RS08
Microcontrollers
freescale.com
MC9RS08KA2
MC9RS08KA1
Data Sheet
MC9RS08KA2
Rev. 4
12/2008
8-Bit RS08 Central Processor Unit (CPU)
• Simplified S08 instruction set with added
high-performance instructions
— LDA, STA, and CLR instructions
support the short addressing mode;
address $0000 to $001F can be
accessed via a single-byte instruction
— ADD, SUB, INC, and DEC instructions
support the tiny addressing mode;
address $0000 to $000F can be
accessed via a single-byte instruction
with reduced instruction cycle
— Shadow PC register instructions: SHA
and SLA
• Pending interrupt indication
• Index addressing via D[X] and X register
• Direct page access to the entire memory
map through paging window
Memory
• On-chip Flash EEPROM
— MC9RS08KA2: 2048 bytes
— MC9RS08KA1: 1024 bytes
• 63 bytes on-chip RAM
Power-Saving Modes
• Wait and stop
• Wakeup from power-saving modes using
real-time interrupt (RTI), KBI, or ACMP
Clock Source
•ICS — Trimmable 20-MHz internal clock
source
— Up to 10-MHz internal bus operation
— 0.2% trimmable resolution, 2%
deviation over temperature and voltage
range
System Protection
• Computer operating properly (COP) reset
running off bus-independent clock source
• Low-voltage detection with reset or stop
wakeup
Peripherals
•MTIM — 8-bit modulo timer
•ACMP — Analog comparator
— Full rail-to-rail supply operation
— Option to compare to fixed internal
bandgap reference voltage
— Can operate in stop mode
•KBI — Keyboard interrupt ports
— Three KBI ports in 6-pin package
— Five KBI ports in 8-pin package
Development Support
• Background debug system
• Breakpoint capability to allow single
breakpoint setting during in-circuit debug
Package Options
• 6-pin dual flat no lead (DFN) package
— Two general-purpose input/output (I/O)
pins
— One general-purpose input pin
— One general-purpose output pin
• 8-pin plastic dual in-line pin (PDIP)
package
— Four general-purpose input/output
(I/O) pins
— One general-purpose input pin
— One general-purpose output pin
• 8-pin narrow body SOIC package
— Four general-purpose input/output
(I/O) pins
— One general-purpose input pin
— One general-purpose output pin
MC9RS08KA2 Features
MC9RS08KA2 Series Data Sheet, Rev. 4
4Freescale Semiconductor
MC9RS08KA2 Series Data Sheet
Covers: MC9RS08KA2
MC9RS08KA1
MC9RS08KA2
Rev. 4
12/2008
MC9RS08KA2 Series Data Sheet, Rev. 4
6Freescale Semiconductor
Revision History
To provide the most up-to-date information, the revision of our documents on the World Wide Web will
be the most current. Your printed copy may be an earlier revision. To verify you have the latest information
available, refer to:
http://freescale.com
The following revision history table summarizes changes contained in this document.
Revision
Number
Revision
Date Description of Changes
1.0 04/2006 Initial public release version
2 12/2006 Added MC9RS08KA1
3 09/2007
Corrected Instruction Set Summary LDX ,X row operand to read 0E 0F. Revised the
Analog Comparator Electrical Specifications including the ACMP Bandgap
reference voltage values. Corrected a transposition in the DFN drawing no. Updated
the ICS Characteristic table in the Electricals Appendix to include the ICS factory
trim and reference the parameters tir_wu and tfll_wu that are discussed in the ICS
chapter.
4 12/2008
Revised Figure 1-2. Updated “How to Reach Us” information.
Changed the mechanical drawing of 6-pin DFN in the Appendix B, “Ordering
Information and Mechanical Drawings.”
This product incorporates SuperFlash® technology licensed from SST.
Freescale‚ and the Freescale logo are trademarks of Freescale Semiconductor, Inc.
© Freescale Semiconductor, Inc., 2006-2008. All rights reserved.
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 7
List of Chapters
Chapter Title Page
List of Chapter s
Chapter 1 MC9RS08KA2 Series Device Overview ......................................... 15
Chapter 2 Pins and Connections..................................................................... 17
Chapter 3 Modes of Operation......................................................................... 21
Chapter 4 Memory............................................................................................. 25
Chapter 5 Resets, Interrupts, and General System Control.......................... 35
Chapter 6 Parallel Input/Output Control ......................................................... 45
Chapter 7 Keyboard Interrupt (RS08KBIV1) ................................................... 51
Chapter 8 Central Processor Unit (RS08CPUV1) ........................................... 57
Chapter 9 Internal Clock Source (RS08ICSV1)............................................... 75
Chapter 10 Analog Comparator (RS08ACMPV1).............................................. 83
Chapter 11 Modulo Timer (RS08MTIMV1) ......................................................... 89
Chapter 12 Development Support ..................................................................... 97
Appendix A Electrical Characteristics.............................................................. 109
Appendix B Ordering Information and Mechanical Drawings........................ 123
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 9
Chapter 1
MC9RS08KA2 Series Device Overview
1.1 Overview .........................................................................................................................................15
1.2 MCU Block Diagram ......................................................................................................................15
1.3 System Clock Distribution ..............................................................................................................16
Chapter 2
Pins and Connections
2.1 Introduction .....................................................................................................................................17
2.2 Device Pin Assignment ...................................................................................................................17
2.3 Recommended System Connections ...............................................................................................18
2.4 Pin Detail .........................................................................................................................................18
2.4.1 Power ..............................................................................................................................19
2.4.2 PTA2/KBIP2/TCLK/RESET/VPP ........................................................................................................ 19
2.4.3 PTA3/ACMPO/BKGD/MS ............................................................................................19
2.4.4 General-Purpose I/O and Peripheral Ports .....................................................................20
Chapter 3
Modes of Operation
3.1 Introduction .....................................................................................................................................21
3.2 Features ...........................................................................................................................................21
3.3 Run Mode ........................................................................................................................................21
3.4 Active Background Mode ...............................................................................................................21
3.5 Wait Mode .......................................................................................................................................22
3.6 Stop Mode .......................................................................................................................................23
3.6.1 Active BDM Enabled in Stop Mode ..............................................................................24
3.6.2 LVD Enabled in Stop Mode ...........................................................................................24
Chapter 4
Memory
4.1 Memory Map ...................................................................................................................................25
4.2 Unimplemented Memory ................................................................................................................27
4.3 Indexed/Indirect Addressing ...........................................................................................................27
4.4 RAM and Register Addresses and Bit Assignments .......................................................................27
4.5 RAM ................................................................................................................................................29
4.6 Flash ................................................................................................................................................29
4.6.1 Features ...........................................................................................................................29
4.6.2 Flash Programming Procedure .......................................................................................30
4.6.3 Flash Mass Erase Operation ...........................................................................................30
Table of Contents
Section Number Title Page
MC9RS08KA2 Series Data Sheet, Rev. 4
10 Freescale Semiconductor
Section Number Title Page
4.6.4 Security ...........................................................................................................................31
4.7 Flash Registers and Control Bits .....................................................................................................32
4.7.1 Flash Options Register (FOPT and NVOPT) .................................................................32
4.7.2 Flash Control Register (FLCR) ......................................................................................33
4.8 Page Select Register (PAGESEL) ...................................................................................................33
Chapter 5
Resets, Interrupts, and General System Control
5.1 Introduction .....................................................................................................................................35
5.2 Features ...........................................................................................................................................35
5.3 MCU Reset ......................................................................................................................................35
5.4 Computer Operating Properly (COP) Watchdog .............................................................................36
5.5 Interrupts .........................................................................................................................................36
5.6 Low-Voltage Detect (LVD) System ................................................................................................37
5.6.1 Power-On Reset Operation .............................................................................................37
5.6.2 LVD Reset Operation .....................................................................................................37
5.6.3 LVD Interrupt Operation ................................................................................................37
5.7 Real-Time Interrupt (RTI) ...............................................................................................................37
5.8 Reset, Interrupt, and System Control Registers and Control Bits ...................................................38
5.8.1 System Reset Status Register (SRS) ...............................................................................38
5.8.2 System Options Register (SOPT) ...................................................................................39
5.8.3 System Device Identification Register (SDIDH, SDIDL) .............................................40
5.8.4 System Real-Time Interrupt Status and Control Register (SRTISC) .............................41
5.8.5 System Power Management Status and Control 1 Register (SPMSC1) .........................43
5.8.6 System Interrupt Pending Register (SIP1) .....................................................................44
Chapter 6
Parallel Input/Output Control
6.1 Pin Behavior in Low-Power Modes ................................................................................................46
6.2 Parallel I/O Registers ......................................................................................................................46
6.2.1 Port A Registers ..............................................................................................................46
6.3 Pin Control Registers ......................................................................................................................47
6.3.1 Port A Pin Control Registers ..........................................................................................47
6.3.1.1 Internal Pulling Device Enable .......................................................................47
6.3.1.2 Pullup/Pulldown Control ................................................................................48
6.3.1.3 Output Slew Rate Control Enable ...................................................................48
Chapter 7
Keyboard Interrupt (RS08KBIV1)
7.1 Introduction .....................................................................................................................................51
7.1.1 Features ...........................................................................................................................51
7.1.2 Modes of Operation ........................................................................................................52
7.1.2.1 Operation in Wait Mode ..................................................................................52
7.1.2.2 Operation in Stop Mode ..................................................................................52
7.1.2.3 Operation in Active Background Mode ..........................................................52
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 11
Section Number Title Page
7.1.3 Block Diagram ................................................................................................................52
7.2 External Signal Description ............................................................................................................52
7.3 Register Definition ..........................................................................................................................53
7.3.1 KBI Status and Control Register (KBISC) .....................................................................53
7.3.2 KBI Pin Enable Register (KBIPE) .................................................................................54
7.3.3 KBI Edge Select Register (KBIES) ................................................................................54
7.4 Functional Description ....................................................................................................................55
7.4.1 Edge Only Sensitivity .....................................................................................................55
7.4.2 Edge and Level Sensitivity .............................................................................................55
7.4.3 KBI Pullup/Pulldown Device .........................................................................................55
7.4.4 KBI Initialization ............................................................................................................55
Chapter 8
Central Processor Unit (RS08CPUV1)
8.1 Introduction .....................................................................................................................................57
8.2 Programmer’s Model and CPU Registers .......................................................................................57
8.2.1 Accumulator (A) .............................................................................................................58
8.2.2 Program Counter (PC) ....................................................................................................59
8.2.3 Shadow Program Counter (SPC) ....................................................................................59
8.2.4 Condition Code Register (CCR) .....................................................................................59
8.2.5 Indexed Data Register (D[X]) ........................................................................................60
8.2.6 Index Register (X) ..........................................................................................................60
8.2.7 Page Select Register (PAGESEL) ..................................................................................61
8.3 Addressing Modes ...........................................................................................................................61
8.3.1 Inherent Addressing Mode (INH) ..................................................................................61
8.3.2 Relative Addressing Mode (REL) ..................................................................................61
8.3.3 Immediate Addressing Mode (IMM) .............................................................................62
8.3.4 Tiny Addressing Mode (TNY) .......................................................................................62
8.3.5 Short Addressing Mode (SRT) .......................................................................................63
8.3.6 Direct Addressing Mode (DIR) ......................................................................................63
8.3.7 Extended Addressing Mode (EXT) ................................................................................63
8.3.8 Indexed Addressing Mode (IX, Implemented by Pseudo Instructions) .........................63
8.4 Special Operations ...........................................................................................................................63
8.4.1 Reset Sequence ...............................................................................................................64
8.4.2 Interrupts .........................................................................................................................64
8.4.3 Wait and Stop Mode .......................................................................................................64
8.4.4 Active Background Mode ...............................................................................................64
8.5 Summary Instruction Table .............................................................................................................65
MC9RS08KA2 Series Data Sheet, Rev. 4
12 Freescale Semiconductor
Section Number Title Page
Chapter 9
Internal Clock Source (RS08ICSV1)
9.1 Introduction .....................................................................................................................................75
9.1.1 Features ...........................................................................................................................76
9.1.2 Modes of Operation ........................................................................................................76
9.1.2.1 FLL Engaged Internal (FEI) ...........................................................................76
9.1.2.2 FLL Bypassed Internal (FBI) ..........................................................................76
9.1.2.3 FLL Bypassed Internal Low Power (FBILP) .................................................76
9.1.2.4 Stop (STOP) ....................................................................................................76
9.1.3 Block Diagram ................................................................................................................76
9.2 External Signal Description ............................................................................................................77
9.3 Register Definition ..........................................................................................................................77
9.3.1 ICS Control Register 1 (ICSC1) .....................................................................................77
9.3.2 ICS Control Register 2 (ICSC2) .....................................................................................78
9.3.3 ICS Trim Register (ICSTRM) ........................................................................................79
9.3.4 ICS Status and Control (ICSSC) ....................................................................................79
9.4 Functional Description ....................................................................................................................80
9.4.1 Operational Modes .........................................................................................................80
9.4.1.1 FLL Engaged Internal (FEI) ...........................................................................80
9.4.1.2 FLL Bypassed Internal (FBI) ..........................................................................80
9.4.1.3 FLL Bypassed Internal Low Power (FBILP) .................................................80
9.4.1.4 Stop .................................................................................................................81
9.4.2 Mode Switching ..............................................................................................................81
9.4.3 Bus Frequency Divider ...................................................................................................81
9.4.4 Low Power Bit Usage .....................................................................................................81
9.4.5 Internal Reference Clock ................................................................................................81
9.4.6 Fixed Frequency Clock ...................................................................................................82
Chapter 10
Analog Comparator (RS08ACMPV1)
10.1 Introduction .....................................................................................................................................83
10.1.1 Features ...........................................................................................................................84
10.1.2 Modes of Operation ........................................................................................................84
10.1.2.1 Operation in Wait Mode ..................................................................................84
10.1.2.2 Operation in Stop Mode ..................................................................................84
10.1.2.3 Operation in Active Background Mode ..........................................................84
10.1.3 Block Diagram ................................................................................................................84
10.2 External Signal Description ............................................................................................................86
10.3 Register Definition ..........................................................................................................................86
10.3.1 ACMP Status and Control Register (ACMPSC) ............................................................86
10.4 Functional Description ....................................................................................................................87
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 13
Section Number Title Page
Chapter 11
Modulo Timer (RS08MTIMV1)
11.1 Introduction .....................................................................................................................................89
11.1.1 Features ...........................................................................................................................90
11.1.2 Modes of Operation ........................................................................................................90
11.1.2.1 Operation in Wait Mode ..................................................................................90
11.1.2.2 Operation in Stop Modes ................................................................................90
11.1.2.3 Operation in Active Background Mode ..........................................................90
11.1.3 Block Diagram ................................................................................................................91
11.2 External Signal Description ............................................................................................................91
11.3 Register Definition ..........................................................................................................................91
11.3.1 MTIM Status and Control Register (MTIMSC) .............................................................92
11.3.2 MTIM Clock Configuration Register (MTIMCLK) ......................................................93
11.3.3 MTIM Counter Register (MTIMCNT) ..........................................................................93
11.3.4 MTIM Modulo Register (MTIMMOD) .........................................................................94
11.4 Functional Description ....................................................................................................................95
11.4.1 MTIM Operation Example .............................................................................................96
Chapter 12
Development Support
12.1 Introduction .....................................................................................................................................97
12.2 Features ...........................................................................................................................................97
12.3 RS08 Background Debug Controller (BDC) ..................................................................................98
12.3.1 BKGD Pin Description ...................................................................................................99
12.3.2 Communication Details ..................................................................................................99
12.3.3 SYNC and Serial Communication Timeout .................................................................102
12.4 BDC Registers and Control Bits ...................................................................................................103
12.4.1 BDC Status and Control Register (BDCSCR) .............................................................103
12.4.2 BDC Breakpoint Match Register ..................................................................................104
12.5 RS08 BDC Commands ..................................................................................................................105
MC9RS08KA2 Series Data Sheet, Rev. 4
14 Freescale Semiconductor
Section Number Title Page
Appendix A
Electrical Characteristics
A.1 Introduction ...................................................................................................................................109
A.2 Absolute Maximum Ratings ..........................................................................................................109
A.3 Thermal Characteristics .................................................................................................................110
A.4 Electrostatic Discharge (ESD) Protection Characteristics ............................................................111
A.5 DC Characteristics .........................................................................................................................111
A.6 Supply Current Characteristics ......................................................................................................115
A.7 Analog Comparator (ACMP) Electricals ......................................................................................117
A.8 Internal Clock Source Characteristics ...........................................................................................117
A.9 AC Characteristics .........................................................................................................................118
A.9.1 Control Timing ...............................................................................................................118
A.10 FLASH Specifications ...................................................................................................................119
Appendix B
Ordering Information and Mechanical Drawings
B.1 Ordering Information ....................................................................................................................123
B.2 Mechanical Drawings ....................................................................................................................123
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 15
Chapter 1
MC9RS08KA2 Series Device Overview
1.1 Overview
The MC9RS08KA2 Series microcontroller unit (MCU) is an extremely low-cost, small pin count device
for home appliances, toys, and small geometry applications. This device is composed of standard on-chip
modules including, a very small and highly efficient RS08 CPU core, 63 bytes RAM, 2K bytes Flash, an
8-bit modulo timer, keyboard interrupt, and analog comparator. The device is available in small 6- and
8-pin packages.
1.2 MCU Block Diagram
The block diagram, Figure 1-1, shows the structure of the MC9RS08KA2 Series MCU.
Figure 1-1. MC9RS08KA2 Series Block Diagram
RS08 CORE
USER
FLASH
USER
RAM
— 63 BYTES
NOTES:
(1) Pins are software configurable with pullup/pulldown device if input port.
(2) Integrated pullup device enabled if reset enabled (RSTPE=1).
(3) These pins are not available in 6-pin package.
POWER AND
PTA
VSS
VDD
INTERNAL CLOCK
SOURCE
BDC
RS08 SYSTEM CONTROL
RTI
CPU
COP
WAKEUP LVD
RESET AND STOP WAKEUP
MODES OF OPERATION
POWER MANAGEMENT
5-BIT KEYBOARD
INTERRUPT MODULE
PTA0/KBIP0/ACMP+
(1)
PTA1/KBIP1/ACMP-
(1)
PTA2/KBIP2/TCLK/RESET/V
PP
(1),( 2)
PTA3/ACMPO/BKGD/MS
ANALOG COMPARATOR
MODULE
MODULO TIMER
MODULE
PTA4/KBIP4
(1),(3)
PTA5/KBIP5
(1), (3)
INTERNAL REGULATOR
(
KBI
)
5
TCLK
ACMP-
ACMP+
ACMPO
(
ICS
)
(
ACMP
)
(
MTIM
)
MC9RS08KA2 — 2048 BYTES
MC9RS08KA1 — 1024 BYTES
Chapter 1 MC9RS08KA2 Series Device Overview
MC9RS08KA2 Series Data Sheet, Rev. 4
16 Freescale Semiconductor
Table 1-1 provides the functional versions of the on-chip modules.
1.3 System Clock Distribution
Figure 1-2. System Clock Distribution Diagram
Figure 1-2 shows a simplified clock connection diagram for the MCU. The bus clock frequency is half of
the ICS output frequency and is used by all of the internal modules.
Table 1-1. Block Versions
Module Version
Analog Comparator (ACMP) 1
Keyboard Interrupt (KBI) 1
Modulo Timer (MTIM) 1
Internal Clock Source (ICS) 1
MTIM
BDC FLASH
ICS
BDCBDC
CPU
SYSTEM CONTROL LOGIC
RTI
RTICLKS
1-kHz
÷2
ICSOUT
ICSFFCLK
ICSIRCLK
FIXED CLOCK (XCLK)
BUS CLOCK
TCLK
COP
÷32
÷2SYNC
1The fixed clock (XCLK) is internally synchronized to the bus clock and must not exceed one half of the
bus clock frequency
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 17
Chapter 2
Pins and Connections
2.1 Introduction
This chapter describes signals that connect to package pins. It includes a pinout diagram, a table of signal
properties, and a detailed discussion of signals.
2.2 Device Pin Assignment
Figure 2-1 and Figure 2-3 show the pin assignments in the packages available for the MC9RS08KA2
Series.
Figure 2-1. MC9RS08KA2 Series in 6-Pin DFN
Figure 2-2. MC9RS08KA2 Series in 8-Pin PDIP
PTA2/KBIP2/TCLK/RESET/VPP
PTA3/ACMPO/BKGD/MS
VDD VSS
PTA0/KBIP0/ACMP+
1
2
3
6
5
4
PTA1/KBIP1/ACMP-
1
PTA2/KBIP2/TCLK/RESET/VPP
PTA3/ACMPO/BKGD/MS
VDD
VSS
PTA4/KBIP4
PTA1/KBIP1/ACMP-
PTA0/KBIP0/ACMP+
PTA5/KBIP5
2
3
4
8
7
6
5
Chapter 2 Pins and Connections
MC9RS08KA2 Series Data Sheet, Rev. 4
18 Freescale Semiconductor
Figure 2-3. MC9RS08KA2 Series in 8-Pin Narrow Body SOIC
2.3 Recommended System Connections
Figure 2-4 shows reference connection for background debug and Flash programming.
Figure 2-4. Reference System Connection Diagram
2.4 Pin Detail
This section provides a detailed description of system connections.
PTA2/KBIP2/TCLK/RESET/VPP
PTA3/ACMPO/BKGD/MS
VDD
VSS
PTA4/KBIP4
PTA1/KBIP1/ACMP-
PTA0/KBIP0/ACMP+
PTA5/KBIP5
1
2
3
4
8
7
6
5
CBUK
10 μF
CBY
0.1 μF
VDD
VDD
VDD
VSS
BKGD/MS
RESET/VPP
PTA0/KBIP0/ACMP+
PTA1/KBIP1/ACMP-
MC9RS08KA2
BACKGROUND
HEADER
PTA4/KBIP4 (Note 1)
PTA5/KBIP5 (Note 1)
NOTES:
1. This pin is not available in the 6-pin package.
Chapter 2 Pins and Connections
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 19
2.4.1 Power
VDD and VSS are the primary power supply pins for the MCU. This voltage source supplies power to all I/O
buffer circuitry and to an internal voltage regulator. The internal voltage regulator provides a regulated
lower-voltage source to the CPU and other internal circuitry of the MCU.
Typically, application systems have two separate capacitors across the power pins: a bulk electrolytic
capacitor, such as a 10-μF tantalum capacitor, to provide bulk charge storage for the overall system, and a
bypass capacitor, such as a 0.1-μF ceramic capacitor, located as near to the MCU power pins as practical
to suppress high-frequency noise.
2.4.2 PTA2/KBIP2/TCLK/RESET/VPP
After a power-on reset (POR) into user mode, the PTA2/KBIP2/TCLK/RESET/VPP pin defaults to a
general-purpose input port pin, PTA2. Setting RSTPE in SOPT configures the pin to be the RESET input
pin. After configured as RESET, the pin will remain as RESET until the next POR. The RESET pin can
be used to reset the MCU from an external source when the pin is driven low. When enabled as the RESET
pin (RSTPE = 1), the internal pullup device is automatically enabled.
External VPP voltage (typically 12 V, see Section A.10, “FLASH Specifications”) is required on this pin
when performing Flash programming or erasing. The VPP connection is always connected to the internal
Flash module regardless of the pin function. To avoid over stressing the Flash, external VPP voltage must
be removed and voltage higher than VDD must be avoided when Flash programming or erasing is not
taking place.
NOTE
This pin does not contain a clamp diode to VDD and should not be driven
above VDD when Flash programming or erasing is not taking place.
2.4.3 PTA3/ACMPO/BKGD/MS
The background / mode select function is shared with an output-only pin on PTA3 pin and the optional
analog comparator output. While in reset, the pin functions as a mode select pin. Immediately after reset
rises, the pin functions as the background pin and can be used for background debug communication.
While functioning as a background / mode select pin, this pin has an internal pullup device enabled. To use
as an output-only port, BKGDPE in SOPT must be cleared.
If nothing is connected to this pin, the MCU will enter normal operating mode at the rising edge of reset.
If a debug system is connected to the 6-pin standard background debug header, it can hold BKGD/MS low
during the power-on-reset, which forces the MCU to active background mode.
The BKGD pin is used primarily for background debug controller (BDC) communications using a custom
protocol that uses 16 clock cycles of the target MCU’s BDC clock per bit time. The target MCU’s BDC
clock equals the bus clock rate; therefore, no significant capacitance should connected to the BKGD/MS
pin that could interfere with background serial communications.
Although the BKGD pin is a pseudo open-drain pin, the background debug communication protocol
provides brief, actively driven, high speedup pulses to ensure fast rise times. Small capacitances from
Chapter 2 Pins and Connections
MC9RS08KA2 Series Data Sheet, Rev. 4
20 Freescale Semiconductor
cables and the absolute value of the internal pullup device play almost no role in determining rise and fall
times on the BKGD pin.
2.4.4 General-Purpose I/O and Peripheral Ports
The remaining pins are shared among general-purpose I/O and on-chip peripheral functions such as timers
and analog comparator. Immediately after reset, all of these pins are configured as high-impedance
general-purpose inputs with internal pullup/pulldown devices disabled.
NOTE
To avoid extra current drain from floating input pins, the reset initialization
routine in the application program should either enable on-chip
pullup/pulldown devices or change the direction of unused pins to outputs.
Table 2-1. Pin Sharing Reference
Pin Name Direction Pullup/Pulldown1
1SWC is software-controlled pullup/pulldown resistor; the register is associated with the respective port.
Alternative Functions2
2Alternative functions are listed lowest priority first. For example, GPIO is the lowest priority alternative function of the
PTA0 pin; ACMP+ is the highest priority alternative function of the PTA0 pin.
VDD —— Power
VSS — — Ground
PTA0 I/O SWC PTA0
KBIP0
ACMP+
General-purpose input/output (GPIO)
Keyboard interrupt (stop/wait wakeup only)
Analog comparator input
PTA1 I/O SWC PTA1
KBIP1
ACMP-
General-purpose input/output (GPIO)
Keyboard interrupt (stop/wait wakeup only)
Analog comparator input
PTA2 I SWC4PTA2
KBIP2
TCLK
RESET
VPP
General-purpose input
Keyboard interrupt (stop/wait wakeup only)
Modulo timer clock source
Reset
VPP
PTA3 I/O3
3Output-only when configured as PTA3 function.
—4
4When PTA2 or PTA3 is configured as RESET or BKGD/MS, respectively, pullup is enabled. When VPP is attached,
pullup/pulldown is disabled automatically.
PTA3
ACMPO
BKGD
MS
General-purpose output
Analog comparator output
Background debug data
Mode select
PTA45
5This pin is not available in 6-pin package. Enabling either the pullup or pulldown device is recommended to prevent extra
current leakage from the floating input pin.
I/O SWC PTA4
KBIP4
General-purpose input/output (GPIO)
Keyboard interrupt (stop/wait wakeup only)
PTA55I/O SWC PTA5
KBIP5
General-purpose input/output (GPIO)
Keyboard interrupt (stop/wait wakeup only)
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 21
Chapter 3
Modes of Operation
3.1 Introduction
This chapter describes the operating modes of the MC9RS08KA2 Series are described in this chapter. It
also details entry into each mode, exit from each mode, and functionality while in each of the modes.
3.2 Features
• Active background mode for code development
• Wait mode:
— CPU shuts down to conserve power
— System clocks continue to run
— Full voltage regulation is maintained
• Stop mode:
— System clocks are stopped; voltage regulator in standby
— All internal circuits remain powered for fast recovery
3.3 Run Mode
This is the normal operating mode for the MC9RS08KA2 Series. This mode is selected when the
BKGD/MS pin is high at the rising edge of reset. In this mode, the CPU executes code from internal
memory with execution beginning at the address $3FFD. A JMP instruction (opcode $BC) with operand
located at $3FFE–$3FFF must be programmed for correct reset operation into the user application. The
operand defines the location at which the user program will start. Instead of using the vector fetching
process as in HC08/S08 families, the user program is responsible for performing a JMP instruction to
relocate the program counter to the correct user program start location.
3.4 Active Background Mode
The active background mode functions are managed through the background debug controller (BDC) in
the RS08 core. The BDC provides the means for analyzing MCU operation during software development.
Active background mode is entered in any of four ways:
• When the BKGD/MS pin is low during power-on-reset (POR) or immediately after issuing a
background debug force reset (BDC_RESET) command
• When a BACKGROUND command is received through the BKGD pin
• When a BGND instruction is executed
Chapter 3 Modes of Operation
MC9RS08KA2 Series Data Sheet, Rev. 4
22 Freescale Semiconductor
• When a BDC breakpoint is encountered
After active background mode is entered, the CPU is held in a suspended state waiting for serial
background commands rather than executing instructions from the user application program.
Background commands are of two types:
• Non-intrusive commands, defined as commands that can be issued while the user program is
running, can be issued through the BKGD pin while the MCU is in run mode. Non-intrusive
commands can also be executed when the MCU is in the active background mode. Non-intrusive
commands include:
— Memory access commands
— Memory-access-with-status commands
— BACKGROUND command
• Active background commands, which can be executed only while the MCU is in active background
mode, include commands to:
— Read or write CPU registers
— Trace one user program instruction at a time
— Leave active background mode to return to the user application program (GO)
Active background mode is used to program user application code into the Flash program memory before
the MCU is operated in run mode for the first time. When the MC9RS08KA2 Series is shipped from the
Freescale Semiconductor factory, the Flash program memory is usually erased so there is no program that
could be executed in run mode until the Flash memory is initially programmed. The active background
mode can also be used to erase and reprogram the Flash memory after it has been previously programmed.
For additional information about the active background mode, refer to the Development Support chapter
of this data sheet.
3.5 Wait Mode
Wait mode is entered by executing a WAIT instruction. Upon execution of the WAIT instruction, the CPU
enters a low-power state in which it is not clocked. The program counter (PC) is halted at the position
where the WAIT instruction is executed. When an interrupt request occurs:
1. MCU exits wait mode and resumes processing.
2. PC is incremented by one and fetches the next instruction to be processed.
It is the responsibility of the user program to probe the corresponding interrupt source that woke the MCU,
because no vector fetching process is involved.
While the MCU is in wait mode, not all background debug commands can be used. Only the
BACKGROUND command and memory-access-with-status commands are available when the MCU is in
wait mode. The memory-access-with-status commands do not allow memory access, but they report an
error indicating that the MCU is in either stop or wait mode. The BACKGROUND command can be used
to wake the MCU from wait mode and enter active background mode.
Chapter 3 Modes of Operation
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 23
Table 3-1 summarizes the behavior of the MCU in wait mode.
3.6 Stop Mode
Stop mode is entered upon execution of a STOP instruction when the STOPE bit in the system option
register is set. In stop mode, all internal clocks to the CPU and the modules are halted. If the STOPE bit is
not set when the CPU executes a STOP instruction, the MCU will not enter stop mode and an illegal
opcode reset is forced.
Table 3-2 summarizes the behavior of the MCU in stop mode.
Upon entering stop mode, all of the clocks in the MCU are halted. The ICS is turned off by default when
the IREFSTEN bit is cleared and the voltage regulator is put in standby. The states of all of the internal
registers and logic, as well as the RAM content, are maintained. The I/O pin states are held.
Exit from stop is done by asserting RESET, any asynchronous interrupt that has been enabled, or the
real-time interrupt. The asynchronous interrupts are the KBI pins, LVD interrupt, or the ACMP interrupt.
If stop is exited by asserting the RESET pin, the MCU will be reset and program execution starts at
location $3FFD. If exited by means of an asynchronous interrupt or real-time interrupt, the next instruction
after the location where the STOP instruction was executed will be executed accordingly. It is the
responsibility of the user program to probe for the corresponding interrupt source that woke the CPU.
A separate self-clocked source (≈1 kHz) for the real-time interrupt allows a wakeup from stop mode with
no external components. When RTIS = 000, the real-time interrupt function and the 1-kHz source are
disabled. Power consumption is lower when the 1-kHz source is disabled, but in that case, the real-time
interrupt cannot wake the MCU from stop.
The trimmed 32-kHz clock in the ICS module can also be enabled for the real-time interrupt to allow a
wakeup from stop mode with no external components. The 32-kHz clock reference is enabled by setting
Table 3-1. Wait Mode Behavior
Mode CPU Digital
Peripherals ICS ACMP Regulator I/O Pins RTI
Wait Standby Optionally on On Optionally
on
On States held Optionally on
Table 3-2. Stop Mode Behavior
Mode CPU Digital
Peripherals ICS1
1ICS requires IREFSTEN = 1 and LVDE and LVDSE must be set to allow operation in stop.
ACMP2
2If bandgap reference is required, the LVDE and LVDSE bits in the SPMSC1 must both be set before entering
stop.
Regulator I/O Pins RTI3
3If the 32-kHz trimmed clock in the ICS module is selected as the clock source for the RTI, LVDE and LVDSE bits
in the SPMSC1 must both be set before entering stop.
Stop Standby Standby Optionally
on
Optionally
on
Standby States held Optionally on
Chapter 3 Modes of Operation
MC9RS08KA2 Series Data Sheet, Rev. 4
24 Freescale Semiconductor
the IREFSTEN bit. For the ICS to run in stop, the LVDE and LVDSE bits in the SPMSC1 must both be
set before entering stop.
3.6.1 Active BDM Enabled in Stop Mode
Entry into active background mode from run mode is enabled if the ENBDM bit in BDCSCR is set. This
register is described in the Development Support chapter of this data sheet. If ENBDM is set when the CPU
executes a STOP instruction, the system clocks to the background debug logic remain active when the
MCU enters stop mode so background debug communication is still possible. In addition, the voltage
regulator does not enter its low-power standby state; it maintains full internal regulation.
Most background commands are not available in stop mode. The memory-access-with-status commands
do not allow memory access, but they report an error indicating that the MCU is in either stop or wait
mode. The BACKGROUND command can be used to wake the MCU from stop and enter active
background mode if the ENBDM bit is set. After active background mode is entered, all background
commands are available.
Table 3-3 summarizes the behavior of the MCU in stop when entry into the active background mode is
enabled.
3.6.2 LVD Enabled in Stop Mode
The LVD system is capable of generating either an interrupt or a reset when the supply voltage drops below
the LVD voltage. If the LVD is enabled in stop (LVDE and LVDSE bits in SPMSC1 both set) at the time
the CPU executes a STOP instruction, the voltage regulator remains active.
Table 3-4 summarizes the behavior of the MCU in stop when LVD reset is enabled.
Table 3-3. BDM Enabled Stop Mode Behavior
Mode CPU Digital
Peripherals ICS ACMP Regulator I/O Pins RTI
Stop Standby Standby On Optionally
on
On States held Optionally on
Table 3-4. LVD Enabled Stop Mode Behavior
Mode CPU Digital
Peripherals ICS ACMP Regulator I/O Pins RTI
Stop Standby Standby Optionally
on
Optionally
on
On States held Optionally on
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 25
Chapter 4
Memory
4.1 Memory Map
The memory map of the MCU is divided into the following groups:
• Fast access RAM using tiny and short instructions ($0000–$000E1)
• Indirect data access D[X] ($000E)
• Index register X for D[X] ($000F)
• Frequently used peripheral registers ($0010–$001E)
• PAGESEL register ($001F)
• RAM ($0020–$004F)
• Paging window ($00C0–$00FF)
• Other peripheral registers ($0200–$023F)
• Nonvolatile memory
— MC9RS08KA2: $3800–$3FFF
— MC9RS08KA1: $3C00—$3FFF
1. Physical RAM in $000E can be accessed through the D[X] register when the content of the index register X is $0E.
Chapter 4 Memory
MC9RS08KA2 Series Data Sheet, Rev. 4
26 Freescale Semiconductor
Figure 4-1. MC9RS08KA2 Series Memory Maps
D[X]
REGISTER X
FAST ACCESS RAM
14 BYTES
FREQUENTLY USED REGISTERS
HIGH PAGE REGISTERS
$000E
$000F
$0000
$000D
$0010
$001E
$0200
$023F
RAM
48 BYTES
$0020
$004F
PAGING WINDOW
$00C0
$00FF
FLASH
$3800
$3FFB
2044 BYTES
UNIMPLEMENTED
UNIMPLEMENTED
NVOPT
$3FFC
$3FFD
$3FFF
FLASH
PAGESEL
$001F
UNIMPLEMENTED
PAGE REGISTER
$00
$08 (reset value)
$E0
CONTENT
MC9RS08KA2 MC9RS08KA1
D[X]
REGISTER X
FAST ACCESS RAM
14 BYTES
FREQUENTLY USED REGISTERS
HIGH PAGE REGISTERS
$000E
$000F
$0000
$000D
$0010
$001E
$0200
$023F
RAM
48 BYTES
$0020
$004F
PAGING WINDOW
$00C0
$00FF
FLASH
$3C00
$3FFB 1020 BYTES
UNIMPLEMENTED
UNIMPLEMENTED
NVOPT
$3FFC
$3FFD
$3FFF
FLASH
PAGESEL
$001F
UNIMPLEMENTED
PAGE REGISTER
$00
$08 (reset value)
$F0
CONTENT
Chapter 4 Memory
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 27
4.2 Unimplemented Memory
Attempting to access either data or an instruction at an unimplemented memory address will cause reset.
4.3 Indexed/Indirect Addressing
Register D[X] and register X together perform the indirect data access. Register D[X] is mapped to address
$000E. Register X is located in address $000F. The 8-bit register X contains the address that is used when
register D[X] is accessed. Register X is cleared to zero upon reset. By programming register X, any
location on the first page ($0000–$00FF) can be read/written via register D[X]. Figure 4-2 shows the
relationship between D[X] and register X. For example, in HC08/S08 syntax lda ,x is comparable to lda
D[X] in RS08 coding when register X has been programmed with the index value.
The physical location of $000E is in RAM. Accessing the location through D[X] returns $000E RAM
content when register X contains $0E. The physical location of $000F is register X, itself. Reading the
location through D[X] returns register X content; writing to the location modifies register X.
Figure 4-2. Indirect Addressing Registers
4.4 RAM and Register Addresses and Bit Assignments
The fast access RAM area can be accessed by instructions using tiny, short, and direct addressing mode
instructions. For tiny addressing mode instructions, the operand is encoded along with the opcode to a
single byte.
D[X]
Register X
Content of this location can be accessed via D[X]
$000E
$000F
$00FF
Address indicated in
$0100
Register X can specify
any location between
$0000–$00FF
Register X
$0000
Chapter 4 Memory
MC9RS08KA2 Series Data Sheet, Rev. 4
28 Freescale Semiconductor
Frequently used registers can make use of the short addressing mode instructions for faster load, store, and
clear operations. For short addressing mode instructions, the operand is encoded along with the opcode to
a single byte.
Table 4-1. Register Summary
Address Register Name Bit 7 6 5 4 3 2 1 Bit 0
$0000–
$000D Fast Access RAM
$000E D[X]1Bit 7654321Bit 0
$000F X Bit 7 6 5 4 3 2 1 Bit 0
$0010 PTAD 00 PTAD5 PTAD4 PTAD3 PTAD2 PTAD1 PTAD0
$0011 PTADD 00 PTADD5 PTADD4 00 PTADD1 PTADD0
$0012 Unimplemented — — — — — — — —
$0013 ACMPSC ACME ACBGS ACF ACIE ACO ACOPE ACMOD
$0014 ICSC1 0CLKS00000IREFSTEN
$0015 ICSC2 BDIV 00LP0 0 0
$0016 ICSTRM TRIM
$0017 ICSSC 0 0 0 0 0CLKST0FTRIM
$0018 MTIMSC TOF TOIE TRST TSTP 0 0 0 0
$0019 MTIMCLK 00CLKS PS
$001A MTIMCNT COUNT
$001B MTIMMOD MOD
$001C KBISC 0000 KBF KBACK KBIE KBIMOD
$001D KBIPE —— KBIPE5 KBIPE4 — KBIPE2 KBIPE1 KBIPE0
$001E KBIES —— KBEDG5 KBEDG4 — KBEDG2 KBEDG1 KBEDG0
$001F PAGESEL AD13 AD12 AD11 AD10 AD9 AD8 AD7 AD6
$0020–
$004F RAM
$0050–
$00BF
Unimplemented — — — — — — — —
$00C0–
$00FF Paging Window
$0100–
$01FF
Unimplemented — — — — — — — —
$0200 SRS POR PIN COP ILOP ILAD 0LVD0
$0201 SOPT COPE COPT STOPE 0 0 0 BKGDPE RSTPE
$0202 SIP1 ——— KBI ACMP MTIM RTI LVD
$0203 Unimplemented — — — — — — — —
$0204 Reserved — — — — — — — —
$0205 Unimplemented — — — — — — — —
$0206 SDIDH REV3 REV2 REV1 REV0 ID
$0207 SDIDL ID
$0208 SRTISC RTIF RTIACK RTICLKS RTIE 0RTIS
$0209 SPMSC1 LVDF LVDACK LVDIE LVDRE LVDSE LVDE 0BGBE
$020A Reserved — — — — — — — —
$020B Reserved — — — — — — — —
= Unimplemented or Reserved
Chapter 4 Memory
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 29
4.5 RAM
The device includes two sections of static RAM. The locations from $0000 to $000D can be directly
accessed using the more efficient tiny addressing mode instructions and short addressing mode
instructions. Location $000E RAM can either be accessed through D[X] register when register X is $0E
or through the paging window location $00CE when PAGESEL register is $00. The second section of
RAM starts from $0020 to $004F, and it can be accessed using direct addressing mode instructions.
The RAM retains data when the MCU is in low-power wait and stop mode. RAM data is unaffected by
any reset provided that the supply voltage does not drop below the minimum value for RAM retention.
4.6 Flash
The Flash memory is intended primarily for program storage. In-circuit programming allows the operating
program to be loaded into the Flash memory after final assembly of the application product. It is possible
to program the entire array through the single-wire background debug interface. Because the device does
not include on-chip charge pump circuitry, external VPP is required for program and erase operations.
4.6.1 Features
Features of the Flash memory include:
$020C–
$020F
Unimplemented — — — — — — — —
$0210 FOPT 0000000 SECD
$0211 FLCR 0000 HVEN MASS 0PGM
$0212–
$0213
Reserved — — — — — — — —
$0214–
$021F
Unimplemented —
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
$0220 PTAPE 00 PTAPE5 PTAPE4 0 PTAPE2 PTAPE1 PTAPE0
$0221 PTAPUD 00 PTAPUD5 PTAPUD4 0 PTAPUD2 PTAPUD1 PTAPUD0
$0222 PTASE 00 PTASE5 PTASE4 PTASE3 0 PTASE1 PTASE0
$0223–
$023F
Unimplemented — — — — — — — —
$3FF8 Reserved — — — — — — — —
$3FF9 Reserved — — — — — — — —
$3FFA2Reserved Reserved for Room Temperature ICS Trim
$3FFB2Reserved Reserved FTRIM
$3FFC NVOPT 0000000 SECD
1Physical RAM in $000E can be accessed through D[X] register when the content of the index register X is $0E.
2If using the MCU untrimmed, $3FFA and $3FFB may be used by applications.
Table 4-1. Register Summary (continued)
Address Register Name Bit 7 6 5 4 3 2 1 Bit 0
= Unimplemented or Reserved
Chapter 4 Memory
MC9RS08KA2 Series Data Sheet, Rev. 4
30 Freescale Semiconductor
• Up to 1000 program/erase cycles at typical voltage and temperature
• Security feature for Flash
4.6.2 Flash Programming Procedure
Programming of Flash memory is done on a row basis. A row consists of 64 consecutive bytes starting
from addresses $3X00, $3X40, $3X80, or $3XC0. Use the following procedure to program a row of Flash
memory:
1. Apply external VPP
.
2. Set the PGM bit. This configures the memory for program operation and enables the latching of
address and data for programming.
3. Write any data to any Flash location, via the high page accessing window $00C0–$00FF, within
the address range of the row to be programmed. (Prior to the data writing operation, the PAGESEL
register must be configured correctly to map the high page accessing window to the corresponding
Flash row).
4. Wait for a time, tnvs.
5. Set the HVEN bit.
6. Wait for a time, tpgs.
7. Write data to the Flash location to be programmed.
8. Wait for a time, tprog.
9. Repeat steps 7 and 8 until all bytes within the row are programmed.
10. Clear the PGM bit.
11. Wait for a time, tnvh.
12. Clear the HVEN bit.
13. After time, trcv, the memory can be accessed in read mode again.
14. Remove external VPP
.
This program sequence is repeated throughout the memory until all data is programmed.
NOTE
Flash memory cannot be programmed or erased by software code executed
from Flash locations. To program or erase Flash, commands must be
executed from RAM or BDC commands. User code should not enter wait or
stop during erase or program sequence.
These operations must be performed in the order shown; other unrelated
operations may occur between the steps.
4.6.3 Flash Mass Erase Operation
Use the following procedure to mass erase the entire Flash memory:
1. Apply external VPP
.
2. Set the MASS bit in the Flash control register.
Chapter 4 Memory
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 31
3. Write any data to any Flash location, via the high page accessing window $00C0–$00FF. (Prior to
the data writing operation, the PAGESEL register must be configured correctly to map the high
page accessing window to the any Flash locations).
4. Wait for a time, tnvs.
5. Set the HVEN bit.
6. Wait for a time tme.
7. Clear the MASS bit.
8. Wait for a time, tnvh1.
9. Clear the HVEN bit.
10. After time, trcv, the memory can be accessed in read mode again.
11. Remove external VPP
.
NOTE
Flash memory cannot be programmed or erased by software code executed
from Flash locations. To program or erase Flash, commands must be
executed from RAM or BDC commands. User code should not enter wait or
stop during an erase or program sequence.
These operations must be performed in the order shown, but other unrelated
operations may occur between the steps.
4.6.4 Security
The MC9RS08KA2 Series includes circuitry to help prevent unauthorized access to the contents of Flash
memory. When security is engaged, Flash is considered a secure resource. The RAM, direct-page registers,
and background debug controller are considered unsecured resources. Attempts to access a secure memory
location through the background debug interface, or whenever BKGDPE is set, are blocked (reads return
all 0s).
Security is engaged or disengaged based on the state of a nonvolatile register bit (SECD) in the FOPT
register. During reset, the contents of the nonvolatile location NVOPT are copied from Flash into the
working FOPT register in high-page register space. A user engages security by programming the NVOPT
location, which can be done at the same time the Flash memory is programmed. Notice the erased state
(SECD = 1) makes the MCU unsecure. When SECD in NVOPT is programmed (SECD = 0), next time
the device is reset via POR, internal reset, or external reset, security is engaged. In order to disengage
security, mass erase must be performed via BDM commands and followed by any reset.
The separate background debug controller can still be used for registers and RAM access. Flash mass erase
is possible by writing to the Flash control register that follows the Flash mass erase procedure listed in
Section 4.6.3, “Flash Mass Erase Operation,” via BDM commands.
Security can always be disengaged through the background debug interface by following these steps:
1. Mass erase Flash via background BDM commands or RAM loaded program.
2. Perform reset and the device will boot up with security disengaged.
Chapter 4 Memory
MC9RS08KA2 Series Data Sheet, Rev. 4
32 Freescale Semiconductor
NOTE
When the device boots up to normal operating mode, where MS pin is high
during reset, with SECD programmed (SECD = 0), Flash security is
engaged. BKGDPE is reset to 0, and all BDM communication is blocked,
and background debug is not allowed.
4.7 Flash Registers and Control Bits
The Flash module has a nonvolatile register, NVOPT ($3FFC), in Flash memory which is copied into the
corresponding control register, FOPT ($0210), at reset.
4.7.1 Flash Options Register (FOPT and NVOPT)
During reset, the contents of the nonvolatile location NVOPT is copied from Flash into FOPT. Bits 7
through 1 are not used and always read 0. This register may be read at any time, but writes have no meaning
or effect. To change the value in this register, erase and reprogram the NVOPT location in Flash memory
as usual and then issue a new MCU reset.
76543210
R0000000SECD
W
Reset This register is loaded from nonvolatile location NVOPT during reset.
= Unimplemented or Reserved
Figure 4-3. Flash Options Register (FOPT)
Table 4-2. FOPT Field Descriptions
Field Description
0
SECD
Security State Code — This bit field determines the security state of the MCU. When the MCU is secured, the
contents of Flash memory cannot be accessed by instructions from any unsecured source including the
background debug interface; refer to Section 4.6.4, “Security”.
0 Security engaged.
1 Security disengaged.
Chapter 4 Memory
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 33
4.7.2 Flash Control Register (FLCR)
4.8 Page Select Register (PAGESEL)
There is a 64-byte window ($00C0–$00FF) in the direct-page reserved for paging access. Programming
the page select register determines the corresponding 64-byte block on the memory map for direct-page
access. For example, when the PAGESEL register is programmed with value $08, the high page registers
($0200–$023F) can be accessed through the paging window ($00C0–$00FF) via direct addressing mode
instructions.
76543210
R0000
HVEN MASS
0
PGM1
W
Reset00000000
= Unimplemented or Reserved
Figure 4-4. Flash Control Register (FLCR)
Table 4-3. FLCR Field Descriptions
Field Description
3
HVEN
High Voltage Enable — This read/write bit enables high voltages to the Flash array for program and erase
operations. HVEN can be set only if either PGM = 1 or MASS = 1 and the proper sequence for program or erase
is followed.
0 High voltage disabled to array.
1 High voltage enabled to array.
2
MASS
Mass Erase Control Bit — This read/write bit configures the memory for mass erase operation.
0 Mass erase operation not selected.
1 Mass erase operation selected.
0
PGM1
1When Flash security is engaged, writing to PGM bit has no effect. As a result, Flash programming is not allowed.
Program Control Bit — This read/write bit configures the memory for program operation. PGM is interlocked
with the MASS bit such that both bits cannot be equal to 1 or set to 1 at the same time.
0 Program operation not selected.
1 Program operation selected.
76543210
R
AD13 AD12 AD11 AD10 AD9 AD8 AD7 AD6
W
Reset00001000
Figure 4-5. Page Select Register (PAGESEL)
Table 4-4. PAGESEL Field Descriptions
Field Description
7:0
AD[13:6]
Page Selector— These bits define the address line bit 6 to bit 13, which determines the 64-byte block boundary
of the memory block accessed via the direct page window. See Figure 4-6 and Ta bl e 4-5 .
Chapter 4 Memory
MC9RS08KA2 Series Data Sheet, Rev. 4
34 Freescale Semiconductor
Table 4-5 shows the memory block to be accessed through paging window ($00C0–$00FF).
NOTE
Physical location $0000-$000E is RAM. Physical location $000F is register
X. D[X] register is mapped to address $000E only. The physical RAM in
$000E can be accessing through D[X] register when X register is either $0E
or $CE with PAGESEL is $00.
When PAGESEL register is $00, paging window is mapped to the first page
($00-$3F). Paged location $00C0–$00CE is mapped to physical location
$0000-$000E, i.e., RAM. Paged location $00CF is mapped to register X.
Therefore, accessing address $CE returns the physical RAM content in
$000E, accessing address $000E returns D[X] register content.
14-bit memory address
Start address of memory block selected 000000
AD[13:6]
Figure 4-6. Memory Block Boundary Selector
Table 4-5. Paging Window for $00C0–$00FF
Page Memory Address
$00 $0000–$003F
$01 $0040–$007F
$02 $0080–$00BF
$03 $00C0–$00FF
$04 $0100–$013F
.
.
.
.
.
.
$FE $3F80–$3FBF
$FF $3FC0–$3FFF
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 35
Chapter 5
Resets, Interrupts, and General System Control
5.1 Introduction
This chapter discusses basic reset and interrupt mechanisms and the various sources of reset and interrupt
in the MC9RS08KA2 Series. Some interrupt sources from peripheral modules are discussed in greater
detail within other chapters of this data sheet. This chapter gathers basic information about all reset and
interrupt sources in one place for easy reference. A few reset and wakeup sources, including the computer
operating properly (COP) watchdog and real-time interrupt (RTI), are not part of on-chip peripheral
systems with their own chapters but are part of the system control logic.
5.2 Features
Reset and interrupt features include:
• Multiple sources of reset for flexible system configuration and reliable operation
• System reset status register (SRS) to indicate the source of the most recent reset
• System interrupt pending register (SIP1) to indicate the status of pending system interrupts
— Analog comparator interrupt with enable
— Keyboard interrupt with enable
— Low-voltage detect interrupt with enable
— Modulo timer interrupt with enable
— Real-time interrupt with enable; available in stop with multiple rates based on a separate 1-kHz
self-clocked source
5.3 MCU Reset
Resetting the MCU provides a way to start processing from a known set of initial conditions. During reset,
most control and status registers are forced to initial values and the program counter is started from
location $3FFD. A JMP instruction (opcode $BC) with operand located at $3FFE–$3FFF must be
programmed into the user application for correct reset operation. The operand defines the location at which
the user program will start. On-chip peripheral modules are disabled and I/O pins are initially configured
as general-purpose high-impedance inputs with pullup/pulldown devices disabled.
The MC9RS08KA2 Series has seven sources for reset:
• External pin reset (PIN) — enabled using RSTPE in SOPT
• Power-on reset (POR)
• Low-voltage detect (LVD)
Chapter 5 Resets, Interrupts, and General System Control
MC9RS08KA2 Series Data Sheet, Rev. 4
36 Freescale Semiconductor
• Computer operating properly (COP) timer
• Illegal opcode detect (ILOP)
• Illegal address detect (ILAD)
• Background debug forced reset via BDC command BDC_RESET
Each of these sources, with the exception of the background debug forced reset, has an associated bit in
the system reset status register (SRS).
5.4 Computer Operating Properly (COP) Watchdog
The COP watchdog is intended to force a system reset if the application software fails to execute as
expected. To prevent a system reset from the COP timer (when it is enabled), application software must
reset the COP counter periodically. If the application program gets lost and fails to reset the COP counter
before it times out, a system reset is generated to force the system back to a known starting point.
After any reset, the COPE becomes set in SOPT, which enables the COP watchdog (see Section 5.8.2,
“System Options Register (SOPT),” for additional information). If the COP watchdog is not used in an
application, it can be disabled by clearing COPE. The COP counter is reset by writing any value to the
address of SRS. This write does not affect the data in the read-only SRS. Instead, the act of writing to this
address is decoded and sends a reset signal to the COP counter.
There is an associated short and long time-out controlled by COPT in SOPT. Table 5-1 summaries the
control functions of the COPT bit. The COP watchdog operates from the 1-kHz clock source and defaults
to the associated long time-out (28 cycles).
Even if the application will use the reset default settings of COPE and COPT, the user should write to the
write-once SOPT registers during reset initialization to lock in the settings. That way, they cannot be
changed accidentally if the application program gets lost. The initial write to SOPT will reset the COP
counter.
In background debug mode, the COP counter will not increment.
When the MCU enters stop mode, the COP counter is re-initialized to zero upon entry to stop mode. The
COP counter begins from zero as soon as the MCU exits stop mode.
5.5 Interrupts
The MC9RS08KA2 Series does not include an interrupt controller with vector table lookup mechanism as
used on the HC08 and HCS08 devices. However, the interrupt sources from modules such as LVD, KBI,
Table 5-1. COP Configuration Options
COPT COP Overflow Count1
1Values shown in this column are based on
tRTI ≈1 ms. See tRTI in the Section A.9.1, “Control
Timing,” for the tolerance of this value.
02
5 cycles (32 ms)
12
8 cycles (256 ms)
Chapter 5 Resets, Interrupts, and General System Control
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 37
and ACMP are still available to wake the CPU from wait or stop mode. It is the responsibility of the user
application to poll the corresponding module to determine the source of wakeup.
Each wakeup source of the module is associated with a corresponding interrupt enable bit. If the bit is
disabled, the interrupt source is gated, and that particular source cannot wake the CPU from wait or stop
mode. However, the corresponding interrupt flag will still be set to indicate that an external wakeup event
has occurred.
The system interrupt pending register (SIP1) indicates the status of the system pending interrupt. When
the read-only bit of the SIP1 is enabled, it shows there is a pending interrupt to be serviced from the
indicated module. Writing to the register bit has no effect. The pending interrupt flag will be cleared
automatically when the all corresponding interrupt flags from the indicated module are cleared.
5.6 Low-Voltage Detect (LVD) System
The MC9RS08KA2 Series includes a system to protect against low voltage conditions in order to protect
memory contents and control MCU system states during supply voltage variations. The system is
comprised of a power-on reset (POR) circuit and an LVD circuit with a predefined trip voltage. The LVD
circuit is enabled with LVDE in SPMSC1. The LVD is disabled upon entering stop mode unless LVDSE
is set in SPMSC1. If LVDSE and LVDE are both set, the current consumption in stop with the LVD enabled
will be greater.
5.6.1 Power-On Reset Operation
When power is initially applied to the MCU, or when the supply voltage drops below the VPOR level, the
POR circuit will cause a reset condition. As the supply voltage rises, the LVD circuit will hold the MCU
in reset until the supply has risen above the VLVD level. Both the POR bit and the LVD bit in SRS are set
following a POR.
5.6.2 LVD Reset Operation
The LVD can be configured to generate a reset upon detection of a low voltage condition by setting
LVDRE to 1. After an LVD reset has occurred, the LVD system will hold the MCU in reset until the supply
voltage has risen above the level VLVD . The LVD bit in the SRS register is set following either an LVD
reset or POR.
5.6.3 LVD Interrupt Operation
When a low voltage condition is detected and the LVD circuit is configured using SPMSC1 for interrupt
operation (LVDE set, LVDIE set, and LVDRE clear), LVDF in SPMSC1 will be set and an LVD interrupt
request will occur.
5.7 Real-Time Interrupt (RTI)
The real-time interrupt function can be used to generate periodic interrupts. The RTI is driven from either
the 1-kHz internal clock reference or the trimmed 32-kHz internal clock reference from the ICS module.
The 32-kHz internal clock reference is divided by 32 by the RTI logic to produce a trimmed 1-kHz clock
Chapter 5 Resets, Interrupts, and General System Control
MC9RS08KA2 Series Data Sheet, Rev. 4
38 Freescale Semiconductor
for applications requiring more accurate real-time interrupts. The RTICLKS bit in SRTISC is used to select
the RTI clock source. Both the1-kHz and 32-kHz clock sources for the RTI can be used when the MCU is
in run, wait or stop mode. For the 32-kHz clock source to run in stop, the LVDE and LVDSE bits in the
SPMSC1 must both be set before entering stop.
The SRTISC register includes a read-only status flag, a write-only acknowledge bit, and a 3-bit control
value (RTIS) used to select one of seven wakeup periods or disable RTI. The RTI has a local interrupt
enable, RTIE, to allow masking of the real-time interrupt. The RTI can be disabled by writing each bit of
RTIS to 0s, and no interrupts will be generated. See Section 5.8.4, “System Real-Time Interrupt Status and
Control Register (SRTISC),” for detailed information about this register.
5.8 Reset, Interrupt, and System Control Registers and Control Bits
Refer to the direct-page register summary in Chapter 4, “Memory,” for the absolute address assignments
for all registers. This section refers to registers and control bits only by their names. A Freescale-provided
equate or header file is used to translate these names into the appropriate absolute addresses.
Some control bits in the SOPT register are related to modes of operation. Although brief descriptions of
these bits are provided here, the related functions are discussed in greater detail in Chapter 3, “Modes of
Operation”.
5.8.1 System Reset Status Register (SRS)
This high page register includes read-only status flags to indicate the source of the most recent reset. When
a debug host forces reset by the BDC_RESET command, all of the status bits in SRS will be cleared.
Writing any value to this register address clears the COP watchdog timer without affecting the contents of
this register. The reset state of these bits depends on what caused the MCU to reset.
Figure 5-1. System Reset Status (SRS)
76543210
R POR PIN COP ILOP ILAD 0 LVD 0
W Writing any value to SRS address clears COP watchdog timer.
POR:10000010
LVR:00000010
Any other
reset:
0 Note 1 Note 1 Note 1 Note 1 0 0 0
1. Any of these reset sources that are active at the time of reset entry will cause the corresponding bit(s) to be set; bits
corresponding to sources that are not active at the time of reset entry will be cleared.
Chapter 5 Resets, Interrupts, and General System Control
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 39
5.8.2 System Options Register (SOPT)
This high page register is a write-once register so only the first write after reset is honored. It can be read
at any time. Any subsequent attempt to write to SOPT (intentionally or unintentionally) is ignored to avoid
accidental changes to these sensitive settings. SOPT must be written during the user’s reset initialization
program to set the desired controls even if the desired settings are the same as the reset settings.
1. When the device is reset into normal operating mode (MS is high during reset), BKGDPE is reset to 1 if Flash security is
disengaged (SECD = 1); BKGDPE is reset to 0 if Flash security is engaged (SECD = 0). When the device is reset into active
BDM mode (MS is low during reset), BKGDPE is always reset to 1 such that BDM communication is allowed.
Table 5-2. SRS Field Descriptions
Field Description
7
POR
Power-On Reset — Reset was caused by the power-on detection logic. Because the internal supply voltage was
ramping up at the time, the low-voltage reset (LVR) status bit is also set to indicate that the reset occurred while
the internal supply was below the LVR threshold.
0 Reset not caused by POR.
1 POR caused reset.
6
PIN
External Reset Pin — Reset was caused by an active-low level on the external reset pin.
0 Reset not caused by external reset pin.
1 External reset pin caused reset.
5
COP
Computer Operating Properly (COP) Watchdog — Reset was caused by the COP watchdog timer timing out.
This reset source can be blocked by COPE = 0.
0 Reset not caused by COP timeout.
1 COP timeout caused reset.
4
ILOP
Illegal Opcode — Reset was caused by an attempt to execute an unimplemented or illegal opcode. The STOP
instruction is considered illegal if stop is disabled by STOPE = 0 in the SOPT register. The BGND instruction is
considered illegal if active background mode is disabled by ENBDM = 0 in the BDCSC register.
0 Reset not caused by an illegal opcode.
1 An illegal opcode caused reset.
3
ILAD
Illegal Address — Reset was caused by an attempt to access either data or an instruction at an unimplemented
memory address.
0 Reset not caused by an illegal address.
1 An illegal address caused reset.
1
LVD
Low Voltage Detect — If the LVDRE bit is set and the supply drops below the LVD trip voltage, an LVD reset will
occur. This bit is also set by POR.
0 Reset not caused by LVD trip or POR.
1 Either LVD trip or POR caused reset.
76543210
R
COPE COPT STOPE
000
BKGDPE RSTPE
W
Reset: 1 1 0 0 0 0 1 (Note 1) u
POR:1100001 (Note1)0
= Unimplemented or Reserved u = Unaffected
Figure 5-2. System Options Register 1 (SOPT)
Chapter 5 Resets, Interrupts, and General System Control
MC9RS08KA2 Series Data Sheet, Rev. 4
40 Freescale Semiconductor
5.8.3 System Device Identification Register (SDIDH, SDIDL)
These high page read-only registers are included so host development systems can identify the RS08
derivative and revision number. This allows the development software to recognize where specific
memory blocks, registers, and control bits are located in a target MCU.
1. The revision number that is hard coded into these bits reflects the current silicon revision level.
Figure 5-3. System Device Identification Register — High (SDIDH)
Table 5-3. SOPT Register Field Descriptions
Field Description
7
COPE
COP Watchdog Enable — This write-once bit selects whether the COP watchdog is enabled.
0 COP watchdog timer disabled.
1 COP watchdog timer enabled (force reset on timeout).
6
COPT
COP Watchdog Timeout — This write-once bit selects the timeout period of the COP.
0 Short timeout period selected.
1 Long timeout period selected.
5
STOPE
Stop Mode Enable — This write-once bit is used to enable stop mode. If stop mode is disabled and a user
program attempts to execute a STOP instruction, an illegal opcode reset is forced.
0 Stop mode disabled.
1 Stop mode enabled.
1
BKGDPE1,2
1When the device is reset into normal operating mode (MS is high during reset), BKGDPE is reset to 1 if Flash security is
disengaged (SECD = 1); BKGDPE is reset to 0 if Flash security is engaged (SECD = 0). When the device is reset into active
BDM mode (MS is low during reset), BKGDPE is always reset to 1 such that BDM communication is allowed.
2BKGDPE can only write once from value 1 to 0. Writing from value 0 to 1 by user software is not allowed. BKGDPE can be
changed back to 1 only by a POR or reset with proper condition as stated in Note 1.
Background Debug Mode Pin Enable — This write-once bit when set enables the PTA3/ACMPO/BKGD/MS
pin to function as BKGD/MS. When clear, the pin functions as one of its output only alternative functions. This
pin defaults to the BKGD/MS function following any MCU reset.
0 PTA3/ACMPO/BKGD/MS pin functions as PTA3 or ACMPO.
1 PTA3/ACMPO/BKGD/MS pin functions as BKGD/MS.
0
RSTPE
RESET Pin Enable — When set, this write-once bit enables the PTA2/KBIP2/TCLK/RESET/VPP pin to function
as RESET. When clear, the pin functions as one of its input-only alternative functions. This pin is input-only port
function following an MCU POR. When RSTPE is set, an internal pullup device is enabled on RESET.
0 PTA2/KBIP2/TCLK/RESET/VPP pin functions as PTA2/KBIP2/TCLK/VPP
.
1 PTA2/KBIP2/TCLK/RESET/VPP pin functions as RESET/VPP
.
76543210
R REV3 REV2 REV1 REV0 ID11 ID10 ID9 ID8
W
Reset: 0 (Note 1) 0 (Note 1) 0 (Note 1) 0 (Note 1) 1 0 0 0
= Unimplemented or Reserved
Chapter 5 Resets, Interrupts, and General System Control
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 41
5.8.4 System Real-Time Interrupt Status and Control Register (SRTISC)
This high page register contains status and control bits for the RTI.
Table 5-4. SDIDH Register Field Descriptions
Field Description
7:4
REV[3:0]
Revision Number — The high-order 4 bits of address SDIDH are hard coded to reflect the current mask set
revision number (0–F).
3:0
ID[11:8]
Part Identification Number — Each derivative in the RS08 Family has a unique identification number. The
MC9RS08KA2 Series is hard coded to the value $0800. See also ID bits in Figure 5-4.
76543210
R ID7 ID6 ID5 ID4 ID3 ID2 ID1 ID0
W
Reset:00000000
= Unimplemented or Reserved
Figure 5-4. System Device Identification Register — Low (SDIDL)
Table 5-5. SDIDL Register Field Descriptions
Field Description
7:0
ID[7:0]
Part Identification Number — Each derivative in the RS08 Family has a unique identification number. The
MC9RS08KA2 Series is hard coded to the value $0800. See also ID bits in Figure 5-3.
76543210
RRTIF 0
RTICLKS RTIE
0
RTIS
WRTIACK
Reset:00000000
= Unimplemented or Reserved
Figure 5-5. System RTI Status and Control Register (SRTISC)
Table 5-6. SRTISC Register Field Descriptions
Field Description
7
RTIF
Real-Time Interrupt Flag — This read-only status bit indicates the periodic wakeup timer has timed out.
0 Periodic wakeup timer not timed out.
1 Periodic wakeup timer timed out.
6
RTIACK
Real-Time Interrupt Acknowledge — This write-only bit is used to acknowledge real-time interrupt request
(write 1 to clear RTIF). Writing 0 has no meaning or effect. Reads always return 0.
5
RTICLKS
Real-Time Interrupt Clock Select — This read/write bit selects the clock source for the real-time interrupt.
0 Real-time interrupt request clock source is internal 1-kHz oscillator.
1 Real-time interrupt request clock source is internal trimmed 32-kHz oscillator (ICS module) and is divided by
32 in RTI logic to produce a trimmed 1-kHz clock source for RTI counter.
Chapter 5 Resets, Interrupts, and General System Control
MC9RS08KA2 Series Data Sheet, Rev. 4
42 Freescale Semiconductor
NOTE
To power down the internal 1-kHz oscillator completely in MCU STOP
mode, RTIS bits must be selected to %000 and RTICLKS bit must be set
to 1.
4
RTIE
Real-Time Interrupt Enable — This read-write bit enables real-time interrupts.
0 Real-time interrupts disabled.
1 Real-time interrupts enabled.
2:0
RTIS
Real-Time Interrupt Delay Selects — These read/write bits select the period for the RTI. See Table 5 -7 .
Table 5-7. Real-Time Interrupt Period
RTIS RTI Timeout1
1Timeout values shown based on RTI clock source of 1 ms period. Consult
electricals for tolerances of internal 1-kHz source, tRTI (Ta bl e A- 8) and the
internal 32-kHz from ICS (Ta b l e A - 7 ).
000 Disable RTI
001 8 ms
010 32 ms
011 64 ms
100 128 ms
101 256 ms
110 512 ms
111 1.024 s
Table 5-6. SRTISC Register Field Descriptions (continued)
Field Description
Chapter 5 Resets, Interrupts, and General System Control
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 43
5.8.5 System Power Management Status and Control 1 Register
(SPMSC1)
This high page register contains status and control bits to support the low voltage detect function, and to
enable the bandgap voltage reference for use by the ACMP and the LVD module.
Figure 5-6. System Power Management Status and Control 1 Register (SPMSC1)
76543210
RLVDF 0
LVDIE LVDRE(1)
1This bit can be written only one time after reset. Additional writes are ignored.
LVDSE LV D E(1) 0
BGBE
WLVDACK
Reset:00011100
= Unimplemented or Reserved
Table 5-8. SPMSC1 Register Field Descriptions
Field Description
7
LVD F
Low-Voltage Detect Flag — Provided LVDE = 1, this read-only status bit indicates a low-voltage detect event.
6
LVDACK
Low-Voltage Detect Acknowledge — This write-only bit is used to acknowledge low voltage detection errors
(write 1 to clear LVDF). Reads always return 0.
5
LVD IE
Low-Voltage Detect Interrupt Enable — This bit enables hardware interrupt requests for LVDF.
0 Hardware interrupt disabled (use polling).
1 Request a hardware interrupt when LVDF = 1.
4
LVDRE
Low-Voltage Detect Reset Enable — This write-once bit enables low-voltage detect events to generate a
hardware reset (provided LVDE = 1).
0 LVDF does not generate hardware resets.
1 Force an MCU reset when LVDF = 1.
3
LVDSE
Low-Voltage Detect Stop Enable — Provided LVDE = 1, this read/write bit determines whether the low-voltage
detect function operates when the MCU is in stop mode.
0 Low-voltage detect disabled during stop mode.
1 Low-voltage detect enabled during stop mode.
2
LVDE
Low-Voltage Detect Enable — This write-once bit enables low-voltage detect logic and qualifies the operation
of other bits in this register.
0 LVD logic disabled.
1 LVD logic enabled.
0
BGBE
Bandgap Buffer Enable — This bit enables an internal buffer for the bandgap voltage reference for use by the
ACMP module on one of its internal channels.
0 Bandgap buffer disabled.
1 Bandgap buffer enabled.
Chapter 5 Resets, Interrupts, and General System Control
MC9RS08KA2 Series Data Sheet, Rev. 4
44 Freescale Semiconductor
5.8.6 System Interrupt Pending Register (SIP1)
This high page register contains status of the pending interrupt from the modules.
Figure 5-7. System Interrupt Pending Register (SIP1)
76543210
R 0 0 0 KBI ACMP MTIM RTI LVD
W
Reset:00000000
= Unimplemented or Reserved
Table 5-9. SIP1 Register Field Descriptions
Field Description
4
KBI
Keyboard Interrupt Pending — This read-only bit indicates there is a pending interrupt from the KBI module.
Clearing the KBF flag of the KBISC register clears this bit. Reset also clears this bit.
0 There is no pending KBI interrupt; i.e., KBF flag and/or KBIE bit is cleared.
1 There is a pending KBI interrupt; i.e., KBF flag and KBIE bit are set.
3
ACMP
Analog Comparator Interrupt Pending — This read-only bit indicates there is a pending interrupt from the
ACMP module. Clearing the ACF flag of the ACMPSC register clears this bit. Reset also clears this bit.
0 There is no pending ACMP interrupt; i.e., ACF flag and/or ACIE bit is cleared.
1 There is a pending a ACMP interrupt; i.e., ACF flag and ACIE bit are set.
2
MTIM
Modulo Timer Interrupt Pending — This read-only bit indicates there is a pending interrupt from the MTIM
module. Clearing the TOF flag of the MTIMSC register clears this bit. Reset also clears this bit.
0 There is no pending MTIM interrupt; i.e., TOF flag and/or TOIE bit is cleared.
1 There is a pending MTIM interrupt; i.e., TOF flag and TOIE bit are set.
1
RTI
Real-Time Interrupt Pending — This read-only bit indicates there is a pending interrupt from the RTI. Clearing
the RTIF flag of the SRTISC register clears this bit. Reset also clears this bit.
0 There is no pending RTI interrupt; i.e., RTIF flag and/or RTIE bit is cleared.
1 There is a pending RTI interrupt; i.e., RTIF flag and RTIE bit are set.
0
LVD
Low-Voltage Detect Interrupt Pending — This read-only bit indicates there is a pending interrupt from the low
voltage detect module. Clearing the LVDF flag of the SPMSC1 register clears this bit. Reset also clears this bit.
0 There is no pending LVD interrupt; i.e., LVDF flag and/or LVDE bit is cleared.
1 There is a pending LVD interrupt; i.e., LVDF flag, LVDIE, and LVDE bits are set.
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 45
Chapter 6
Parallel Input/Output Control
This section explains software controls related to parallel input/output (I/O) and pin control. The
MC9RS08KA2 Series has one parallel I/O port, which includes two I/O pins in the 6-pin package or four
I/O pins in the 8-pin packages, one output-only pin, and one input-only pin. See Chapter 2, “Pins and
Connections,” for more information about pin assignments and external hardware considerations for these
pins.
All of these I/O pins are shared with on-chip peripheral functions as shown in Table 2-1. The peripheral
modules have priority over the I/Os so that when a peripheral is enabled, the I/O functions associated with
the shared pins are disabled. After reset, the shared peripheral functions are disabled so that the pins are
controlled by the I/O. All of the I/Os are configured as inputs (PTADDn = 0) with pullup/pulldown devices
disabled (PTAPEn = 0), except for output-only pin PTA3, which defaults to the BKGD/MS function.
Reading and writing of parallel I/Os is performed through the port data registers. The direction, either input
or output, is controlled through the port data direction registers. The parallel I/O port function for an
individual pin is illustrated in the block diagram shown in Figure 6-1.
Figure 6-1. Parallel I/O Block Diagram
The data direction control bit (PTADDn) determines whether the output buffer for the associated pin is
enabled, and also controls the source for port data register reads. The input buffer for the associated pin is
always enabled unless the pin is enabled as an analog function or is an output-only pin.
QD
QD
1
0
Port Read
PTADDn
PTADn
Output Enable
Output Data
Input Data
Synchronizer
Data
BUSCLK
Chapter 6 Parallel Input/Output Control
MC9RS08KA2 Series Data Sheet, Rev. 4
46 Freescale Semiconductor
When a shared digital function is enabled for a pin, the output buffer is controlled by the shared function.
However, the data direction register bit will continue to control the source for reads of the port data register.
When a shared analog function is enabled for a pin, both the input and output buffers are disabled. A value
of 0 is read for any port data bit where the bit is an input (PTADDn = 0) and the input buffer is disabled.
In general, whenever a pin is shared with both an alternative digital function and an analog function, the
analog function has priority such that if both the digital and analog functions are enabled, the analog
function controls the pin.
It is a good programming practice to write to the port data register before changing the direction of a port
pin to become an output. This ensures that the pin will not be driven temporarily with an old data value
that happened to be in the port data register.
Associated with the parallel I/O ports is a set of registers located in the high page register space that operate
independently of the parallel I/O registers. These registers are used to control pullup/pulldown and slew
rate for the pins. See Section 6.3, “Pin Control Registers” for more information.
6.1 Pin Behavior in Low-Power Modes
In wait and stop modes, all pin states are maintained because internal logic stays powered up. Upon
recovery, all pin functions are the same as before entering stop.
6.2 Parallel I/O Registers
This section provides information about the registers associated with the parallel I/O ports. The parallel
I/O registers are located within the $001F memory boundary of the memory map, so that short and direct
addressing mode instructions can be used.
Refer to tables in Chapter 4, “Memory,” for the absolute address assignments for all parallel I/O. This
section refers to registers and control bits only by their names. A Freescale Semiconductor-provided
equate or header file normally is used to translate these names into the appropriate absolute addresses.
6.2.1 Port A Registers
Port A parallel I/O function is controlled by the data and data direction registers described in this section.
76543210
R00
PTAD5 PTAD4 PTAD3
PTAD2
PTAD1 PTAD0
W
Reset:00000000
Figure 6-2. Port A Data Register (PTAD)
Chapter 6 Parallel Input/Output Control
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 47
6.3 Pin Control Registers
This section provides information about the registers associated with the parallel I/O ports that are used
for pin control functions.
Refer to tables in Chapter 4, “Memory,” for the absolute address assignments of the pin control registers.
This section refers to registers and control bits only by their names. A Freescale Semiconductor-provided
equate or header file normally is used to translate these names into the appropriate absolute addresses.
6.3.1 Port A Pin Control Registers
The pins associated with port A are controlled by the registers provided in this section. These registers
control the pin pullup/pulldown and slew rate of the port A pins independent of the parallel I/O registers.
6.3.1.1 Internal Pulling Device Enable
An internal pulling device can be enabled for each port pin by setting the corresponding bit in the pulling
device enable register (PTAPEn). The pulling device is disabled if the pin is configured as an output by the
parallel I/O control logic or any shared peripheral output function regardless of the state of the
Table 6-1. PTAD Register Field Descriptions
Field Description
5:0
PTAD[5:0]
Port A Data Register Bits — For port A pins that are inputs, reads return the logic level on the pin. For port A
pins that are configured as outputs, reads return the last value written to this register. Writes are latched into all
bits of this register. For port A pins that are configured as outputs, the logic level is driven out the corresponding
MCU pin.
Reset forces PTAD to all 0s, but these 0s are not driven out the corresponding pins because reset also configures
all port pins as high-impedance inputs with pullup/pulldowns disabled.
76543210
R00
PTADD5 PTADD4 00
PTADD1 PTADD0
W
Reset:00000000
Figure 6-3. Port A Data Direction Register (PTADD)
Table 6-2. PTADD Register Field Descriptions
Field Description
5:4,1:0
PTADD[5:4,1:0]
Data Direction for Port A Bits — These read/write bits control the direction of port A pins and what is read
for PTAD reads.
0 Input (output driver disabled) and reads return the pin value.
1 Output driver enabled for port A bit n and PTAD reads return the contents of PTADn.
Chapter 6 Parallel Input/Output Control
MC9RS08KA2 Series Data Sheet, Rev. 4
48 Freescale Semiconductor
corresponding pulling device enable register bit. The pulling device is also disabled if the pin is controlled
by an analog function.
6.3.1.2 Pullup/Pulldown Control
Pullup/pulldown control is used to select the pullup or pulldown device enabled by the corresponding
PTAPE bit.
Figure 6-5. Pullup/Pulldown Device Control for Port A (PTAPUD)
6.3.1.3 Output Slew Rate Control Enable
Slew rate control can be enabled for each port pin by setting the corresponding bit in the slew rate control
register (PTASEn). When enabled, slew control limits the rate at which an output can transition in order to
reduce EMC emissions. Slew rate control has no effect on pins that are configured as inputs.
76543210
R00
PTAPE5 PTAPE4 0PTAPE2 PTAPE1 PTAPE0
W
Reset:00000000
Figure 6-4. Internal Pulling Device Enable for Port A Register (PTAPE)
Table 6-3. PTAPE Register Field Descriptions
Field Description
5:4,2:0
PTAPE[5:4,2:0]
Internal Pulling Device Enable for Port A Bits — Each of these control bits determines whether the internal
pulling device is enabled for the associated PTA pin. For port A pins that are configured as outputs, these bits
have no effect and the internal pullup devices are disabled.
0 Internal pulling device disabled for port A bit n.
1 Internal pulling device enabled for port A bit n.
76543210
R00
PTAPUD5 PTAPUD4 0PTAPUD2 PTAPUD1 PTAPUD0
W
Reset:00000000
Table 6-4. PTAPUD Register Field Descriptions
Field Description
5:4,2:0
PTAPUD[5:4,2:0]
Pullup/Pulldown Device Control for Port A Bits — Each of these control bits determines whether the
internal pullup or pulldown device is selected for the associated PTA pin. The actual pullup/pulldown device
is only enabled by enabling the associated PTAPE bit.
0 Internal pullup device is selected for port A bit n.
1 Internal pulldown device is selected for port A bit n.
Chapter 6 Parallel Input/Output Control
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 49
76543210
R00
PTASE5 PTASE4 PTASE3 0PTASE1 PTASE0
W
Reset:00111011
Figure 6-6. Slew Rate Enable for Port A Register (PTASE)
Table 6-5. PTASE Register Field Descriptions
Field Description
5:3;1:0
PTASE[5:3;1:0]
Output Slew Rate Enable for Port A Bits — Each of these control bits determines whether the output slew
rate control is enabled for the associated PTA pin. For port A pins that are configured as inputs, these bits have
no effect.
0 Output slew rate control disabled for port A bit n.
1 Output slew rate control enabled for port A bit n.
Chapter 6 Parallel Input/Output Control
MC9RS08KA2 Series Data Sheet, Rev. 4
50 Freescale Semiconductor
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 51
Chapter 7
Keyboard Interrupt (RS08KBIV1)
7.1 Introduction
The keyboard interrupt (KBI) module provides independently enabled external interrupt sources.
Figure 7-1. MC9RS08KA2 Series Block Diagram with KBI Block and Pins Highlighted
7.1.1 Features
The KBI features include:
• Each keyboard interrupt pin has an individual pin enable bit
• Each keyboard interrupt pin is programmable as falling edge (or rising edge) only, or both falling
edge and low level (or both rising edge and high level) interrupt sensitivity
• One software-enabled keyboard interrupt
• Exit from low-power modes
RS08 CORE
USER FLASH — 2,048 BYTES
USER RAM — 63 BYTES
NOTES:
(1) Pins are software configurable with pullup/pulldown device if input port.
(2) Integrated pullup device enabled if reset enabled (RSTPE=1).
(3) These pins are not available in 6-pin package
POWER AND
PTA
VSS
VDD
INTERNAL CLOCK
SOURCE
BDC
RS08 SYSTEM CONTROL
RTI
CPU
COP
WAKEUP LVD
RESET AND STOP WAKEUP
MODES OF OPERATION
POWER MANAGEMENT
5-BIT KEYBOARD
INTERRUPT MODULE
PTA0/KBIP0/ACMP+ (1)
PTA1/KBIP1/ACMP- (1)
PTA2/KBIP2/TCLK/RESET/VPP (1),( 2)
PTA3/ACMPO/BKGD/MS
ANALOG COMPARATOR
MODULE
MODULO TIMER
MODULE
PTA4/KBIP4 (1),(3)
PTA5/KBIP5 (1), (3)
INTERNAL REGULATOR
(KBI)
5
TCLK
ACMP-
ACMP+
ACMPO
(ICS)
(ACMP)
(MTIM)
Chapter 7 Keyboard Interrupt (RS08KBIV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
52 Freescale Semiconductor
7.1.2 Modes of Operation
This section defines the KBI operation in wait, stop, and background debug modes.
7.1.2.1 Operation in Wait Mode
The KBI continues to operate in wait mode if enabled before executing the WAIT instruction. Therefore,
an enabled KBI pin (KBPEn = 1) can be used to bring the MCU out of wait mode if the KBI interrupt is
enabled (KBIE = 1).
7.1.2.2 Operation in Stop Mode
The KBI operates asynchronously in stop mode if enabled before executing the STOP instruction.
Therefore, an enabled KBI pin (KBPEn = 1) can be used to bring the MCU out of stop mode if the KBI
interrupt is enabled (KBIE = 1).
7.1.2.3 Operation in Active Background Mode
When the microcontroller is in active background mode, the KBI will continue to operate normally.
7.1.3 Block Diagram
The block diagram for the keyboard interrupt module is shown Figure 7-2.
Figure 7-2. Keyboard Interrupt (KBI) Block Diagram
7.2 External Signal Description
The KBI input pins can be used to detect either falling edges, or both falling edge and low level interrupt
requests. The KBI input pins can also be used to detect either rising edges, or both rising edge and high
level interrupt requests.
The signal properties of KBI are shown in Table 7-1.
Table 7-1. Signal Properties
Signal Function I/O
KBIPn Keyboard interrupt pins I
DQ
CK
CLR
V
DD
KBMOD
KBIE
KEYBOARD
INTERRUPT FF
KBACK
RESET
SYNCHRONIZER
KBF
STOP BYPASS
STOP
BUSCLK
KBIPEn
0
1
S
KBEDGn
KBIPE0
0
1
S
KBEDG0
KBIP0
KBIPn
KBI
INTERRUPT
REQUEST
Chapter 7 Keyboard Interrupt (RS08KBIV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 53
7.3 Register Definition
The KBI includes three registers:
• An 8-bit pin status and control register
• An 8-bit pin enable register
• An 8-bit edge select register
Refer to the direct-page register summary in Chapter 4, “Memory,” for the absolute address assignments
for all KBI registers. This section refers to registers and control bits only by their names.
The KBI registers are summarized in Table 7-2.
7.3.1 KBI Status and Control Register (KBISC)
KBISC contains the status flag and control bits, which are used to configure the KBI.
Table 7-2. KBI Register Summary
Name 76543210
KBISC
R0000KBF0
KBIE KBMOD
WKBACK
KBIPE
R0 0
KBIPE5 KBIPE4
0
KBIPE2 KBIPE1 KBIPE0
W
KBIES
R0 0
KBEDG5 KBEDG4
0
KBEDG2 KBEDG1 KBEDG0
W
76543210
R 0 0 0 0 KBF 0
KBIE KBMOD
WKBACK
Reset:00000000
= Unimplemented
Figure 7-3. KBI Status and Control Register (KBISC)
Table 7-3. KBISC Register Field Descriptions
Field Description
3
KBF
Keyboard Interrupt Flag — KBF indicates that a keyboard interrupt is detected. Writes have no effect on KBF.
0 No keyboard interrupt detected.
1 Keyboard interrupt detected.
2
KBACK
Keyboard Acknowledge — Writing a 1 to KBACK is part of the flag-clearing mechanism. KBACK always reads
as 0.
Chapter 7 Keyboard Interrupt (RS08KBIV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
54 Freescale Semiconductor
7.3.2 KBI Pin Enable Register (KBIPE)
KBIPE contains the pin enable control bits.
7.3.3 KBI Edge Select Register (KBIES)
KBIES contains the edge select control bits.
1
KBIE
Keyboard Interrupt Enable — KBIE enables keyboard interrupt requests.
0 Keyboard interrupt request not enabled.
1 Keyboard interrupt request enabled.
0
KBMOD
Keyboard Detection Mode — KBMOD (along with the KBEDG bits) controls the detection mode of the keyboard
interrupt pins.
0 Keyboard detects edges only.
1 Keyboard detects both edges and levels.
76543210
R0 0
KBIPE5 KBIPE4
0
KBIPE2 KBIPE1 KBIPE0
W
Reset:00000000
Figure 7-4. KBI Pin Enable Register (KBIPE)
Table 7-4. KBIPE Register Field Descriptions
Field Description
5,4, 2:0
KBIPEn
Keyboard Pin Enables — Each of the KBIPEn bits enables the corresponding keyboard interrupt pin.
0 Corresponding pin not enabled as keyboard interrupt.
1 Corresponding pin enabled as keyboard interrupt.
76543210
R0 0
KBEDG5 KBEDG4
0
KBEDG2 KBEDG1 KBEDG0
W
Reset:00000000
Figure 7-5. KBI Edge Select Register (KBIES)
Table 7-5. KBIES Register Field Descriptions
Field Description
5,4, 2:0
KBEDGn
Keyboard Edge Selects — Each of the KBEDGn bits selects the falling edge/low level or rising edge/high level
function of the corresponding pin.
0 Falling edge/low level.
1 Rising edge/high level.
Table 7-3. KBISC Register Field Descriptions (continued)
Field Description
Chapter 7 Keyboard Interrupt (RS08KBIV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 55
7.4 Functional Description
This on-chip peripheral module is called a keyboard interrupt (KBI) module because it was originally
designed to simplify the connection and use of row-column matrices of keyboard switches. However, these
inputs are also useful as extra external interrupt inputs and as an external means of waking the MCU from
stop or wait low-power modes.
The KBI module allows its pins to act as additional interrupt sources. Writing to the KBIPEn bits in the
keyboard interrupt pin enable register (KBIPE) independently enables or disables each KBI pin. Each KBI
pin can be configured as edge sensitive or edge and level sensitive based on the KBMOD bit in the
keyboard interrupt status and control register (KBISC). Edge sensitive can be software programmed to be
either falling or rising; the level can be either low or high. The polarity of the edge or edge and level
sensitivity is selected using the KBEDGn bits in the keyboard interrupt edge select register (KBIES).
Synchronous logic is used to detect edges. Prior to detecting an edge, enabled keyboard inputs must be at
the deasserted logic level. A falling edge is detected when an enabled keyboard input signal is seen as a
logic 1 (the deasserted level) during one bus cycle and then a logic 0 (the asserted level) during the next
cycle. A rising edge is detected when the input signal is seen as a logic 0 during one bus cycle and then a
logic 1 during the next cycle.
7.4.1 Edge Only Sensitivity
A valid edge on an enabled KBI pin will set KBF in KBISC. If KBIE in KBISC is set, an interrupt request
will be presented to the CPU. Clearing of KBF is accomplished by writing a 1 to KBACK in KBISC.
7.4.2 Edge and Level Sensitivity
A valid edge or level on an enabled KBI pin will set KBF in KBISC. If KBIE in KBISC is set, an interrupt
request will be presented to the CPU. Clearing of KBF is accomplished by writing a 1 to KBACK in
KBISC, provided all enabled keyboard inputs are at their deasserted levels. KBF will remain set if any
enabled KBI pin is asserted while attempting to clear by writing a 1 to KBACK.
7.4.3 KBI Pullup/Pulldown Device
The KBI pins does not automatically configure an internal pullup/pulldown device when a KBI pin is
enabled. An internal pull device can be used by configuring the associated I/O port pull device enable
register (PTAPE) and pullup/pulldown control register (PTAPUD).
7.4.4 KBI Initialization
When a keyboard interrupt pin is first enabled, it is possible to get a false keyboard interrupt flag. To
prevent a false interrupt request during keyboard initialization, the user should do the following:
1. Mask keyboard interrupts by clearing KBIE in KBISC.
2. If using internal pullup/pulldown device, configure the associated I/O port pullup/pulldown device.
3. Enable the KBI polarity by setting the appropriate KBEDGn bits in KBIES.
4. Enable the KBI pins by setting the appropriate KBIPEn bits in KBIPE.
Chapter 7 Keyboard Interrupt (RS08KBIV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
56 Freescale Semiconductor
5. Write to KBACK in KBISC to clear any false interrupts.
6. Set KBIE in KBISC to enable interrupts.
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 57
Chapter 8
Central Processor Unit (RS08CPUV1)
8.1 Introduction
This chapter is a summary of information about the registers, addressing modes, and instruction set of the
RS08 Family CPU. For a more detailed discussion, refer to the RS08 Core Reference Manual, volume 1,
Freescale Semiconductor document order number RS08RMv1.
The RS08 CPU has been developed to target extremely low-cost embedded applications using a
process-independent design methodology, allowing it to keep pace with rapid developments in silicon
processing technology.
The main features of the RS08 core are:
• Streamlined programmer’s model
• Subset of HCS08 instruction set with minor instruction extensions
• Minimal instruction set for cost-sensitive embedded applications
• New instructions for shadow program counter manipulation, SHA and SLA
• New short and tiny addressing modes for code size optimization
• 16K bytes accessible memory space
• Reset will fetch the first instruction from $3FFD
• Low-power modes supported through the execution of the STOP and WAIT instructions
• Debug and FLASH programming support using the background debug controller module
• Illegal address and opcode detection with reset
8.2 Programmer’s Model and CPU Registers
Figure 8-1 shows the programmer’s model for the RS08 CPU. These registers are not located in the
memory map of the microcontroller. They are built directly inside the CPU logic.
Chapter 8 Central Processor Unit (RS08CPUV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
58 Freescale Semiconductor
Figure 8-1. CPU Registers
In addition to the CPU registers, there are three memory mapped registers that are tightly coupled with the
core address generation during data read and write operations. They are the indexed data register (D[X]),
the index register (X), and the page select register (PAGESEL). These registers are located at $000E,
$000F, and $001F, respectively.
Figure 8-2. Memory Mapped Registers
8.2.1 Accumulator (A)
This general-purpose 8-bit register is the primary data register for RS08 MCUs. Data can be read from
memory into A with a load accumulator (LDA) instruction. The data in A can be written into memory with
a store accumulator (STA) instruction. Various addressing mode variations allow a great deal of flexibility
in specifying the memory location involved in a load or store instruction. Exchange instructions allow
values to be exchanged between A and SPC high (SHA) and also between A and SPC low (SLA).
Arithmetic, shift, and logical operations can be performed on the value in A as in ADD, SUB, RORA,
INCA, DECA, AND, ORA, EOR, etc. In some of these instructions, such as INCA and LSLA, the value
in A is the only input operand and the result replaces the value in A. In other cases, such as ADD and AND,
there are two operands: the value in A and a second value from memory. The result of the arithmetic or
logical operation replaces the value in A.
Some instructions, such as memory-to-memory move instructions (MOV), do not use the accumulator.
DBNZ also relieves A because it allows a loop counter to be implemented in a memory variable rather than
the accumulator.
During reset, the accumulator is loaded with $00.
PC
SPC
CARRY
ZERO
0
0
0
7
13
13
ACCUMULATOR A
SHADOW PROGRAM COUNTER
87
PROGRAM COUNTER
CCRCZ
CONDITION CODE REGISTER
07
07
07
INDEXED DATA REGISTER D[X] (location $000E)
INDEX REGISTER X (location $000F)
PAGE SELECT REG PAGESEL (location $001F)
Chapter 8 Central Processor Unit (RS08CPUV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 59
8.2.2 Program Counter (PC)
The program counter is a 14-bit register that contains the address of the next instruction or operand to be
fetched.
During normal execution, the program counter automatically increments to the next sequential memory
location each time an instruction or operand is fetched. Jump, branch, and return operations load the
program counter with an address other than that of the next sequential location. This is called a
change-of-flow.
During reset, the program counter is loaded with $3FFD and the program will start execution from this
specific location.
8.2.3 Shadow Program Counter (SPC)
The shadow program counter is a 14-bit register. During a subroutine call using either a JSR or a BSR
instruction, the return address will be saved into the SPC. Upon completion of the subroutine, the RTS
instruction will restore the content of the program counter from the shadow program counter.
During reset, the shadow program counter is loaded with $3FFD.
8.2.4 Condition Code Register (CCR)
The 2-bit condition code register contains two status flags. The content of the CCR in the RS08 is not
directly readable. The CCR bits can be tested using conditional branch instructions such as BCC and BEQ.
These two register bits are directly accessible through the BDC interface. The following paragraphs
provide detailed information about the CCR bits and how they are used. Figure 8-3 identifies the CCR bits
and their bit positions.
Figure 8-3. Condition Code Register (CCR)
The status bits (Z and C) are cleared to 0 after reset.
The two status bits indicate the results of arithmetic and other instructions. Conditional branch instructions
will either branch to a new program location or allow the program to continue to the next instruction after
the branch, depending on the values in the CCR status bit. Conditional branch instructions, such as BCC,
BCS, and BNE, cause a branch depending on the state of a single CCR bit.
Often, the conditional branch immediately follows the instruction that caused the CCR bit(s) to be updated,
as in this sequence:
cmp #5 ;compare accumulator A to 5
blo lower ;branch if A smaller 5
more: deca ;do this if A not higher than or same as 5
lower:
CARRY
ZERO
CCR
CZ
CONDITION CODE REGISTER
Chapter 8 Central Processor Unit (RS08CPUV1)
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60 Freescale Semiconductor
Other instructions may be executed between the test and the conditional branch as long as the only
instructions used are those which do not disturb the CCR bits that affect the conditional branch. For
instance, a test is performed in a subroutine or function and the conditional branch is not executed until the
subroutine has returned to the main program. This is a form of parameter passing (that is, information is
returned to the calling program in the condition code bits).
Z — Zero Flag
The Z bit is set to indicate the result of an operation was $00.
Branch if equal (BEQ) and branch if not equal (BNE) are simple branches that branch based solely
on the value in the Z bit. All load, store, move, arithmetic, logical, shift, and rotate instructions
cause the Z bit to be updated.
C — Carry
After an addition operation, the C bit is set if the source operands were both greater than or equal
to $80 or if one of the operands was greater than or equal to $80 and the result was less than $80.
This is equivalent to an unsigned overflow. A subtract or compare performs a subtraction of a
memory operand from the contents of a CPU register so after a subtract operation, the C bit is set
if the unsigned value of the memory operand was greater than the unsigned value of the CPU
register. This is equivalent to an unsigned borrow or underflow.
Branch if carry clear (BCC) and branch if carry set (BCS) are branches that branch based solely on
the value in the C bit. The C bit is also used by the unsigned branches BLO and BHS. Add, subtract,
shift, and rotate instructions cause the C bit to be updated. The branch if bit set (BRSET) and
branch if bit clear (BRCLR) instructions copy the tested bit into the C bit to facilitate efficient
serial-to-parallel conversion algorithms. Set carry (SEC) and clear carry (CLC) allow the carry bit
to be set or cleared directly. This is useful in combination with the shift and rotate instructions and
for routines that pass status information back to a main program, from a subroutine, in the C bit.
The C bit is included in shift and rotate operations so those operations can easily be extended to
multi-byte operands. The shift and rotate operations can be considered 9-bit shifts that include an
8-bit operand or CPU register and the carry bit of the CCR. After a logical shift, C holds the bit that
was shifted out of the 8-bit operand. If a rotate instruction is used next, this C bit is shifted into the
operand for the rotate, and the bit that gets shifted out the other end of the operand replaces the
value in C so it can be used in subsequent rotate instructions.
8.2.5 Indexed Data Register (D[X])
This 8-bit indexed data register allows the user to access the data in the direct page address space indexed
by X. This register resides at the memory mapped location $000E. For details on the D[X] register, please
refer to Section 8.3.8, “Indexed Addressing Mode (IX, Implemented by Pseudo Instructions).”
8.2.6 Index Register (X)
This 8-bit index register allows the user to index or address any location in the direct page address space.
This register resides at the memory mapped location $000F. For details on the X register, please refer to
Section 8.3.8, “Indexed Addressing Mode (IX, Implemented by Pseudo Instructions).”
Chapter 8 Central Processor Unit (RS08CPUV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 61
8.2.7 Page Select Register (PAGESEL)
This 8-bit page select register allows the user to access all memory locations in the entire
16K-byte address space through a page window located from $00C0 to $00FF. This register
resides at the memory mapped location $001F. For details on the PAGESEL register, please refer to
the RS08 Core Reference Manual.
8.3 Addressing Modes
Whenever the MCU reads information from memory or writes information into memory, an addressing
mode is used to determine the exact address where the information is read from or written to. This section
explains several addressing modes and how each is useful in different programming situations.
Every opcode tells the CPU to perform a certain operation in a certain way. Many instructions, such as load
accumulator (LDA), allow several different ways to specify the memory location to be operated on, and
each addressing mode variation requires a separate opcode. All of these variations use the same instruction
mnemonic, and the assembler knows which opcode to use based on the syntax and location of the operand
field. In some cases, special characters are used to indicate a specific addressing mode (such as the #
[pound] symbol, which indicates immediate addressing mode). In other cases, the value of the operand
tells the assembler which addressing mode to use. For example, the assembler chooses short addressing
mode instead of direct addressing mode if the operand address is from $0000 to $001F. Besides allowing
the assembler to choose the addressing mode based on the operand address, assembler directives can also
be used to force direct or tiny/short addressing mode by using the “>” or “<” prefix before the operand,
respectively.
Some instructions use more than one addressing mode. For example, the move instructions use one
addressing mode to access the source value from memory and a second addressing mode to access the
destination memory location. For these move instructions, both addressing modes are listed in the
documentation. All branch instructions use relative (REL) addressing mode to determine the destination
for the branch, but BRCLR, BRSET, CBEQ, and DBNZ also must access a memory operand. These
instructions are classified by the addressing mode used for the memory operand, and the relative
addressing mode for the branch offset is assumed.
The discussion in the following paragraphs includes how each addressing mode works and the syntax clues
that instruct the assembler to use a specific addressing mode.
8.3.1 Inherent Addressing Mode (INH)
This addressing mode is used when the CPU inherently knows everything it needs to complete the
instruction and no addressing information is supplied in the source code. Usually, the operands that the
CPU needs are located in the CPU’s internal registers, as in LSLA, CLRA, INCA, SLA, RTS, and others.
A few inherent instructions, including no operation (NOP) and background (BGND), have no operands.
8.3.2 Relative Addressing Mode (REL)
Relative addressing mode is used to specify the offset address for branch instructions relative to the
program counter. Typically, the programmer specifies the destination with a program label or an
Chapter 8 Central Processor Unit (RS08CPUV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
62 Freescale Semiconductor
expression in the operand field of the branch instruction; the assembler calculates the difference between
the location counter (which points at the next address after the branch instruction at the time) and the
address represented by the label or expression in the operand field. This difference is called the offset and
is an 8-bit two’s complement number. The assembler stores this offset in the object code for the branch
instruction.
During execution, the CPU evaluates the condition that controls the branch. If the branch condition is true,
the CPU sign-extends the offset to a 14-bit value, adds the offset to the current PC, and uses this as the
address where it will fetch the next instruction and continue execution rather than continuing execution
with the next instruction after the branch. Because the offset is an 8-bit two’s complement value, the
destination must be within the range –128 to +127 locations from the address that follows the last byte of
object code for the branch instruction.
A common method to create a simple infinite loop is to use a branch instruction that branches to itself. This
is sometimes used to end short code segments during debug. Typically, to get out of this infinite loop, use
the debug host (through background commands) to stop the program, examine registers and memory, or
to start execution from a new location. This construct is not used in normal application programs except
in the case where the program has detected an error and wants to force the COP watchdog timer to timeout.
(The branch in the infinite loop executes repeatedly until the watchdog timer eventually causes a reset.)
8.3.3 Immediate Addressing Mode (IMM)
In this addressing mode, the operand is located immediately after the opcode in the instruction stream. This
addressing mode is used when the programmer wants to use an explicit value that is known at the time the
program is written. A # (pound) symbol is used to tell the assembler to use the operand as a data value
rather than an address where the desired value will be accessed.
The size of the immediate operand is always 8 bits. The assembler automatically will truncate or extend
the operand as needed to match the size needed for the instruction. Most assemblers generate a warning if
a 16-bit operand is provided.
It is the programmer’s responsibility to use the # symbol to tell the assembler when immediate addressing
will be used. The assembler does not consider it an error to leave off the # symbol because the resulting
statement is still a valid instruction (although it may mean something different than the programmer
intended).
8.3.4 Tiny Addressing Mode (TNY)
TNY addressing mode is capable of addressing only the first 16 bytes in the address map, from $0000 to
$000F. This addressing mode is available for INC, DEC, ADD, and SUB instructions. A system can be
optimized by placing the most computation-intensive data in this area of memory.
Because the 4-bit address is embedded in the opcode, only the least significant four bits of the address must
be included in the instruction; this saves program space and execution time. During execution, the CPU
adds 10 high-order 0s to the 4-bit operand address and uses the combined 14-bit address ($000x) to access
the intended operand.
Chapter 8 Central Processor Unit (RS08CPUV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 63
8.3.5 Short Addressing Mode (SRT)
SRT addressing mode is capable of addressing only the first 32 bytes in the address map, from $0000 to
$001F. This addressing mode is available for CLR, LDA, and STA instructions. A system can be optimized
by placing the most computation-intensive data in this area of memory.
Because the 5-bit address is embedded in the opcode, only the least significant five bits of the address must
be included in the instruction; this saves program space and execution time. During execution, the CPU
adds nine high-order 0s to the 5-bit operand address and uses the combined 14-bit address ($000x or
$001x) to access the intended operand.
8.3.6 Direct Addressing Mode (DIR)
DIR addressing mode is used to access operands located in direct address space ($0000 through $00FF).
During execution, the CPU adds six high-order 0s to the low byte of the direct address operand that follows
the opcode. The CPU uses the combined 14-bit address ($00xx) to access the intended operand.
8.3.7 Extended Addressing Mode (EXT)
In the extended addressing mode, the 14-bit address of the operand is included in the object code in the
low-order 14 bits of the next two bytes after the opcode. This addressing mode is only used in JSR and
JMP instructions for jump destination address in RS08 MCUs.
8.3.8 Indexed Addressing Mode (IX, Implemented by Pseudo Instructions)
Indexed addressing mode is sometimes called indirect addressing mode because an index register is used
as a reference to access the intended operand.
An important feature of indexed addressing mode is that the operand address is computed during execution
based on the current contents of the X index register located in $000F of the memory map rather than being
a constant address location that was determined during program assembly. This allows writing of a
program that accesses different operand locations depending on the results of earlier program instructions
(rather than accessing a location that was determined when the program was written).
The index addressing mode supported by the RS08 Family uses the register X located at $000F as an index
and D[X] register located at $000E as the indexed data register. By programming the index register X, any
location in the direct page can be read/written via the indexed data register D[X].
These pseudo instructions can be used with all instructions supporting direct, short, and tiny addressing
modes by using the D[X] as the operand.
8.4 Special Operations
Most of what the CPU does is described by the instruction set, but a few special operations must be
considered, such as how the CPU starts at the beginning of an application program after power is first
applied. After the program begins running, the current instruction normally determines what the CPU will
do next. Two exceptional events can cause the CPU to temporarily suspend normal program execution:
Chapter 8 Central Processor Unit (RS08CPUV1)
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64 Freescale Semiconductor
• Reset events force the CPU to start over at the beginning of the application program, which forces
execution to start at $3FFD.
• A host development system can cause the CPU to go to active background mode rather than
continuing to the next instruction in the application program.
8.4.1 Reset Sequence
Processing begins at the trailing edge of a reset event. The number of things that can cause reset events can
vary slightly from one RS08 derivative to another; however, the most common sources are: power-on
reset, the external RESET pin, low-voltage reset, COP watchdog timeout, illegal opcode detect, and illegal
address access. For more information about how the MCU recognizes reset events and determines the
difference between internal and external causes, refer to the Resets and Interrupts chapter.
Reset events force the MCU to immediately stop what it is doing and begin responding to reset. Any
instruction that was in process will be aborted immediately without completing any remaining clock
cycles. A short sequence of activities is completed to decide whether the source of reset was internal or
external and to record the cause of reset. For the remainder of the time, the reset source remains active and
the internal clocks are stopped to save power. At the trailing edge of the reset event, the clocks resume and
the CPU exits from the reset condition. The program counter is reset to $3FFD and an instruction fetch
will be started after the release of reset.
For the device to execute code from the on-chip memory starting from $3FFD after reset, care must be
taken to not force the BKDG pin low on the end of reset because this will force the device into active
background mode where the CPU will wait for a command from the background communication interface.
8.4.2 Interrupts
The interrupt mechanism in RS08 is not used to interrupt the normal flow of instructions; it is used to wake
up the RS08 from wait and stop modes. In run mode, interrupt events must be polled by the CPU. The
interrupt feature is not compatible with Freescale’s HC05, HC08, or HCS08 Families.
8.4.3 Wait and Stop Mode
Wait and stop modes are entered by executing a WAIT or STOP instruction, respectively. In these modes,
the clocks to the CPU are shut down to save power and CPU activity is suspended. The CPU remains in
this low-power state until an interrupt or reset event wakes it up. Please refer to the Resets and Interrupts
chapter for the effects of wait and stop on other device peripherals.
8.4.4 Active Background Mode
Active background mode refers to the condition in which the CPU has stopped executing user program
instructions and is waiting for serial commands from the background debug system. Refer to the
Development Support chapter for detailed information on active background mode.
The arithmetic left shift pseudo instruction is also available because its operation is identical to logical shift
left.
Chapter 8 Central Processor Unit (RS08CPUV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 65
8.5 Summary Instruction Table
Instruction Set Summary Nomenclature
The nomenclature listed here is used in the instruction descriptions in Table 8-1 through Table 8-2.
Operators
( ) = Contents of register or memory location shown inside parentheses
←= Is loaded with (read: “gets”)
⇔ = Exchange with
& = Boolean AND
| = Boolean OR
⊕= Boolean exclusive-OR
: = Concatenate
+=Add
CPU registers
A = Accumulator
CCR = Condition code register
PC = Program counter
PCH = Program counter, higher order (most significant) six bits
PCL = Program counter, lower order (least significant) eight bits
SPC = Shadow program counter
SPCH = Shadow program counter, higher order (most significant) six bits
SPCL = Shadow program counter, lower order (least significant) eight bits
Memory and addressing
M=A memory location or absolute data, depending on addressing mode
rel = The relative offset, which is the two’s complement number stored in the last
byte of machine code corresponding to a branch instruction
X=Pseudo index register, memory location $000F
,X or D[X] = Memory location $000E pointing to the memory location defined by the
pseudo index register (location $000F)
Condition code register (CCR) bits
Z = Zero indicator
C = Carry/borrow
CCR activity notation
– = Bit not affected
0 = Bit forced to 0
1 = Bit forced to 1
¦= Bit set or cleared according to results of operation
U = Undefined after the operation
Machine coding notation
Chapter 8 Central Processor Unit (RS08CPUV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
66 Freescale Semiconductor
dd = Low-order eight bits of a direct address $0000–$00FF (high byte assumed to
be $00)
ii = One byte of immediate data
hh = High-order 6-bit of 14-bit extended address prefixed with 2-bit of 0
ll = Low-order byte of 14-bit extended address
rr = Relative offset
Source form
Everything in the source forms columns, except expressions in italic characters, is literal information
which must appear in the assembly source file exactly as shown. The initial 3- to 5-letter mnemonic is
always a literal expression. All commas, pound signs (#), parentheses, and plus signs (+) are literal
characters.
n— Any label or expression that evaluates to a single integer in the range 0–7.
x— Any label or expression that evaluates to a single hexadecimal integer in the
range $0–$F.
opr8i — Any label or expression that evaluates to an 8-bit immediate value.
opr4a — Any label or expression that evaluates to a Tiny address (4-bit value). The
instruction treats this 4-bit value as the low order four bits of an address in the
16-Kbyte address space ($0000–$000F). This 4-bit value is embedded in the
low order four bits in the opcode.
opr5a — Any label or expression that evaluates to a Short address (5-bit value). The
instruction treats this 5-bit value as the low order five bits of an address in the
16-Kbyte address space ($0000–$001F). This 5-bit value is embedded in the
low order 5 bits in the opcode.
opr8a — Any label or expression that evaluates to an 8-bit value. The instruction treats
this 8-bit value as the low order eight bits of an address in the 16-Kbyte
address space ($0000–$00FF).
opr16a — Any label or expression that evaluates to a 14-bit value. On the RS08 core, the
upper two bits are always 0s. The instruction treats this value as an address in
the 16-Kbyte address space.
rel — Any label or expression that refers to an address that is within –128 to +127
locations from the next address after the last byte of object code for the current
instruction. The assembler will calculate the 8-bit signed offset and include it in
the object code for this instruction.
Address modes
INH = Inherent (no operands)
IMD = Immediate to Direct (in MOV instruction)
IMM = Immediate
DD = Direct to Direct (in MOV instruction)
DIR = Direct
SRT = Short
TNY = Tiny
EXT = Extended
REL = 8-bit relative offset
Chapter 8 Central Processor Unit (RS08CPUV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 67
Table 8-1. Instruction Set Summary (Sheet 1 of 6)
Source
Form Description Operation
Effect
on
CCR
Address
Mode
Opcode
Operand
Cycles
ZC
ADC #opr8i
ADC opr8a
ADC ,X (1)
ADC X
Add with Carry A ← (A) + (M) + (C)
A ← (A) + (X) + (C)
¦¦
IMM
DIR
IX
DIR
A9
B9
B9
B9
ii
dd
0E
0F
2
3
3
3
ADD #opr8i
ADD opr8a
ADD opr4a
ADD ,X (1)
ADD X
Add without Carry A ← (A) + (M) ¦¦
IMM
DIR
TNY
IX
DIR
AB
BB
6x
6E
6F
ii
dd
2
3
3
3
3
AND #opr8i
AND opr8a
AND ,X (1)
AND X
Logical AND A ← (A) & (M)
A ← (A) & (X)
¦—
IMM
DIR
IX
DIR
A4
B4
B4
B4
ii
dd
0E
0F
2
3
3
3
ASLA(1) Arithmetic Shift Left ¦¦INH 48 1
BCC rel Branch if Carry Bit Clear PC ← (PC) + $0002 + rel, if (C) = 0 — — REL 34 rr 3
BCLR n,opr8a
BCLR n,D[X]
BCLR n,X
Clear Bit n in Memory Mn ← 0 ——
DIR (b0)
DIR (b1)
DIR (b2)
DIR (b3)
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
IX (b0)
IX (b1)
IX (b2)
IX (b3)
IX (b4)
IX (b5)
IX (b6)
IX (b7)
DIR (b0)
DIR (b1)
DIR (b2)
DIR (b3)
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
11
13
15
17
19
1B
1D
1F
11
13
15
17
19
1B
1D
1F
11
13
15
17
19
1B
1D
1F
dd
dd
dd
dd
dd
dd
dd
dd
0E
0E
0E
0E
0E
0E
0E
0E
0F
0F
0F
0F
0F
0F
0F
0F
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
BCS rel Branch if Carry Bit Set
(Same as BLO) PC ← (PC) + $0002 + rel, if (C) = 1 ——REL 35 rr 3
BEQ rel Branch if Equal PC ← (PC) + $0002 + rel, if (Z) = 1 ——REL 37 rr 3
BGND Background Enter Background Debug Mode ——INH BF 5+
1. This is a pseudo instruction supported by the normal RS08 instruction set.
2. This instruction is different from that of the HC08 and HCS08 in that the RS08 does not auto-increment the index register.
C
b0
b7
0
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MC9RS08KA2 Series Data Sheet, Rev. 4
68 Freescale Semiconductor
BHS rel (1) Branch if Higher or Same
(Same as BCC) PC ← (PC) + $0002 + rel, if (C) = 0 ——REL 34 rr 3
BLO rel (1) Branch if Lower (Same
as BCS) PC ← (PC) + $0002 + rel, if (C) = 1 ——REL 35 rr 3
BNE rel Branch if Not Equal PC ← (PC) + $0002 + rel, if (Z) = 0 ——REL 36 rr 3
BRA rel Branch Always PC ← (PC) + $0002 + rel ——REL 30 rr 3
BRN rel (1) Branch Never PC ← (PC) + $0002 ——REL 30 00 3
BRCLR n,opr8a,rel
BRCLR n,D[X],rel
BRCLR n,X,rel
Branch if Bit n in Memory
Clear PC ← (PC) + $0003 + rel, if (Mn) = 0 —¦
DIR (b0)
DIR (b1)
DIR (b2)
DIR (b3)
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
IX (b0)
IX (b1)
IX (b2)
IX (b3)
IX (b4)
IX (b5)
IX (b6)
IX (b7)
DIR (b0)
DIR (b1)
DIR (b2)
DIR (b3)
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
01
03
05
07
09
0B
0D
0F
01
03
05
07
09
0B
0D
0F
01
03
05
07
09
0B
0D
0F
dd rr
dd rr
dd rr
dd rr
dd rr
dd rr
dd rr
dd rr
0E rr
0E rr
0E rr
0E rr
0E rr
0E rr
0E rr
0E rr
0F rr
0F rr
0F rr
0F rr
0F rr
0F rr
0F rr
0F rr
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
Table 8-1. Instruction Set Summary (Sheet 2 of 6)
Source
Form Description Operation
Effect
on
CCR
Address
Mode
Opcode
Operand
Cycles
ZC
1. This is a pseudo instruction supported by the normal RS08 instruction set.
2. This instruction is different from that of the HC08 and HCS08 in that the RS08 does not auto-increment the index register.
Chapter 8 Central Processor Unit (RS08CPUV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 69
BRSET n,opr8a,rel
BRSET n,D[X],rel
BRSET n,X,rel
Branch if Bit n in Memory
Set PC ← (PC) + $0003 + rel, if (Mn) = 1 —¦
DIR (b0)
DIR (b1)
DIR (b2)
DIR (b3)
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
IX (b0)
IX (b1)
IX (b2)
IX (b3)
IX (b4)
IX (b5)
IX (b6)
IX (b7)
DIR (b0)
DIR (b1)
DIR (b2)
DIR (b3)
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
00
02
04
06
08
0A
0C
0E
00
02
04
06
08
0A
0C
0E
00
02
04
06
08
0A
0C
0E
dd rr
dd rr
dd rr
dd rr
dd rr
dd rr
dd rr
dd rr
0E rr
0E rr
0E rr
0E rr
0E rr
0E rr
0E rr
0E rr
0F rr
0F rr
0F rr
0F rr
0F rr
0F rr
0F rr
0F rr
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
BSET n,opr8a
BSET n,D[X]
BSET n,X
Set Bit n in Memory Mn ← 1 ——
DIR (b0)
DIR (b1)
DIR (b2)
DIR (b3)
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
IX (b0)
IX (b1)
IX (b2)
IX (b3)
IX (b4)
IX (b5)
IX (b6)
IX (b7)
DIR (b0)
DIR (b1)
DIR (b2)
DIR (b3)
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
10
12
14
16
18
1A
1C
1E
10
12
14
16
18
1A
1C
1E
10
12
14
16
18
1A
1C
1E
dd
dd
dd
dd
dd
dd
dd
dd
0E
0E
0E
0E
0E
0E
0E
0E
0F
0F
0F
0F
0F
0F
0F
0F
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
Table 8-1. Instruction Set Summary (Sheet 3 of 6)
Source
Form Description Operation
Effect
on
CCR
Address
Mode
Opcode
Operand
Cycles
ZC
1. This is a pseudo instruction supported by the normal RS08 instruction set.
2. This instruction is different from that of the HC08 and HCS08 in that the RS08 does not auto-increment the index register.
Chapter 8 Central Processor Unit (RS08CPUV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
70 Freescale Semiconductor
BSR rel Branch Subroutine
PC ← (PC) + 2
Push PC to shadow PC
PC ← (PC) + rel ——REL AD rr 3
CBEQA #opr8i,rel
CBEQ opr8a,rel
CBEQ ,X,rel (1),(2)
CBEQ X,rel (1)
Compare and Branch if
Equal
PC ← (PC) + $0003 + rel, if (A) – (M) = $00
PC ← (PC) + $0003 + rel, if (A) – (M) = $00
PC ← (PC) + $0003 + rel, if (A) – (X) = $00 ——
IMM
DIR
IX
DIR
41
31
31
31
ii rr
dd rr
0E rr
0F rr
4
5
5
5
CLC Clear Carry Bit C ← 0 —0 INH 38 1
CLR opr8a
CLR opr5a
CLR ,X (1)
CLRA
CLRX (1)
Clear
M ← $00
A ← $00
X ← $00
1—
DIR
SRT
IX
INH
INH
3F
8x / 9x
8E
4F
8F
dd 3
2
2
1
2
CMP #opr8i
CMP opr8a
CMP ,X (1)
CMP X (1)
Compare Accumulator
with Memory
(A) – (M)
(A) – (X)
¦¦
IMM
DIR
IX
INH
A1
B1
B1
B1
ii
dd
0E
0F
2
3
3
3
COMA Complement
(One’s Complement) A ← (A) ¦1INH 43 1
DBNZ opr8a,rel
DBNZ ,X,rel (1)
DBNZA rel
DBNZX rel (1)
Decrement and Branch if
Not Zero
A ← (A) – $01 or M ← (M) - $01
PC ← (PC) + $0003 + rel if (result) ≠ 0 for DBNZ
direct
PC ← (PC) + $0002 + rel if (result) ≠ 0 for
DBNZA
X ← (X) – $01
PC ← (PC) + $0003 + rel if (result) ≠ 0
——
DIR
IX
INH
INH
3B
3B
4B
3B
dd rr
0E rr
rr
0F rr
7
7
4
7
DEC opr8a
DEC opr4a
DEC ,X (1)
DECA
DEC X
Decrement
M ← (M) – $01
A ← (A) – $01
X ← (X) – $01
¦—
DIR
TNY
IX
INH
DIR
3A
5x
5E
4A
5F
dd 5
4
4
1
4
EOR #opr8i
EOR opr8a
EOR ,X (1)
EOR X
Exclusive OR
Memory with
Accumulator
A ← (A ⊕ M)
A ← (A ⊕ X)
¦—
IMM
DIR
IX
DIR
A8
B8
B8
B8
ii
dd
0E
0F
2
3
3
3
INC opr8a
INC opr4a
INC ,X (1)
INCA
INCX (1)
Increment
M ← (M) + $01
A ← (A) + $01
X ← (X) + $01
¦—
DIR
TNY
IX
INH
INH
3C
2x
2E
4C
2F
dd 5
4
4
1
4
JMP opr16a Jump PC ← Effective Address — — EXT BC hh ll 4
JSR opr16a Jump to Subroutine
PC ← (PC) + 3
Push PC to shadow PC
PC ← Effective Address — — EXT BD hh ll 4
LDA #opr8i
LDA opr8a
LDA opr5a
LDA ,X (1)
Load Accumulator from
Memory A ← (M) ¦—
IMM
DIR
SRT
IX
A6
B6
Cx/Dx
CE
ii
dd
2
3
3
3
Table 8-1. Instruction Set Summary (Sheet 4 of 6)
Source
Form Description Operation
Effect
on
CCR
Address
Mode
Opcode
Operand
Cycles
ZC
1. This is a pseudo instruction supported by the normal RS08 instruction set.
2. This instruction is different from that of the HC08 and HCS08 in that the RS08 does not auto-increment the index register.
Chapter 8 Central Processor Unit (RS08CPUV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 71
LDX #opr8i (1)
LDX opr8a (1)
LDX ,X (1)
Load Index Register from
Memory $0F ← (M) ¦—
IMD
DIR
IX
3E
4E
4E
ii 0F
dd 0F
0E 0E
4
5
5
LSLA Logical Shift Left ¦¦INH 48 1
LSRA Logical Shift Right ¦¦INH 44 1
MOV opr8a,opr8a
MOV #opr8i,opr8a
MOV D[X],opr8a
MOV opr8a,D[X]
MOV #opr8i,D[X]
Move (M)destination ← (M)source ¦—
DD
IMD
IX/DIR
DIR/IX
IMM/IX
4E
3E
4E
4E
3E
dd dd
ii dd
0E dd
dd 0E
ii 0E
5
4
5
5
4
NOP No Operation None ——INH AC 1
ORA #opr8i
ORA opr8a
ORA ,X (1)
ORA X
Inclusive OR
Accumulator and
Memory
A ← (A) | (M)
A ← (A) | (X) ¦—
IMM
DIR
IX
DIR
AA
BA
BA
BA
ii
dd
0E
0F
2
3
3
3
ROLA Rotate Left through Carry ¦¦INH 49 1
RORA Rotate Right through
Carry ¦¦INH 46 1
RTS Return from Subroutine Pull PC from shadow PC ——INH BE 3
SBC #opr8i
SBC opr8a
SBC ,X (1)
SBC X
Subtract with Carry A ← (A) – (M) – (C)
A ← (A) – (X) – (C)
¦¦
IMM
DIR
IX
DIR
A2
B2
B2
B2
ii
dd
0E
0F
2
3
3
3
SEC Set Carry Bit C ← 1 —1 INH 39 1
SHA Swap Shadow PC High
with A A ⇔ SPCH ——INH 45 1
SLA Swap Shadow PC Low
with A A ⇔ SPCL ——INH 42 1
STA opr8a
STA opr5a
STA ,X (1)
STA X
Store Accumulator in
Memory M ← (A) ¦—
DIR
SRT
IX
SRT
B7
Ex / Fx
EE
EF
dd
3
2
2
2
STX opr8a (1) Store Index Register in
Memory M ← (X) ¦— DIR 4E 0F dd 5
STOP Put MCU into stop mode ——INH AE 2+
Table 8-1. Instruction Set Summary (Sheet 5 of 6)
Source
Form Description Operation
Effect
on
CCR
Address
Mode
Opcode
Operand
Cycles
ZC
1. This is a pseudo instruction supported by the normal RS08 instruction set.
2. This instruction is different from that of the HC08 and HCS08 in that the RS08 does not auto-increment the index register.
C
b0
b7
0
b0
b7
C0
C
b0
b7
b0
b7
C
Chapter 8 Central Processor Unit (RS08CPUV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
72 Freescale Semiconductor
SUB #opr8i
SUB opr8a
SUB opr4a
SUB ,X (1)
SUB X
Subtract A ← (A) – (M)
A ← (A) – (X)
¦¦
IMM
DIR
TNY
IX
DIR
A0
B0
7x
7E
7F
ii
dd
2
3
3
3
3
TAX(1) Transfer A to X X ← (A) ¦—INH EF 2
TST opr8a (1)
TSTA (1)
TST ,X (1)
TSTX (1)
Test for Zero
(M) – $00
(A) – $00
(X) – $00
¦—
DD
INH
IX
INH
4E
AA
4E
4E
dd dd
00
0E 0E
0F 0F
5
2
5
5
TXA(1) Transfer X to A A ← (X) ¦— INH CF 3
WAIT Put MCU into WAIT
mode ——INH AF 2+
Table 8-1. Instruction Set Summary (Sheet 6 of 6)
Source
Form Description Operation
Effect
on
CCR
Address
Mode
Opcode
Operand
Cycles
ZC
1. This is a pseudo instruction supported by the normal RS08 instruction set.
2. This instruction is different from that of the HC08 and HCS08 in that the RS08 does not auto-increment the index register.
Chapter 8 Central Processor Unit (RS08CPUV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 73
Table 8-2. Opcode Map
DIR DIR TNY DIR/REL INH TNY TNY TNY SRT SRT IMM/INH DIR/EXT SRT SRT SRT SRT
0123456789ABCDEF
05
BRSET0
3DIR
5
BSET0
2DIR
4
INC
1TNY
3
BRA
2REL
4
DEC
1TNY
3
ADD
1TNY
3
SUB
1TNY
2
CLR
1SRT
2
CLR
1SRT
2
SUB
2IMM
3
SUB
2DIR
3
LDA
1SRT
3
LDA
1SRT
2
STA
1SRT
2
STA
1SRT
15
BRCLR0
3DIR
5
BCLR0
2DIR
4
INC
1TNY
5
CBEQ
3DIR
4
CBEQA
3IMM
4
DEC
1TNY
3
ADD
1TNY
3
SUB
1TNY
2
CLR
1SRT
2
CLR
1SRT
2
CMP
2IMM
3
CMP
2DIR
3
LDA
1SRT
3
LDA
1SRT
2
STA
1SRT
2
STA
1SRT
25
BRSET1
3DIR
5
BSET1
2DIR
4
INC
1TNY
1
SLA
1INH
4
DEC
1TNY
3
ADD
1TNY
3
SUB
1TNY
2
CLR
1SRT
2
CLR
1SRT
2
SBC
2IMM
3
SBC
2DIR
3
LDA
1SRT
3
LDA
1SRT
2
STA
1SRT
2
STA
1SRT
35
BRCLR1
3DIR
5
BCLR1
2DIR
4
INC
1TNY
1
COMA
1INH
4
DEC
1TNY
3
ADD
1TNY
3
SUB
1TNY
2
CLR
1SRT
2
CLR
1SRT
3
LDA
1SRT
3
LDA
1SRT
2
STA
1SRT
2
STA
1SRT
45
BRSET2
3DIR
5
BSET2
2DIR
4
INC
1TNY
3
BCC
2REL
1
LSRA
1INH
4
DEC
1TNY
3
ADD
1TNY
3
SUB
1TNY
2
CLR
1SRT
2
CLR
1SRT
2
AND
2IMM
3
AND
2DIR
3
LDA
1SRT
3
LDA
1SRT
2
STA
1SRT
2
STA
1SRT
55
BRCLR2
3DIR
5
BCLR2
2DIR
4
INC
1TNY
3
BCS
2REL
1
SHA
1INH
4
DEC
1TNY
3
ADD
1TNY
3
SUB
1TNY
2
CLR
1SRT
2
CLR
1SRT
3
LDA
1SRT
3
LDA
1SRT
2
STA
1SRT
2
STA
1SRT
65
BRSET3
3DIR
5
BSET3
2DIR
4
INC
1TNY
3
BNE
2REL
1
RORA
1INH
4
DEC
1TNY
3
ADD
1TNY
3
SUB
1TNY
2
CLR
1SRT
2
CLR
1SRT
2
LDA
2IMM
3
LDA
2DIR
3
LDA
1SRT
3
LDA
1SRT
2
STA
1SRT
2
STA
1SRT
75
BRCLR3
3DIR
5
BCLR3
2DIR
4
INC
1TNY
3
BEQ
2REL
4
DEC
1TNY
3
ADD
1TNY
3
SUB
1TNY
2
CLR
1SRT
2
CLR
1SRT
3
STA
2DIR
3
LDA
1SRT
3
LDA
1SRT
2
STA
1SRT
2
STA
1SRT
85
BRSET4
3DIR
5
BSET4
2DIR
4
INC
1TNY
1
CLC
1INH
1
LSLA
1INH
4
DEC
1TNY
3
ADD
1TNY
3
SUB
1TNY
2
CLR
1SRT
2
CLR
1SRT
2
EOR
2IMM
3
EOR
2DIR
3
LDA
1SRT
3
LDA
1SRT
2
STA
1SRT
2
STA
1SRT
95
BRCLR4
3DIR
5
BCLR4
2DIR
4
INC
1TNY
1
SEC
1INH
1
ROLA
1INH
4
DEC
1TNY
3
ADD
1TNY
3
SUB
1TNY
2
CLR
1SRT
2
CLR
1SRT
2
ADC
2IMM
3
ADC
2DIR
3
LDA
1SRT
3
LDA
1SRT
2
STA
1SRT
2
STA
1SRT
A5
BRSET5
3DIR
5
BSET5
2DIR
4
INC
1TNY
5
DEC
2DIR
1
DECA
1INH
4
DEC
1TNY
3
ADD
1TNY
3
SUB
1TNY
2
CLR
1SRT
2
CLR
1SRT
2
ORA
2IMM
3
ORA
2DIR
3
LDA
1SRT
3
LDA
1SRT
2
STA
1SRT
2
STA
1SRT
B5
BRCLR5
3DIR
5
BCLR5
2DIR
4
INC
1TNY
6
DBNZ
3DIR
4
DBNZA
2INH
4
DEC
1TNY
3
ADD
1TNY
3
SUB
1TNY
2
CLR
1SRT
2
CLR
1SRT
2
ADD
2IMM
3
ADD
2DIR
3
LDA
1SRT
3
LDA
1SRT
2
STA
1SRT
2
STA
1SRT
C5
BRSET6
3DIR
5
BSET6
2DIR
4
INC
1TNY
5
INC
2DIR
1
INCA
1INH
4
DEC
1TNY
3
ADD
1TNY
3
SUB
1TNY
2
CLR
1SRT
2
CLR
1SRT
1
NOP
1INH
4
JMP
3EXT
3
LDA
1SRT
3
LDA
1SRT
2
STA
1SRT
2
STA
1SRT
D
5
BRCLR6
3DIR
5
BCLR6
2DIR
4
INC
1TNY
4
DEC
1TNY
3
ADD
1TNY
3
SUB
1TNY
2
CLR
1SRT
2
CLR
1SRT
3
BSR
2REL
4
JSR
3EXT
3
LDA
1SRT
3
LDA
1SRT
2
STA
1SRT
2
STA
1SRT
E
5
BRSET7
3DIR
5
BSET7
2DIR
4
INC
1TNY
4
MOV
3IMD
5
MOV
3DD
4
DEC
1TNY
3
ADD
1TNY
3
SUB
1TNY
2
CLR
1SRT
2
CLR
1SRT
2+
STOP
1INH
3
RTS
1INH
3
LDA
1SRT
3
LDA
1SRT
2
STA
1SRT
2
STA
1SRT
F
5
BRCLR7
3DIR
5
BCLR7
2DIR
4
INC
1TNY
3
CLR
2DIR
1
CLRA
1INH
4
DEC
1TNY
3
ADD
1TNY
3
SUB
1TNY
2
CLR
1SRT
2
CLR
1SRT
2+
WAIT
1INH
5+
BGND
1INH
3
LDA
1SRT
3
LDA
1SRT
2
STA
1SRT
2
STA
1SRT
INH Inherent REL Relative
IMM Immediate SRT Short
DIR Direct TNY Tiny
EXT Extended
DD Direct-Direct IMD Immediate-Direct
High Byte of Opcode in Hexadecimal B
Gray box is decoded as illegal instruction
Low Byte of Opcode in Hexadecimal 0
3
SUB
2DIR
RS08 Cycles
Opcode Mnemonic
Number of Bytes /
Addressing Mode
LOW
HIGH
Chapter 8 Central Processor Unit (RS08CPUV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
74 Freescale Semiconductor
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 75
Chapter 9
Internal Clock Source (RS08ICSV1)
9.1 Introduction
The internal clock source (ICS) module provides clock source choices for the MCU. The module contains
a frequency-locked loop (FLL) as a clock source that is controllable by an internal reference clock. The
module can provide this FLL clock or the internal reference clock as a source for the MCU system clock,
ICSOUT.
Whichever clock source is chosen, ICSOUT is passed through a bus clock divider (BDIV), which allows
a lower final output clock frequency to be derived. ICSOUT is two times the bus frequency.
Figure 9-1 shows the MC9RS08KA2 Series block diagram with the ICS highlighted.
Figure 9-1. MC9RS08KA2 Series Block Diagram Highlighting ICS Block
RS08 CORE
USER RAM — 63 BYTES
NOTES:
(1) Pins are software configurable with pullup/pulldown device if input port.
(2) Integrated pullup device enabled if reset enabled (RSTPE=1).
(3) These pins are not available in 6-pin package
POWER AND
PTA
VSS
VDD
INTERNAL CLOCK
SOURCE
BDC
RS08 SYSTEM CONTROL
RTI
CPU
COP
WAKEUP LVD
RESET AND STOP WAKEUP
MODES OF OPERATION
POWER MANAGEMENT
5-BIT KEYBOARD
INTERRUPT MODULE
PTA0/KBIP0/ACMP+ (1)
PTA1/KBIP1/ACMP- (1)
PTA2/KBIP2/TCLK/RESET/VPP (1),( 2)
PTA3/ACMPO/BKGD/MS
ANALOG COMPARATOR
MODULE
MODULO TIMER
MODULE
PTA4/KBIP4 (1),(3)
PTA5/KBIP5 (1), (3)
INTERNAL REGULATOR
(KBI)
5
TCLK
ACMP-
ACMP+
ACMPO
(ICS)
(ACMP)
(MTIM)
USER
FLASH
MC9RS08KA2 — 2048 BYTES
MC9RS08KA1 — 1024 BYTES
Internal Clock Source (RS08ICSV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
76 Freescale Semiconductor
9.1.1 Features
Key features of the ICS module are:
• Frequency-locked loop (FLL) is trimmable for accuracy
— 0.2% resolution using internal 32 kHz reference
— 2% deviation over voltage and temperature using internal 32 kHz reference
— DCO output is 512 times internal reference frequency
• Internal reference clock has 9 trim bits available
• Internal reference clock can be selected as the clock source for the MCU
• Whichever clock is selected as the source can be divided down
— 2 bit select for clock divider is provided (allowable dividers are: 1, 2, 4, and 8)
• FLL engaged internal mode is automatically selected out of reset
9.1.2 Modes of Operation
There are four modes of operation for the ICS: FEI, FBI, FBILP, and stop.
9.1.2.1 FLL Engaged Internal (FEI)
In FLL engaged internal mode, which is the default mode, the ICS supplies a clock derived from the FLL
which is controlled by the internal reference clock.
9.1.2.2 FLL Bypassed Internal (FBI)
In FLL bypassed internal mode, the FLL is enabled and controlled by the internal reference clock, but is
bypassed. The ICS supplies a clock derived from the internal reference clock.
9.1.2.3 FLL Bypassed Internal Low Power (FBILP)
In FLL bypassed internal low power mode, the FLL is disabled and bypassed, and the ICS supplies a clock
derived from the internal reference clock.
9.1.2.4 Stop (STOP)
In stop mode, the FLL is disabled and the internal reference clocks can be selected to be enabled or
disabled. The ICS does not provide an MCU clock source.
9.1.3 Block Diagram
Figure 9-2 shows the ICS block diagram.
Internal Clock Source (RS08ICSV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 77
Figure 9-2. Internal Clock Source (ICS) Block Diagram
9.2 External Signal Description
No ICS signal connects off chip.
9.3 Register Definition
Table 9-1 is a summary of ICS registers.
9.3.1 ICS Control Register 1 (ICSC1)
Table 9-1. ICS Register Summary
Name 76543 2 1 0
ICSC1
R 0
CLKS
0 0 0 0 0
IREFSTEN
W
ICSC2
R
BDIV
00
LP
000
W
ICSTRM
R
TRIM
W
ICSSC
R00000CLKST0
FTRIM
W
DCO
Filter
TRIM
9
CLKS
n=0-3
/ 2n
Internal
Reference
Clock
BDIV
9
ICSOUT1
ICSIRCLK
IREFSTEN
LP
ICSFFCLK
DCOOUT
FLL
(32 kHz)
1 ICSOUT is two times the bus frequency
ICSIRCLK / 2
Internal Clock Source (RS08ICSV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
78 Freescale Semiconductor
9.3.2 ICS Control Register 2 (ICSC2)
7 6543210
R0
CLKS
00 0 00
IREFSTEN
W
Reset: 0 0 0 0 0 0 0 0
= Unimplemented
Figure 9-3. ICS Control Register 1 (ICSC1)
Table 9-2. ICSC1 Field Descriptions
Field Description
6
CLKS
Clock Source Select — Selects the clock source that controls the bus frequency. The actual bus frequency
depends on the value of the BDIV bits.
0 Output of FLL is selected
1 Internal reference clock is selected
0
IREFSTEN
Internal Reference Stop Enable — Controls whether the internal reference clock remains enabled when the
ICS enters stop mode.
1 Internal reference clock remains enabled in stop
0 Internal reference clock is disabled in stop
7 6543210
R
BDIV
00
LP
00 0
W
Reset:0 1000000
= Unimplemented
Figure 9-4. ICS Control Register 2 (ICSC2)
Table 9-3. ICSC2 Field Descriptions
Field Description
7:6
BDIV
Bus Frequency Divider — Selects the amount to divide down the clock source selected by the CLKS bit. This
controls the bus frequency.
00 Encoding 0 — Divides selected clock by 1
01 Encoding 1 — Divides selected clock by 2 (reset default)
10 Encoding 2 — Divides selected clock by 4
11 Encoding 3 — Divides selected clock by 8
3
LP
Low Power Select — Controls whether the FLL is disabled in FLL bypassed modes.
1 FLL is disabled in bypass modes
0 FLL is not disabled in bypass mode
Internal Clock Source (RS08ICSV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 79
9.3.3 ICS Trim Register (ICSTRM)
9.3.4 ICS Status and Control (ICSSC)
7 6543210
R
TRIM
W
POR: 1 0 0 0 0 0 0 0
Reset:U UUUUUUU
Figure 9-5. ICS Trim Register (ICSTRM)
Table 9-4. ICSTRM Field Descriptions
Field Description
7:0
TRIM
ICS Trim Setting — The TRIM bits control the internal reference clock frequency by controlling the internal
reference clock period. The bits’ effect are binary weighted (i.e., bit 1 will adjust twice as much as bit 0).
Increasing the binary value in TRIM will increase the period, and decreasing the value will decrease the period.
An additional fine trim bit is available in ICSSC as the FTRIM bit.
7 6543210
R 0 0 0 0 0 CLKST 0
FTRIM
W
POR: 0 0 0 0 0 0 0 0
Reset: 0 0 0 0 0 0 0 U
= Unimplemented
Figure 9-6. ICS Status and Control Register (ICSSC)
Table 9-5. ICSSC Field Descriptions
Field Description
2
CLKST
Clock Mode Status — The CLKST read-only bit indicate the current clock mode. The CLKST bit does not update
immediately after a write to the CLKS bit due to internal synchronization between clock domains.
0 Output of FLL is selected
1 Internal reference clock is selected
0
FTRIM
ICS Fine Trim — The FTRIM bit controls the smallest adjustment of the internal reference clock frequency.
Setting FTRIM will increase the period and clearing FTRIM will decrease the period by the smallest amount
possible.
Internal Clock Source (RS08ICSV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
80 Freescale Semiconductor
9.4 Functional Description
9.4.1 Operational Modes
The states of the ICS are shown as a state diagram and are described in this section. The arrows indicate
the allowed movements between the states.
Figure 9-7. Clock Switching Modes
9.4.1.1 FLL Engaged Internal (FEI)
FLL engaged internal (FEI) is the default mode of operation out of any reset and is entered when CLKS is
written to 0.
In FLL engaged internal mode, the ICSOUT clock is derived from the FLL clock, which is controlled by
the internal reference clock. The FLL loop will lock the frequency to 512 times the filter frequency.
9.4.1.2 FLL Bypassed Internal (FBI)
The FLL bypassed internal (FBI) mode is entered when CLKS is written to 1 and LP bit is a 0.
In FLL bypassed internal mode, the ICSOUT clock is derived from the internal reference clock. The FLL
clock is controlled by the internal reference clock, and the FLL loop will lock the FLL frequency to 512
times the filter frequency.
9.4.1.3 FLL Bypassed Internal Low Power (FBILP)
The FLL bypassed internal low power (FBILP) mode is entered when CLKS is written to 1 and LP = 1.
In FLL bypassed internal low power mode, the ICSOUT clock is derived from the internal reference clock
and the FLL is disabled.
FLL Bypassed
Internal Low
Power(FBILP)
CLKS=0
1 ICS enters its Stop state when MCU enters stop, FLL is always disabled. ICS returns to the state that
was active before MCU entered stop, unless a reset occurs while in stop.
2 If IREFSTEN is set when MCU enters stop, the ICSIRCLK remains running.
FLL Engaged
Internal (FEI)
FLL Bypassed
Internal (FBI)
CLKS=1
LP=0
CLKS=1
LP=1
Stop1, 2
Internal Clock Source (RS08ICSV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 81
9.4.1.4 Stop
ICS stop mode is entered whenever the MCU enters stop. In this mode, all ICS clocks are stopped except
ICSIRCLK which will remaining running if IREFSTEN is written to a 1.
When the MCU is interrupted from stop, the ICS will go back to the operating mode that was running when
the MCU entered stop. If the internal reference was not running in stop (IREFSTEN = 0), the ICS will take
some time, tir_wu, for the internal reference to wakeup. If the internal reference was already running in stop
(IREFSTEN = 1), entering into FEI will take some time, tfll_wu, for the FLL to return its previous acquired
frequency.
9.4.2 Mode Switching
When changing from FBILP to either FEI or FBI, or anytime the trim value is written, the user should wait
the FLL acquisition time, tacquire, before FLL will be guaranteed to be at desired frequency.
9.4.3 Bus Frequency Divider
The BDIV bits can be changed at anytime and the actual switch to the new frequency will occur
immediately.
9.4.4 Low Power Bit Usage
The low power bit (LP) is provided to allow the FLL to be disabled and thus conserve power when it is
not being used. However, in some applications it may be desirable to enable the FLL and allow it to lock
for maximum accuracy before switching to an FLL engaged mode. The FLL is disabled in bypass mode
when LP = 1.
9.4.5 Internal Reference Clock
The ICSIRCLK frequency can be re-targeted by trimming the period of the internal reference clock. This
can be done by writing a new value to the TRIM bits in the ICSTRM register. Writing a larger value will
slow down the ICSIRCLK frequency, and writing a smaller value to the ICSTRM register will speed up
the ICSIRCLK frequency. The TRIM bits will affect the ICSOUT frequency if the ICS is in FLL engaged
internal (FEI), FLL bypassed internal (FBI), or FLL bypassed internal low power (FBILP) mode. The
TRIM and FTRIM values will not be affected by a reset. For the ICS to run in stop, the LVDE and LVDSE
bits in the SPMSC1 must both be set before entering stop.
Until ICSIRCLK is trimmed, ICSOUT frequencies may exceed the maximum chip-level frequency and
violate the chip-level clock timing specifications (see the Device Overview chapter). The BDIV is reset to
a divide by 2 to prevent the bus frequency from exceeding the maximum. The user should trim the device
to an allowable frequency before changing BDIV to a divide by 1 operation.
Internal Clock Source (RS08ICSV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
82 Freescale Semiconductor
9.4.6 Fixed Frequency Clock
The ICS provides the ICSFFCLK output which can be used as an additional clock source to a peripheral
such as a timer, when the ICS is in FEI. ICSFFCLK is not a valid clock source for a peripheral when in
either FBI or FBILP modes. ICSFFCLK is ICSRCLK divided by two.
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 83
Chapter 10
Analog Comparator (RS08ACMPV1)
10.1 Introduction
The analog comparator module (ACMP) provides a circuit for comparing two analog input voltages or for
comparing one analog input voltage to an internal reference voltage. The comparator circuit is designed to
operate across the full range of the supply voltage (rail to rail operation).
Figure 10-1 shows the MC9RS08KA2 Series block diagram with the ACMP highlighted.
Figure 10-1. MC9RS08KA2 Series Block Diagram Highlighting ACMP Block and Pins
RS08 CORE
USER RAM — 63 BYTES
NOTES:
(1) Pins are software configurable with pullup/pulldown device if input port.
(2) Integrated pullup device enabled if reset enabled (RSTPE=1).
(3) These pins are not available in 6-pin package
POWER AND
PTA
VSS
VDD
INTERNAL CLOCK
SOURCE
BDC
RS08 SYSTEM CONTROL
RTI
CPU
COP
WAKEUP LVD
RESET AND STOP WAKEUP
MODES OF OPERATION
POWER MANAGEMENT
5-BIT KEYBOARD
INTERRUPT MODULE
PTA0/KBIP0/ACMP+ (1)
PTA1/KBIP1/ACMP- (1)
PTA2/KBIP2/TCLK/RESET/VPP (1),( 2)
PTA3/ACMPO/BKGD/MS
ANALOG COMPARATOR
MODULE
MODULO TIMER
MODULE
PTA4/KBIP4 (1),(3)
PTA5/KBIP5 (1), (3)
INTERNAL REGULATOR
(KBI)
5
TCLK
ACMP-
ACMP+
ACMPO
(ICS)
(ACMP)
(MTIM)
USER
FLASH
MC9RS08KA2 — 2048 BYTES
MC9RS08KA1 — 1024 BYTES
Analog Comparator (RS08ACMPV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
84 Freescale Semiconductor
10.1.1 Features
The ACMP has the following features:
• Full rail-to-rail supply operation
• Less than 40 mV of input offset
• Less than 15 mV of hysteresis
• Selectable interrupt on rising edge, falling edge, or either rising or falling edges of comparator
output
• Option to compare to fixed internal bandgap reference voltage
• Option to allow comparator output to be visible on a pin, ACMPO
• Remains operational in stop mode
10.1.2 Modes of Operation
This section defines the ACMP operation in wait, stop, and background debug modes.
10.1.2.1 Operation in Wait Mode
The ACMP continues to operate in wait mode if enabled before executing the WAIT instruction.
Therefore, the ACMP can be used to bring the MCU out of wait mode if the ACMP interrupt is enabled
(ACIE = 1). For lowest possible current consumption, the ACMP should be disabled by software if not
required as an interrupt source during wait mode.
10.1.2.2 Operation in Stop Mode
The ACMP continues to operate in stop mode if enabled and compare operation remains active. If ACOPE
is enabled, comparator output operates as in the normal operating mode and comparator output is placed
onto the external pin. The MCU is brought out of stop when a compare event occurs and ACIE is enabled;
ACF flag sets accordingly.
If stop is exited with a reset, the ACMP will be put into its reset state.
10.1.2.3 Operation in Active Background Mode
When the MCU is in active background mode, the ACMP will continue to operate normally.
10.1.3 Block Diagram
The block diagram for the analog comparator module is shown in Figure 10-2.
Analog Comparator (RS08ACMPV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 85
Figure 10-2. Analog Comparator (ACMP) Block Diagram
+
-
Interrupt
Control
ACBGS
Internal Bus
Status and Control
Register
ACMOD
set ACF
ACME ACF
ACIE
ACOPE
Comparator
ACMP
INTERRUPT
REQUEST
ACMP+
ACMP-
ACMPO
ACO
Internal
Bandgap
Reference
Voltage
ACME
Analog Comparator (RS08ACMPV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
86 Freescale Semiconductor
10.2 External Signal Description
The ACMP has two analog input pins, ACMP+ and ACMP–, and one digital output pin, ACMPO. Each
of the input pins can accept an input voltage that varies across the full operating voltage range of the MCU.
As shown in Figure 10-2, the ACMP– pin is connected to the inverting input of the comparator, and the
ACMP+ pin is connected to the non-inverting input of the comparator if ACBGS=0. As shown in
Figure 10-2, the ACMPO pin can be enabled to drive an external pin.
The signal properties of ACMP are shown in Table 10-1.
10.3 Register Definition
The ACMP includes one register:
• An 8-bit status and control register
Refer to the direct-page register summary in the memory chapter of this data sheet for the absolute address
assignments for all ACMP registers.
10.3.1 ACMP Status and Control Register (ACMPSC)
ACMPSC contains the status flag and control bits which are used to enable and configure the ACMP.
Table 10-1. Signal Properties
Signal Function I/O
ACMP- Inverting analog input to the ACMP
(Minus input)
I
ACMP+ Non-inverting analog input to the ACMP
(Positive input)
I
ACMPO Digital output of the ACMP O
76543210
R
ACME ACBGS ACF ACIE
ACO
ACOPE ACMOD
W
Reset:00000000
= Unimplemented
Figure 10-3. ACMP Status and Control Register (ACMPSC)
Analog Comparator (RS08ACMPV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 87
10.4 Functional Description
The analog comparator can be used to compare two analog input voltages applied to ACMP+ and ACMP–;
or it can be used to compare an analog input voltage applied to ACMP– with an internal bandgap reference
voltage. ACBGS is used to select between the bandgap reference voltage or the ACMP+ pin as the input
to the non-inverting input of the analog comparator.
The comparator output is high when the non-inverting input is greater than the inverting input, and it is
low when the non-inverting input is less than the inverting input. ACMOD is used to select the condition
which will cause ACF to be set. ACF can be set on a rising edge of the comparator output, a falling edge
of the comparator output, or either a rising or a falling edge (toggle). The comparator output can be read
directly through ACO. The comparator output can also be driven onto the ACMPO pin using ACOPE.
Table 10-2. ACMPSC Field Descriptions
Field Description
7
ACME
Analog Comparator Module Enable — ACME enables the ACMP module.
0 ACMP not enabled.
1 ACMP is enabled.
6
ACBGS
Analog Comparator Bandgap Select — ACBGS is used to select between the internal bandgap reference
voltage or the ACMP+ pin as the non-inverting input of the analog comparator.
0 External pin ACMP+ selected as non-inverting input to comparator.
1 Internal bandgap reference voltage selected as non-inverting input to comparator.
5
ACF
Analog Comparator Flag — ACF is set when a compare event occurs. Compare events are defined by ACMOD.
ACF is cleared by writing a one to ACF.
0 Compare event has not occurred.
1 Compare event has occurred.
4
ACIE
Analog Comparator Interrupt Enable — ACIE enables the interrupt for the ACMP. When ACIE is set, an
interrupt will be asserted when ACF is set.
0 Interrupt disabled.
1 Interrupt enabled.
3
ACO
Analog Comparator Output — Reading ACO will return the current value of the analog comparator output. ACO
is reset to a 0 and will read as a 0 when the ACMP is disabled (ACME = 0).
2
ACOPE
Analog Comparator Output Pin Enable — ACOPE is used to enable the comparator output to be placed onto
the external pin, ACMPO. ACOPE will only control the pin if the ACMP is active (ACME=1).
0 Analog comparator output not available on ACMPO.
1 Analog comparator output is driven out on ACMPO.
1:0
ACMOD
Analog Comparator Mode — ACMOD selects the type of compare event which sets ACF.
00 Encoding 0 — Comparator output falling edge.
01 Encoding 1 — Comparator output rising edge.
10 Encoding 2 — Comparator output falling edge.
11 Encoding 3 — Comparator output rising or falling edge.
Analog Comparator (RS08ACMPV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
88 Freescale Semiconductor
NOTE
Comparator inputs are high impedence analog pins which are sensitive to
noise. Noisy VDD and/or pin toggling adjacent to the analog inputs may
cause the comparator offset/hysteresis performance to exceed the specified
values. Maximum source impedence is restricted to the value specified in
Table A-6. To achieve maximum performance device is recommended to
enter WAIT/STOP mode for ACMP measurement and adjacent pin toggling
must be avoided.
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 89
Chapter 11
Modulo Timer (RS08MTIMV1)
11.1 Introduction
The MTIM is a simple 8-bit timer with several software selectable clock sources and a programmable
interrupt.
The central component of the MTIM is the 8-bit counter that can operate as a free-running counter or a
modulo counter. A timer overflow interrupt can be enabled to generate periodic interrupts for time-based
software loops.
The TCLK input is connected to the PTA2 pin of the MC9RS08KA2 Series. The XCLK input is connected
to the ICSFFCLK clock divided by two, where the ICSFFCLK is the fixed-frequency internal reference
clock from the ICS module.
Figure 11-1 shows the MC9RS08KA2 Series block diagram with the MTIM highlighted.
Figure 11-1. MC9RS08KA2 Series Block Diagram Highlighting MTIM Block and Pin
RS08 CORE
USER RAM — 63 BYTES
NOTES:
(1) Pins are software configurable with pullup/pulldown device if input port.
(2) Integrated pullup device enabled if reset enabled (RSTPE=1).
(3) These pins are not available in 6-pin package
POWER AND
PTA
VSS
VDD
INTERNAL CLOCK
SOURCE
BDC
RS08 SYSTEM CONTROL
RTI
CPU
COP
WAKEUP LVD
RESET AND STOP WAKEUP
MODES OF OPERATION
POWER MANAGEMENT
5-BIT KEYBOARD
INTERRUPT MODULE
PTA0/KBIP0/ACMP+ (1)
PTA1/KBIP1/ACMP- (1)
PTA2/KBIP2/TCLK/RESET/VPP (1),( 2)
PTA3/ACMPO/BKGD/MS
ANALOG COMPARATOR
MODULE
MODULO TIMER
MODULE
PTA4/KBIP4 (1),(3)
PTA5/KBIP5 (1), (3)
INTERNAL REGULATOR
(KBI)
5
TCLK
ACMP-
ACMP+
ACMPO
(ICS)
(ACMP)
(MTIM)
USER
FLASH
MC9RS08KA2 — 2048 BYTES
MC9RS08KA1 — 1024 BYTES
Modulo Timer (RS08MTIMV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
90 Freescale Semiconductor
11.1.1 Features
Timer system features include:
• 8-bit up-counter
— Free-running or 8-bit modulo limit
— Software controllable interrupt on overflow
— Counter reset bit (TRST)
— Counter stop bit (TSTP)
• Four software selectable clock sources for input to prescaler:
— System bus clock — rising edge
— Fixed frequency clock (XCLK) — rising edge
— External clock source on the TCLK pin — rising edge
— External clock source on the TCLK pin — falling edge
• Nine selectable clock prescale values:
— Clock source divide by 1, 2, 4, 8, 16, 32, 64, 128, or 256
11.1.2 Modes of Operation
This section defines the MTIM’s operation in stop, wait and background debug modes.
11.1.2.1 Operation in Wait Mode
The MTIM continues to run in wait mode if enabled before executing the WAIT instruction. Therefore,
the MTIM can be used to bring the MCU out of wait mode if the timer overflow interrupt is enabled. For
lowest possible current consumption, the MTIM must be disabled by software if not needed as an interrupt
source during wait mode.
11.1.2.2 Operation in Stop Modes
The MTIM is disabled in all stop modes, regardless of the settings before executing the STOP instruction.
Therefore, the MTIM cannot be used as a wake up source from stop mode.
If stop is exited with a reset, the MTIM will be put into its reset state. If stop is exited with an interrupt,
the MTIM continues from the state it was in when stop was entered. If the counter was active upon entering
stop, the count will resume from the current value.
11.1.2.3 Operation in Active Background Mode
The MTIM suspends all counting until the MCU returns to normal user operating mode. Counting resumes
from the suspended value as long as an MTIM reset did not occur (TRST written to a 1 or any value is
written to the MTIMMOD register).
Modulo Timer (RS08MTIMV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 91
11.1.3 Block Diagram
The block diagram for the modulo timer module is shown Figure 11-2.
Figure 11-2. Modulo Timer (MTIM) Block Diagram
11.2 External Signal Description
The MTIM includes one external signal, TCLK, used to input an external clock when selected as the
MTIM clock source. The signal properties of TCLK are shown in Table 11-1.
The TCLK input must be synchronized by the bus clock. Also, variations in duty cycle and clock jitter
must be accommodated. Therefore, the TCLK signal must be limited to one-fourth of the bus frequency.
The TCLK pin can be muxed with a general-purpose port pin. See the Pins and Connections chapter for
the pin location and priority of this function.
11.3 Register Definition
Each MTIM includes four registers, which are summarized in Table 11-2:
• An 8-bit status and control register
• An 8-bit clock configuration register
• An 8-bit counter register
• An 8-bit modulo register
Refer to the direct-page register summary in the memory section of this data sheet for the absolute address
assignments for all MTIM registers. This section refers to registers and control bits only by their names.
Table 11-1. Signal Properties
Signal Function I/O
TCLK External clock source input into MTIM I
BUSCLK
TCLK SYNC
CLOCK
SOURCE
SELECT
PRESCALE AND
SELECT DIVIDE
BY
8-BIT MODULO
(MTIMMOD)
8-BIT COMPARATOR
TRST
TSTP
CLKS PS
XCLK
TOIE
MTIM
INTERRUPT
REQUEST
TOF
8-BIT COUNTER
(MTIMCNT)
Modulo Timer (RS08MTIMV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
92 Freescale Semiconductor
11.3.1 MTIM Status and Control Register (MTIMSC)
MTIMSC contains the overflow status flag and control bits which are used to configure the interrupt
enable, reset the counter, and stop the counter.
Table 11-2. MTIM Register Summary
Name 76543210
MTIMSC
RTOF
TOIE
0
TSTP
0000
WTRST
MTIMCLK
R0 0
CLKS PS
W
MTIMCNT
RCOUNT
W
MTIMMOD
R
MOD
W
7 6543210
RTOF
TOIE
0
TSTP
0000
WTRST
Reset: 0 0 0 1 0 0 0 0
Figure 11-3. MTIM Status and Control Register (MTIMSC)
Table 11-3. MTIMSC Field Descriptions
Field Description
7
TOF
MTIM Overflow Flag — This read-only bit is set when the MTIM counter register overflows to $00 after reaching
the value in the MTIM modulo register. Clear TOF by reading the MTIMSC register while TOF is set, then writing
a 0 to TOF. TOF is also cleared when TRST is written to a 1 or when any value is written to the MTIMMOD
register.
0 MTIM counter has not reached the overflow value in the MTIM modulo register.
1 MTIM counter has reached the overflow value in the MTIM modulo register.
6
TOIE
MTIM Overflow Interrupt Enable — This read/write bit enables MTIM overflow interrupts. If TOIE is set, then an
interrupt is generated when TOF = 1. Reset clears TOIE. Do not set TOIE if TOF = 1. Clear TOF first, then set
TOIE.
0 TOF interrupts are disabled. Use software polling.
1 TOF interrupts are enabled.
5
TRST
MTIM Counter Reset — When a 1 is written to this write-only bit, the MTIM counter register resets to $00 and
TOF is cleared. Reading this bit always returns 0.
0 No effect. MTIM counter remains at current state.
1 MTIM counter is reset to $00.
4
TSTP
MTIM Counter Stop — When set, this read/write bit stops the MTIM counter at its current value. Counting
resumes from the current value when TSTP is cleared. Reset sets TSTP to prevent the MTIM from counting.
0 MTIM counter is active.
1 MTIM counter is stopped.
Modulo Timer (RS08MTIMV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 93
11.3.2 MTIM Clock Configuration Register (MTIMCLK)
MTIMCLK contains the clock select bits (CLKS) and the prescaler select bits (PS).
11.3.3 MTIM Counter Register (MTIMCNT)
MTIMCNT is the read-only value of the current MTIM count of the 8-bit counter.
7 6543210
R 0 0
CLKS PS
W
Reset: 0 0 0 0 0 0 0 0
Figure 11-4. MTIM Clock Configuration Register (MTIMCLK)
Table 11-4. MTIMCLK Field Description
Field Description
5:4
CLKS
Clock Source Select — These two read/write bits select one of four different clock sources as the input to the
MTIM prescaler. Changing the clock source while the counter is active does not clear the counter. The count
continues with the new clock source. Reset clears CLKS to 00.
00 Encoding 0 — Bus clock (BUSCLK).
01 Encoding 1 — Fixed-frequency clock (XCLK).
10 Encoding 3 — External source (TCLK pin), falling edge.
11 Encoding 4 — External source (TCLK pin), rising edge.
3:0
PS
Clock Source Prescaler — These four read/write bits select one of nine outputs from the 8-bit prescaler.
Changing the prescaler value while the counter is active does not clear the counter. The count continues with the
new prescaler value. Reset clears PS to 0000.
0000 Encoding 0 — MTIM clock source ÷ 1.
0001 Encoding 1 — MTIM clock source ÷ 2.
0010 Encoding 2 — MTIM clock source ÷ 4.
0011 Encoding 3 — MTIM clock source ÷ 8.
0100 Encoding 4 — MTIM clock source ÷ 16.
0101 Encoding 5 — MTIM clock source ÷ 32.
0110 Encoding 6 — MTIM clock source ÷ 64.
0111 Encoding 7 — MTIM clock source ÷ 128.
1000 Encoding 8 — MTIM clock source ÷ 256.
All other encodings default to MTIM clock source ÷ 256.
7 6543210
RCOUNT
W
Reset: 0 0 0 0 0 0 0 0
Figure 11-5. MTIM Counter Register (MTIMCNT)
Modulo Timer (RS08MTIMV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
94 Freescale Semiconductor
11.3.4 MTIM Modulo Register (MTIMMOD)
Table 11-5. MTIMCNT Field Description
Field Description
7:0
COUNT
MTIM Count — These eight read-only bits contain the current value of the 8-bit counter. Writes have no effect to
this register. Reset clears the count to $00.
7 6543210
R
MOD
W
Reset: 0 0 0 0 0 0 0 0
Figure 11-6. MTIM Modulo Register (MTIMMOD)
Table 11-6. MTIMMOD Descriptions
Field Description
7:0
MOD
MTIM Modulo — These eight read/write bits contain the modulo value used to reset the count and set TOF. A
value of $00 puts the MTIM in free-running mode. Writing to MTIMMOD resets the COUNT to $00 and clears
TOF. Reset sets the modulo to $00.
Modulo Timer (RS08MTIMV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 95
11.4 Functional Description
The MTIM is composed of a main 8-bit up-counter with an 8-bit modulo register, a clock source selector,
and a prescaler block with nine selectable values. The module also contains software selectable interrupt
logic.
The MTIM counter (MTIMCNT) has three modes of operation: stopped, free-running, and modulo. Out
of reset, the counter is stopped. If the counter is started without writing a new value to the modulo register,
then the counter will be in free-running mode. The counter is in modulo mode when a value other than $00
is in the modulo register while the counter is running.
After any MCU reset, the counter is stopped and reset to $00, and the modulus is set to $00. The bus clock
is selected as the default clock source and the prescale value is divide by 1. To start the MTIM in
free-running mode, simply write to the MTIM status and control register (MTIMSC) and clear the MTIM
stop bit (TSTP).
Four clock sources are software selectable: the internal bus clock, the fixed frequency clock (XCLK), and
an external clock on the TCLK pin, selectable as incrementing on either rising or falling edges. The MTIM
clock select bits (CLKS) in MTIMCLK are used to select the desired clock source. If the counter is active
(TSTP = 0) when a new clock source is selected, the counter will continue counting from the previous
value using the new clock source.
Nine prescale values are software selectable: clock source divided by 1, 2, 4, 8, 16, 32, 64, 128, or 256.
The prescaler select bits (PS) in MTIMCLK select the desired prescale value. If the counter is active
(TSTP = 0) when a new prescaler value is selected, the counter will continue counting from the previous
value using the new prescaler value.
The MTIM modulo register (MTIMMOD) allows the overflow compare value to be set to any value from
$01 to $FF. Reset clears the modulo value to $00, which results in a free running counter.
When the counter is active (TSTP = 0), the counter increments at the selected rate until the count matches
the modulo value. When these values match, the counter overflows to $00 and continues counting. The
MTIM overflow flag (TOF) is set whenever the counter overflows. The flag sets on the transition from the
modulo value to $00. Writing to MTIMMOD while the counter is active resets the counter to $00 and
clears TOF.
Clearing TOF is a two-step process. The first step is to read the MTIMSC register while TOF is set. The
second step is to write a 0 to TOF. If another overflow occurs between the first and second steps, the
clearing process is reset and TOF will remain set after the second step is performed. This will prevent the
second occurrence from being missed. TOF is also cleared when a 1 is written to TRST or when any value
is written to the MTIMMOD register.
The MTIM allows for an optional interrupt to be generated whenever TOF is set. To enable the MTIM
overflow interrupt, set the MTIM overflow interrupt enable bit (TOIE) in MTIMSC. TOIE must never be
written to a 1 while TOF = 1. Instead, TOF must be cleared first, then the TOIE can be set to 1.
Modulo Timer (RS08MTIMV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
96 Freescale Semiconductor
11.4.1 MTIM Operation Example
This section shows an example of the MTIM operation as the counter reaches a matching value from the
modulo register.
Figure 11-7. MTIM Counter Overflow Example
In the example of Figure 11-7, the selected clock source could be any of the four possible choices. The
prescaler is set to PS = %0010 or divide-by-4. The modulo value in the MTIMMOD register is set to $AA.
When the counter, MTIMCNT, reaches the modulo value of $AA, the counter overflows to $00 and
continues counting. The timer overflow flag, TOF, sets when the counter value changes from $AA to $00.
An MTIM overflow interrupt is generated when TOF is set, if TOIE = 1.
selected
clock source
MTIMCNT
MTIM clock
(PS=%0010)
MTIMMOD: $AA
$A7 $A8 $A9 $AA $00 $01
TOF
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 97
Chapter 12
Development Support
12.1 Introduction
Development support systems in the RS08 family include the RS08 background debug controller (BDC).
The BDC provides a single-wire debug interface to the target MCU. This interface provides a convenient
means for programming the on-chip FLASH and other nonvolatile memories. Also, the BDC is the
primary debug interface for development and allows non-intrusive access to memory data and traditional
debug features such as CPU register modify, breakpoint, and single-instruction trace commands.
In the RS08 Family, address and data bus signals are not available on external pins. Debug is done through
commands fed into the target MCU via the single-wire background debug interface, including resetting the
device without using a reset pin.
Figure 12-1. Connecting MCU to Host for Debugging
12.2 Features
Features of the RS08 background debug controller (BDC) include:
• Uses a single pin for background debug serial communications
• Non-intrusive of user memory resources; BDC registers are not located in the memory map
• SYNC command to determine target communications rate
• Non-intrusive commands allow access to memory resources while CPU is running user code
without stopping applications
• Active background mode commands for CPU register access
• GO and TRACE1 commands
• BACKGROUND command can wake CPU from wait or stop modes
MCU
USER PCB
COMMAND TRANSLATOR
TARGET RS08 POD HOST
RS-232
USB, Ethernet
Chapter 12 Development Support
MC9RS08KA2 Series Data Sheet, Rev. 4
98 Freescale Semiconductor
• BDC_RESET command allows host to reset MCU without using a reset pin
• One hardware address breakpoint built into BDC
• RS08 clock source runs in stop mode if BDM enabled to allow debugging when CPU is in stop
mode
• COP watchdog suspended while in active background mode
12.3 RS08 Background Debug Controller (BDC)
All MCUs in the RS08 Family contain a single-wire background debug interface which supports in-circuit
programming of on-chip non-volatile memory and sophisticated debug capabilities. Unlike debug
interfaces on earlier 8-bit MCUs, this debug system provides for minimal interference with normal
application resources. It does not use any user memory or locations in the memory map. It requires use of
only the output-only BKGD pin. This pin will be shared with simple user output-only functions (typically
port, comparator outputs, etc.), which can be easily debugged in normal user mode.
RS08 BDM commands are divided into two groups:
• Active background mode commands require that the target MCU is in active background mode (the
user program is not running). The BACKGROUND command causes the target MCU to enter
active background mode. Active background mode commands allow the CPU registers to be read
or written and allow the user to trace one (TRACE1) user instruction at a time or GO to the user
program from active background mode.
• Non-intrusive commands can be executed at any time even while the user program is running.
Non-intrusive commands allow a user to read or write MCU memory locations or access status and
control registers within the background debug controller (BDC).
Typically, a relatively simple interface pod is used to translate commands from a host computer into
commands for the custom serial interface to the single-wire background debug system. Depending on the
development tool vendor, this interface pod may use a standard RS-232 serial port, a parallel printer port,
or some other type of communication such as Ethernet or a universal serial bus (USB) to communicate
between the host PC and the pod.
Figure 12-2 shows the standard header for connection of a RS08 BDM pod. A pod is a small interface
device that connects a host computer such as a personal computer to a target RS08 system. BKGD and
GND are the minimum connections required to communicate with a target MCU. The pseudo-open-drain
RESET signal is included in the connector to allow a direct hardware method for the host to force or
monitor (if RESET is available as output) a target system reset.
The RS08 BDM pods supply the VPP voltage to the RS08 MCU when in-circuit programming is required.
The VPP connection from the pod is shared with RESET as shown in Figure 12-2. For VPP requirements
see the FLASH specifications in the electricals appendix.
Chapter 12 Development Support
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 99
Figure 12-2. Standard RS08 BDM Tool Connector
Background debug controller (BDC) serial communications use a custom serial protocol that was first
introduced on the M68HC12 Family of microcontrollers. This protocol requires that the host knows the
communication clock rate, which is determined by the target BDC clock rate. If a host is attempting to
communicate with a target MCU that has an unknown BDC clock rate, a SYNC command may be sent to
the target MCU to request a timed sync response signal from which the host can determine the correct
communication speed.
For RS08 MCUs, the BDC clock is the same frequency as the MCU bus clock. For a detailed description
of the communications protocol, refer to Section 12.3.2, “Communication Details."
12.3.1 BKGD Pin Description
BKGD is the single-wire background debug interface pin. BKGD is a pseudo-open-drain pin that contains
an on-chip pullup, therefore it requires no external pullup resistor. Unlike typical open-drain pins, the
external resistor capacitor (RC) time constant on this pin, which is influenced by external capacitance,
plays almost no role in signal rise time. The custom protocol provides for brief, actively driven speedup
pulses to force rapid rise times on this pin without risking harmful drive level conflicts. Refer to
Section 12.3.2, “Communication Details," for more detail.
The primary function of this pin is bidirectional serial communication of background debug commands
and data. During reset, this pin selects between starting in active background mode and normal user mode
running an application program. This pin is also used to request a timed sync response pulse to allow a
host development tool to determine the target BDC clock frequency.
By controlling the BKGD pin and forcing an MCU reset (issuing a BDC_RESET command, or through a
power-on reset (POR)), the host can force the target system to reset into active background mode rather
than start the user application program. This is useful to gain control of a target MCU whose FLASH
program memory has not yet been programmed with a user application program.
When no debugger pod is connected to the 6-pin BDM interface connector, the internal pullup on BKGD
determines the normal operating mode.
On some RS08 devices, the BKGD pin may be shared with an alternative output-only function. To support
BDM debugging, the user must disable this alternative function. Debugging of the alternative function
must be done in normal user mode without using BDM.
12.3.2 Communication Details
The BDC serial interface requires the host to generate a falling edge on the BKGD pin to indicate the start
of each bit time. The host provides this falling edge whether data is transmitted or received.
2
4
65
3
1
RESET/VPP
BKGD GND
VDD
NO CONNECT
NO CONNECT
Chapter 12 Development Support
MC9RS08KA2 Series Data Sheet, Rev. 4
100 Freescale Semiconductor
The BDC serial communication protocol requires the host to know the target BDC clock speed.
Commands and data are sent most significant bit first (MSB-first) at 16 BDC clock cycles per bit. The
interface times out if 512 BDC clock cycles occur between falling edges from the host. Any BDC
command that was in progress when this timeout occurs is aborted without affecting the memory or
operating mode of the target MCU system.
Figure 12-3 shows an external host transmitting a logic 1 or 0 to the BKGD pin of a target MCU. The host
is asynchronous to the target so there is a 0-to-1 cycle delay from the host-generated falling edge to where
the target perceives the beginning of the bit time. Ten target BDC clock cycles later, the target senses the
bit level on the BKGD pin. Typically, the host actively drives the pseudo-open-drain BKGD pin during
host-to-target transmissions to speed up rising edges. Because the target does not drive the BKGD pin
during the host-to-target period, there is no need to treat the line as an open-drain signal during this period.
Figure 12-3. BDC Host-to-Target Serial Bit Timing
Figure 12-4 shows the host receiving a logic 1 from the target MCU. Because the host is asynchronous to
the target, there is a 0-to-1 cycle delay from the host-generated falling edge on BKGD to the perceived
start of the bit time in the target. The host holds the BKGD pin low long enough for the target to recognize
it (at least two target BDC cycles). The host must release the low drive before the target drives a brief
active-high speedup pulse seven cycles after the perceived start of the bit time. The host must sample the
bit level approximately 10 cycles after it started the bit time.
EARLIEST START
TARGET SENSES BIT LEVEL
10 CYCLES
SYNCHRONIZATION
UNCERTAINTY
BDC CLOCK
(TARGET MCU)
HOST
TRANSMIT 1
HOST
TRANSMIT 0
PERCEIVED START
OF BIT TIME
OF NEXT BIT
Chapter 12 Development Support
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 101
Figure 12-4. BDC Target-to-Host Serial Bit Timing (Logic 1)
Figure 12-5 shows the host receiving a logic 0 from the target MCU. Because the host is asynchronous to
the target, there is a 0-to-1 cycle delay from the host-generated falling edge on BKGD to the start of the
bit time as perceived by the target. The host initiates the bit time but the target finishes it. Because the target
wants the host to receive a logic 0, it drives the BKGD pin low for 13 BDC clock cycles, then briefly drives
it high to speed up the rising edge. The host samples the bit level approximately 10 cycles after starting
the bit time.
HOST SAMPLES BKGD PIN
10 CYCLES
BDC CLOCK
(TARGET MCU)
HOST DRIVE
TO BKGD PIN
TARGET MCU
SPEEDUP PULSE
PERCEIVED START
OF BIT TIME
HIGH IMPEDANCE
HIGH IMPEDANCE HIGH IMPEDANCE
BKGD PIN
R-C RISE
10 CYCLES
EARLIEST START
OF NEXT BIT
Chapter 12 Development Support
MC9RS08KA2 Series Data Sheet, Rev. 4
102 Freescale Semiconductor
Figure 12-5. BDM Target-to-Host Serial Bit Timing (Logic 0)
12.3.3 SYNC and Serial Communication Timeout
The host initiates a host-to-target serial transmission by generating a falling edge on the BKGD pin. If
BKGD is kept low for more than 128 target clock cycles, the target understands that a SYNC command
was issued. In this case, the target will keep waiting for a rising edge on BKGD to answer the SYNC
request pulse. If the rising edge is not detected, the target will keep waiting indefinitely, without any
timeout limit. When a rising edge on BKGD occurs after a valid SYNC request, the BDC will drive the
BKGD pin low for exactly 128 BDC cycles.
Consider now the case where the host returns BKGD to logic 1 before 128 cycles. This is interpreted as a
valid bit transmission, and not as a SYNC request. The target will keep waiting for another falling edge
marking the start of a new bit. If, however, a new falling edge is not detected by the target within 512 clock
cycles since the last falling edge, a timeout occurs and the current command is discarded without affecting
memory or the operating mode of the MCU. This is referred as a soft-reset to the BDC.
If a read command is issued but the data is not retrieved within 512 serial clock cycles, a soft-reset will
occur causing the command to be disregarded. The data is not available for retrieving after the timeout has
occurred. A soft-reset is also used to end a READ_BLOCK or WRITE_BLOCK command.
The following describes the actual bit-time requirements for a host to guarantee logic 1 or 0 bit
transmission without the target timing out or interpreting the bit as a SYNC command:
• To send a logic 0, BKGD must be kept low for a minimum of 12 BDC cycles and up to 511 BDC
cycles except for the first bit of a command sequence, which will be detected as a SYNC request.
• To send a logic 1, BKGD must be held low for at least four BDC cycles, be released by the eighth
cycle, and be held high until at least the sixteenth BDC cycle.
10 CYCLES
BDC CLOCK
(TARGET MCU)
HOST DRIVE
TO BKGD PIN
TARGET MCU
DRIVE AND
PERCEIVED START
OF BIT TIME
HIGH IMPEDANCE
BKGD PIN
10 CYCLES
SPEEDUP PULSE
SPEEDUP
PULSE
EARLIEST START
OF NEXT BIT
HOST SAMPLES BKGD PIN
Chapter 12 Development Support
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 103
• Subsequent bits must occur within 512 BDC cycles of the last bit sent.
12.4 BDC Registers and Control Bits
The BDC contains two non-CPU accessible registers:
• The BDC status and control register (BDCSCR) is an 8-bit register containing control and status
bits for the background debug controller.
• The BDC breakpoint register (BDCBKPT) holds a 16-bit breakpoint match address.
These registers are accessed with dedicated serial BDC commands and are not located in the memory
space of the target MCU (so they do not have addresses and cannot be accessed by user programs).
Some of the bits in the BDCSCR have write limitations; otherwise, these registers may be read or written
at any time. For example, the ENBDM control bit may not be written while the MCU is in active
background mode. This prevents the ambiguous condition of the control bit forbidding active background
mode while the MCU is already in active background mode. Also, the status bits (BDMACT, WS, and
WSF) are read-only status indicators and can never be written by the WRITE_CONTROL serial BDC
command.
12.4.1 BDC Status and Control Register (BDCSCR)
This register can be read or written by serial BDC commands (READ_STATUS and WRITE_CONTROL)
but is not accessible to user programs because it is not located in the normal memory map of the MCU.
76543210
R
ENBDM
BDMACT
BKPTEN FTS
0WSWSF0
W
Normal
Reset 00000000
Reset in
Active BDM: 11000000
= Unimplemented or Reserved
Figure 12-6. BDC Status and Control Register (BDCSCR)
Table 12-1. BDCSCR Register Field Descriptions
Field Description
7
ENBDM
Enable BDM (Permit Active Background Mode) — Typically, this bit is written to 1 by the debug host shortly
after the beginning of a debug session or whenever the debug host resets the target and remains 1 until a normal
reset clears it. If the application can go into stop mode, this bit is required to be set if debugging capabilities are
required.
0 BDM cannot be made active (non-intrusive commands still allowed).
1 BDM can be made active to allow active background mode commands.
6
BDMACT
Background Mode Active Status — This is a read-only status bit.
0 BDM not active (user application program running).
1 BDM active and waiting for serial commands.
Chapter 12 Development Support
MC9RS08KA2 Series Data Sheet, Rev. 4
104 Freescale Semiconductor
12.4.2 BDC Breakpoint Match Register
This 16-bit register holds the 14-bit address for the hardware breakpoint in the BDC. The BKPTEN and
FTS control bits in BDCSCR are used to enable and configure the breakpoint logic. Dedicated serial BDC
commands (READ_BKPT and WRITE_BKPT) are used to read and write the BDCBKPT register.
Breakpoints are normally set while the target MCU is in active background mode before running the user
application program. However, because READ_BKPT and WRITE_BKPT are non-intrusive commands,
they could be executed even while the user program is running. For additional information about setup and
use of the hardware breakpoint logic in the BDC, refer to the RS08 Family Reference Manual.”
5
BKPTEN
BDC Breakpoint Enable — If this bit is clear, the BDC breakpoint is disabled and the FTS (force tag select)
control bit and BDCBKPT match register are ignored
0 BDC breakpoint disabled.
1 BDC breakpoint enabled.
4
FTS
Force/Tag Select — When FTS = 1, a breakpoint is requested whenever the CPU address bus matches the
BDCBKPT match register. When FTS = 0, a match between the CPU address bus and the BDCBKPT register
causes the fetched opcode to be tagged. If this tagged opcode ever reaches the end of the instruction queue,
the CPU enters active background mode rather than executing the tagged opcode.
0 Tag opcode at breakpoint address and enter active background mode if CPU attempts to execute that
instruction.
1 Breakpoint match forces active background mode at next instruction boundary (address need not be an
opcode).
2
WS
Wait or Stop Status — When the target CPU is in wait or stop mode, most BDC commands cannot function.
However, the BACKGROUND command can be used to force the target CPU out of wait or stop and into active
background mode where all BDC commands work. Whenever the host forces the target MCU into active
background mode, the host must issue a READ_STATUS command to check that BDMACT = 1 before
attempting other BDC commands.
0 Target CPU is running user application code or in active background mode (was not in wait or stop mode when
background became active).
1 Target CPU is in wait or stop mode, or a BACKGROUND command was used to change from wait or stop to
active background mode.
1
WSF
Wait or Stop Failure Status — This status bit is set if a memory access command failed due to the target CPU
executing a wait or stop instruction at or about the same time. The usual recovery strategy is to issue a
BACKGROUND command to get out of wait or stop mode into active background mode, repeat the command
that failed, then return to the user program. (Typically, the host would restore CPU registers and stack values and
re-execute the wait or stop instruction.)
0 Memory access did not conflict with a wait or stop instruction.
1 Memory access command failed because the CPU entered wait or stop mode.
Table 12-1. BDCSCR Register Field Descriptions (continued)
Field Description
Chapter 12 Development Support
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 105
12.5 RS08 BDC Commands
BDC commands are sent serially from a host computer to the BKGD pin of the target MCU. All commands
and data are sent MSB-first using a custom BDC communications protocol. Active background mode
commands require that the target MCU is currently in the active background mode while non-intrusive
commands may be issued at any time whether the target MCU is in active background mode or running a
user application program.
Table 12-2 shows all RS08 BDC commands, a shorthand description of their coding structure, and the
meaning of each command.
Coding Structure Nomenclature
The following nomenclature is used in Table 12-2 to describe the coding structure of the BDC commands.
Commands begin with an 8-bit command code in the host-to-target direction
(most significant bit first)
/ = Separates parts of the command
d = Delay 16 to 511 target BDC clock cycles
soft-reset = Delay of at least 512 BDC clock cycles from last host falling-edge
AAAA = 16-bit address in the host-to-target direction1
RD = Eight bits of read data in the target-to-host direction
WD = Eight bits of write data in the host-to-target direction
RD16 = 16 bits of read data in the target-to-host direction
WD16 = 16 bits of write data in the host-to-target direction
SS = the contents of BDCSCR in the target-to-host direction (STATUS)
CC = Eight bits of write data for BDCSCR in the host-to-target direction (CONTROL)
RBKP = 16 bits of read data in the target-to-host direction (from BDCBKPT breakpoint
register)
WBKP = 16 bits of write data in the host-to-target direction (for BDCBKPT breakpoint
register)
1514131211109876543210
R0 0
A13 A12 A11 A10 A9 A8 A7 A6 A5 A4 A3 A2 A1 A0
W
Any
Reset 0000000000000000
= Unimplemented or Reserved
Figure 12-7. BDC Breakpoint Match Register (BDCBKPT)
1. The RS08 CPU uses only 14 bits of address and occupies the lower 14 bits of the 16-bit AAAA address field. The values of
address bits 15 and 14 in AAAA are truncated and thus do not matter.
Chapter 12 Development Support
MC9RS08KA2 Series Data Sheet, Rev. 4
106 Freescale Semiconductor
Table 12-2. RS08 BDC Command Summary
Command
Mnemonic
Active Background
Mode/
Non-Intrusive
Coding
Structure Description
SYNC Non-intrusive n/a1Request a timed reference pulse to deter-
mine target BDC communication speed
BDC_RESET Any CPU mode 182Request an MCU reset
BACKGROUND Non-intrusive 90/d Enter active background mode if enabled
(ignore if ENBDM bit equals 0)
READ_STATUS Non-intrusive E4/SS Read BDC status from BDCSCR
WRITE_CONTROL Non-intrusive C4/CC Write BDC controls in BDCSCR
READ_BYTE Non-intrusive E0/AAAA/d/RD Read a byte from target memory
READ_BYTE_WS Non-intrusive E1/AAAA/d/SS/RD Read a byte and report status
WRITE_BYTE Non-intrusive C0/AAAA/WD/d Write a byte to target memory
WRITE_BYTE_WS Non-intrusive C1/AAAA/WD/d/SS Write a byte and report status
READ_BKPT Non-intrusive E2/RBKP Read BDCBKPT breakpoint register
WRITE_BKPT Non-intrusive C2/WBKP Write BDCBKPT breakpoint register
GO Active background
mode 08/d
Go to execute the user application pro-
gram starting at the address currently in
the PC
TRACE1 Active background
mode 10/d
Trace one user instruction at the address
in the PC, then return to active back-
ground mode
READ_BLOCK Active background
mode 80/AAAA/d/RD3Read a block of data from target memory
starting from AAAA continuing until a
soft-reset is detected
WRITE_BLOCK Active background
mode 88/AAAA/WD/d4Write a block of data to target memory
starting at AAAA continuing until a
soft-reset is detected
READ_A Active background
mode 68/d/RD Read accumulator (A)
Chapter 12 Development Support
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 107
WRITE_A Active background
mode 48/WD/d Write accumulator (A)
READ_CCR_PC Active background
mode 6B/d/RD165Read the CCR bits z, c concatenated with
the 14-bit program counter (PC)
RD16=zc:PC
WRITE_CCR_PC Active background
mode 4B/WD16/d6Write the CCR bits z, c concatenated with
the 14-bit program counter (PC)
WD16=zc:PC
READ_SPC Active background
mode 6F/d/RD167Read the 14-bit shadow program counter
(SPC)
RD16=0:0:SPC
WRITE_SPC Active background
mode 4F/WD16/d8
Write 14-bit shadow program counter
(SPC)
WD16 = x:x:SPC, the two most significant
bits shown by “x” are ignored by target
1The SYNC command is a special operation which does not have a command code.
218 was HCS08 BDC command for TAGGO.
3Each RD requires a delay between host read data byte and next read, command ends when target detects a soft-reset.
4Each WD requires a delay between host write data byte and next byte, command ends when target detects a soft-reset.
5HCS08 BDC had separate READ_CCR and READ_PC commands, the RS08 BDC combined this commands.
6HCS08 BDC had separate WRITE_CCR and WRITE_PC commands, the RS08 BDC combined this commands.
76F is READ_SP (read stack pointer) for HCS08 BDC.
84F is WRITE_SP (write stack pointer) for HCS08 BDC.
Table 12-2. RS08 BDC Command Summary (continued)
Command
Mnemonic
Active Background
Mode/
Non-Intrusive
Coding
Structure Description
Chapter 12 Development Support
MC9RS08KA2 Series Data Sheet, Rev. 4
108 Freescale Semiconductor
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 109
Appendix A
Electrical Characteristics
A.1 Introduction
This chapter contains electrical and timing specifications.
A.2 Absolute Maximum Ratings
Absolute maximum ratings are stress ratings only, and functional operation at the maxima is not
guaranteed. Stress beyond the limits specified in Table A-1 may affect device reliability or cause
permanent damage to the device. For functional operating conditions, refer to the remaining tables in this
chapter.
This device contains circuitry protecting against damage due to high static voltage or electrical fields;
however, it is advised that normal precautions be taken to avoid application of any voltages higher than
maximum-rated voltages to this high-impedance circuit. Reliability of operation is enhanced if unused
inputs are tied to an appropriate logic voltage level (for instance, either VSS or VDD) or the programmable
pull-up resistor associated with the pin is enabled.
Table A-1. Absolute Maximum Ratings
Rating Symbol Value Unit
Supply voltage VDD –0.3 to +5.8 V
Maximum current into VDD IDD 120 mA
Digital input voltage VIn –0.3 to VDD +0.3 V
Instantaneous maximum current
Single pin limit (applies to all port pins)1, 2, 3
1Input must be current limited to the value specified. To determine the value of the required current-limiting resistor, calculate
resistance values for positive (VDD) and negative (VSS) clamp voltages, then use the larger of the two resistance values.
2All functional non-supply pins are internally clamped to VSS and VDD except the RESET/VPP pin which is internally clamped
to VSS only.
3Power supply must maintain regulation within operating VDD range during instantaneous and operating maximum current
conditions. If positive injection current (VIn > VDD) is greater than IDD, the injection current may flow out of VDD and could result
in external power supply going out of regulation. Ensure external VDD load will shunt current greater than maximum injection
current. This will be the greatest risk when the MCU is not consuming power. Examples are: if no system clock is present, or
if the clock rate is very low which would reduce overall power consumption.
ID± 25 mA
Storage temperature range Tstg –55 to 150 °C
Appendix A Electrical Characteristics
MC9RS08KA2 Series Data Sheet, Rev. 4
110 Freescale Semiconductor
A.3 Thermal Characteristics
This section provides information about operating temperature range, power dissipation, and package
thermal resistance. Power dissipation on I/O pins is usually small compared to the power dissipation in
on-chip logic and voltage regulator circuits and it is user-determined rather than being controlled by the
MCU design. In order to take PI/O into account in power calculations, determine the difference between
actual pin voltage and VSS or VDD and multiply by the pin current for each I/O pin. Except in cases of
unusually high pin current (heavy loads), the difference between pin voltage and VSS or VDD will be very
small.
The average chip-junction temperature (TJ) in °C can be obtained from:
TJ = TA + (PD × θJA)Eqn. A-1
where:
TA = Ambient temperature, °C
θJA = Package thermal resistance, junction-to-ambient, °C/W
PD = Pint + PI/O
Pint = IDD × VDD, Watts — chip internal power
PI/O = Power dissipation on input and output pins — user determined
For most applications, PI/O << Pint and can be neglected. An approximate relationship between PD and TJ
(if PI/O is neglected) is:
Table A-2. Thermal Characteristics
Rating Symbol Value Unit
Operating temperature range (packaged) TATL to TH
–40 to 85
°C
Maximum junction temperature TJMAX 105 °C
Thermal resistance 1,2,3,4
6-pin DFN
1s
2s2p
8-pin PDIP
1s
2s2p
8-pin SOIC
1s
2s2p
1Junction temperature is a function of die size, on-chip power dissipation, package thermal resistance,
mounting site (board) temperature, ambient temperature, air flow, power dissipation of other
components on the board, and board thermal resistance.
2Junction to Ambient Natural Convection
31s - Single Layer Board, one signal layer
42s2p - Four Layer Board, 2 signal and 2 power layers
θJA
225
53
115
74
160
98
°C/W
Appendix A Electrical Characteristics
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 111
PD = K ÷ (TJ + 273°C) Eqn. A-2
Solving Equation A-1 and Equation A-2 for K gives:
K = PD × (TA + 273°C) + θJA × (PD)2Eqn. A-3
where K is a constant pertaining to the particular part. K can be determined from Equation A-3 by
measuring PD (at equilibrium) for a known TA. Using this value of K, the values of PD and TJ can be
obtained by solving equations 1 and 2 iteratively for any value of TA.
A.4 Electrostatic Discharge (ESD) Protection Characteristics
Although damage from static discharge is much less common on these devices than on early CMOS
circuits, normal handling precautions should be used to avoid exposure to static discharge. Qualification
tests are performed to ensure that these devices can withstand exposure to reasonable levels of static
without suffering any permanent damage. All ESD testing is in conformity with CDF-AEC-Q00 Stress
Test Qualification for Automotive Grade Integrated Circuits. (http://www.aecouncil.com/) A device is
considered to have failed if, after exposure to ESD pulses, the device no longer meets the device
specification requirements. Complete dc parametric and functional testing is performed per the applicable
device specification at room temperature followed by hot temperature, unless specified otherwise in the
device specification.
A.5 DC Characteristics
This section includes information about power supply requirements, I/O pin characteristics, and power
supply current in various operating modes.
Table A-3. ESD Protection Characteristics
Parameter Symbol Value Unit
ESD Target for Machine Model (MM)
MM circuit description VTHMM 200 V
ESD Target for Human Body Model (HBM)
HBM circuit description VTHHBM 2000 V
Table A-4. DC Characteristics
(Temperature Range = –40 to 85°C Ambient)
Parameter Symbol Min Typical Max Unit
Supply voltage (run, wait and stop modes.)
0 < fBus <10MHz VDD 1.8 —5.5
V
Minimum RAM retention supply voltage applied to VDD VRAM 0.8 1 ——V
Low-voltage Detection threshold
(VDD falling)
(VDD rising)
VLVD 1.80
1.88
1.86
1.94
1.95
2.03
V
Power on RESET (POR) voltage VPOR 0.9 1.4 1.7 V
Input high voltage (VDD > 2.3V) (all digital inputs) VIH 0.70 × VDD ——V
Input high voltage (1.8 V ≤ VDD ≤ 2.3 V) (all digital inputs) VIH 0.85 × VDD ——V
Appendix A Electrical Characteristics
MC9RS08KA2 Series Data Sheet, Rev. 4
112 Freescale Semiconductor
Input low voltage (VDD > 2.3 V) (all digital inputs) VIL ——
0.30 ×
VDD
V
Input low voltage (1.8 V ≤ VDD ≤ 2.3 V)
(all digital inputs) VIL ——
0.30 ×
VDD
V
Input hysteresis (all digital inputs) Vhys 0.06 × VDD ——V
Input leakage current (per pin)
VIn = VDD or VSS, all input only pins |IIn|—0.0251.0μA
High impedance (off-state) leakage current (per pin)
VIn = VDD or VSS, all input/output |IOZ|—0.0251.0μA
Internal pullup/pulldown resistors2 (all port pins) RPU 20 45 65 kΩ
Output high voltage (port A)
IOH = –5 mA (VDD ≥ 4.5 V)
IOH = –3 mA (VDD ≥ 3 V)
IOH = –2 mA (VDD ≥ 1.8 V)
VOH VDD – 0.8 — —
—
—
V
Maximum total IOH for all port pins |IOHT|— —40mA
Output low voltage (port A)
IOL = 5 mA (VDD ≥ 4.5 V)
IOL = 3 mA (VDD ≥ 3 V)
IOL = 2 mA (VDD ≥ 1.8 V)
VOL ——
0.8
0.8
0.8
V
Maximum total IOL for all port pins IOLT ——40mA
dc injection current3, 4, 5 6
VIn < VSS, VIn > VDD
Single pin limit
Total MCU limit, includes sum of all stressed pins
|IIC|— —
0.2
0.8
mA
mA
Input capacitance (all non-supply pins) CIn ——7pF
1This parameter is characterized and not tested on each device.
2Measurement condition for pull resistors: VIn = VSS for pullup and VIn = VDD for pulldown.
3All functional non-supply pins are internally clamped to VSS and VDD except the RESET/VPP which is internally clamped to
VSS only.
4Input must be current limited to the value specified. To determine the value of the required current-limiting resistor, calculate
resistance values for positive and negative clamp voltages, then use the larger of the two values.
5Power supply must maintain regulation within operating VDD range during instantaneous and operating maximum current
conditions. If positive injection current (VIn > VDD) is greater than IDD, the injection current may flow out of VDD and could result
in external power supply going out of regulation. Ensure external VDD load will shunt current greater than maximum injection
current. This will be the greatest risk when the MCU is not consuming power. Examples are: if no system clock is present, or
if clock rate is very low which would reduce overall power consumption.
6This parameter is characterized and not tested on each device.
Table A-4. DC Characteristics (continued)
(Temperature Range = –40 to 85°C Ambient)
Parameter Symbol Min Typical Max Unit
Appendix A Electrical Characteristics
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 113
Figure 12-8. Typical IOH vs. VDD-VOH
VDD = 5 V
Figure 12-9. Typical IOH vs. VDD-VOH
VDD = 3 V
Figure 12-10. Typical IOH vs. VDD-VOH
VDD = 1.8 V
Appendix A Electrical Characteristics
MC9RS08KA2 Series Data Sheet, Rev. 4
114 Freescale Semiconductor
Figure 12-11. Typical IOL vs. VOL
VDD = 5 V
Figure 12-12. Typical IOL vs. VOL
VDD = 3 V
Figure 12-13. Typical VDD-VOH vs. VDD at IOH=2mA
Appendix A Electrical Characteristics
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 115
Figure 12-14. Typical VOL vs. VDD at IOL=2mA
A.6 Supply Current Characteristics
Table A-5. Supply Current Characteristics
Parameter Symbol VDD (V) Typical1Max2Temp. (°C)
Run supply current3 measured at
(fBus = 10 MHz)
RIDD10 55.6 mA
5.8 mA 6.5 mA 25
85
34.7 mA
4.8 mA 5.5 mA 25
85
1.8 2.3 mA
2.4 mA 3 mA 25
85
Run supply current3 measured at
(fBus = 1.25 MHz)
RIDD1 51 mA
1.1 mA 1.5 mA 25
85
30.9 mA
0.95 mA 1.2 mA 25
85
1.8 0.6 mA
0.62 mA 0.8 mA 25
85
Stop mode supply current
SIDD
51 μA
3 μA
2 μA
5 μA
25
85
30.9 μA
2.5 μA
2 μA
5 μA
25
85
1.8 0.7 μA
2 μA
2 μA
4 μA
25
85
Bandgap buffer adder from stop
(BGBE = 1) —
520 μA 30 μA
25
85
320 μA 30 μA
25
85
1.8 20 μA 30 μA
25
85
Appendix A Electrical Characteristics
MC9RS08KA2 Series Data Sheet, Rev. 4
116 Freescale Semiconductor
ACMP adder from stop
(ACME = 1) —
515 μA 20 μA
25
85
315 μA 20 μA
25
85
1.8 15 μA 20 μA
25
85
RTI adder from stop
with 1-kHz clock source enabled4—
5 300 nA 500 nA 25
85
3 300 nA 500 nA 25
85
1.8 300 nA 500 nA 25
85
RTI adder from stop
with 32-kHz ICS internal clock source reference
enabled
—
5140 μA 165 μA25
85
3140 μA 165 μA25
85
1.8 135 μA 160 μA25
85
LVI adder from stop
(LVDE=1 and LVDSE=1) —
5 70 μA 85 μA25
85
3 70 μA 85 μA25
85
1.8 65 μA 80 μA25
85
1Typicals are measured at 25°C.
2Maximum value is measured at the nominal VDD voltage times 10% tolerance. Values given here are preliminary estimates
prior to completing characterization
3Does not include any dc loads on port pins
4Most customers are expected to find that auto-wakeup from stop can be used instead of the higher current wait mode. Wait
mode typical is 560 μA at 3 V and 422 μA at 2V with fBus = 1 MHz.
Table A-5. Supply Current Characteristics (continued)
Parameter Symbol VDD (V) Typical1Max2Temp. (°C)
Appendix A Electrical Characteristics
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 117
Figure 12-15. Typical Run IDD vs. VDD for FEI mode
A.7 Analog Comparator (ACMP) Electricals
A.8 Internal Clock Source Characteristics
Table A-6. Analog Comparator Electrical Specifications
Characteristic Symbol Min Typical Max Unit
Supply voltage VDD 1.80 — 5.5 V
Analog input voltage VAIN VSS – 0.3 — VDD V
Analog source impedance RAS ——10kΩ
Analog input offset voltage1
1These data are characterized but not production tested. Measurements are made with the device entered STOP mode.
VAIO —2040mV
Analog Comparator hysteresis1VH3.0 9.0 15.0 mV
Analog Comparator bandgap reference voltage1VBG 1.155 1.190 1.230 V
Supply current (active)1IDDAC —2035μA
Analog input leakage current1IALKG ——1.0μA
Analog Comparator initialization delay1tAINIT ——1.0μs
Table A-7. Internal Clock Source Specifications
Characteristic Symbol Min Typ1Max Unit
Average internal reference frequency — factory trimmed at
VDD = 5 V and temperature = 25°Cfint_ft —20—MHz
Average internal reference frequency - untrimmed fint_ut 25 31.25 41.66 kHz
Average internal reference frequency - trimmed fint_t 31.25 31.25 39.0625 kHz
DCO output frequency range - untrimmed fdco_ut 12.8 16 21.33 MHz
DCO output frequency range - trimmed fdco_t 16 16 20 MHz
Resolution of trimmed DCO output frequency
at fixed voltage and temperature Δfdco_res_t ——±0.2 %fdco
Total deviation of trimmed DCO output frequency
over voltage and temperature Δfdco_t ——±2%fdco
FLL acquisition time2,3 tacquire —— 1ms
Appendix A Electrical Characteristics
MC9RS08KA2 Series Data Sheet, Rev. 4
118 Freescale Semiconductor
A.9 AC Characteristics
This section describes ac timing characteristics for each peripheral system.
A.9.1 Control Timing
Figure A-1. Reset Timing
Stop recovery time (FLL wakeup to previous acquired
frequency)
IREFSTEN=0
IREFSTEN=1
t_wakeup
tir_wu
tfll_wu
—100
86 —
μs
1Data in typical column was characterized at 3.0 V and 5.0 V, 25°C or is typical recommended value.
2This parameter is characterized and not tested on each device.
3This specification applies to any time the FLL reference source or reference divider is changed, trim value changed or changing
from FLL disabled (FBILP) to FLL enabled (FEI, FBI).
Table A-8. Control Timing
Parameter Symbol Min Typical Max Unit
Bus frequency (tcyc = 1/fBus)f
Bus dc — 10 MHz
Real time interrupt internal oscillator period tRTI 700 1000 1300 μs
External RESET pulse width1
1This is the shortest pulse that is guaranteed to pass through the pin input filter circuitry. Shorter pulses may or may not be
recognized.
textrst 150 — — ns
KBI pulse width2
2This is the minimum pulse width that is guaranteed to pass through the pin synchronization circuitry. Shorter pulses may or
may not be recognized. In stop mode, the synchronizer is bypassed so shorter pulses can be recognized in that case.
tKBIPW 1.5 tcyc ——ns
KBI pulse width in stop1tKBIPWS 100 — — ns
Port rise and fall time (load = 50 pF)3
Slew rate control disabled (PTxSE = 0)
Slew rate control enabled (PTxSE = 1)
3Timing is shown with respect to 20% VDD and 80% VDD levels. Temperature range –40°C to 85°C.
tRise, tFall —
—
11
35
—
—
ns
Table A-7. Internal Clock Source Specifications
Characteristic Symbol Min Typ1Max Unit
textrst
RESET
Appendix A Electrical Characteristics
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 119
Figure A-2. KBI Pulse Width
A.10 FLASH Specifications
This section provides details about program/erase times and program-erase endurance for the FLASH
memory.
For detailed information about program/erase operations, see Chapter 4, “Memory.”
tKBIPW
KBI Pin
tKBIPW
KBI Pin
(rising or high level)
(falling or low level)
tKBIPWS
tKBIPWS
Appendix A Electrical Characteristics
MC9RS08KA2 Series Data Sheet, Rev. 4
120 Freescale Semiconductor
Table A-9. FLASH Characteristics
Characteristic Symbol Min Typical1
1Typicals are measured at 25°C.
Max Unit
Supply voltage for program/erase VDD 2.7 — 5.5 V
Program/Erase voltage VPP 11.8 12 12.2 V
VPP current
Program
Mass erase
IVPP_prog
IVPP_erase
—
—
—
—
200
100
μA
μA
Supply voltage for read operation
0 < fBus < 10 MHz VRead 1.8 — 5.5 V
Byte program time tprog 20 — 40 μs
Mass erase time tme 500 — — ms
Cumulative program HV time2
2thv is the cumulative high voltage programming time to the same row before next erase. Same address can not
be programmed more than twice before next erase.
thv —— 8ms
Total cumulative HV time
(total of tme & thv applied to device) thv_total — — 2 hours
HVEN to program setup time tpgs 10 — — μs
PGM/MASS to HVEN setup time tnvs 5——μs
HVEN hold time for PGM tnvh 5——μs
HVEN hold time for MASS tnvh1 100 — — μs
VPP to PGM/MASS setup time tvps 20 — — ns
HVEN to VPP hold time tvph 20 — — ns
VPP rise time3
3Fast VPP rise time may potentially trigger the ESD protection structure, which may result in over current flowing
into the pad and cause permanent damage to the pad. External filtering for the VPP power source is
recommended. An example VPP filter is shown in Figure A-3.
tvrs 200 — — ns
Recovery time trcv 1——μs
Program/erase endurance
TL to TH = –40°C to + 85°C—1000 — — cycles
Data retention tD_ret 15 100 — years
Appendix A Electrical Characteristics
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 121
Figure A-3. Example VPP Filtering
Figure A-4. Flash Program Timing
100 Ω
VPP
12 V 1 nF
PGM
HVEN
VPP2 tvps
trs
tnvh trcv
tvph
thv
1 Next Data applies if programming multiple bytes in a single row, reference 4.6.2, “Flash Programming Procedure”.
2 VDD must be at a valid operating voltage before voltage is applied or removed from the VPP pin.
WRITE DATA1
tnvs
tpgs
tprog
Data Next
Data
Appendix A Electrical Characteristics
MC9RS08KA2 Series Data Sheet, Rev. 4
122 Freescale Semiconductor
Figure A-5. Flash Mass Erase Timing
MASS
HVEN
VPP1 tvps
trs
tnvh1
trcv
tvph
tme
1 VDD must be at a valid operating voltage before voltage is applied or removed from the VPP pin.
tnvs
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 123
Appendix B
Ordering Information and Mechanical Drawings
B.1 Ordering Information
This section contains ordering numbers for MC9RS08KA2 Series devices. See below for an example of
the device numbering system.
B.2 Mechanical Drawings
This following pages contain mechanical specifications for MC9RS08KA2 Series package options:
• 6-pin DFN (dual flat no-lead)
• 8-pin PDIP (plastic dual in-line pin)
• 8-pin NB-SOIC (narrow body small outline integrated circuit)
Table B-1. Device Numbering System
Device Number
Memory Package
FLASH RAM Type Designator Document No.
MC9RS08KA2
MC9RS08KA1
2 KB
1 KB 63 bytes
6 DFN DB 98ARL10602D
8 PDIP PC 98ASB42420B
8 NB-SOIC SC 98ASB42564B
MC
Temperature range
Family
Memory
Status
Core
(C = –40 °C to 85 °C)
(9 = FLASH-based)
9RS08 KA XX
(MC = Fully Qualified) Package designator (See Ta b le B - 1 )
2
Memory designator
(2 = 2 KB)
C
(1 = 1 KB)
Appendix B Ordering Information and Mechanical Drawings
MC9RS08KA2 Series Data Sheet, Rev. 4
124 Freescale Semiconductor
Document Number: MC9RS08KA2
Rev. 4
12/2008
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