
ADDLW
ANDLW
CALL
CLRWDT
GOTO
IORLW
MOVLW
RETFIE
RETLW
RETURN
SLEEP
SUBLW
XORLW
k
k
k
-
k
k
k
-
k
-
-
k
k
Add literal and W
AND literal with W
Call subroutine
Clear Watchdog Timer
Go to address
Inclusive OR literal with W
Move litera l to W
Return from interrupt
Return with literal in W
Return from Subroutine
Go into Standby mode
Subtract W from literal
Exclusive OR literal with W
1
1
2
1
2
1
1
2
2
2
1
1
1
11
11
10
00
10
11
11
00
11
00
00
11
11
111x
1001
0kkk
0000
1kkk
1000
00xx
0000
01xx
0000
0000
110x
1010
kkkk
kkkk
kkkk
0110
kkkk
kkkk
kkkk
0000
kkkk
0000
0110
kkkk
kkkk
kkkk
kkkk
kkkk
0100
kkkk
kkkk
kkkk
1001
kkkk
1000
0011
kkkk
kkkk
C,DC,Z
Z
TO,PD
Z
TO,PD
C,DC,Z
Z
Note 1: When an I/O register is modified as a f unction of it self (e.g., MOVF PORTB, 1), the value used will be that value present
on the pins themselves. For example, if the data latch is ‘1’ f or a pin configured as input and is driven low by an external
device, the data will be written back with a ‘0’.
2: If this instruction is executed on the TMR0 register (and where applicable, d = 1), the prescaler will be cleared if
assigned to the Timer0 module.
3: If the Program Counter (PC) is modified or a conditional test is true, the instruction requires two cycles. The second
cycle is executed as a NOP.
Note: Additional information on the mid-range instruction set is available in the “PIC® Mid-Range MCU Family
Reference Manual (DS33023).
2002-2013 Microchip Technology Inc. DS30487D-page 151
PIC16F87/88
16.2 Instruction Descri ptions
ADDLW Add Literal and W
Syntax: [ label ] ADDLW k
Operands: 0 k 255
Operation: (W) + k (W)
Status Affected: C, DC, Z
Description: The contents of the W register
are added to the eight-bit literal ‘k
and the result is placed in the W
register.
ADDWF Add W and f
Syntax: [ label ] ADDWF f,d
Operands: 0 f 127
d [0,1]
Operation: (W) + (f) (destination)
Status Affected: C, DC, Z
Desc ription: Add the conten ts of the W regist er
with reg ister ‘f’. If ‘d’ = 0, the resu lt
is stored in the W register. If
‘d’ = 1, the resu lt is stored ba ck in
register ‘f’.
ANDLW AND Literal with W
Syntax: [ label ] ANDLW k
Operands: 0 k 255
Operation: (W) .AND. (k) (W)
Status Affected: Z
Description: The contents of W register are
AND’ed with the eight-bit literal
‘k’. The result is pl aced in the W
register.
ANDWF AND W with f
Syntax: [ label ] ANDWF f,d
Operands: 0 f 127
d [0,1]
Operation: (W) .AND. (f) (destin ation)
Status Af fected: Z
Description: AND the W register with register
‘f’. If ‘d’ = 0, the result is stored in
the W regis ter. If ‘d’ = 1, the resu lt
is stored back in register ‘f’.
BCF Bit Clear f
Syntax: [ label ] BCF f,b
Operands: 0 f 127
0 b 7
Operation: 0 (f<b >)
Status Af fected: None
Description: Bit ‘b’ in register ‘f’ is clea red.
BSF Bit Set f
Syntax: [ label ] BSF f,b
Operands: 0 f 127
0 b 7
Operation: 1 (f<b >)
Status Af fected: None
Description: Bit ‘b’ in register ‘f’ is set.
PIC16F87/88
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BTFSS Bit Test f, Skip if Set
Syntax: [ label ] BTFSS f,b
Operands: 0 f 127
0 b < 7
Operation: skip if (f<b>) = 1
Status Affected: None
Descrip tion: If bit ‘b’ in register ‘f’ = 0, the next
instructi on is exec uted .
If bit ‘b’ = 1, then the next
instructi on is discarded and a NOP
is exec ute d i nst ead, making this a
2T
CY instruction.
BTFSC Bit Test, Skip if Clear
Syntax: [ label ] BTFSC f,b
Operands: 0 f 127
0 b 7
Operation: skip if (f<b>) = 0
Status Affected: None
Description: If bit ‘b’ in register ‘f’ = 1, the next
instruction is executed.
If bit ‘b’, in register ‘f’, = 0, the next
inst ruc tion is di sc ard ed and a NOP
is exec ute d ins te ad, m ak in g thi s a
2 TCY instruction.
CALL Call Subroutine
Syntax: [ label ] CALL k
Operands: 0 k 204 7
Operation: (PC) + 1 TOS,
k PC<10:0>,
(PCLATH<4:3>) PC<12:11>
Status Affected: None
Description: Call subroutine. First, return
address (PC + 1) is pushed onto
the stack. The eleven-bit
immediate address is loaded into
PC bits <10:0>. The upper bits of
the PC are loa ded from PCLATH.
CALL is a two-cycle instruction.
CLRF Clear f
Syntax: [ label ] CLRF f
Operands: 0 f 127
Operation: 00h (f),
1 Z
Status Af fected: Z
Description: The contents of register ‘f’ are
cleared and the Z bit is set.
CLRW Clear W
Syntax: [ label ] CLRW
Operands: None
Operation: 00h (W),
1 Z
Status Af fected: Z
Description: W register is cleared. Zero bit (Z)
is se t.
CLRWDT Clear Watchdog Timer
Syntax: [ label ] CLRWDT
Operands: None
Operation: 00h WDT,
0 WDT prescaler,
1 TO,
1 PD
Status Af fected: TO, PD
Description: CLRWDT instruction resets the
W atchdog T imer . It also resets the
prescaler of the WDT. Status bits
TO and PD are set.
2002-2013 Microchip Technology Inc. DS30487D-page 153
PIC16F87/88
COMF Complement f
Syntax: [ label ] COMF f,d
Operands: 0 f 127
d [0,1]
Operation: (f) (destination)
Status Affected: Z
Description: The contents of register ‘f’ are
complemented. If ‘d’ = 0, the
result is stored in W. If ‘d’ = 1, the
result is stored back in register ‘f’.
DECF Decrement f
Syntax: [ label ] DECF f,d
Operands: 0 f 127
d [0,1]
Operation: (f) – 1 (destination)
Status Affected: Z
Description: Decrement register ‘f’. If ‘d’ = 0,
the result is stored in the W
register. If ‘d’ = 1, the result is
stored back in register ‘f’.
DECFSZ Decrement f, Skip if 0
Syntax: [ label ] DECFSZ f,d
Operands: 0 f 127
d [0,1]
Operation: (f) – 1 (destination);
skip if result = 0
Status Affected: None
Description: The contents of register ‘f’ are
decremented. If ‘d’ = 0, the result
is placed in the W register. If
‘d’ = 1, the result is placed back in
register ‘f’.
If the result is ‘1’, the next
instruction is executed. If the
resu lt is ‘0’, then a NOP is
executed instead, making it a
2T
CY instruction.
GOTO Unconditional Branch
Syntax: [ label ] GOTO k
Operands: 0 k 2047
Operation: k PC<10:0>,
PCLATH<4:3> PC<12:11>
Status Af fected: None
Description: GOTO is an unconditional branch.
The e leven-bit immedia te v alu e i s
loaded into PC bits <10:0>. The
upper bits of PC are loaded
from PCLATH<4:3>. GOTO is a
two-cycle instruction.
INCF Increment f
Syntax: [ label ] INCF f,d
Operands: 0 f 127
d [0,1 ]
Operation: (f) + 1 (destination)
Status Af fected: Z
Description: The contents of register ‘f’ are
incremented. If ‘d’ = 0, the res ult
is placed in the W register. If
‘d’ = 1, the resul t is placed back in
register ‘f’.
INCFSZ Increment f, Skip if 0
Syntax: [ label ] INCFSZ f,d
Operands: 0 f 127
d [0,1]
Operation: (f) + 1 (destination),
skip if result = 0
Status Af fected: None
Description: The contents of register ‘f’ are
incremen ted. If ‘d’ = 0, th e result is
placed in the W register. If ‘d’ = 1,
the result is placed back in
register ‘f’.
If the result is ‘1’, the next
instruction is executed. If the
result is0’, a NOP is executed
instead, making it a 2 TCY
instruction.
PIC16F87/88
DS30487D-page 154 2002-2013 Microchip Technology Inc.
IORLW Inclusive OR Literal with W
Syntax: [ label ] IORLW k
Operands: 0 k 255
Operation: (W) .OR. k (W)
Status Affected: Z
Desc ription: The con tents of t he W register are
OR’ed with the eight-bit literal ‘k’.
The result is placed in the W
register.
IORWF Inclusive OR W with f
Syntax: [ label ] IORWF f,d
Operands: 0 f 127
d [0,1]
Operation: (W) .OR. (f) (destinatio n)
Status Affected: Z
Description: Inclusive OR the W register with
register ‘f’. If ‘d’ = 0, the result is
placed in th e W re gis ter. If ‘d’ = 1,
the result is placed back in
register ‘f’.
MOVF Move f
Syntax: [ label ] MOVF f,d
Operands: 0 f 127
d [0,1]
Operation: (f) (destinati on )
Status Affected: Z
Description: The contents of register ‘f’ are
moved t o a destination depen dant
upon the status of ‘d’. If ‘d’ = 0,
the destination i s W register. If
‘d’ = 1, the destination is file
register ‘f’ it self. ‘d ’ = 1 is useful to
test a file register, since status
flag Z is affected.
MOVLW Move Literal to W
Syntax: [ label ] MOVLW k
Operands: 0 k 255
Operation: k (W)
Status Af fected: None
Description: The eight-bit literal ‘k’ is loaded
into W register. The don’t cares
will assemble as 0’s.
MOVWF Move W to f
Syntax: [ label ] MOVWF f
Operands: 0 f 127
Operation: (W) (f)
Status Af fected: None
Description: Move data from W register to
register ‘f’.
NOP No Operation
Syntax: [ label ] NOP
Operands: None
Operation: No operation
Status Af fected: None
Description: No operation.
2002-2013 Microchip Technology Inc. DS30487D-page 155
PIC16F87/88
RETFIE Return from Interrupt
Syntax: [ label ] RETFIE
Operands: None
Operation: TOS PC,
1 GIE
Status Affected: None
RETLW Return with Literal in W
Syntax: [ label ] RETLW k
Operands: 0 k 255
Operation: k (W);
TOS PC
Status Affected: None
Description: The W register is loaded with the
eight-bit literal ‘k’. The program
counter is loaded from the top of
the stack (the return address).
This is a two-cycle instruction.
RETURN Return from Subroutine
Syntax: [ label ] RETURN
Operands: None
Operation: TOS PC
Status Affected: None
Description: Return from subrouti ne. The sta ck
is POPed an d t he top o f th e s t a ck
(TOS) is loaded into the program
counter. This is a two-cycle
instruction.
RLF Rotate Left f through Carry
Syntax: [ label ] RLF f,d
Operands: 0 f 127
d [0,1]
Operation: See description below
Status Af fected: C
Description: The contents of register ‘f’ are
rotated one bit to the left through
the C arry flag. I f ‘d’ = 0, the res ult
is placed in the W register. If
‘d’ = 1, the resul t is st ored back in
register ‘f’.
RRF Rotate Right f through Carry
Syntax: [ label ] RRF f,d
Operands: 0 f 127
d [0,1]
Operation: See description below
Status Af fected: C
Description: The contents of register ‘f’ are
rotate d one bit to the righ t through
the Carry flag. If ‘d’ = 0, the result
is placed in the W register. If
‘d’ = 1, the result is placed ba ck in
register ‘f’.
SLEEP Sleep
Syntax: [ label ]SLEEP
Operands: None
Operation: 00h WDT,
0 WDT prescaler,
1 TO,
0 PD
Status Af fected: TO, PD
Description: The Power-Down status bit, PD,
is cleared. Time-out status bit,
TO, is set. Watchdog Timer and
its prescaler are cleared.
The processor is put into Sleep
mode with the oscillator stopped.
Register fC
PIC16F87/88
DS30487D-page 156 2002-2013 Microchip Technology Inc.
SUBLW Subtract W from Literal
Syntax: [ label ] SUBLW k
Operands: 0 k 255
Operation: k – (W) W)
Status Affected: C, DC, Z
Desc ript ion : The W re gis ter is su btra cted (two’s
complement method) from the
eight-bi t literal ‘k’. The result is
placed in the W register.
SUBWF Subtract W from f
Syntax: [ label ] SUBWF f,d
Operands: 0 f 127
d [0,1]
Operation: (f) – (W) destination)
Status Affected: C, DC, Z
Description: Subtract (two’s complement
method) W reg ister from regist er ‘f’.
If ‘d’ = 0, the result is sto r ed in the
W register. If ‘d’ = 1, the result is
stored back in register ‘f’.
SWAPF Swap Nibbles in f
Syntax: [ label ] SWAPF f,d
Operands: 0 f 127
d [0,1]
Operation: (f<3:0>) (destination<7:4>),
(f<7:4>) (destination<3:0>)
Status Affected: None
Description: The upper and lower nibbles of
register ‘f’ are exchanged. If
‘d’ = 0, the result is placed in W
register. If ‘d’ = 1, the result is
placed in register ‘f’.
XORLW Exclusive OR Literal with W
Syntax: [ label ]XORLW k
Operands: 0 k 255
Operation: (W) .XOR. k W)
Status Af fected: Z
Description: The co ntents of the W register
are XOR’ed with the eight-bit
literal ‘k’. T he res ult is placed in
the W register.
XORWF Exclusive OR W with f
Syntax: [ label ] XORWF f,d
Operands: 0 f 127
d [0,1]
Operation: (W) .XOR. (f) destination)
Status Af fected: Z
Description: Exclusive OR the contents of the
W register with register ‘f’. If
‘d’ = 0, the resu lt is stored in the
W register. If ‘d’ = 1, the result is
stored back in register ‘f’.
2002-2013 Microchip Technology Inc. DS30487D-page 157
PIC16F87/88
17.0 DEVELOPMENT SUPPORT
The PIC® microcontrollers and dsPIC® digital signal
controllers are supported with a full range of software
and hardware development tools:
Integrated Development Environment
- MPLAB® IDE Software
Compilers/Assemblers/Linkers
- MPLAB C Compiler for Various Device
Families
- HI-TECH C® for Various Device Families
- MPASMTM Assembler
-MPLINK
TM Object Linker/
MPLIBTM Object Librarian
- MPLAB Assembler/Linker/Librarian for
Various Device Families
Simulators
- MPLAB SIM Software Simulator
•Emulators
- MPLAB REAL ICE™ In-Circuit Emulator
In-Circuit Debuggers
- MPLAB ICD 3
- PICkit™ 3 Debug Express
Device Progra mmers
- PICkit™ 2 Programmer
- MPLAB PM3 Device Programmer
Low-Cost Demonstration/D evelopmen t Boards,
Evaluation Kits, and Starter Kits
17.1 MPLAB Integrated Development
Environment Software
The MPLAB IDE software brings an ease of software
development previously unseen in the 8/16/32-bit
microcontroller market. The MPLAB IDE is a Wind ows®
operating system-based application that contains:
A single graphical interface to all debugging tools
- Simulator
- Programmer (sold separately)
- In-Circuit Emul ator (sold separately)
- In-C ircuit Debug ger ( s old separately)
A full-featured editor with color-coded context
A multiple project manager
Customizable data windows with direct edit of
contents
High-level source code debugging
Mouse over variable inspection
Drag and drop variables from source to watch
windows
Exten si ve on-l in e help
Integra tion of select third party tools, such as
IAR C Compilers
The MPLAB IDE allows you to:
Edit your sour ce files (either C or assembly)
One-tou ch compile o r assemble , and downl oad to
emulator and simulator tools (automatically
updates all project information)
Debug us ing :
- Sour ce files (C or assembly)
- Mixed C and assembly
- Machine code
MPLAB IDE supports multiple debugging tools in a
single development paradigm, from the cost-effective
simulators, through low-cost in-circuit debuggers, to
full-featured emulators. This eliminates the learning
curve when upgrading to tools with increased flexibility
and power.
PIC16F87/88
DS30487D-page 158 2002-2013 Microchip Technology Inc.
17.2 MPLAB C Compilers for Various
Device Families
The MPLAB C Compiler code development systems
are complete ANSI C compilers for Microc hip’s PIC18,
PIC24 and PIC32 families of microcontrollers and the
dsPIC30 and dsPIC33 families of digita l signal control-
lers. These compilers provide powerful integration
capabilities, superior code optimization and ease of
use.
For easy source level debugging, the comp ilers provide
symbol info rmation tha t is optimized to the MPLAB IDE
debugger.
17.3 HI-TECH C for Various Device
Families
The HI-TECH C Compiler code development systems
are complete ANSI C compilers for Microchip’s PIC
family of microcontrollers and the dsPIC family of digital
signal controllers. These compilers provide powerful
integration capabilities, omniscient code generation
and ease of use.
For easy source level debugging, the comp ilers provide
symbol info rmation tha t is optimized to the MPLAB IDE
debugger.
The compilers include a macro as sembler, linker, pre-
process or , and one-s tep driver , and can run on multipl e
platforms.
17.4 MPASM Assembler
The MPASM Assembler is a full-featured, universal
macro assembler for PIC10/12/16/18 MCUs.
The MPASM Assembler generates relocatable object
files fo r the MPLINK Ob ject Linker , Int el® standa rd HEX
files, MAP files to detail memory usage and symbol
reference, absolute LST files that contain source lines
and generated machine code and COFF files for
debugging.
The MPASM Assembler features include:
Integration into MPLAB IDE projects
User-defined macros to streamline
assembly code
Conditional assembly for multi-purpose
sour ce fil es
Directi ves that allow complete control over the
assembly process
17.5 MPLINK Object Linker/
MPLIB Object Librarian
The MPLINK Object Linker combines relocatable
objects created by the MPASM Assembler and the
MPLA B C18 C Compiler. It can link relocatable objec ts
from precompiled libraries, using directives from a
linker script.
The MPLIB O bject Li brarian manage s the cre ation an d
modification of library files of precompiled code. When
a rout in e from a l ibra ry is called fro m a so urc e file, only
the modules that contain that routine will be linked in
with the application. This allows large libraries to be
used efficiently in many different applications.
The object linker/library features include:
Efficient linking of single libraries instead of many
smaller files
Enhanced code maintainability by grouping
related modules together
Flexible creation of libraries with easy module
listing, replacement , deletion and extracti on
17.6 MPLAB Assembler, Linker and
Librarian for Various Device
Families
MPLAB Assembler produces relocatable machine
code from symbolic assembly language for PIC24,
PIC32 and dsPIC devices. MPLAB C Compiler uses
the asse mbler to pro duce i ts o bje ct file . The ass embl er
generates relocatable object files that can then be
archived or linked with other relocata ble object files and
arch ives to c rea te an e xecu tabl e fil e. N otab le fe atu res
of the assembler include:
Support for the entire device instruction set
Support for fixed-point and floating-point data
Command line interface
Rich dire cti ve set
Flexible macro language
MPLAB IDE compatibility
2002-2013 Microchip Technology Inc. DS30487D-page 159
PIC16F87/88
17.7 MPLAB SIM Software Simulator
The MPLAB SIM Software Simulator allows code
development in a PC-hosted environment by simulat-
ing the PIC MCUs and dsPIC® DSCs on an instruction
level. On any given instruction, the data areas can be
examined or modified and stimuli can be applied from
a comprehensive stimulus controller. Registers can be
logged to files for further run-time analysis. The trace
buffer and logic analyzer display extend the power of
the simulator to record and track program execution,
actions on I/O, most periph erals and i nternal regi sters.
The MPLAB SIM Software Simulator fully supports
symbolic debugging using the MPLAB C Compilers,
and the MPASM and MPLAB Assemblers. The soft-
ware simulator offers the flexibility to develop and
debug code outside of the hardware laboratory envi-
ronment, making it an excellent, economical software
developm ent tool .
17.8 MPLAB REAL ICE In-Circuit
Emulator System
MPLAB REAL ICE In-Circuit Emulator System is
Microchip’s next generation high-speed emulator for
Microchip Flash DSC and MCU devices. It debugs and
programs PIC® Flash MCUs and dsPIC® Flash DSCs
with the easy-to-use, powerful graphical user interface of
the MPLAB Integrated D evelopment Environment (IDE),
included with each kit.
The emulator is connected to the design engineer’s PC
using a high-speed USB 2.0 interface and is connected
to the target with either a connector compatible with in-
circuit debugger systems (RJ11) or with the new high-
speed, noise tolerant, Low-Voltage Differential Signal
(LVDS) interconnection (CAT5).
The emulator is field upgrad able through future firmware
downloads in MPLAB IDE. In upcoming releases of
MPLAB IDE, new devices will be supported, and new
features will be added. MPLAB REAL ICE offers
significant advantages over competitive emulators
including low-cost, full-speed emulation, run-time
variable watches, trace analysis, complex breakpoi nts, a
ruggedized probe interface and long (up to three meters)
interconnection cables.
17.9 MPLAB ICD 3 In-Circuit Debugger
System
MPLAB ICD 3 In-Circuit Debugger System is Micro-
chip's most cost effective high-speed hardware
debugger/programmer for Microchip Flash Digital Sig-
nal Controller (DSC) and microcontroller (MCU)
device s. It debugs and programs PIC® Flash microcon-
trollers and dsPIC® DSCs with the powerful, yet easy-
to-use graphical user interface of MPLAB Integrated
Development Environment (IDE).
The MPLAB ICD 3 In-Circuit Debugger probe is con-
nect ed to t he des ign e nginee r's PC using a hig h-spee d
USB 2.0 i nte rfac e a nd is co nnected to the t a rget w ith a
connector compa tible with the MPLAB ICD 2 or MPLAB
REAL ICE systems (RJ-11). MPLAB ICD 3 support s all
MPLAB ICD 2 headers.
17.10 PICkit 3 In-Circuit Debugger/
Programmer and
PICkit 3 Debug Express
The MPLAB PICkit 3 allows debugging and program-
ming of PIC® and dsPIC® Flash microcontrollers at a
most af fordable price point using the powerful graphical
user interface of the MPLAB Integrated Development
Environment (IDE). The MPLAB PICkit 3 is connected
to the design engineer's PC using a full speed USB
interface and can be connected to the target via an
Microchip debug (RJ-11) connector (compatible with
MPLAB ICD 3 and MPLAB REAL ICE). The connector
uses two device I/O pins and the reset line to imple-
ment in-circuit debugging and In-Circuit Serial Pro-
gramming™.
The PICkit 3 Debug Express include the PICkit 3, demo
board and microcontroller , hookup cables and CDROM
with user’s guide, lessons, tutorial, compiler and
MPLAB IDE software.
PIC16F87/88
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17.11 PICkit 2 Development
Programmer/Debugger and
PICkit 2 Debug Express
The P ICkit™ 2 Develo pment Program mer/Debu gger i s
a low-cost development tool with an easy to use inter-
face fo r programmin g and debu gging Micr ochip’s Flash
families of microcontrollers. The full featured
Windows® programming interface supports baseline
(PIC10F, PIC12F5xx, PIC16F5xx), midrange
(PIC12F6xx, PIC16F), PIC18F, PIC24, dsPIC30,
dsPIC33, and PIC32 families o f 8 - bi t, 1 6-b it, an d 3 2-b it
microcontrollers, and many Microchip Serial EEPROM
produ cts . With Mic rochip ’s power ful MPL AB Integrate d
Development Environment (IDE) the PICkit™ 2
enables in-circuit debugging on most PIC® microcon-
trollers. In-Circuit-Debugging runs, halts and single
steps the program while the PIC microcontroller is
embedded in the application. When halted at a break-
point, the file reg ist ers can be ex amin ed and m odifie d.
The PICkit 2 Debug Express include the PICkit 2, demo
board and microcontroller , hookup cables and CDROM
with user’s guide, lessons, tutorial, compiler and
MPLAB IDE software.
17.12 MPLAB PM3 Device Programmer
The MPLAB PM3 Device Programmer is a universal,
CE compliant device programmer with programmable
voltage verification at VDDMIN and VDDMAX for
maximum reliability. It features a large LCD display
(128 x 64 ) for me nus an d err or messag es an d a modu-
lar, detachable socket assembly to support various
package types. The ICSP™ cable assembly is included
as a standard item. In Stand-Alone mode, the MPLAB
PM3 Devic e Programmer can rea d, verify an d program
PIC devices without a PC connection. It can also set
code protection in this mode. The MPLAB PM3
connects to the host PC via an RS-232 or U SB cable.
The MPL AB PM3 has high-spe ed comm unications and
optimized algorithms for quick programming of large
memory devices and inc orporates an MMC card for file
storage and data applications.
17.13 Demonstration/Development
Boards, Evaluation Kits, and
Starter Kits
A wide variety of demonstration, development and
evaluation boards for various PIC MCUs and dsPIC
DSCs allows quick application development on fully func-
tional systems. Most boards includ e prototyping a reas for
adding custom circuitry and provide application firmware
and source code for examination and modification.
The board s support a variety of features, including LEDs,
temperature sensors, switches, speakers, RS-232
interfaces , LCD displays, potentiometers and additional
EEPROM memory .
The demonstration and development boards can be
used in teac hing environments, for prototyping custom
circuits and for learning about various microcontroller
applications.
In addition to the PICDEM™ and dsPICDEM™ demon-
stration/development board series of circuits, Microchip
has a line of evaluation kits and demonstration software
for analog filter design, KEELOQ® security ICs, CAN,
IrDA®, PowerSmart battery management, SEEVAL®
evaluation system, Sigma-Delta ADC, flow rate
sensing, plus many more.
Also available are starter kits that contain everything
needed to experience t he specified d evice. This usually
includes a single application and debug capability, all
on one board.
Check the Microchip web page (www.microchip.com)
for the complete list of demonstration, development
and evaluation kits.
2002-2013 Microchip Technology Inc. DS30487D-page 161
PIC16F87/88
18.0 ELECTRIC AL CHARACTERISTICS
Absolute Maximum Ratings †
Ambient temperature under bias.............................................................................................................-40°C to +125°C
Storage temperature .............................................................................................................................. -65°C to +150°C
Voltage on any pin with respect to VSS (except VDD and MCLR) ...................................................-0.3V to (VDD + 0.3V)
Volta ge on VDD with respect to VSS ............................................................................................................ -0.3 to +7.5V
Volta ge on MC LR with respect to VSS (Note 2).............................................................................................-0.3 to +14V
Total power dissipation (Note 1) ..................................................................................................................................1W
Maximum current out of VSS pin...........................................................................................................................200 mA
Maximum current int o VDD pin..............................................................................................................................200 mA
Input clamp current, IIK (VI < 0 or VI > VDD) 20 mA
Output clamp current, IOK (VO < 0 or VO > VDD) 20 mA
Maximum output current sunk by any I/O pin..........................................................................................................25 mA
Maximum output current sourced by any I/O pin....................................................................................................25 mA
Maximum current sunk byPORTA........................................................................................................................100 mA
Maximum current sourced by PORTA...................................................................................................................100 mA
Maximum current sunk byPORTB........................................................................................................................100 mA
Maximum current sourced by PORTB ..................................................................................................................100 mA
Note 1: Power dissip ation is calcu lated as follows: Pdis = VDD x {IDD IOH} + {(VDD – V OH) x IOH} + (VOL x IOL)
2: Voltage spikes at the MCLR pin may caus e latch-up. A series resistor of greater than 1 k should be used
to pull MCLR to VDD, rather than tying the pin directly to VDD.
† NOTICE: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the
device. This is a stress rating only and functional operation of the device at those or any other conditions above those
indicated in the operation listings of this specification is not impl ied. Exposure to maximum rating conditions for
extended periods may affect device reliability.
PIC16F87/88
DS30487D-page 162 2002-2013 Microchip Technology Inc.
FIGURE 18-1: PIC16F 87 /88 VOLTAGE-FREQUENCY GRAPH (INDUSTRIAL, EXTENDED)
FIGURE 18-2: PIC16L F87 /88 VOLTAGE-FREQUENCY GRAPH (INDUSTRIAL)
Frequency
Voltage
6.0V
5.5V
4.5V
4.0V
2.0V
20 MHz
5.0V
3.5V
3.0V
2.5V
16 MHz
Frequency
Voltage
6.0V
5.5V
4.5V
4.0V
2.0V
5.0V
3.5V
3.0V
2.5V
FMAX = (12 MHz/V) (VDDAPPMIN – 2.5V) + 4 MHz
Note 1: VDDAPPMIN is the minimum voltage of the PIC® device in th e application.
4 MHz 10 MHz
Note 2: FMAX has a maximum frequency of 10 MHz.
2002-2013 Microchip Technology Inc. DS30487D-page 163
PIC16F87/88
18.1 DC Characteristics: Supply Vol tage
PIC16F87/88 (Industrial, Extended)
PIC16LF87/88 (Industrial)
PIC16LF87/88
(Industrial) Standard Operating Conditions (unless otherwise stated)
Operating temperature -40°C TA +85°C for industrial
PIC16F87/88
(Industrial, Extended)
Standard Operating Conditions (unless otherwise stated)
Operating temperature -40°C TA +85°C for industrial
-40°C TA +125°C for extended
Param
No. Symbol Characteristic Min Typ Max Units Conditions
VDD Supply Voltag e
D001 PIC16LF87/88 2.0 5.5 V HS, XT, RC and LP Oscillator mode
D001 PIC16F87/88 4.0 5.5 V
D002 VDR RAM Data Retention
Voltage(1) 1.5 V
D003 VPOR VDD Start Voltage
to ensure internal
Power-on Reset signal
0.7 V See Section 15.4 “Power-on Reset (POR)”
for details
D004 SVDD VDD Rise Rate
to ensure internal
Power-on Reset signal
0.05 V/ms See Section 15.4 “Power-on Reset (POR)”
for details
VBOR Brown-out R e set Voltage
D005 PIC16LF87/88 3.65 4.35 V
D005 PIC16F87/88 3.65 4.35 V FMAX = 14 MHz(2)
Legend: Shading of rows is t o assist in readability of the table.
Note 1: This is the limit to which VDD can be lowered in Sleep mode, or during a device Reset, without losing RAM data.
2: When BOR is enabled, the device will operate correctly until the VBOR voltage trip point is reached.
PIC16F87/88
DS30487D-page 164 2002-2013 Microchip Technology Inc.
18.2 DC Characteristics: Power-Down and Supply Current
PIC16F87/88 (I ndustrial, Extended)
PIC16LF87/88 (I ndustrial)
PIC16LF87/88
(Industrial) Standard Operating Condition s (unless otherwise stated)
Operating temperature -40°C TA +85°C for industrial
PIC16F87/88
(Industrial, Extended)
Standard Operating Condition s (unless otherwise stated)
Operating temperature -40°C TA +85°C for industrial
-40°C TA +125°C for extended
Param
No. Device Typ Max Units Conditions
Power-Down Current (IPD)(1)
PIC16LF87/88 0.1 0.4 A -40°C
0.1 0.4 A +25°C VDD = 2.0V
0.4 1.5 A +85°C
PIC16LF87/88 0.3 0.5 A -40°C
0.3 0.5 A +25°C VDD = 3.0V
0.7 1.7 A +85°C
All devices 0.6 1.0 A -40°C
VDD = 5.0V
0.6 1.0 A +25°C
1.2 5.0 A +85°C
Extended devices 6 28 A+125°C
Legend: Shading of rows is t o assist in readability of the table.
Note 1: The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with
the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that add delta
current disabled (such as WDT, Timer1 Oscillator, BOR, etc.).
2: The supply current is mainly a function of operati ng volt age, frequency and mode. Other factors, such as I/O pin loading
and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on
the current consumption.
The test conditions for all IDD measurements in active operation mode are:
OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD;
MCLR = VDD; WDT enabled/disabled as specified.
3: For RC oscillator configurations, current through REXT is not included. The current through the resistor can be estimated
by the formula Ir = VDD/2REXT (mA) with REXT in k.
2002-2013 Microchip Technology Inc. DS30487D-page 165
PIC16F87/88
Supply Current (IDD)(2,3)
PIC16LF87/88 9 20 A -40°C
FOSC = 32 kHZ
(LP Oscillator)
715A +25°C VDD = 2.0V
715A +85°C
PIC16LF87/88 16 30 A -40°C
14 25 A +25°C VDD = 3.0V
14 25 A +85°C
All devices 32 40 A -40°C
VDD = 5.0V
26 35 A +25°C
26 35 A +85°C
Extended Devices 35 53 A +125°C
18.2 DC Characteristics: Power-Down and Supply Current
PIC16F87/88 (I ndustrial, Extended)
PIC16LF87/88 (I ndustrial) (Continued)
PIC16LF87/88
(Industrial) Standard Operating Condition s (unless otherwise stated)
Operating temperature -40°C TA +85°C for industrial
PIC16F87/88
(Industrial, Extended)
Standard Operating Condition s (unless otherwise stated)
Operating temperature -40°C TA +85°C for industrial
-40°C TA +125°C for extended
Param
No. Device Typ Max Units Conditions
Legend: Shading of rows is t o assist in readability of the table.
Note 1: The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with
the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that add delta
current disabled (such as WDT, Timer1 Oscillator, BOR, etc.).
2: The supply current is mainly a function of operati ng voltage, frequency and mode. Other factors, such as I/O pin loading
and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on
the current consumption.
The test conditions for all IDD measurements in active operation mode are:
OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD;
MCLR = VDD; WDT enabled/disabled as specified.
3: For RC oscillator configurations, current through REXT is not included. The current through the resistor can be estimated
by the formula Ir = VDD/2REXT (mA) with REXT in k.
PIC16F87/88
DS30487D-page 166 2002-2013 Microchip Technology Inc.
Supply Current (IDD)(2,3)
PIC16LF87/88 72 95 A -40°C VDD = 2.0V
FOSC = 1 MHZ
(RC Oscillator)(3)
76 90 A +25°C
76 90 A +85°C
PIC16LF87/88 138 175 A -40°C
136 170 A +25°C VDD = 3.0V
136 170 A +85°C
All devices 310 380 A -40°C
VDD = 5.0V
290 360 A +25°C
280 360 A +85°C
Extended devices 330 500 A 125°C
PIC16LF87/88 270 335 A -40°C
FOSC = 4 MHz
(RC Oscillator)(3)
280 330 A +25°C VDD = 2.0V
285 330 A +85°C
PIC16LF87/88 460 610 A -40°C
450 600 A +25°C VDD = 3.0V
450 600 A +85°C
All devices 900 1060 A -40°C
VDD = 5.0V
890 1050 A +25°C
890 1050 A +85°C
Extended devices . 920 1.5 mA +125°C
18.2 DC Characteristics: Power-Down and Supply Current
PIC16F87/88 (I ndustrial, Extended)
PIC16LF87/88 (I ndustrial) (Continued)
PIC16LF87/88
(Industrial) Standard Operating Condition s (unless otherwise stated)
Operating temperature -40°C TA +85°C for industrial
PIC16F87/88
(Industrial, Extended)
Standard Operating Condition s (unless otherwise stated)
Operating temperature -40°C TA +85°C for industrial
-40°C TA +125°C for extended
Param
No. Device Typ Max Units Conditions
Legend: Shading of rows is t o assist in readability of the table.
Note 1: The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with
the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that add delta
current disabled (such as WDT, Timer1 Oscillator, BOR, etc.).
2: The supply current is mainly a function of operati ng volt age, frequency and mode. Other factors, such as I/O pin loading
and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on
the current consumption.
The test conditions for all IDD measurements in active operation mode are:
OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD;
MCLR = VDD; WDT enabled/disabled as specified.
3: For RC oscillator configurations, current through REXT is not included. The current through the resistor can be estimated
by the formula Ir = VDD/2REXT (mA) with REXT in k.
2002-2013 Microchip Technology Inc. DS30487D-page 167
PIC16F87/88
Supply Current (IDD)(2,3)
All devices 1.8 2.3 mA -40°C
FOSC = 20 MHZ
(HS Oscillator)
1.6 2.2 mA +25°C VDD = 4.0V
1.3 2.2 mA +85°C
All devices 3.0 4.2 mA -40°C
VDD = 5.0V
2.5 4.0 mA +25°C
2.5 4.0 mA +85°C
Extended devices 3.0 5.0 mA +85°C
18.2 DC Characteristics: Power-Down and Supply Current
PIC16F87/88 (I ndustrial, Extended)
PIC16LF87/88 (I ndustrial) (Continued)
PIC16LF87/88
(Industrial) Standard Operating Condition s (unless otherwise stated)
Operating temperature -40°C TA +85°C for industrial
PIC16F87/88
(Industrial, Extended)
Standard Operating Condition s (unless otherwise stated)
Operating temperature -40°C TA +85°C for industrial
-40°C TA +125°C for extended
Param
No. Device Typ Max Units Conditions
Legend: Shading of rows is t o assist in readability of the table.
Note 1: The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with
the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that add delta
current disabled (such as WDT, Timer1 Oscillator, BOR, etc.).
2: The supply current is mainly a function of operati ng voltage, frequency and mode. Other factors, such as I/O pin loading
and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on
the current consumption.
The test conditions for all IDD measurements in active operation mode are:
OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD;
MCLR = VDD; WDT enabled/disabled as specified.
3: For RC oscillator configurations, current through REXT is not included. The current through the resistor can be estimated
by the formula Ir = VDD/2REXT (mA) with REXT in k.
PIC16F87/88
DS30487D-page 168 2002-2013 Microchip Technology Inc.
Supply Current (IDD)(2,3)
PIC16LF87/88 8 20 A -40°C
FOSC = 31.25 kHz
(RC_RUN mode,
Internal RC Oscillator)
715A +25°C VDD = 2.0V
715A +85°C
PIC16LF87/88 16 30 A -40°C
14 25 A +25°C VDD = 3.0V
14 25 A +85°C
All devices 32 40 A -40°C
VDD = 5.0V
29 35 A +25°C
29 35 A +85°C
Extended devices 35 45 A +125°C
PIC16LF87/88 132 160 A -40°C
FOSC = 1 MHz
(RC_RUN mode,
Internal RC Oscillator)
126 155 A +25°C VDD = 2.0V
126 155 A +85°C
PIC16LF87/88 260 310 A -40°C
230 300 A +25°C VDD = 3.0V
230 300 A +85°C
All devices 560 690 A -40°C
VDD = 5.0V
500 650 A +25°C
500 650 A +85°C
Extended devices 570 710 A +125°C
18.2 DC Characteristics: Power-Down and Supply Current
PIC16F87/88 (I ndustrial, Extended)
PIC16LF87/88 (I ndustrial) (Continued)
PIC16LF87/88
(Industrial) Standard Operating Condition s (unless otherwise stated)
Operating temperature -40°C TA +85°C for industrial
PIC16F87/88
(Industrial, Extended)
Standard Operating Condition s (unless otherwise stated)
Operating temperature -40°C TA +85°C for industrial
-40°C TA +125°C for extended
Param
No. Device Typ Max Units Conditions
Legend: Shading of rows is t o assist in readability of the table.
Note 1: The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with
the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that add delta
current disabled (such as WDT, Timer1 Oscillator, BOR, etc.).
2: The supply current is mainly a function of operati ng volt age, frequency and mode. Other factors, such as I/O pin loading
and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on
the current consumption.
The test conditions for all IDD measurements in active operation mode are:
OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD;
MCLR = VDD; WDT enabled/disabled as specified.
3: For RC oscillator configurations, current through REXT is not included. The current through the resistor can be estimated
by the formula Ir = VDD/2REXT (mA) with REXT in k.
2002-2013 Microchip Technology Inc. DS30487D-page 169
PIC16F87/88
Supply Current (IDD)(2,3)
PIC16LF87/88 310 420 A -40°C
FOSC = 4 MHz
(RC_RUN mode,
Internal RC Oscillator)
300 410 A +25°C VDD = 2.0V
300 410 A +85°C
PIC16LF87/88 550 650 A -40°C
530 620 A +25°C VDD = 3.0V
530 620 A +85°C
All devices 1.2 1.5 mA -40°C
VDD = 5.0V
1.1 1.4 mA +25°C
1.1 1.4 mA +85°C
Extended devices 1.3 1.6 mA +125°C
18.2 DC Characteristics: Power-Down and Supply Current
PIC16F87/88 (I ndustrial, Extended)
PIC16LF87/88 (I ndustrial) (Continued)
PIC16LF87/88
(Industrial) Standard Operating Condition s (unless otherwise stated)
Operating temperature -40°C TA +85°C for industrial
PIC16F87/88
(Industrial, Extended)
Standard Operating Condition s (unless otherwise stated)
Operating temperature -40°C TA +85°C for industrial
-40°C TA +125°C for extended
Param
No. Device Typ Max Units Conditions
Legend: Shading of rows is t o assist in readability of the table.
Note 1: The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with
the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that add delta
current disabled (such as WDT, Timer1 Oscillator, BOR, etc.).
2: The supply current is mainly a function of operati ng voltage, frequency and mode. Other factors, such as I/O pin loading
and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on
the current consumption.
The test conditions for all IDD measurements in active operation mode are:
OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD;
MCLR = VDD; WDT enabled/disabled as specified.
3: For RC oscillator configurations, current through REXT is not included. The current through the resistor can be estimated
by the formula Ir = VDD/2REXT (mA) with REXT in k.
PIC16F87/88
DS30487D-page 170 2002-2013 Microchip Technology Inc.
Supply Current (IDD)(2,3)
PIC16LF87/88 .950 1.3 mA -40°C
FOSC = 8 MHz
(RC_RUN mode,
Internal RC Oscillator)
.930 1.2 mA +25°C VDD = 3.0V
.930 1.2 mA +85°C
All devices 1.8 3.0 mA -40°C
VDD = 5.0V
1.7 2.8 mA +25°C
1.7 2.8 mA +85°C
Extended devices 2.0 4.0 mA +125°C
PIC16LF87/88 9 13 A -10°C
FOSC = 32 kHz
(SEC_RUN mode,
Timer1 as clock)
914A +25°C VDD = 2.0V
11 16 A +70°C
PIC16LF87/88 12 34 A -10°C
12 31 A +25°C VDD = 3.0V
14 28 A +70°C
All devices 20 72 A -10°C
20 65 A +25°C VDD = 5.0V
25 59 A +70°C
18.2 DC Characteristics: Power-Down and Supply Current
PIC16F87/88 (I ndustrial, Extended)
PIC16LF87/88 (I ndustrial) (Continued)
PIC16LF87/88
(Industrial) Standard Operating Condition s (unless otherwise stated)
Operating temperature -40°C TA +85°C for industrial
PIC16F87/88
(Industrial, Extended)
Standard Operating Condition s (unless otherwise stated)
Operating temperature -40°C TA +85°C for industrial
-40°C TA +125°C for extended
Param
No. Device Typ Max Units Conditions
Legend: Shading of rows is t o assist in readability of the table.
Note 1: The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with
the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that add delta
current disabled (such as WDT, Timer1 Oscillator, BOR, etc.).
2: The supply current is mainly a function of operati ng volt age, frequency and mode. Other factors, such as I/O pin loading
and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on
the current consumption.
The test conditions for all IDD measurements in active operation mode are:
OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD;
MCLR = VDD; WDT enabled/disabled as specified.
3: For RC oscillator configurations, current through REXT is not included. The current through the resistor can be estimated
by the formula Ir = VDD/2REXT (mA) with REXT in k.
2002-2013 Microchip Technology Inc. DS30487D-page 171
PIC16F87/88
D022
(IWDT)Module Differential Currents (IWDT, IBOR, ILVD, IOSCB, IAD)
Wa tchdog Timer 1.5 3.8 A -40°C
2.2 3.8 A +25°C VDD = 2. 0V
2.7 4.0 A +85°C
2.3 4.6 A -40°C
2.7 4.6 A +25°C VDD = 3. 0V
3.1 4.8 A +85°C
3.0 10.0 A -40°C
VDD = 5.0V
3.3 10.0 A +25°C
3.9 13.0 A +85°C
Extended devices 5.0 21.0 A +125°C
D022A
(IBOR)Brown-out Reset 40 60 A-40C to +85CV
DD = 5.0V
D025
(IOSCB)Timer1 Oscillator 1.7 2.3 A -40°C
32 kHz on Timer1
1.8 2.3 A +25°C VDD = 2. 0V
2.0 2.3 A +85°C
2.2 3.8 A -40°C
2.6 3.8 A +25°C VDD = 3. 0V
2.9 3.8 A +85°C
3.0 6.0 A -40°C
3.2 6.0 A +25°C VDD = 5. 0V
3.4 7.0 A +85°C
D026
(IAD)A/D Converter 0.001 2.0 A-40C to +85CV
DD = 2.0V
A/D on, Sleep, not converting
0.001 2.0 A-40C to +85CV
DD = 3.0V
0.003 2.0 A-40C to +85CVDD = 5.0V
Extended devices 4.0 8.0 A-40C to +125C
18.2 DC Characteristics: Power-Down and Supply Current
PIC16F87/88 (I ndustrial, Extended)
PIC16LF87/88 (I ndustrial) (Continued)
PIC16LF87/88
(Industrial) Standard Operating Condition s (unless otherwise stated)
Operating temperature -40°C TA +85°C for industrial
PIC16F87/88
(Industrial, Extended)
Standard Operating Condition s (unless otherwise stated)
Operating temperature -40°C TA +85°C for industrial
-40°C TA +125°C for extended
Param
No. Device Typ Max Units Conditions
Legend: Shading of rows is t o assist in readability of the table.
Note 1: The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with
the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that add delta
current disabled (such as WDT, Timer1 Oscillator, BOR, etc.).
2: The supply current is mainly a function of operati ng voltage, frequency and mode. Other factors, such as I/O pin loading
and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on
the current consumption.
The test conditions for all IDD measurements in active operation mode are:
OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD;
MCLR = VDD; WDT enabled/disabled as specified.
3: For RC oscillator configurations, current through REXT is not included. The current through the resistor can be estimated
by the formula Ir = VDD/2REXT (mA) with REXT in k.
PIC16F87/88
DS30487D-page 172 2002-2013 Microchip Technology Inc.
18.3 DC Characteristics: Internal RC Accuracy
PIC16F87/88 (Ind us tria l , Exte n ded)
PIC16LF87/88 (Industrial)
PIC16LF87/88
(Industrial) Standard Operating Conditions (unless otherwise stated)
Operating temperature -40°C TA +85°C for industrial
PIC16F87/88
(Industrial, Extended)
Standard Operating Conditions (unless otherwise stated)
Operating temperature -40°C TA +85°C for industrial
-40°C TA +125°C for extended
Param
No. Device Min Typ Max Units Conditions
INTOSC Accuracy @ Freq = 8 MHz, 4 MHz, 2 MHz, 1 MHz, 500 kHz, 250 kHz, 125 kHz(1)
PIC16LF87/88 -2 ±1 2 % +25°C VDD = 2.7-3.3V-5 5 % -10°C to +85°C
-10 10 % -40°C to +85°C
PIC16F87/88 -2 ±1 2 % 25°C VDD = 4.5-5. 5V-5 5 % -10°C to +85°C
-10 10 %-40°C to +85°C
Extended devices -15 15 % -40°C to +125°C VDD = 4.5-5.5V
INTRC Accuracy @ Freq = 31 kHz(2)
PIC16LF87/88 26.562 35 .938 kHz -40°C to +85°C VDD = 2.7-3.3V
PIC16F87/88 26.562 35.938 kHz -40°C to +85°C VDD = 4.5-5.5V
Legend: Shading of rows is t o assist in readability of the table.
Note 1: Frequency calibrated at 25°C. OSCTUNE register can be used to compensate for temperature drift.
2: INTRC frequency after calibration.
2002-2013 Microchip Technology Inc. DS30487D-page 173
PIC16F87/88
18.4 DC Characteristics: PIC16F87/88 (Industrial, Extended)
PIC16LF87/88 (Industrial)
DC CHARACTERISTICS
Standard Operating Conditions (unless otherwise stated)
Operating temperature -40°C TA +8 C for industrial
-40°C TA +125°C for extended
Operating voltage VDD range as described in DC Specification,
Section 1 8.1 “DC Characteristics: Supply Voltage.
Param
No. Sym Characteristic Min Typ† Max Units Conditions
VIL Input Low Voltage
I/O ports:
D030 with TTL buffer VSS —0.15 VDD V For entire VDD range
D030A VSS —0.8V V4.5V VDD 5.5V
D031 with Schm itt Trigger buffer VSS 0.2 VDD V
D032 MCLR, OSC1 (in RC mode) VSS 0.2 VDD V(Note 1)
D03 3 OSC1 (in XT and LP mo de) VSS —0.3V V
OSC1 (in HS mode) VSS 0.3 VDD V
Ports RB1 and RB4:
D034 with Schm itt Trigger buffer VSS 0.3 VDD V For entire VDD range
VIH Input High Voltage
I/O ports:
D040 with TTL buffer 2.0 VDD V4.5V VDD 5.5V
D040A 0.25 VDD + 0.8V VDD V For entire VDD range
D041 with Schm itt Trigger buffer 0.8 VDD —VDD V For entire VDD range
D042 MCLR 0.8 VDD —VDD V
D042A OSC1 (in XT and LP mode) 1.6 V VDD V
OSC1 (in HS mode) 0.7 VDD —VDD V
D043 OSC1 (in RC mode) 0.9 VDD —VDD V(Note 1)
Ports RB1 and RB4:
D044 with Schm itt Trigger buffer 0.7 VDD —VDD V For entire VDD range
D070 IPURB PORTB Weak Pull-up Current 50 250 400 AVDD = 5V, VPIN = VSS
IIL Input Leakage Current (Notes 2, 3)
D060 I/O ports ±1 AVss VPIN VDD, pin at
high-impedance
D061 MCLR ±5 AVss VPIN VDD
D063 OSC1 ±5 AVss VPIN VDD, XT, HS
and LP oscillator
configuration
* These parameters are characterized but not tested.
Dat a in “Typ” column is at 5V, 25°C unless o therwise st ate d. These pa ramete rs are for des ign guid ance only
and are not tested.
Note 1: In RC oscilla tor configuration, th e OS C1/C LKI pin is a Schm itt Trigger in put. It is not rec om mend ed that the
PIC16F87/88 be driven with external clock in RC mode.
2: The leakage current on the M CL R pin is strongl y depend ent on the applied voltage level. The spec ified levels
represent normal operating condi tions. Higher leaka ge current may be measu red at dif f erent input voltages.
3: Negative current is defined as current sourced by the pin.
PIC16F87/88
DS30487D-page 174 2002-2013 Microchip Technology Inc.
VOL Output Low Voltage
D080 I/O ports 0.6 V IOL = 8.5 mA, VDD = 4.5V,
-40C to +125C
D083 OSC2/CLKO
(RC oscillator configuration) ——0.6VI
OL = 1.6 mA, VDD = 4.5V,
-40C to +125C
VOH Output High Volt a ge
D090 I/O ports (Note 3) VDD – 0.7 V IOH = -3.0 mA, VDD = 4.5V,
-40C to +125C
D092 OSC2/CLKO
(RC oscillator configuration) VDD 0.7 V IOH = -1.3 mA, VDD = 4.5V,
-40C to +125C
Capacitive Loading Specs on Output Pins
D100 COSC2 OSC2 pin 15 pF In XT, HS and LP modes
when external clock is used
to drive OSC1
D101 CIO All I/O pins and OSC2
(in RC mode) ——50pF
D102 CBSCL, SDA in I2C™ mode ——400pF
Data EEPROM Memory
D120 EDEndurance 100K
10K 1M
100K
E/W
E/W -40C to 85C
+85C to +125C
D121 VDRW VDD for Read/W ri te VMIN 5.5 V Using EECON to read/write,
VMIN = min. operating voltage
D122 TDEW Erase/Write Cycle Time 4 8 ms
Program Flash Memory
D130 EPEndurance 10K
1K 100K
10K
E/W
E/W -40C to 85C
+85C to +125C
D131 VPR VDD for Read VMIN —5.5 V
D132A VDD for Erase/Write VMIN 5.5 V Using EECON to read/write,
VMIN = min. operating voltage
D133 TPE Erase Cycle Time 2 4 ms
D134 TPW Wr ite C ycle Time 2 4 ms
18.4 DC Characteristics: PIC16F87/88 (Industrial, Extended)
PIC16LF87/88 (Industrial) (Continued)
DC CHARACTERISTICS
Standard Operating Conditions (unless otherwise stated)
Operating temperature -40°C TA +8 C for industrial
-40°C TA +125°C for extended
Operating voltage VDD range as described in DC Specification,
Section 1 8.1 “DC Characteristics: Supply Voltage.
Param
No. Sym Characteristic Min Typ† Max Units Conditions
* These parameters are characterized but not tested.
Dat a in “Typ” column is at 5V, 25°C unless o therwise st ate d. These pa ramete rs are for des ign guid ance only
and are not tested.
Note 1: In RC oscilla tor configuration, th e OS C1/C LKI pin is a Schm itt Trigger in put. It is not rec om mend ed that the
PIC16F87/88 be driven with external clock in RC mode.
2: The leakage current on the M CL R pin is strongl y depend ent on the applied voltage level. The spec ified levels
represent normal operating condi tions. Higher leaka ge current may be meas ured at dif ferent input v olt ages .
3: Negative current is defined as current sourced by the pin.
2002-2013 Microchip Technology Inc. DS30487D-page 175
PIC16F87/88
TABLE 18-1: COMPARATOR SPECIFICATIONS
TABLE 18-2: VOLTAGE REFERENCE SPECIFICATIONS
Operating Condit ions : 3.0V < VDD < 5.5V, -40°C < TA < +85°C, unless otherwise stated
Param
No. Sym Characteristics Min Typ Max Units Comments
D300 VIOFF Input Offset V o lt a ge ±5.0 ±10 mV
D301 VICM Input Common Mode Voltage* 0 VDD – 1.5 V
D302 CMRR Common Mode Rejecti on Ratio* 55 dB
300
300A TRESP Response Time(1)* —150400
600 ns
ns PIC16F87/88
PIC16LF87/88
301 TMC2OV Comparator Mode Chan ge to
Output Valid* ——10s
* These parameters are characterized but not tested.
Note 1: Respo nse tim e me as ured wi th on e com p a rator input at (VDD 1.5)/2 while the other input transitions from
VSS to VDD.
Operating Condit ions : 3.0V < VDD < 5.5V, -40°C < TA < +85°C, unless otherwise stated
Spec
No. Sym Characteristics Min Typ Max Units Comments
D310 VRES Resolution VDD/24 VDD/32 LSb
D311 VRAA Absolute Accuracy
1/2
1/2 LSb
LSb Low Range (CVRR = 1)
High Range (CVRR = 0)
D312 VRUR Unit Resi stor Value (R)* 2k
310 TSET Settling Time(1)*— — 10 s
* These parameters are characterized but not tested.
Note 1: Settling time measured while CVRR = 1 and CVR<3:0> transitions from0000’ to ‘1111’.
PIC16F87/88
DS30487D-page 176 2002-2013 Microchip Technology Inc.
18.5 Timing Parameter Symbology
The timing parameter symbols have been created
using one of the following formats:
FIGURE 18-3: LOA D CONDITIONS
1. TppS2ppS 3. TCC:ST (I2C specifications only)
2. TppS 4. Ts (I2C specifications only)
TF Frequency T Time
Lowercase letters (pp) and their meanings:
pp
cc CCP1 osc OSC1
ck CLKO rd RD
cs CS rw RD or WR
di SDI sc SCK
do SDO ss SS
dt Data in t0 T0CKI
io I/O port t1 T1CKI
mc MCLR wr WR
Uppe rcase letters and their meanings:
SFFall PPeriod
HHigh RRise
I Invalid (High-impedance) V Valid
L Low Z High-impedance
I2C only
AA out put access High High
BUF Bus free Low Low
TCC:ST (I2C specifications only)
CC
HD Hold SU Setup
ST
DAT DATA input hold STO Stop condition
STA Start condition
VDD/2
CL
RL
Pin Pin
VSS VSS
CL
RL= 464
CL= 50 pF for all pins except OSC2, but including PORTD and PORTE outputs as ports
15 pF for OSC2 output
Load Condition 1 Load Condition 2
2002-2013 Microchip Technology Inc. DS30487D-page 177
PIC16F87/88
FIGURE 18-4: EXT ER NAL CLOCK TIMING
OSC1
CLKO
Q4 Q1 Q2 Q3 Q4 Q1
1
23344
TABLE 18-3: EXTERNAL CLOCK TIMING REQUIREMENTS
Parameter
No. Sym Characteristic Min Typ† Max Units Conditions
FOSC External CLKI Frequency
(Note 1) DC 1 MHz XT and RC Osci llator mode
DC 2 0 MHz HS Osc illator mode
DC 32 kHz LP Oscillator mode
Oscilla tor Frequency
(Note 1) DC 4 MHz RC Oscillator mode
0.1 4 MHz XT Oscillator mode
4
5
20
200 MHz
kHz HS Osc illator mode
LP Oscillator mode
1T
OSC External CLKI Period
(Note 1) 1000 ns XT and RC Oscillator
modes
50 ns HS Oscillator mode
5 ms LP Oscillator mode
Oscillator Perio d
(Note 1) 250 ns RC Oscillator mode
250 10,000 ns XT Oscillator mode
50 25 0 ns HS Oscillator mode
5 ms LP Oscillator mode
2T
CY Instruction Cycle Time
(Note 1) 200 TCY DC ns TCY = 4/FOSC
3 TosL,
TosH External Clock in (OSC1) High or
Low Time 500 — ns XT oscillator
2.5 ms LP oscillator
15 ns HS oscillator
4TosR,
TosF External Clock in (OSC1) Rise or
Fall Time — — 25 ns XT oscillator
— — 50 ns LP oscillator
15 ns HS oscillator
Data in “Typ” column is at 5V, 25°C unless otherwise stated. These parameters are for design guidance
only and are not tested .
Note 1: Instruction cycle period (TCY) equals four times the input oscillator time base period. All specified values
are based on charac teri za tion data for that particular oscillator type under stand ard ope rati ng con di tion s
with the device executing code. Exceeding these specified limits may result in an unstable oscillator
operation and/or higher than expected current consumption. All devices are tested to operate at “min.”
values with an external clock applied to the OSC1/CLKI pin. When an external clock input is used, the
“max.” cycle time limit is “DC” (no clock) for all devices.
PIC16F87/88
DS30487D-page 178 2002-2013 Microchip Technology Inc.
FIGURE 18-5: CLKO AND I/O TIMING
TABLE 18-4: CLKO AND I/O TIMING REQUIREMENTS
Note: Refer to Figure 18-3 for load conditions.
OSC1
CLKO
I/O Pin
(Input)
I/O Pin
(Output)
Q4 Q1 Q2 Q3
10
13 14
17
20, 21
19 18
15
11
12 16
Old Value New Value
Param
No. Symbol Characteristic Min Typ† Max Units Conditions
10* TosH2ckL OSC1 to CL KO 75 200 ns (Note 1)
11* TosH2ckH OSC1 to CL KO 75 200 ns (Note 1)
12* TckR CLKO Rise Time 35 100 ns (Note 1)
13* TckF CLK O Fall Time 35 100 ns (Note 1)
14* TckL2ioV CLKO to Port Out Valid 0.5 TCY + 20 ns (Note 1)
15* TioV2ck H Port In Valid before CLKO T
OSC + 200 ns (Note 1)
16* TckH2ioI Port In Hold after CLKO 0—ns(Note 1)
17* TosH2ioV OSC1 (Q1 cycle) to Port Out Valid 100 255 ns
18* TosH2ioI OSC1 (Q2 cycle) to
Port Input Invalid (I/O in
hold time)
PIC16F87/88 100 ns
PIC16LF87/88 200 ns
19* TioV2osH Port Input Valid to OSC1 (I /O in setup time) 0 ns
20* TIOR Port Output Rise Time PIC16F87/88 10 40 ns
PIC16LF87/88 145 ns
21* TIOF Port Output Fall Time PIC16F87/88 10 40 ns
PIC16LF87/88 145 ns
22††* TINP INT Pin High or Low Time TCY ——ns
23††* TRBP RB7:RB4 Change INT High or Low Time TCY ——ns
* Thes e parameters are characterized but not tested.
Data in “T yp” column is at 5V, 25°C unless otherwise stated. These parameters are for design guidance only and are not
tested.
†† These parameters are asynchronous events not related to any internal clock edges.
Note 1: Measurements are taken in RC mode where CLKO output is 4 x TOSC.
2002-2013 Microchip Technology Inc. DS30487D-page 179
PIC16F87/88
FIGURE 18-6: RESET, WATCHDOG TI MER, OSCILLATOR START-UP TIMER AND
POWER-UP TIMER TIMING
FIGURE 18-7: BROWN-OUT RESET TIMING
TABLE 18-5: RESET, WATCHDOG TIMER, OSCILLATOR START-UP TIMER, POWER-UP TIMER
AND BROWN-OUT RESET REQUIREMENTS
Parameter
No. Sym Characteristic Min Typ† Max Units Conditions
30 TmcL MCLR Pulse Wid th (Low) 2 sVDD = 5V, -40°C to +85°C
31* TWDT Watchdog Timer Time-out Period
(16-bit prescaler = 0100 and no
postscaler)
13.6 16 18.4 ms VDD = 5V, -40°C to +85°C
32 TOST Oscillation Start-up Timer Period 1024 TOSC ——TOSC = OSC1 period
33* TPWRT Power-up Timer Period 61.2 72 82.8 ms VDD = 5V, -40°C to +85°C
34 TIOZ I/O High-impedance from MCLR
Low or Watchdog Timer Reset ——2.1s
35 TBOR Brown-out Reset Pulse Width 100 sVDD VBOR (D005)
* Thes e parameters are characterized but not tested.
Data in “T yp” column is at 5V, 25°C unless otherwise stated. These parameters are for design guidance only and are
no t te sted.
VDD
MCLR
Internal
POR
PWRT
Time-out
Oscillator
Time-out
Internal
Reset
Watchdog
Timer
Reset
33
32
30
31
34
I/O Pins
34
Note: Refer to Figure 18-3 for load conditions.
VDD VBOR
35
PIC16F87/88
DS30487D-page 180 2002-2013 Microchip Technology Inc.
FIGURE 18-8: TIMER0 AND TIMER1 EXTERNAL CLOCK TIMINGS
TABLE 18-6: TIMER0 AND TIMER1 EXTERNAL CLOCK REQUIREMENTS
Param
No. Symbol Characteristic Min Typ† Max Units Conditions
40* Tt0H T0CKI High Pulse Width No Pres caler 0.5 TCY + 20 ns Must also meet
parameter 42
With Prescaler 10 ns
41* Tt0L T0CKI Low Pulse Width No Prescaler 0.5 TCY + 20 ns Mu st also meet
parameter 42
With Prescaler 10 ns
42* Tt0P T0CKI Period No Prescaler TCY + 40 ns
Wi th Pr e sc al e r Greater of:
20 or TCY + 40
N
ns N = prescale val ue
(2, 4, ..., 256)
45* Tt1H T1CKI High
Time Synchronous , Pres caler = 1 0.5 TCY + 20 ns Mu st also meet
parameter 47
Synchronous,
Pres caler = 2, 4, 8 PIC16F87/88 15 ns
PIC16LF87/88 25 ns
Asynchronous PIC16F87/88 30 ns
PIC16LF87/88 50 ns
46* Tt1L T1CKI Low
Time Synchronous , Pres caler = 1 0.5 TCY + 20 ns Mu st also meet
parameter 47
Synchronous,
Pres caler = 2, 4, 8 PIC16F87/88 15 ns
PIC16LF87/88 25 ns
Asynchronous PIC16F87/88 30 ns
PIC16LF87/88 50 ns
47* Tt1P T1CKI Input
Period Synchronous PIC16F87/88 Greater of:
30 or TCY + 40
N
ns N = prescale value
(1, 2, 4, 8)
PIC16LF87/88 Greater of:
50 or TCY + 40
N
N = prescale value
(1, 2, 4, 8)
Asynchronous PIC16F87/88 60 ns
PIC16LF87/88 100 ns
Ft1 Timer1 Oscillator Input Frequency Range
(Oscillator enabled by setting bit T1OSCEN) DC 32.768 kHz
48 TCKEZtmr1 Delay from External Clock Edge to T imer Increment 2 T OSC —7 TOSC
* Thes e parameters are characterized but not tested.
Data in “T yp” column is at 5V, 25°C unless otherwise stated. These parameters are for design guidance only and are
no t te sted.
Note: Refer to Figure 18-3 for load conditions.
46
47
45
48
41
42
40
RA4/T0CKI
RB6/T1OSO/T1CKI
TMR0 or TMR1
2002-2013 Microchip Technology Inc. DS30487D-page 181
PIC16F87/88
FIGURE 18-9: CAP TURE/ COMPARE/PWM TIMINGS (CCP1)
TABLE 18-7: CAPTURE/COMPARE/PWM REQUIREMENTS (CCP1)
Note: Refer to Figure 18-3 for load conditions.
CCP1
(Capture Mode)
50 51
52
53 54
CCP1
(Compare or PWM Mode)
Param
No. Symbol Characteristic Min Typ† Max Units Conditions
50* TccL CCP1
Input Low Time No Prescaler 0.5 TCY + 20 ns
With Prescale r PIC16F87/88 10 ns
PIC16LF87/88 20 ns
51* TccH CCP1
Input High Time No Prescaler 0.5 TCY + 20 ns
With Prescale r PIC16F87/88 10 ns
PIC16LF87/88 20 ns
52* TccP CCP1 Input Period 3 TCY + 40
N ns N = prescale
value (1, 4 or 16)
53* TccR CCP1 Output Rise Time PIC16F87/88 10 25 ns
PIC16LF87/88 25 50 ns
54* TccF CCP1 Output Fall Time PIC16F87/88 10 25 ns
PIC16LF87/88 25 45 ns
* These parameters are characterized but not tested.
Data in “Typ” column is at 5V, 25°C unless otherwise stated. These parameters are for design guidance
only and are not tested .
PIC16F87/88
DS30487D-page 182 2002-2013 Microchip Technology Inc.
FIGURE 18-10 : SPI MAST E R MODE TIMING (CKE = 0, SMP = 0)
FIGURE 18-11: SPI MASTER MODE TIMING (CKE = 1, SMP = 1)
SS
SCK
(CKP = 0)
SCK
(CKP = 1)
SDO
SDI
70
71 72
73 74
75, 76
78
79
80
79
78
MSb LSb
Bit 6 - - - - - -1
MSb In LSb In
Bit 6 - - - -1
Note: Refer to Figure 18-3 for load conditions.
SS
SCK
(CKP = 0)
SCK
(CKP = 1)
SDO
SDI
81
71 72
74
75, 76
78
80
MSb
79
73
MSb In
Bit 6 - - - - - -1
LSb In
Bit 6 - - - -1
LSb
Note: Refer to Figure 18-3 for load conditions.
2002-2013 Microchip Technology Inc. DS30487D-page 183
PIC16F87/88
FIGURE 18-12 : SPI SLAVE MODE TIMING (CKE = 0)
FIGURE 18-13 : SPI SLAVE MODE TIMING (CKE = 1)
SS
SCK
(CKP = 0)
SCK
(CKP = 1)
SDO
SDI
70
71 72
73 74
75, 76 77
78
79
80
79
78
SDI
MSb LSb
Bit 6 - - - - - -1
MSb In Bit 6 - - - -1 LSb In
83
Note: Refer to Figure 18-3 for load conditions.
SS
SCK
(CKP = 0)
SCK
(CKP = 1)
SDO
SDI
71 72
82
SDI
74
75, 76
MSb Bit 6 - - - - - -1 LSb
77
MSb In Bit 6 - - - -1 LSb In
80
83
Note: Refer to Figure 18-3 for load conditions.
70
PIC16F87/88
DS30487D-page 184 2002-2013 Microchip Technology Inc.
TABLE 18-8: SPI MODE REQUIREMENTS
FIGURE 18-14 : I2C™ BUS START/STOP BITS TIMING
Param
No. Symbol Characteristic Min Typ† Max Units Conditions
70* TssL2scH,
TssL2scL SS to SCK or SCK Input TCY ——ns
71* TscH SCK Input High Ti me (Slave mo de) TCY + 20 ns
72* TscL SCK Input Low Time (Slave mode) TCY + 20 ns
73* T diV2scH,
TdiV2scL Setup Time of SDI Data Input to SCK Edge 100 ns
74* TscH2diL,
TscL2diL Hold Time of SDI Data Input to SCK Edge 100 ns
75* T doR SDO Data Output Rise Time PIC16F87/88
PIC16LF87/88
10
25 25
50 ns
ns
76* T doF SDO Data Output Fall Time 10 25 ns
77* TssH2doZ SS to SDO Output High-Impedance 10 50 ns
78* TscR SCK Output Rise Time
(Master mode) PIC16F87/88
PIC16LF87/88
10
25 25
50 ns
ns
79* TscF SCK Output Fall Time (Master mode) 10 25 ns
80* TscH2doV,
TscL2doV SDO Data Output Valid after SCK
Edge PIC16F87/88
PIC16LF87/88
50
145 ns
ns
81* TdoV2scH,
TdoV2scL SDO Data Output Setup to SCK Edge TCY ——ns
82* TssL2doV SDO Data Output Valid after SS Edge 50 ns
83* TscH2ssH,
TscL2ssH SS after SCK Edge 1.5 TCY + 40 ns
* Thes e parameters are characterized but not tested.
Data in “T yp” column is at 5V, 25°C unless otherwise stated. These parameters are for design guidance only and are
no t te sted.
Note: Refer to Figure 18-3 for load conditions.
91
92
93
SCL
SDA
Start
Condition Stop
Condition
90
2002-2013 Microchip Technology Inc. DS30487D-page 185
PIC16F87/88
TABLE 18-9: I2C™ BUS STAR T/STOP BITS REQUIREMENTS
FIGURE 18-15 : I2C™ BUS DATA TIMING
Param
No. Symbol Characteristic Min Typ Max Units Conditions
90* TSU:STA Start Condition 100 kHz mode 4700 ns Only relevant for Repeated
Start condition
Setup Time 400 kHz mode 600
91* THD:STA S tart Condition 100 kHz mode 4000 ns After this period, the first clock
pulse is generated
Hold Time 400 kHz mode 600
92* TSU:STO Stop Condition 100 kHz mode 4700 ns
Setup Time 400 kHz mode 600
93 THD:STO Stop Condition 100 kHz mode 4000 ns
Hold Time 400 kHz mode 600
* These parameters are characterized but not tested.
Note: Refer to Figure 18-3 for load conditions.
90
91 92
100 101
103
106 107
109 109 110
102
SCL
SDA
In
SDA
Out
PIC16F87/88
DS30487D-page 186 2002-2013 Microchip Technology Inc.
TABLE 18-10: I2C™ BUS DATA REQUIREMENTS
Param.
No. Symbol Characteristic Min Max Units Conditions
100* THIGH Clock High Time 100 kHz mode 4.0 s
400 kHz mode 0.6 s
SSP Module 1.5 TCY
101* TLOW Clock Low Time 100 kHz mode 4.7 s
400 kHz mode 1.3 s
SSP Module 1.5 TCY
102* TRSDA and SCL Rise
Time 100 kHz mode 1000 ns
400 kHz mode 20 + 0.1 CB300 ns CB is specified to be from
10-400 pF
103* TFSDA and SCL Fall
Time 100 kHz mode 300 ns
400 kHz mode 20 + 0.1 CB300 ns CB is specified to be from
10-400 pF
90* TSU:STA Start Condition
Setup Time 100 kHz mode 4.7 s Only relevant for
Repeated Start
condition
400 kHz mode 0.6 s
91* THD:STA Start Condition Hold
Time 100 kHz mode 4.0 s After this period, the first
clock pulse is generated
400 kHz mode 0.6 s
106* THD:DAT Data Input Hold
Time 100 kHz mode 0 ns
400 kHz mode 0 0.9 s
107* TSU:DAT Data Input Setup
Time 100 kHz mode 250 ns (Note 2)
400 kHz mode 100 ns
92* TSU:STO Stop Condition
Setup Time 100 kHz mode 4.7 s
400 kHz mode 0.6 s
109* TAA Output Valid from
Clock 100 kHz mode 3500 ns (Note 1)
400 kHz mode ns
110* TBUF Bus Free Time 100 kHz mode 4.7 s Tim e the bu s mus t be free
before a new transm ission
can start
400 kHz mode 1.3 s
CBBus Capacitive Loading 400 pF
* These parameters are characterized but not tested.
Note 1: As a transmitter, the device must provide this internal minimum delay time to bridge the undefined region
(min. 300 ns) of the falling edge of SCL to avoid unintended generation of Start or Stop conditions.
2: A Fast mode (400 kHz) I2C™ bus device can be used in a Standard mode (100 kHz) I2C bus system, but
the requiremen t, TSU:DAT 250 ns , m ust th en b e m et. Thi s w i ll a uto ma tic all y b e the case if the dev ic e d oes
not stretch the low period of the SCL signal. If such a device does stretch the low period of the SCL signal,
it must outp ut the next da ta bit to th e SDA line, T R max. + TSU:DAT = 1000 + 25 0 = 1250 ns (ac cording to the
Standard mode I2C bus spe c ification), before the SCL line i s released.
2002-2013 Microchip Technology Inc. DS30487D-page 187
PIC16F87/88
FIGURE 18-16: AUSART SYNCHRONOUS TRANSMISSION (MASTER/SLAVE) TIMING
TABLE 18-11: AUSART SYNCHRONOUS TRANSMISSION REQUIREMENTS
FIGURE 18-17: AUSART SYNCHRONOUS RECEIVE (MASTER/SLAVE) TIMING
TABLE 18-12: AUSART SYNCHRONOUS RECEIVE REQUIREMENTS
Param
No. Sym Characteristic Min Typ† Max Units Conditions
120 TckH2dtV SYNC XM IT (MASTER &
SLAVE)
Clock High to Data Out Valid
PIC16F87/88 80 ns
PIC16LF87/88 100 ns
121 Tckrf Clock Out Rise Time and Fall
Time (Master mode) PIC16F87/88 45 ns
PIC16LF87/88 50 ns
122 Tdtrf Data Out Rise Time and Fall
Time PIC16F87/88 45 ns
PIC16LF87/88 50 ns
Data in “Typ” column is at 5V, 25 C unless otherwise stated. These parameters are for design guidance only and are not
tested.
Param
No. Sym Characteristic Min Typ† Max Units Conditions
125 TdtV2ckL SYNC RCV (MASTER & SLAVE)
Data Setup before CK (DT setup time) 15 ns
126 TckL2dtl Data Hold after CK (DT hold time) 15 ns
Data in “Typ” column is at 5V, 25C unless otherwise stated. These parameters are for design guidance
only and are not tested .
Note: Refer to Figure 18-3 for load conditions.
121 121
122
RB5/SS/TX/CK
RB2/SDO/RX/DT
pin
pin
120
Note: Refer to Figure 18-3 fo r load conditions.
125
126
RB5/SS/TX/CK
RB2/SDO/RX/DT
pin
pin
PIC16F87/88
DS30487D-page 188 2002-2013 Microchip Technology Inc.
TABLE 18-13: A/D CONVERTER CHARACTERISTICS: PIC16F87/88 (INDUSTRIAL, EXTENDED)
PIC16LF87/88 (INDUSTRIAL)
Param
No. Sym Characteristic Min Typ† Max Units Conditions
A01 NRResolution 10-bit bit VREF = VDD = 5.12V,
VSS VAIN VREF
A03 EIL Integral Linearity Error <±1 LSb VREF = VDD = 5.12V,
VSS VAIN VREF
A04 EDL Different ial Linearity Error <±1 LSb VREF = VDD = 5.12V,
VSS VAIN VREF
A06 EOFF Offset Error <±2 LSb VREF = VDD = 5.12V,
VSS VAIN VREF
A07 EGN Gain Error 1 LSb VREF = VDD = 5.12V,
VSS VAIN VREF
A10 Monotonicity guaranteed(3) ——VSS VAIN VREF
A20 VREF Ref erence Voltage
(VREF+ – VREF-) 2.0 VDD + 0.3 V
A21 VREF+ Reference Voltage High AVDD2.5V AVDD + 0.3V V
A22 VREF- Reference Voltage Low AVSS – 0.3V VREF+ 2.0V V
A25 VAIN Analog Input Voltage VSS – 0.3V VREF + 0.3V V
A30 ZAIN Recommended Impedance of
Analog V oltage Source ——2.5k(Note 4)
A40 IAD A/D Conversion
Current (VDD)PIC16F87/88 220 A Average current
consumption when A/D is on
(Not e 1)
PIC16LF87/88 90 A
A50 IREF VREF Input Current (Note 2)
5
150
A
A
During VAIN acquisition.
Based on dif ferential of VHOLD
to VAIN to charge CHOLD,
see Section 12.1 “A/D
Acquisition Requirements”.
During A/D conversion cycle
* Thes e parameters are characterized but not tested.
Data in “T yp” column is at 5V, 25°C unless otherwise stated. These parameters are for design guidance only and are
no t te sted.
Note 1: When A/D is off, it will not consume any current other than minor leakage current. The power-down current specification
includes any such leakage from the A/D module.
2: VREF current is from RA3 pin or VDD pin, whichever is selected as reference input.
3: The A/D conversion result never decreases with an increase in the input voltage and has no missing codes.
4: Maximum allowed impedance for analog voltage source is 10 kThis requires higher acquisition time.
2002-2013 Microchip Technology Inc. DS30487D-page 189
PIC16F87/88
FIGURE 18-18: A/D CONVERSION TIMING
TABLE 18-14: A/D CONVERSION REQUIREMENTS
131
130
132
BSF ADCON0, GO
Q4
A/D CLK
A/D DATA
ADRES
ADIF
GO
SAMPLE
OLD_DATA
Sampling St opped
DONE
NEW_DATA
(TOSC/2)(1)
987 210
Note: If the A/D clock source is selected as RC, a time of TCY is added before the A/D clock start s. This allows the SLEEP
instruction to be executed.
1 TCY
 
Param
No. Symbol Characteristic Min Typ† Max Units Conditions
130 TAD A/D Clock Period PIC16F87/88 1.6 sTOSC based, VREF 3.0V
PIC16LF87/88 3.0 sT
OSC based, VREF 2.0V
PIC16F87/88 2.0 4.0 6.0 s A/D RC mode
PIC16LF87/88 3.0 6.0 9.0 s A /D RC mode
131 TCNV Conversion Time (not including S/H time)
(Note 1) —12TAD
132 TACQ Acquisition Time (Note 2)
10*
40
s
s The minimum time is the
amplifier settling time. This may
be used if the “new” input
voltage has not changed by
more than 1 LSb (i.e., 5.0 mV @
5.12V) from the last sampled
voltage (as stated on CHOLD).
134 TGO Q4 to A/D Clock Start TOSC/2 § I f the A/D clock source is
selected as RC, a time of TCY is
added before the A/D clock
starts. This allows the SLEEP
instruction to be executed.
* Thes e parameters are characterized but not tested.
Data in “T yp” column is at 5V, 25°C unless otherwise stated. These parameters are for design guidance only and are
no t te sted.
§ This specification ensured by design.
Note 1: A DRE S registers may be read on the following TCY cycle.
2: See Section 12.1 “A/D Acquisition Requirements” for minimum conditions.
PIC16F87/88
DS30487D-page 190 2002-2013 Microchip Technology Inc.
NOTES:
2002-2013 Microchip Technology Inc. DS30487D-page 191
PIC16F87/88
19.0 DC AND AC CHARACTERISTICS GRAPHS AND TABLES
“T ypical” represents the mean of the distribution at 25C. “Maximum” or “minimum” represents (mean + 3) or (mean 3)
respectively, where is a st anda rd deviation, ov er the whole temperature range.
FIGURE 19-1: TYPICAL IDD vs. FOSC OVER VDD (HS MODE)
FIGURE 19-2: MAXIMU M IDD vs. FOSC OVER VDD (HS MODE)
Note: The g r ap hs and t ables provide d f oll ow in g th is no te a r e a s t ati sti ca l s um ma ry based on a lim ite d number of
samples and are provided for informational purposes only. The performance characteristic s listed herein
are not tested or guaranteed. In some graphs or tables, the data presented may be outside the specified
operating range (e.g., outside specified power supply range) and therefore, outside the warranted range.
0
1
2
3
4
5
6
7
4 6 8 10 12 14 16 18 20
FOSC (MHz)
IDD (mA)
2.0V
2.5V
3.0V
3.5V
4.0V
4.5V
5.0V
5.5V
Typical: statistical mean @ 25°C
Maximum: mean + 3 (-40°C to +125°C)
Minimum: mean – 3 (-40°C to +125°C)
0
1
2
3
4
5
6
7
8
4 6 8 10 12 14 16 18 20
FOSC (MHz)
IDD (mA)
2.0V
2.5V
3.0V
3.5V
4.0V
4.5V
5.0V
5.5V
Typical: statistical mean @ 25°C
Maximum: mean + 3 (-40°C to +125°C)
Minimum: mean – 3 (-40°C to +125°C)
PIC16F87/88
DS30487D-page 192 2002-2013 Microchip Technology Inc.
FIGURE 19-3: TYPICAL IDD vs. FOSC OVER VDD (XT MODE)
FIGURE 19-4: MAXIMU M IDD vs. FOSC OVER VDD (XT MODE)
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
0 500 1000 1500 2000 2500 3000 3500 4000
FOSC (MHz)
IDD (mA)
2.0V
2.5V
3.0V
3.5V
4.0V
4.5V
5.0V
5.5V
Typical: statistical mean @ 25°C
Maximum: mean + 3 (-40°C to +125°C)
Minimum: mean – 3 (-40°C to +125°C)
0.0
0.5
1.0
1.5
2.0
2.5
0 500 1000 1500 2000 2500 3000 3500 4000
FOSC (MHz)
IDD (mA)
2.0V
2.5V
3.0V
3.5V
4.0V
4.5V
5.0V
5.5V
Typical: statistical mean @ 25°C
Maximum: mean + 3 (-40°C to +125°C)
Minimum: mean – 3 (-40°C to +125°C)
2002-2013 Microchip Technology Inc. DS30487D-page 193
PIC16F87/88
FIGURE 19-5: TYPICAL IDD vs. FOSC OVER VDD (LP MODE)
FIGURE 19-6: MAXIMU M IDD vs. FOSC OVER VDD (LP MODE)
0
10
20
30
40
50
60
70
20 30 40 50 60 70 80 90 100
FOSC (kHz)
IDD (uA)
2.0V
2.5V
3.0V
3.5V
4.0V
4.5V
5.0V
5.5V
Typical: statistical mean @ 25°C
Maximum: mean + 3 (-40°C to +125°C)
Minimum: mean – 3 (-40°C to +125°C)
0
20
40
60
80
100
120
20 30 40 50 60 70 80 90 100
FOSC (kHz)
IDD (uA)
2.0V
2.5V
3.0V
3.5V
4.0V
4.5V
5.0V
5.5V
Typical: statistical mean @ 25°C
Maximum: mean + 3 (-40°C to +125°C)
Minimum: mean – 3 (-40°C to +125°C)
PIC16F87/88
DS30487D-page 194 2002-2013 Microchip Technology Inc.
FIGURE 19-7: TYPICAL IDD vs. VDD, -4 0C TO +125C, 1 MHz TO 8 MHz
(RC_RUN MODE, ALL PERIPHERALS DISABLED)
FIGURE 19-8: MAXIMU M IDD vs. VDD, -40C TO +125C, 1 MHz TO 8 MHz
(RC_RUN MODE, ALL PERIPHERALS DISABLED)
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.02.03.04.05.06.07.08.0
FOSC (MHz)
IDD (mA)
5.5V
5.0V
4.5V
4.0V
3.5V
3.0V
2.5V
2.0V
Typical: statistical mean @ 25°C
Maximum: mean + 3 (-40°C to +125°C)
Minimum: mean – 3 (-40°C to +125°C)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
1.02.03.04.05.06.07.08.0
FOSC (MHz)
IDD (mA)
5.5V
5.0V
4.5V
4.0V
3.5V
3.0V
2.5V
2.0V
Typical: statistical mean @ 25°C
Maximum: mean + 3 (-40°C to +125°C)
Minimum: mean – 3 (-40°C to +125°C)
2002-2013 Microchip Technology Inc. DS30487D-page 195
PIC16F87/88
FIGURE 19-9: IDD vs. VDD, SEC_RUN MODE, -10C TO +125C, 32.768 kHz
(XTAL 2 x 22 pF, ALL PERIPHERALS DISABLED)
FIGURE 19-10 : IPD vs. VDD, -40C TO +125C (SLEEP MODE, ALL PERIPHERALS DISABLED)
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
45.0
2.02.53.03.54.04.55.05.5
Vdd(V)
Idd(A)
Max (+70°C)
T
yp
(
+25°C
)
Typical: statistical mean @ 25°C
Maximum: mean + 3 (-40°C to +125°C)
Minimum: mean – 3 (-40°C to +125°C)
0.001
0.01
0.1
1
10
100
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
VDD (V)
IPD (uA)
Typ (25°C)
Max (85°C)
Max (125°C)
Typical: statistical mean @ 25°C
Maximum: mean + 3 (-40°C to +125°C)
Minimum: mean – 3 (-40°C to +125°C)
PIC16F87/88
DS30487D-page 196 2002-2013 Microchip Technology Inc.
FI GU RE 1 9- 11: AVERAGE FOSC vs. VDD FOR V ARIOUS V ALUES OF R (RC MODE, C = 20 pF, +25C)
FIGURE 19-12: AVE RAGE FOSC vs. VDD FOR VARIOUS VALUES OF R
(RC MODE, C = 100 pF, +25C)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
VDD (V)
Freq (MHz)
100 k O hm
10 kOhm
5.1 kO hm
Oper ation above 4 MHz is no t r ecommended
0.0
0.5
1.0
1.5
2.0
2.5
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
VDD (V)
Freq (MHz)
100 k O hm
10 kOhm
5.1 kOhm
3.3 kOhm
2002-2013 Microchip Technology Inc. DS30487D-page 197
PIC16F87/88
FIGURE 19-13: AVE RAGE FOSC vs. VDD FOR VARIOUS VALUES OF R
(RC MODE, C = 300 pF, +25C)
FIGURE 19-14 : IPD TIMER1 OSCILLATOR, -10°C TO +70°C (SLEEP MODE,
TMR1 COUNTER DISABLED)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
VDD (V)
Freq (MHz)
100 kOhm
10 kOhm
5.1 kOhm
3.3 kOhm
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
2.02.53.03.54.04.55.05.5
VDD (V)
IPD (A)
Typ (+25°C)
Max (-10°C to +70°C)
Typical: statistical mean @ 25°C
Maximum: mean + 3 (-40°C to +125°C)
Minimum: mean – 3 (-40°C to +125°C)
PIC16F87/88
DS30487D-page 198 2002-2013 Microchip Technology Inc.
FIGURE 19-15 : IPD WDT, -40°C TO +125°C (SLEEP MODE, ALL PERIPHERALS DISABLED)
FIGURE 19-16 : IPD BOR vs. VDD, -40 °C TO +1 25°C (S L EEP MO D E,
BOR ENABLED AT 2.00V-2.16V)
0
2
4
6
8
10
12
14
16
18
2.02.53.03.54.04.55.05.5
VDD (V)
IWDT (A)
Max (-40°C to +125°C)
Max (- 40°C to +8 C)
Typ (25°C)
Typical: statistical mean @ 25°C
Maximum: mean + 3 (-40°C to +125°C)
Minimum: mean – 3 (-40°C to +125°C)
10
100
1,000
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
VDD (V)
IDD (A)
Device in
Reset
Device in
Sleep
Indeterminant
State
Max (125°C)
Typ (2 5°C )
Max (125°C)
Typ (25°C)
Typical: statistical mean @ 25°C
Maxi mum: mean + 3 (-40°C to +125°C)
Minimum: mean – 3 (-40°C to +125°C)
Note: Device current in Reset
depends on oscillator mode,
frequency and circuit.
2002-2013 Microchip Technology Inc. DS30487D-page 199
PIC16F87/88
FIGURE 19-17 : IPD A/D, -40C TO +125C, SLEEP MODE, A/D ENABLED (NOT CONVERTING)
FIGURE 19-18: TYPICAL, MINIMUM AND MAXIMUM VOH vs. IOH (VDD = 5V, -40C TO +125C)
0
2
4
6
8
10
12
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
VDD (V)
IA/D (A)
Max
(-40°C to +125°C)
Max
(-40°C to +85°C)
Typ (+25°C)
Typical: statistical mean @ 25°C
Maximum: mean + 3 (-40°C to +125°C)
Minimum: mean – 3 (-40°C to +125°C)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
0 5 10 15 20 25
IOH (-mA)
VOH (V)
Max
Ty p (25°C)
Min
Typical: statistical mean @ 25°C
Maximum: mean + 3 (-4 C to +125°C )
Minimum: mean – 3 (-40°C to +125°C)
PIC16F87/88
DS30487D-page 200 2002-2013 Microchip Technology Inc.
FIGURE 19-19: TYPICAL, MINIMUM AND MAXIMUM VOH vs. IOH (VDD = 3V, -40C TO +125C)
FIGURE 19-20: TYPICAL, MINIMUM AND MAXIMUM VOL vs. IOL (VDD = 5V, -40C TO +125C)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
0 5 10 15 20 25
IOH (-mA)
VOH (V)
Max
Typ (25°C )
Min
Typical: statistical mean @ 25°C
Maximu m: mean + 3 (-40°C to +125°C)
Minimum: mean – 3 (-40°C to +125°C)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0 5 10 15 20 25
IOL (-mA)
VOL (V)
Max (125°C)
Max (85°C)
Ty p (25°C)
Min (-40°C)
Typical: statistical mean @ 25°C
Maxi mum: mean + 3 (-40°C to +125°C)
Minimum: mean – 3 (-40°C to +125°C)
2002-2013 Microchip Technology Inc. DS30487D-page 201
PIC16F87/88
FIGURE 19-21: TYPICAL, MINIMUM AND MAXIMUM VOL vs. IOL (VDD = 3V, -40C TO + 125C)
FIGURE 19-22: MINIMUM AND MAXIMUM VIN vs. VDD (TTL INPUT, -40C TO +125C)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0 5 10 15 20 25
IOL (-mA)
VOL (V)
Max (1 2C)
Max (85° C)
Typ (25°C )
Min (-40°C)
Typical: statistical mean @ 25°C
Maximum: mean + 3 (-40°C to +125°C)
Minimum: mean – 3 (-40°C to +125°C)
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
VDD (V)
VIN (V)
VTH Max (-40°C)
VTH Min (125°C)
VTH Typ (25°C)
Typical: statistical mean @ 25°C
Maximum: mean + 3 (-40°C to +125°C)
Minimum: mean – 3 (-40°C to +125°C)
PIC16F87/88
DS30487D-page 202 2002-2013 Microchip Technology Inc.
FIGURE 19-23: MINIMUM AND MAXIMUM VIN vs. VDD (ST INPUT, -40C TO +125C)
FIGURE 19-24: MINIMUM AND MAXIMUM VIN vs. VDD (I2C™ INPUT, -40C TO +125C)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
VDD (V)
VIN (V)
VIH Max (125°C)
VIH Mi n (-40°C)
VIL Max (-40°C)
VIL Min (125°C)
Typical: statistical mean @ 25°C
Maximu m: mean + 3 (-40°C to +125°C)
Minimum: mean – 3 (-40°C to +125°C)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
VDD (V)
VIN (V)
VIH Max
VIH Min
VILMax
VIL Min
Typical: statistical mean @ 25°C
Maximum: mean + 3 (-40°C to +125°C)
Minimum: mean – 3 (-40°C to +125°C)
VIL Max
2002-2013 Microchip Technology Inc. DS30487D-page 203
PIC16F87/88
FIGURE 19-25: A/D NONLINEARITY vs. VREFH (VDD = VREFH, -40C TO +125C)
FIGURE 19-26: A/D NONLINEARITY vs. VREFH (VDD = 5V, -40C TO +125C)
0
0.5
1
1.5
2
2.5
3
3.5
4
22.533.544.555.5
VDD and VREFH (V)
Differential or Integral Nonlinearity (LSB)
-40C
25C
85C
125C
-40°C
+25°C
+85°C
+125°C
0
0.5
1
1.5
2
2.5
3
22.533.544.555.5
VREFH (V)
Differential or Integral Nonlinearilty (LSB)
Max (-40C to 125C)
Typ (25C)
Typ (+25°C)
Max (-40°C to +125°C)
PIC16F87/88
DS30487D-page 204 2002-2013 Microchip Technology Inc.
NOTES:
2002-2013 Microchip Technology Inc. DS30487D-page 205
PIC16F87/88
20.0 PACKAGING INFORMATION
20.1 Package Marking Information
20-Lead SSOP (5.30 mm) Exam ple
18-Lead SO IC (7. 50 m m ) Example
PIC16F88
-I/SO
0510017
PIC16F88
-I/SS
0510017
Legend: XX...X Customer-specific information
Y Year code (last digit of calendar year)
YY Year code (last 2 digits of calendar year)
WW Week code (week of January 1 is week ‘01’)
NNN Alphanumeric traceability code
Pb-free JEDEC designator for Matte Tin (Sn)
*This package is Pb-free. The Pb-free JEDEC designator ( )
can be found on the outer packaging for this pa ckage.
Note: In the event the full Microc hip p art num ber can not be ma rked on on e line, i t will
be carried over to the next line, thus limiting the number of available
characters for c ustomer-specific information.
3
e
3
e
3
e
3
e
18-Lead PDIP (300 mil) Example
PIC16F88-I/P
3
e
0510017
28-Lead QFN (6x6 mm) Example
XXXXXXXX
XXXXXXXX
YYWWNNN
PIN 1 PIN 1
PIC16F88
-I/SS
0510017
3
e
PIC16F87/88
DS30487D-page 206 2002-2013 Microchip Technology Inc.
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2002-2013 Microchip Technology Inc. DS30487D-page 207
PIC16F87/88
Note: For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
PIC16F87/88
DS30487D-page 208 2002-2013 Microchip Technology Inc.
Note: For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
2002-2013 Microchip Technology Inc. DS30487D-page 209
PIC16F87/88
Note: For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
PIC16F87/88
DS30487D-page 210 2002-2013 Microchip Technology Inc.
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2002-2013 Microchip Technology Inc. DS30487D-page 211
PIC16F87/88
Note: For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
PIC16F87/88
DS30487D-page 212 2002-2013 Microchip Technology Inc.
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2002-2013 Microchip Technology Inc. DS30487D-page 213
PIC16F87/88
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PIC16F87/88
DS30487D-page 214 2002-2013 Microchip Technology Inc.
NOTES:
2002-2013 Microchip Technology Inc. DS30487D-page 215
PIC16F87/88
APPENDIX A: REVISION HISTORY
Revision A (November 2003)
Original data sheet for PIC16F87/88 devices.
Revision B (August 2003)
The specifications in Section 18.0 “Electrical
Characteristics” have been updated to include the
addition of maximum specifications to the DC
Charac terist ics t ables , text c larificati on has b een made
to Section 4.6.2 “Clock Switching” and there have
been minor updates to the data sheet text.
Revision C (January 2005)
This revision includes the DC and AC Characteristics
Graphs and Tables. The Electrical Specifications in
Section 18.0 “Electrical Characteristics” have been
updated and there have been minor corrections to the
data sheet text.
Revision D (October 2011)
This revision updated the package marking and pack-
age outline drawings in Section 20.0 “Packaging
Information”.
APPENDIX B: DEVICE
DIFFERENCES
The differences betwe en th e dev ic es in th is dat a she et
are listed in Table B-1.
TABLE B-1: DIFFERENCES BETWEEN
THE PIC16F87 AND PIC16F88
Features PIC16F87 PIC16F88
Analog-to-Digital
Converter N/A 10-bit, 7-channel
PIC16F87/88
DS30487D-page 216 2002-2013 Microchip Technology Inc.
NOTES:
2002-2013 Microchip Technology Inc. DS30487D-page 217
PIC16F87/88
INDEX
A
A/D Acquisition Requirements ........................................119
ADIF Bi t .................. .......... ........... .......... ...................118
Analog-to-Digital Converter ......................................115
Associ a te d Re g i sters ... .......... ........... .......... ........... ..122
Calculating Acquisition Time ....................................119
Configuring Ana log Port Pins ...................................121
Configuring the Interrupt ..........................................118
Configuring the Module ............................................118
Conversi o n Clo ck ....... ..................... ..................... ....120
Conversions ............................................................. 121
Converter Characteristics ........................................190
Delays ......................................................................119
Effects of a Reset .....................................................122
GO/DONE Bit ...........................................................118
Internal Sampling Switch (Rss) Impedance .. ...........119
Operation During Sleep ...........................................122
Operation in Power-Managed Modes ......................120
Result Regi sters ................. ........... ..................... ......121
Source Impedance ............................................... ....119
Time Dela ys ......................... ........... ..................... ....119
Using the CCP Trigger .............................................122
Absolute Maximum Ratings .............................................163
ACK ....................................................................................95
ADCON0 Register ......................................................16, 115
ADCON1 Register ......................................................17, 115
Addressable Universal Synchronous A synchronous Rece iver
Transmitter. See AUSAR T
ADRESH Register ......................................................16, 115
ADRESH, ADRES L Regi ster Pair ................. ........... ........118
ADRESL Register ......................................................17, 115
ANSEL Register .............................................17, 54, 60, 115
Application Notes
AN556 (Implementing a Table Read) ........................27
AN578 (Use of the SSP Module in the I2C Multi-Master
Environment) .....................................................89
AN607 (Power-up Trouble Shooting) .......................135
Assembler
MPASM Ass embler ..................................................160
Asynchronous Reception
Associated Registers .......................................107, 109
Asynchronous Transmission
Associ a te d Re g i sters ... .......... ........... .......... ........... ..105
AUSART ............................................................................99
Address Detect Enable (ADDEN Bit) .......................100
Asynchronous Mode ................................................104
Asynchronous R eceive (9-bit Mode) ........................108
Asynchronous Receive wit h Address Detect. See Asyn-
chronous Receive (9-Bit Mode).
Asynchronous Receiver ...........................................106
Asynchronous Reception .........................................107
Asynchronous Transmitter .......................................104
Baud Rate Generator (BRG) ................................... 101
Baud Rate Formula ......................................... 101
Baud Rates, Asynchronous Mode (B RG H = 0) 102
Baud Rates, Asynchronous Mode (B RG H = 1) 102
High Baud Rate Select (BRGH Bit) ................... 99
INTRC Baud Rates, Asynchronous Mode (BRGH =
0) ............................................................. 103
INTRC Baud Rates, Asynchronous Mode (BRGH =
1) ............................................................. 103
INTR C Opera tion .... ..... ...... ...... ..... ...... .. ...... ..... 101
Low-Power Mode Operation ............................ 101
Sampling ......................................................... 101
Clock So urce Se le c t (C SR C Bi t) . ........... .. .. ...... .. .. ..... 99
Continuous Receive Enable (CREN Bit) ................. 100
Framing Error (FERR Bit) ........................................ 100
Mode Select (SY N C Bi t) .. ...... .. ...... .. ..... ...... .. ...... .. .. ... 99
Rece i ve Dat a , 9 th b i t (R X9D B i t) .......... ...... .. ...... ..... 100
Receive Enable, 9-bit (RX9 Bit) ............................... 100
Serial Port Enable (SPEN Bit) ........................... 99, 100
Single Receive Enable (SREN Bit) .......................... 100
Synchronous Master Mode ...................................... 110
Synchronous Master Reception .............................. 112
Synchronous Master Transmission ......................... 110
Synchronous Slave Mode ........................................ 113
Synchronous Slave Reception ................................ 114
Synchronous Slave Transmit ................................... 113
Transmit Data, 9th Bit (TX9D) ................................... 99
Transmit Enable (TXEN Bit) ...................................... 99
Transmit Enable, Nine-bit (TX9 Bit) ...... ..................... 99
Transmit Shift Register Statu s (TRMT Bit) ................ 99
B
Baud Rate Generator
Associated Registers ............................................... 101
BF Bit ................................................................................. 95
Block Diagrams
A/D ........................................................................... 118
Analog Input Model .......................................... 119, 127
AUSART Receive ............................................ 106, 108
AUSA R T Trans mi t .... .. ..... .. ...... .. ...... .. ..... .. ...... .. ...... . 104
Capture Mode Operation .................. ....... .... .. .... .. .. .... 84
Comparator I/O Operating Modes ........................... 124
Comparator Output ...................................... ............ 126
Comparator Voltage Reference ............................... 130
Compare Mode Operation ......................... .. .. .... .. .. .... 85
Fail-Safe Clock Monitor ........................................... 146
In-Circuit Serial Programming Connections ............ 149
Interrupt Logic .......................................................... 141
On-Chip Res et Circuit ......... ..................... ................ 134
PIC16F87 .................................................................... 8
PIC16F88 .................................................................... 9
RA0/AN0:RA1/AN1 Pins ............................................ 54
RA2/ AN2/CVref /Vre f- Pin .. .. ...... .. ...... .. . ...... .. .. ...... .. .. . 55
RA3/AN3/ Vref+/C1OUT Pin .... .......... ........... .............. 55
RA4/ AN4/T 0 C KI/C2 OUT Pin . .. ...... .. .. ..... .. ...... .. ...... .. . 56
RA5/MCLR/Vpp Pin ................................................... 56
RA6/OSC2/CLKO Pin ................................................ 57
RA7/OSC1/CLKI Pin .......................... ........................ 58
RB0/INT/CCP1 Pin ................... ..................... .......... .. 61
RB1/SDI /SDA Pin ................. .......... . .......... .......... ...... 62
RB2/SDO/RX/DT Pin ................................................. 63
RB3/PGM/CCP1 Pin .................................................. 64
RB4/ SCK/SC L Pi n ...... .. ..... .. .. .. ...... .. .. ........... .. ...... .. .. . 65
PIC16F87/88
DS30487D-page 218 2002-2013 Mic rochip Technology Inc.
RB5/SS/TX/CK Pin ...................... ..............................66
RB6/AN5/PGC/T1OSO/T1CKI Pin .............................67
RB7/AN6/ PGD/T1OSI Pin ........................... ........... ....68
Simpl i fied PWM .............. .......... ........... .......................86
SSP in I2C Mode ........................................................94
SSP in SPI Mode .......................................................92
Syste m Cl o ck ............... .......... ........... .......... ........... ....43
Timer0/WDT Prescaler ..............................................69
Timer1 ........................................................................ 75
Timer2 ........................................................................ 81
Watchdog Timer (WDT) ...........................................143
BOR. See Brown-out Reset.
BRGH Bit ..........................................................................101
Brown-out Reset (BOR) ...........................131, 134, 135, 137
BOR Status (BO R Bit) ................ ........... .......... ...........26
C
C Compilers
MPLAB C18 ................. .......... ........... .......... ........... ..160
Capture/Compare/PWM (CCP) ................... .......... ........... ..83
Capture Mode ................................ ....... .. .... .. .. .... .......84
CCP Pin Configuration .......................................84
Softwa re In terrupt ........ .......... ........... .......... .......84
Timer1 Mode Selection . .....................................84
Capture, Compare and Timer1 Associated Registers 85
CCP Prescaler ...........................................................84
CCP Timer Resources ...............................................83
CCP1IF ......................................................................84
CCPR1 .......................................................................84
CCPR1H:CCPR1L .....................................................84
Compare Mode ....................................... .. .... .. .... .......85
CCP Pin Configuration .......................................85
Softwa re In terrupt Mode ................. .......... .........85
Special Event Trigger .........................................85
Special Event Trigger Output of CCP1 ..............85
Timer1 Mode Selection . .....................................85
PWM and Timer2 Associated Registers ....................87
PWM Mode .................................. ............... ...... .........86
Example Frequencies/Resolutions ....................87
Operation Setup .................................................87
CCP1CON Regis te r ................. .......... ..................... ...........16
CCP1M0 Bit .......................................................................83
CCP1M1 Bit .......................................................................83
CCP1M2 Bit .......................................................................83
CCP1M3 Bit .......................................................................83
CCP1X Bit ......... .......... ........... .......... ........... ..................... ..83
CCP1Y Bit ......... .......... ........... .......... ........... ..................... ..83
CCPR1H Register .................................. ......................16, 83
CCPR1L Regis te r ................... .......... ........... .................16, 83
Clock Sources ....................................................................41
Selection Using OSCCON Register ........ ...................41
Clock Switching ..................................................................41
Transition and the Watchdog Timer ...........................42
Transition Sequence ..................................................43
CMCON Register ...............................................................17
Code Examples
Call of a Subroutine in Page 1 from Page 0 ...............27
Changing Between Capture Prescalers .....................84
Changing Prescaler Assignment From WDT to Timer0 .
71
Erasing a Fl a sh Program Memory Row ................... ..33
Implementing a Real-Time Clock Using a Timer1 Inter-
rupt Ser vice .............. .......... ........... .......... ...........79
Indirect Addressing ....................................................28
Initia lizing PORTA ......................................................53
Reading a 16-Bit Free Running Timer .......................76
Reading Data EEPROM ........................... .... .... .........31
Reading Flash Program Memory ............................... 32
Saving STATUS, W and PCLATH Registers in RAM ....
142
Writing a 16-Bit Free Running Timer ......................... 76
Writi n g to D a ta EEPRO M ..... ..... .. .. ...... .. ...... . ...... .. .. ... 31
Writing to Flash Program Memory ............................. 35
Code Protection ....................................................... 131, 149
Comparator Module ................... .. ....... .... .. .. .... .. ....... .... .. ..123
Analog Input Connection Considerations ................ 127
Associated Registers ............................................... 128
Configuration ........................................................... 124
Effects of a Reset .................. ........... ..................... .. 127
External Reference Signal ....................................... 125
Internal Reference Signal ........................................ 125
Interrupts ................................................................. 126
Operation ................................................................. 125
Operation During Sleep ........................................... 127
Outputs .................................................................... 125
Reference ................................................................ 125
Response Time .................... ......... .... .. .... .... ......... .. .. 125
Comparator Specifications ............................................... 177
Comparator Voltage Reference ........................ ......... .. .. .. 129
Associated Registers ............................................... 130
Computed GOTO ............................................................... 27
Configuration Bits ............................................................ 131
Crystal and Ceramic Resonators ..... .................................. 3 7
Customer Change Notification Service ............................ 226
Customer Notification Service ....... .................................. 226
Custome r Support ..... ........... .......... ........... .......... ........... ..226
CVRCON Regis te r ......................... ........... ..................... .... 17
D
Data EEPROM Memory ..................................................... 29
Associated Registers ................................................. 36
EEADR Register ........................................................ 29
EEADRH Register ..................................................... 29
EECON1 Regist e r ............ .......................................... 29
EECON2 Regist e r ............ .......................................... 29
EEDATA Register ...................................................... 29
EEDATH Register ...................................................... 29
Operation During Code-Protect . ................................ 36
Protection Against Spur io u s Writes ............... .......... ..36
Reading ..................................................................... 31
Write Complete Flag (EEIF Bit) ................................. 29
Writing ....................................................................... 31
Data Memory
Spec i a l Func t io n R e g i sters ...... .. ...... ...... .. ..... ...... .. ..... 16
DC and AC Characteristics
Graphs and Tables .................................................. 193
DC Characteristics
Inte rn a l R C A cc u racy .. .. ...... .. ..... .. ...... ...... .. ..... .. ...... . 1 7 4
PIC16F87/88, PIC16LF87/88 .. ................................ 175
Power-Down and Supply Current ............................ 166
Supply Voltage .............. .... .. ......... .. .... .. .... .. ......... .. .. 165
Development Support ...................................................... 159
Device Differences ............................... ............................ 217
Device Overview .................................................................. 7
Direct Add ressing ........................ ........... ..................... ...... 28
2002-2013 Microchip Technology Inc. DS30487D-page 219
PIC16F87/88
E
EEADR Regist er ..........................................................18, 29
EEADRH Register ........................................................18, 29
EECON1 Regist e r .......................... ........... .......... .........18, 29
EECON2 Regist e r .......................... ........... .......... .........18, 29
EEDATA Register ........................................................18, 29
EEDATH Register ........................................................18, 29
Electrical Characteristics ..................................................163
Errata ...................................................................................6
Exiting Sleep with an Interrupt ............................ ....... .... ....52
External Clock Input ...........................................................38
External Clock Input (RA4/T0CKI). See Timer0.
External Interrupt Input (RB0/INT). See Interrupt Sources.
F
Fail-Safe Clock Monitor ............................................131, 146
Flash Program Mem o ry ... .......... ............... .......... ........... ....29
Associ a te d Re g i sters ... .......... ........... .......... ........... ....36
EEADR Register ........................................................29
EEADRH Register ......................................................29
EECON1 Regist e r ..................................... ........... ......29
EECON2 Regist e r ..................................... ........... ......29
EEDATA Register ......................................................29
EEDATH Register ......................................................29
Erasing .......................................................................32
Reading ......................................................................32
Writing ........................................................................34
FSR Register .........................................................16, 17, 28
G
General Purpose Register File ...........................................14
I
I/O Ports .............. ....................................................... ........53
PORTA .......................................................................53
PORTB .......................................................................59
TRISB Register ..........................................................59
I2CAddressing ................................................................. 95
Associ a te d Re gisters ...................... .......... ........... ......97
Master Mode ..............................................................97
Mode .......................................................................... 94
Mode Selection ..........................................................94
Multi-Master Mode .....................................................97
Reception ...................................................................95
SCL and SDA Pins .....................................................95
Slave Mode ................................................................95
Transmission ..............................................................95
ID Locations .............................................................131, 149
In-Circuit Debugger ..........................................................149
In-Cir cuit Serial Programming ..........................................131
In-C ircui t Se rial Pro g ramm in g (ICSP) .......... .. ...... . ...... .. .. . 1 4 9
INDF Register ........................................................16, 17, 28
Indirect Addressing ............................................................28
Instruction Set ..................................................................151
Descriptions ............................................................. 153
General Format ....................................... .... ........... ..151
Read-Modify-Write Operations ................................151
Summary Ta b l e .............. ........... .......... ........... ..........152
ADDLW .................................................................... 153
ADDWF ....................................................................153
ANDLW .................................................................... 153
ANDWF ....................................................................153
BCF ..........................................................................153
BSF .......................................................................... 153
BTFSC ..................................................................... 154
BTFSS ..................................................................... 154
CALL ........................................................................ 154
CLRF ....................................................................... 154
CLRW ...................................................................... 154
CLRWDT ................................................................. 154
COMF ...................................................................... 155
DECF ....................................................................... 155
DECFSZ .................................................................. 155
GOTO ...................................................................... 155
INCF ........................................................................ 155
INCFSZ .................................................................... 155
IORLW ..................................................................... 156
IORWF ..................................................................... 156
MOVF ...................................................................... 156
MOVLW ................................................................... 156
MOVWF ................................................................... 156
NOP ......................................................................... 156
RETFIE .................................................................... 157
RETLW .................................................................... 157
RETURN .................................................................. 157
RLF .......................................................................... 157
RRF ......................................................................... 157
SLEEP ..................................................................... 157
SUBLW .................................................................... 158
SUBWF .................................................................... 158
SWAPF .................................................................... 158
XORLW ................................................................... 158
XORWF ................................................................... 158
INT Interrup t (RB0/ IN T ) . See Interrupt Sources.
INTCON Register
GIE Bi t ....................... ........... .............. ........... .......... .. 21
INT0IE Bit .................................................................. 21
INT0IF Bit .................................................................. 21
PEIE Bit ....................... ........... .......... ......................... 21
RBIE Bit ..................................................................... 21
RBIF Bit ............... .......... ........... .......... ........... .......... .. 21
TMR0IE Bit ................................................................ 21
Inte rn a l Oscil lator Blo c k .... .. ..... .. ...... .. ...... .. ..... .. ...... .. ...... ... 3 9
INTRC Modes ............................................................ 40
Inter net Addre ss .......... .......... ........... .......... ........... .......... 226
Inte rr u p t So u r ces .... .. ...... .. ...... ..... .. ...... .. ...... . ...... ..... 131, 1 4 0
AUSART Receive/Transmit Complete ....................... 99
RB0/ INT Pin , E xterna l .... ..... .. .. ...... .. ..... .. ...... .. ...... .. . 142
TMR0 Overflow ........................................................ 142
Interrupts
RB7:RB4 Port Change ........................................ .... .. 59
Inte rr u pts, Context Savin g D u ri n g ...... .. ...... .. ..... .. .. ...... .. ... 1 4 2
Interrupts, Enable Bits
A/D Converter Interrupt Enable (ADIE Bit) ................ 22
AUSART Receive Interrupt Enable (RCIE Bit) .......... 22
AUSART Tr ansmit Interrupt Enable (TXIE Bit) .......... 22
CCP1 Interrupt Enable (CCP1IE Bit) ......................... 22
Comparator Interrupt Enable (CMIE Bit) ................... 24
EEPROM Write Operation Interrupt Enable (EEIE Bit) .
24
Global Interrupt Enable (GIE Bit) ....................... 21, 140
Interrupt-on-Change (RB7: RB4) Enable (RBIE Bit) . 142
Oscillator Fail Interrupt Enable (OSFIE Bit) ............... 24
Peripheral Interrupt Enable (PEIE Bit) .. ..................... 21
Port Change Interrupt Enable (RBIE Bit) ................... 21
RB0/INT Enable (INT0IE Bit) ..................................... 21
Synchronous Serial Port (SS P) Interrupt Enable (SSPIE
Bit) ..................................................................... 22
TMR0 Overflow Enable (TMR0IE Bit) .................... .. .. 21
PIC16F87/88
DS30487D-page 220 2002-2013 Mic rochip Technology Inc.
TMR1 Overflow Interrupt Enable (TMR1IE Bit) ..........22
TMR2 to PR2 Match Interrupt Enable (TMR2IE Bit) ..22
Interrupts, Flag Bits
A/D Converter Interru p t Fla g (ADIF Bit) ...... ...............23
AUSART Receive Interrupt Flag (RCIF Bit) ...............23
AUSART Transmit Interrupt Flag (TXIF Bit) ...............23
CCP1 Interrupt Flag (CCP1IF Bit) ..............................23
Comp arato r Inter rupt Fl a g (C MIF Bi t) ...... ...... .. ..... .. ...2 5
EEPROM Write Operation Interrupt Flag (EEIF Bit) ..25
Interrupt-on-Change (RB7: RB4) F lag (RBIF Bit) 21, 142
Oscillator Fail Interrupt Flag (OSFIF Bit) ....................25
RB0/INT Flag (INT0IF Bit) ..........................................21
Synchronous Serial Port (SSP) Interrupt Flag (SSPIF Bit)
............................................................................23
TMR0 Overflow Flag (TMR0IF Bit) ................. .........142
TMR1 Overflow Interrupt Flag (TMR1IF Bit) ..............23
TMR2 to PR2 Interrupt Flag (TMR2IF Bit) .................23
INTRC Modes
Adjustment ................................................................. 40
L
Loading of PC ................... ..... .. .... .. .. .. .. .. ....... .. .. .. .... .. .. ..... ..27
Low Voltage ICSP Programming .....................................150
M
Master Clear (MCLR)
MCLR Reset, Normal Operation ................. .... .134, 137
MCLR Reset, Sleep ................... .. .. ....... .. .. .. .. .. .134, 137
Operation and ESD Protection .................................135
Memory Organization .........................................................13
Data Memor y ........ ........... .......... ..................... ...........13
Program Memory .......................................................13
Microc h i p In ternet Web Site ................. ........... .......... .......226
MPLAB ASM30 Assembler, Linker, Librarian ..................160
MPLAB Integrated Development Environment Software .159
MPLAB PM3 Device Programmer ....................................162
MPLAB REAL ICE In-Circuit Emulator System ................161
MPLINK Obje c t Linker/MP L IB Objec t Librar ia n ...... .........160
O
Opcode Field Descriptions ...............................................151
OPTION_REG Register
INTEDG Bi t ............... ........... .......... ........... .......... .......20
PS2:PS0 Bits .............................................................20
PSA Bit .......................................................................20
RBPU Bit ......... .......... ........... .......... ........... .......... .......20
T0CS Bit .....................................................................20
T0SE Bit .....................................................................20
OSCCON Register .............................................................17
Oscillator Configuration ......................................................37
ECIO ..........................................................................37
EXTRC .....................................................................136
HS ...................................................................... 37, 136
INTIO1 .......................................................................37
INTIO2 .......................................................................37
INTRC ......................................................................136
LP .......................................................................37, 136
RC ........................................................................37, 39
RCIO ..........................................................................37
XT ......................................................................37, 136
Oscillator Control Register
Modify in g IRCF Bits ..... ..................... .......... ........... ....43
Oscillator Delay upon Power-up, W ake- up and Clock Switch-
ing ..............................................................................44
Oscillator Start-up Timer (OST) ...............................131, 135
Oscillator Switching ............................................................41
OSCTUNE Regis te r ......................... ........... .......... .............17
P
Packaging Information ..................................................... 207
Marking .................................................................... 207
Pagin g , Program Memory .......... ........... .............. ........... .... 27
PCL Register ......................................................... 16, 17, 27
PCLATH Register .................................................. 16, 17, 27
PCON R e g i ster .. .. ...... . ...... .. ...... .. ..... .. ...... .. ...... .. ..... .. . 1 7 , 1 3 6
BOR Bit ...................................................................... 26
POR Bit ...................................................................... 26
PIE1 Register ..................................................................... 17
ADIE Bit ..................................................................... 22
CCP1IE Bit .............. .......... ............... .......... ............... 22
RCIE Bit ..................................................................... 22
SSPIE Bit ................................................................... 22
TMR1IE Bit ................................................................ 22
TMR2IE Bit ................................................................ 22
TXIE Bit ..................................................................... 22
PIE2 Register ..................................................................... 17
CMIE Bit .................................................................... 24
EEIE Bit ............... .......... ........... .............. ........... ........ 24
OSFIE Bit ................. .......... ........... .............. ........... .... 24
Pinout Descriptions
PIC16F87/88 .............................................................10
PIR1 Register .................................................................... 16
ADIF Bi t ..................... .......... ........... .......... ............... .. 23
CCP1IF Bit ................... .......... ........... .......... ........... .... 23
RCIF Bit .....................................................................23
SSPIF Bit ................................................................... 23
TMR1IF Bit ................................................................. 23
TMR2IF Bit ................................................................. 23
TXIF Bit ...................................................................... 23
PIR2 Register .................................................................... 16
CMIF Bit ................... .......... ........... .......... ........... ........ 25
EEIF Bit ..................................................................... 25
OSFIF Bit ................................................................... 25
POP ................................................................................... 27
POR. See Power-on Reset.
PORTA ..............................................................................10
Associated Register Summary .................................. 54
PORTA Register ................................................................ 16
PORTB ..............................................................................11
Associated Register Summary .................................. 60
PORTB Register .................................................. 16, 18
Pull-up Enable (RBPU Bit) ......................................... 20
RB0/INT Edge Select (INTEDG Bit) .......................... 20
RB0/INT Pin , External ............... .......... ........... .......... 142
RB2/SDO/RX /DT Pin ....... ................................ 100, 101
RB5/SS/TX/CK Pin .................................................. 100
RB7:RB4 Interrupt-on-Change .............................. .. 142
RB7:RB4 Interrupt-on-Change Enable (RBIE Bit ) ... 142
RB7:RB4 Interrupt-on-Change Flag (RBIF Bit) .. 21, 142
TRISB Register .......................................................... 99
Postscaler, WDT
Assignment (PSA Bit) ................................................ 20
Rate Select (PS2:PS0 Bits) ....................................... 20
Power-Down Mode. See Sleep.
Power-Managed Modes ..................................................... 45
RC_RUN .................................................................... 45
SEC_RUN ................................................ .................. 46
SEC_RUN/RC_RUN to Primary Clock Source .......... 47
Power-on Reset (POR) ............................ 131, 134, 135, 137
POR Status (POR Bit) ............................................... 26
Power Cont r ol ( PC ON) Re g i s t e r .. .. ...... .. ...... . ...... .. ... 136
Power-Down (PD Bi t) ...... ...... .. ..... .. ...... .. ...... . ...... .. ... 134
Time-out (TO Bi t) .... ...... .. ...... .. ..... .. ...... .. ...... . ..... 19 , 1 3 4
Power-up Timer (PWRT) ......................................... 131, 135
2002-2013 Microchip Technology Inc. DS30487D-page 221
PIC16F87/88
PR2 Register ................................................................17, 81
Prescaler, Timer0
Assignment (PSA Bit) ................. .......... ........... ..........20
Rate Select (PS2:PS0 Bits) .......................................20
Program Counter
Reset Conditions ......................... ..................... ........137
Program Mem ory
Inter rupt Vector .............. ............................. ........... ....13
Map and Stack
PIC16F87/88 ......................................................13
Paging ........................................................................27
Reset Vec tor ........................ ........... .......... ........... ......13
Program Verification ........................................................149
PUSH ................................................................................. 27
R
R/W Bit ...............................................................................95
RA0/AN0 Pi n ...................... .......... ........... .......... .................10
RA1/AN1 Pi n ...................... .......... ........... .......... .................10
RA2/AN2/CVref/Vref- Pin ...................................................10
RA3/AN3/Vref+/C1OUT Pin ...............................................10
RA4/AN4/T0CKI/C2OUT Pin .............................................10
RA5/MCLR/Vpp Pin ..... .......... ........... .......... .......................10
RA6/OSC2/CLKO Pin ........................................................10
RA7/OSC1/CLKI Pin ..........................................................10
RB0/INT/CCP1 Pin ............................................................11
RB1/SDI/SDA Pin ..............................................................11
RB2/SDO/RX/DT Pin ......... .......... ........... .......... ........... ......11
RB3/PGM/ CCP1 Pin .............. ........... ..................... .......... ..11
RB4/SCK/SCL Pin .............................................................11
RB5/SS/TX/CK Pin ...................... .............................. ........11
RB6/AN5/PGC/T1OSO/T1CKI Pin .....................................11
RB7/AN6/ PGD/T1OSI Pin ................. ..................... .......... ..11
RBIF Bit ................... ........... .......... ........... .......... ........... ......59
RCIO Oscillator ..................................................................39
RCREG Register ................................................................16
RCSTA Regis te r .................... ........... .......... ........... ............16
ADDEN Bit ...............................................................100
CREN Bit ..... ........... .......... ........... .......... ...................100
FERR Bit ..................................................................100
RX9 Bit .....................................................................100
RX9D Bit ..................................................................100
SPEN Bit ............................................................99, 100
SREN Bit ........... ........... .......... ........... .......... ........... ..100
Reader Response ............................................................227
Receive Overflow Ind i cator Bit, SSPOV ............. ...............91
Register File Map
PIC16F87 ...................................................................14
PIC16F88 ...................................................................15
Registers
ADCON0 (A/D Control 0) .........................................116
ADCON1 (A/D Control 1) .........................................117
ANSEL (Analog Select) ............................................115
CCP1CON (Capture/Comp are/P WM Contr ol 1) ........83
CMC ON ( C o mpar a t o r C o n tro l ) .. .. ...... ...... .. ..... .. ...... .1 2 3
CONFIG1 (Configuration Word 1) ............................132
CONFIG2 (Configuration Word 2) ............................133
CVRCON (Comparator Voltage Reference Control) 129
EECON1 (Data EEPROM Access Control 1) ............30
FSR ............................................................................28
Initialization Conditions (table) ................ .. .......137–138
INTCON (Interrupt Control) ........................................21
OPTION_R EG (Option Contr o l) ...........................20, 70
OSCCON (Oscillator Control) ....................................42
OSCTUNE (Oscillator Tuning) ........ ..................... ......40
PCON (Power Control) ..............................................26
PIE1 (Peripheral Interrupt Enable 1) ......................... 22
PIE2 (Peripheral Interrupt Enable 2) ......................... 24
PIR1 (Peripheral Interrupt Request (Flag) 1) ............. 23
PIR2 (Peripheral Interrupt Request (Flag) 2) ............. 25
RCSTA (Receive Status and Control) ..................... 100
Spec i a l Func t io n , S u mmary . ...... ...... .. ..... ...... .. ...... ..... 16
SSPCON (Synchronous Serial Port Control) ............. 91
SSPSTAT (Synchronous Serial Port Status) ............. 90
STATUS (Arithmetic Status) ...................................... 19
T1CON (Timer1 Control) ................................... ........ 74
T2CON (Timer2 Control) ................................... ........ 82
TXSTA (Transmit Status and Control) ....................... 99
WDTCON (Watchdog T imer Control) ... ................... 144
Reset ....................................................................... 131, 134
Brown-out Reset (BOR). See Brown-out Reset (BOR).
MCLR Reset. See MCL R.
Power-on Reset (POR). See Power-on Reset (PO R).
Reset Conditions for All Registers ........................... 137
Reset Conditions for PCON Register ...................... 137
Reset Conditions for Program Counter ................... 137
Reset Conditions for STATUS Register .................. 137
WDT Reset. See Watchdog Timer (WDT).
Revision History ............................... ................................ 217
RP0 Bit .............................................................................. 13
RP1 Bit .............................................................................. 13
S
SCI. See AUSART
SCL ........ .......... ................... ................... ............. .......... ..... 95
Serial Communication Interface. See AUS ART.
Slave Mode
SCL ............................................................................ 95
SDA ........................................................................... 95
Sleep ............................................................... 131, 134, 147
Software Simulator (MPLAB SIM) ................................... 161
SPBRG Register ................................................................ 17
Special Event Trigger ...................................................... 122
Special Features of the CPU ........................................... 131
Special Function Registers ................................................ 16
Special Function Registers (SFRs) .................................... 16
SPI Associated Registers ................................................. 92
Seria l C l o ck .. .. ...... .. ...... .. ..... ...... .. ...... .. ..... .. ...... .. ...... . 89
Seria l D a ta In ........ .. ...... .. ..... .. ...... .. ...... . ...... ...... .. ...... . 89
Serial Data Out .......................................................... 89
Slave Select ............................................................... 89
SSP ACK ........................................................................... 95
I2CI2C Oper a ti o n .. ...... ..... .. ...... .. ...... ..... .. ...... .. ...... ... 94
SSPADD Regist e r ............ .......................................... ........ 17
SSPBUF Register .............................................................. 16
SSPCON Re g i ster .......... .. ...... . ...... .. ...... .. .. ..... .. ...... .. ...... .. . 16
SSPOV .............................................................................. 91
SSPOV Bit ......................................................................... 95
SSPSTAT Regi ster .............. ........... .......... ........... .......... .... 17
Stack ...... ........ ..... ........ ........ ....... ........ ...... ....... ........ ...... ..... 27
Overflows ................................................................... 27
Underflow .................................................................. 27
PIC16F87/88
DS30487D-page 222 2002-2013 Mic rochip Technology Inc.
STATUS Register
C Bit .................. ........... .......... ........... .......... ........... ....19
DC Bit .........................................................................19
IRP Bit ............................ ......................... ...................19
PD Bit .................................................................19, 134
RP Bits .......................................................................19
TO Bit .................................................................19, 134
Z Bit ............................................................................19
Synchronous Master Reception
Associ a te d Re g i sters ......... .......... ........... .......... .......112
Synchronous Master Transmission
Associ a te d Re g i sters ......... .......... ........... .......... .......111
Synchronous Serial Port (SSP) ..........................................89
Overview ....................................................................89
SPI Mode ...................................................................89
Synchronous Slave Reception
Associ a te d Re g i sters ......... .......... ........... .......... .......114
Synchronous Slave Transmission
Associ a te d Re g i sters ......... .......... ........... .......... .......113
T
T1CKPS0 Bit ......................................................................74
T1CKPS1 Bit ......................................................................74
T1CON Regis te r ........ ..................... ........... .......... ........... ....16
T1OSCEN Bit .....................................................................74
T1SYNC Bit ................. .......................................................74
T2CKPS0 Bit ......................................................................82
T2CKPS1 Bit ......................................................................82
T2CON Regis te r ........ ..................... ........... .......... ........... ....16
Tad ................................................................................... 120
Time-out Sequence .............................. .. ......... .... .... .... .....136
Timer0 ................................................................................ 69
Associ a te d Re gisters ............................ .......... ...........71
Clock Source Edge Select (T0SE Bit) ........................20
Clock Sou rc e Se le ct (T0CS Bit) .............. .......... .........20
External Clock ............................................................70
Interrupt ......................................................................69
Operation ...................................................................69
Overflow Enable (TMR0IE Bit) ...................................21
Overflow Flag (TMR0 IF Bit) ....... ........... .......... .........142
Overflow Inte rrupt .............. .......... ........... .......... .......142
Prescaler .................................................................... 70
T0CKI ......................................................................... 70
Timer1 ................................................................................ 73
Associ a te d Re g i sters ......... .......... ........... .......... .........79
Capacitor Selection ....................................................77
Counter Operation ..................... .... ....... .... .. .... .. .........75
Operation ...................................................................73
Operation in Asynchronous Counter Mode ................76
Reading and Writing ..................... .. .... .. .. .. .. .......76
Operation in Synchronized Counter Mode .................75
Operation in Timer Mode ...........................................75
Oscillator .................................................................... 77
Oscillator Layout Considerations ...............................77
Prescaler .................................................................... 78
Resetting Timer1 Register Pair ..................................78
Resetting Timer1 Using a CCP Trigger Output ..........78
Use as a Real-Time Clock .........................................78
Timer2 ................................................................................ 81
Associ a te d Re gisters ............................ .......... ...........82
Output ........................................................................81
Postscaler ..................................................................81
Prescaler .................................................................... 81
Prescaler and Postscaler ...........................................81
Timing Diagrams
A/D Conver sion .... .......... ........... ..................... .......... 191
Asynchronous Mast er Transm ission ........................ 105
Asynchronous Master Transmission (Back to Back) 105
Asynchronous Receptio n ......... ................................ 106
Asynchronous Recept ion with Address Byte First ... 109
Asynchronous Reception with Address Detect ........ 109
AUSART Synchronous Receive (Master/Slave) ...... 189
AUSART Synchronous Transmi ssion (Mas ter/Slave ) ...
189
Brown-o u t Re set ...... ..................... ..................... ...... 181
Capture/Compare /PWM (CCP1) .... ......................... 183
CLKO and I/O .......................................................... 180
External Clock .......................................................... 179
Fail-Safe Clock Monitor ........................................... 146
I2C Bus Data ............................................................ 187
I2C Bus Start/Stop Bits ............................................ 186
I2C Reception (7-Bit Address) ................................... 96
I2C Tra ns mi ssio n (7 - Bi t Addre ss ) ...... .. ...... .. ..... .. ....... 9 6
Primary System Clock After Reset (EC, RC, INTRC) 50
Prima ry Sy s tem Cloc k Af te r R e se t (H S, XT, LP) .... ... 49
PWM Output ................ .......... ........... .......... ........... .... 86
Reset, Watchdog Timer, Oscillator Start-up Timer and
Power-up Ti mer .. .. ...... .. ..... .. ...... .. .. ...... . ...... .. ... 181
Slow Rise Time (MCLR Tied to Vdd Through RC Net-
work) ................................................................ 140
SPI Ma ster Mode .......... .. ...... .. ..... .. ...... .. ...... . ...... .. ..... 93
SPI Master Mode (CKE = 0, SMP = 0) .................... 184
SPI Master Mode (CKE = 1, SMP = 1) .................... 184
SPI Sla v e M ode (CKE = 0) . ..... .. ...... .. ...... .. .. ..... . 93, 18 5
SPI Sla v e M ode (CKE = 1) . ..... .. ...... .. ...... .. .. ..... . 93, 18 5
Switching to SEC_RUN Mode ................................... 46
Synchronous Reception (Master Mode, SREN) ...... 113
Synchronous Transmission ..................................... 111
Synchronous Transmission (T hrough TXEN) .......... 111
Time-out Sequence on Power-up (MCLR Tied to Vdd
Through Pull-up Resistor) ................................ 139
Time-out Sequence on Power-up (MCLR Tied to Vdd
Through RC Network): Case 1 ........................ 139
Time-out Sequence on Power-up (MCLR Tied to Vdd
Through RC Network): Case 2 ........................ 139
Timer0 and Timer1 External Clock .......................... 182
Timer1 Incrementing Edge ........................................ 75
Transition Between SEC_RUN/RC_RUN and Primary
Clock .................................................................. 48
Two-Speed Start-up Mode ....................................... 145
Wake-up from Sleep via Interrupt ............................ 148
XT, HS, LP, EC and EXTRC to RC_RUN Mode ........ 45
Timing Pa rameter Symbolo g y .......... .......... ........... . ......... 178
Timing Requirements
A/D Conver sion .... .......... ........... ..................... .......... 191
AUSART Synchronous Receive .............................. 189
AUSART Synchronous Transmi ssion ...................... 189
Capture/Compare /PWM (CCP1) .... ......................... 183
CLKO and I/O .......................................................... 180
External Clock .......................................................... 179
I2C Bus Data ............................................................ 188
I2C Bus Start/Stop Bits ............................................ 187
Reset, Watchdog Timer, O scillator Sta rt-up Time r, P ow-
er-up Timer and Brown-out Reset ................... 181
SPI Mode ................................................................. 186
Timer0 and Timer1 External Clock .......................... 182
TMR0 Register ............................................................. 16, 18
TMR1CS Bit ....................... .......... ........... .......... ........... ...... 74
TMR1H Register ................................................................ 16
2002-2013 Microchip Technology Inc. DS30487D-page 223
PIC16F87/88
TMR1L Register .................................................................16
TMR1ON Bit .......................................................................74
TMR2 Register ...................................................................16
TMR2ON Bit .......................................................................82
TOUTPS0 Bit .....................................................................82
TOUTPS1 Bit .....................................................................82
TOUTPS2 Bit .....................................................................82
TOUTPS3 Bit .....................................................................82
TRISA Register ............................................................17, 53
TRISB Register ............................................................17, 18
Two-Speed Clock Start-up Mode .....................................145
Two-Speed Start-up .... .....................................................131
TXREG Register ................................................................16
TXSTA Regi ster .... ........... .......... ........... .......... ........... ........17
BRGH Bit ...................................................................99
CSRC Bit ..... ........... ..................... .......... ........... ..........99
SYNC Bit .............. ..................... .......... ........... .......... ..99
TRMT Bit ...................... .......... ........... .......... ........... ....99
TX9 Bit .......................................................................99
TX9D Bit .....................................................................99
TXEN Bit ....................................................................99
V
Vdd Pin ..............................................................................11
Voltage Reference Specifications ....................... ......... ....177
Vss Pin ................ ........... .......... ........... .......... ........... ..........11
W
Wake-up from Sleep ................................................131, 148
Interrupts ..................................................................137
MCLR Reset .................. ........... ..................... ..........137
WDT Reset ................ .......... ........... ..................... ....137
Wake-up Using Interrupts ................................................148
Watchdog Timer (WDT) ...................................... .....131, 143
Associ a te d Re g i sters ... .......... ........... .......... ........... ..144
WDT Reset, Normal Operation ........................134, 137
WDT Reset, Sleep ............. .. ....... .. .. .. .... .. .. .. .....134, 137
WCOL ................................................................................91
WDTCON Registe r ...... .......... ........... .......... ........... .......... ..18
Write Collision Detect Bit, WCOL .......................................91
WWW Address .................................................................226
WWW, On-Line Support ......................................................6
PIC16F87/88
DS30487D-page 224 2002-2013 Mic rochip Technology Inc.
NOTES:
2002-2013 Microchip Technology Inc. DS30487D-page 225
PIC16F87/88
THE MICROCHIP WEB SITE
Microc hip pro vides onl ine s upport v ia our W WW site at
www.mic rochip.com. This web si te i s us ed as a m ean s
to make files and information easily available to
customers. Accessible by using your favorite Internet
browser, the web site contains the following
information:
Product Support – Data sheets and errata,
application notes and sample programs, design
resources, user’s guides and hardware support
documents, latest software releases and archived
software
General Technical Support – Frequently Asked
Questions (FAQ), technical support requests,
online dis cu ss io n gr oups, Microchip con sul t an t
program member listing
Business of Microchip – Product selector and
ordering guides, latest Microchip press releases,
listing o f seminars and ev ents, listings of
Microchip sales offices, distributors and factory
representatives
CUSTOMER CHANGE NOTIFICATION
SERVICE
Microchip’s customer notification service helps keep
customers current on Microchip products. Subscribers
will receive e-mail notification whenever there are
changes, updates, revisions or errata related to a
specif ied produ ct family or develo pment tool of interes t.
To register, access the Microchip web site at
www.microchip.com, click on Customer Change
Notification and follow the registration instructions.
CUSTOMER SUPP ORT
Users of Microchip products can receive assistance
through several channels:
Distributor or Representative
Local Sales Office
Field Application Engineer (FAE)
Technical Support
Customers should contact their distributor,
representative or field application engineer (FAE) for
support. Local sales offices are also available to help
customers. A listing of sales offices and locations is
included in the back of this document.
Tec hnical suppo rt is a vailable through the web site
at: http://support.microchip.com
PIC16F87/88
DS30487D-page 226 2002-2013 Microchip Technology Inc.
READER RESP ONSE
It is ou r intention to pro vi de you w it h th e b es t do cu me nt ation possib le to e ns ure suc c es sfu l u se of y ou r Mic r oc hip pro d-
uct. If you wi sh to prov ide you r comment s on org aniza tion, clar ity, su bject m atter, and ways in w hich o ur docum entatio n
can better serve you, please FAX your comments to the Technical Publications Manager at (480) 792-4150.
Please li st the following information, and use this outline to provide us with your comments about this document.
To: Technical Publications Manager
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Questions:
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DS30487DPIC16F87/88
1. What are the best features of this document?
2. How does this document meet your hardware and software development needs?
3. Do you find the organization of this document easy to follow? If not, why?
4. What additions to the document do you think would enhance the structure and subject?
5. What deletions from the document could be made without affecting the overall usefulness?
6. Is there any incorrect or misleading information (what and where)?
7. How would you improve this document?
2002-2013 Microchip Technology Inc. DS30487D-page 227
PIC16F87/88
PIC16F87/88 PRODUCT IDENTIFICATION SYSTEM
To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office.
PART NO. X/XX XXX
PatternPackageTemperature
Range
Device
Devi ce PIC16F87: Standard VDD range
PIC16F87T: (Tape and Reel)
PIC16LF87: Extended VDD range
Temperature Range - = 0°C to +70°C
I = -40°C to +8 5°C (Ind ust rial )
E = -40°C to +125°C (Extended)
Package P = PDIP
SO = SOIC
SS = SSOP
ML = QFN
Pattern QTP, SQTP, ROM Code (factory specified) or
Special Requirements. Blank for OTP and
Windowed devices.
Examples:
a) PIC16 F8 7-I /P = Indus trial tem p., PDIP
package, Extend ed VDD limits.
b) PIC16F87-I/SO = Industrial temp., SOIC
package, normal VDD limits.
Note 1: F = CMOS Flash
LF = Low-power CMOS Flash
2: T = in tape and reel – SOIC, SSOP
packages only .
PIC16F87/88
DS30487D-page 228 2002-2013 Microchip Technology Inc.
2002-2013 Microchip Technology Inc. DS30487D-page 229
Information contained in this publication regarding device
applications a nd the lik e is provided only for your convenien ce
and may be superseded by u pdates. It is y our responsibil it y to
ensure that your application meets with your specifications.
MICROCHIP MAKES NO REPRESENTATIONS OR
WARRANTIES OF ANY KIND WHETHER EXPRESS OR
IMPLIED, WRITTEN OR ORAL, STATUTORY OR
OTHERWISE, RELATED TO THE INFORMATION,
INCLUDING BUT NOT LIMITED TO ITS CONDITION,
QUALITY, PERFORMANCE, MERCHANTABILITY OR
FITNESS FOR PURPOSE. Microchip disclaims all liability
arising from this information and its use. Use of Microchip
devices in life support and/or safety applications is entirely at
the buyer’s risk, and the buyer agrees to defend, indemnify and
hold harmless Microchip from any and all damages, claims,
suits, or expenses resulting from such use. No licenses are
conveyed, implicitly or otherwise, under any Microchip
intellectual property rights.
Trademarks
The Microchip name and logo, the Microchip logo, dsPIC,
FlashFlex, KEELOQ, KEELOQ logo, MPLAB, PIC, PICmicro,
PICSTART, PIC 32 logo, rfPIC, SST, SST Logo, SuperFlash
and UNI/O are registered trademarks of Microchip T echnology
Incorporated in the U.S.A. and other countries.
FilterLab, Hampshire, HI-TECH C, Linear Active Thermistor,
MTP, SEEVAL and The Embedded Contr ol Solutions
Company are registered trademarks of Microchip Technology
Incorporated in the U.S.A.
Silicon Storage Technology is a registered trademark of
Microchip Technology I nc. in other countries.
Analog-for-the-Digital Age, Application Maestro, BodyCom,
chipKIT, chipKIT logo, CodeGuard, dsPICDEM ,
dsPICDEM.net, dsPICworks, dsSPEAK, ECAN,
ECONOMONIT OR, FanSense, HI-TIDE, In-Circ u it Se r i a l
Programm ing, ICSP, Mindi, MiWi, MPASM, MPF, MPLAB
Certified logo, MPLIB, MPLINK, mTouch, Omniscient Code
Generation, PICC, PICC-18, PICDEM, PICDEM.net, PICkit,
PICtail, REAL ICE, rfLAB, Select Mode, SQI, Serial Quad I/O,
Total Endurance, TSHARC, UniWinDriver, WiperLock, ZENA
and Z-Scale are trademarks of Microchip Technology
Incorporated in the U.S.A. and other countries.
SQTP is a service mark of Microchip T echnology Incorporated
in the U.S.A.
GestIC and ULPP are registered trademarks of Microchip
Tec hnology Germ any II GmbH & C o. & KG, a subsidiary of
Microchip Technology Inc., in other countries.
All other trademarks mentioned herein are property of their
respective companies.
© 2002-2013, Microchip Technology Incorporated, Printed in
the U.S.A., All Rights Reserved.
Printed on recycled paper.
ISBN: 9781620769416
Note the following details of the code protection feature on Microchip devices:
Microchip products meet the specification contained in t heir particular Microchip Data Sheet.
Microchip believes that its family of products is one of t he most secure famili es of its kind on t he market today, when used in t he
intended manner and under normal conditions.
There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our
knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data
Sheets. Most likely, the person doing so is engaged in theft of intellectual property.
Microchip is willing to work with the customer who is concerned about the integrity of their code.
Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not
mean that we are guaranteeing the product as “unbreakable.
Code protection is c onstantly evolving. We a t Microc hip are co m mitted to continuously improving the code prot ect ion featur es of our
products. Attempts to break Microchip’ s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts
allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.
Microchip received ISO/TS-16949:2009 certification for its worldwide
headquarters, design and wafer fabrication facilities in Chandler and
Tempe, Arizona; Gresham, Oregon and design centers in California
and India. The Company’s quality system processes and procedures
are for its PIC® MCUs and dsPIC® DSCs, KEELOQ® code hopping
devices, Serial EEPROMs, microperiph erals, nonvolatile memory and
analog products. In addition, Microchip’s quality system for the design
and manufacture of development systems is ISO 9001:2000 certified.
QUALITY MANAGEMENT S
YSTEM
CERTIFIED BY DNV
== ISO/TS 16949 ==
DS30487D-page 230 2002-2013 Microchip Technology Inc.
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