PERIPHERAL INTERFACE ADAPTER (PIA)
The MC6821 Peripheral Interface Adapter provides the universal
means of interfacing peripheral equipment to the M6800 family of
microprocessors. This device is capable of interfacing the MPU to
peripherals through two 8-bit bidirectional peripheral data buses and
four control lines. No external logic is required for interfacing to most
peripheral devices.
The functional configuration of the PIA is programmed by the MPU
during system initialization. Each of the peripheral data lines can be pro-
grammed to act as an input or output, and each of the four con-
trol/interrupt lines may be programmed for one of several control
modes. This allows a high degree of flexibility in the overall operation of
the interface.
@ 8-Bit Bidirectional Data Bus for Communication with the
MPU
@ Two Bidirectional 8-Bit Buses for Interface to Peripherals
@ Two Programmable Control Registers
@ Two Programmable Data Direction Registers
@ Four Individually-Controlled Interrupt Input Lines; Two *>~+s\~, *V$3
Usable as Peripheral Control Outputs *&a ‘3,
“‘i
\; k“ 3
,J
@ Handshake Control Logic for Input and Output Periphe~~~~‘~~~~.~‘~“‘
Operation .h*+ .,‘:#
Kit\&
‘i.
High-Impedance Three-State and Direct Transis$r DriGe
Peripheral Lines >@. ‘+
!a<$.
_ “&
Program Controlled Interrupt and InterruptV&$%$e Capability
CMOS Drive Capability on Side A Peri~~~~~~~~~~~s
Two TTL Drive Capability on All A a~~~~~~~e Buffers
_’
0 TTL-Compatible ,A.
/ ;;;g>* *v*
@ Static Operation x;<+
,*e .\+
“<&
i ‘\<
,V,&,, ‘~‘“:
vi, A
,,;# *&p
1 Plastic
P Suffix
1
INFORMATION
Frequency
(MHz)
1.0
1.0
1.5
1.5
2.0
1.0
1.0
1.5
1.5
2.0
Temperature
OT to 70°C
- 40°C
to 85’C
OT to 7OT
- 40°C
to 85’C
OT to 7OT
ooc to 7OT
- 4O’C
to 85’C
0°C to 70°C
- 40°C
to 85°C
OT to 70°C
Order Number
MC6821 L
MC6821 CL
MC68A21 L
MC68A21 CL
MC68B21 L
MC6821 S
MC6821 CS
MC68A21 S
MC68A21 CS
MC68B21 S
1.0
1.0
1.5
1.5
2.0
ooc to 70°C
MC6821 P
- 40°C
to 85OC MC682lCP
0°C to 7OT MC68A21 P
- 40°C
to 85°C MC68A21 CP
0°C to 7ooc
MC68B21 P
IN-CHAN
ERDIP PACKAGE
PLASTIC PACKAGE
CASE 711
PIN ASSIGNMENT
@MOTOROLA INC ,1985 DS9435R5
MAXIMUM RATINGS
Characteristics Symbol Value Unit
Supply Voltage “cc -0.3 to +7.0 v
Input Voltage “in -0.3 to +7.0 v
Operating Temperature Range TL to TH
MC6821, MC68A21, MC68B21 T A 0 to 70 T
MC6821C. MC68A21C -40 to +85
Storage Temperature Range Tstg -55to +150 “C
THERMAL CHARACTERISTICS
Characteristic
Thermal Resistance
Ceramic
Plastic
Symbol
BJA
Value
50
loo
Unit
T/W
I Cerdip
I
60 I
POWER CONSIDERATIONS
The average chip-junction temperature, TJ, in OC can be obtained from:
TJ=TA+(PD*BJA)
Where:
This device contains clrcuttry to protect the
inputs against damage due to high static
voltages or electric fields, however, It IS ad-
vised that normal precautions be taken lo
avoid applications of any voltage higher than
maxlmum rated voltages to this high-
Impedance circuit. For proper operation It IS
recommended that V,, and Vout be CQI?~.
“b@ ,%i
stralned to the range VSS 5 (V.,m,.‘~~:$[‘
VrJut~~VCC- i”
”
<;g ;.& ‘h
Unused inputs must always ~-~~~~~~~~~n
appropriate logic voltage lev$@&*;f@ther
VSS or VCC). .” ‘I_ \*< ;g
\*$ *& S?W
1 x’:2$.\ -“;
“-$y$\ ‘kji>b
1.
>kt,;,. ”
‘, i
q,;p
(I)
TA = Ambient Temperature, ‘C
BJ,L,= Package Thermal Resistance, Junction-to-Ambient, sC@$:, ._ ‘,\,,,P
PD=PINT+ PPORT
PINT= ICC
x VCC, Watts - Chip Internal Power a>t+~+t,p
*-$’ “.TS~ “$~,
PpDRT= Port Power Dissipation, Watts - User D~~~~i~~d
For most applications PPoRT~PINT and can be neglected. ,,‘-,~ ‘ix A$
P~~~~ ‘* may become significant if the device is configured to
drive Darlington bases or sink LED loads. _-
**q
An approximate relationship between PD and TJ (if PBQRT i$ neglected) is:
PD = K + (T J + 273’C) ‘_ ‘y;,
“:.
“k\ Q
Solving equations 1 and 2 for K gives: ‘ST<.*. “. ”
~ -; “$” _ b *\
\\
K = PD*iTA + 273%) +
0Jj@D2 ,~~~~~,~~~~ -) (3)
Where K is a constant pertaining to the par;Q&,&r part. K can be determined from equation (3) by measurtng PD (at equlllbrium)
*>;>,v\,t:, “B
for a known TA. Using this value of K the ~~~~~~,~~ PD and TJ can be obtained by solving equations II) and (2) iteratively for any
value of TA.
DC ELECTRICAL CHARAC@&dS
(V CC = 5.0 Vdc f 5%, VSS = 0, TA= TL to TH unless otherwise noted)
I _” rib\,, , f
,j Characteristic ) Symbol 1 Min ) Typ 1 Max I Unit ]
BUS CONTROL INPlJ~~&&$ Ehable, RESET, RSO, RSl, CSO, CSl, CS2)
\- ,, “IH vss+2.0 - “cc V
“IL VSS-0.3 - VSS+O.8 V
lin - 1.0 2.5 FA
Capacita& Cu’$= 0, TA= 25OC, f = 1 .O MHz) Cin - - 7.5 PF
--
INTEF&&j”t”&dfTPUTS (IRQA, IROB)
@@&$% VOltage (ILoad = 3.2 mA) VOL - -
?$$&&tput Leakage Current vss+o.4 v
IO2 - 1.0 10 @A
Caaacitance (Vin = 0, Tn = 25OC. f = 1 .O MHz) cm It - - 5.0 PF
DATA BUS (DO-D71
Input High Voltage
Input Low Voltage
Hi-Z Input Leakage Current lVin=0.4 to 2.4 V)
Output High Voltage (ILoad = - 205 PA)
Output Low Voltage (lLoad= 1.6 mA)
Capacitance IVin = 0, TA = 25OC, f = 1 .O MHz)
VIH vss+2.0 - “cc V
VIL VSS-0.3 - VSS+O.8 V
‘I2 - 2.0 10 LtA
VOH VSS+2.4 - - V
VOL - - vss+o.4 v
Cin - - 12.5 PF
DC ELECTRICAL CHARACTERISTICS
(Continued)
Characteristic
PERIPHERAL BUS (PAO-PA7, PBO-PB7, CAl, CA2, CBl, CB2) 1 Symbol 1 Min 1 Typ 1 Max [ Unit ]
Capacitance (Vin = 0, TA= 25”C, f = 1 .O MHz)
POWER REQUIREMENTS
Internal Power Dissipation (Measured at TL=O”C)
1 c I”
PlNT
I Is
Symbol Characteristic
I”I111.
I I
Number
‘The data bus output buffers are no longer.&k@hg or srnkrng current by tDHPmax (Hugh Impedance)
&\ V,k< *i”
‘>*\>y,.\ <,- ,>*
_ .y<*:, ”
Notes:
1. Voltage levels shown are V~s0.4 V, VHr2.4 V, unless otherwise specified.
2. Measurement points shown are 0.8 V and 2.0 V, unless otherwise specified.
3
PERIPHERAL TlMlNG CHARACTERISTICS
(VW = 5 0 V * 5%. VSS = 0 V, TA= TI- to TH unless otherwlse speclfied)
Characteristic
(PAO-PA7, CA2)
Test Point 7 eL 30 pF
I
T
FIGURE 3 - TTL EQUIVALENT
TEST LOAD
(PAD-PA7, PBO-PB7, CA2, CB2)
P 5.0v
t
RL=1.25 kht
Test Point
C=3OpF, R=12 k
MM06150
or Equiv.
MMD7000
or Equiv.
FIGURE 5 - NMOS EQUIVALENT
TEST LOAD
(IRQ Only)
5.0 v
Test Point
4
100 PF
T
1.5 kQ
a
-
FIGURE 6 - PERIPHERAL DATA SETUP AND HOLD TIMES FIGURE 7 - CA2 DELAY TIME
(Read Mode) (Read Mode; CRA-5= CRA3= 1, CRA-4= 0)
Enable j+-/j-
FIGURE 8 - CA2 DELAY TIME
(Read Mode; CRAd= 1, CRA3= CRA-4= 0)
FIGURE 10 - PERIPHERAL DATA AND CB2 DELAY TIMES
(Write Mode; CRBd=CRB-3= 1, CRB-4=0) ,&
*A “*,*<
‘SF\ “.>l
Enable
CRB-3=CRB-4=0)
CA2
r
*Assumes part was dese
the previous E pulse.
FIGURE 9 - PERIPHERAL CM
(Write Mode; CRA4= 0)
FIGURE 11 - CB2 DELAY TIME
(Write Mode; CRB-5= CRB-3= 1, CRB-4=0)
FIGURE 13 - INTERRUPT PULSE WIDTH AND m RESPONSE
IROA’6. j_ tRs,*-L
*Assumes Interrupt Enable Bits are set.
*Assumes part was deselected during
any previous E pulse.
Note: Timing measurements are referenced to and from a low voltage of 0.8 volts and a high voltage of 2.0 volts, unless otherwise noted
FIGURE 14 - IRQ RELEASE TIME FIGURE 15 - RESET LOW TIME
-I
Note: Timing measuremenrs are referenced to and from a low voltage of 0.8 volts and a high voltage of 2.0 volts, unless otherwis6+~@$&~
A- \*J& / *
_ &q “5’
_ \
FIGURE 16 - EXPANDED BLOCK DIAGRAM
IRQA 36 40 CA1
.
39 CA2
4
DO 33 -s-J---
01 32
02 31
D3 30 Data BUS
Buffers
04 29 (DEB)
D5 28
D6 27 2 PA0
3 PA1
4 PAZ
5 PA3
6 PA4
7 PA5
8 PA6
9 PA7
07 26
--Jr
10 PBO
11 PBl output
Register B
(ORB) Pertpheral
lnlerface
B
12 PB2
i3 PB3
14 PB4
15 PB5
16 PB6
17 PBJ
c -18 CBI
Interrupt sratus
IRQB 37 4 Control B -19 CB2
PIA INTERFACE SIGNALS FOR MPU
The PIA interfaces to the M6800 bus with an 8-bit bidirec-
tional data bus, three chip select lines, two register select
lines, two interrupt request lines, a read/write line, an enable
line and a reset line. To ensure proper operation with the
MC6800, MC6802, or MC6808 microprocessors, VMA
should be used as an active part of the address decoding.
Bidirectional Data (DO-D71 - The bidirectional data lines
(DO-D7) allow the transfer of data between the MPU and the
PIA. The data bus output drivers are three-state devices that
remain in the high-impedance (off) state except when the
MPU performs a PIA read operation. The read/write line is in
the read (high) state when the PIA is selected for a read
operation.
Enable (E) - The enable pulse, E, is the only timing
signal that is supplied to the PIA. Timing of all other signals
is referenced to the leading and trailing edges of the E pulse.
Read/Write (R/W) - This signal is generated by the
MPU to control the direction of data transfers on the data
bus. A low state on the PIA read/write line enables the input
buffers and data is transferred from the MPU to the PIA on
the E signal if the device has been selected. A high on the
read/write line sets up the PIA for a transfer of data to the
bus. The PIA output buffers are enabled when the proper ad-
dress and the enable pulse E are present.
RESET - The active low RESET line is used to re$${3all
register bits in the PIA to a logical zero (low). This lin&Qar%e
d$*h~bs ; ‘”
used as a power-on reset and as a master rese@%nng
system operation * ” \~\\>;,~S*;
Chip Selects (CSO, CSI, and cs2) ~~~%&$$e’three input
signals are used to select the PIA. C&O’%<% CSI must be
high and CS2 must be low for sel~~~~~~~he device. Data
transfers are then performed und&h&ontrol of the enable
$..+ ‘at; _ *a $,.‘
and read/write signals. The ct$p s@ect lines must be stable
for the duration of the E pulse. The device is deselected
when any of the chip selects are in the inactive state
Register Selects (RSO and RSI) - The two register
written or read.
interrupt by the MPU may be accomplished
routine that, on a prioritized basis, sequentially
s and tests the two control registers in each PIA for in-
flag bits that are set.
The interrupt flags are cleared (zeroed) as a result of an
MPU Read Peripheral Data Operation of the corresponding
data register. After being cleared, the interrupt flag bit can-
not be enabled to be set until the PIA is deselected during an
E pulse. The E pulse is used to condition the interrupt control
lines (CAI, CA2, CBI, CB2). When these lines are used as
interrupt inputs, at least one E pulse must occur from the in-
active edge to the active edge of the interrupt input signal to
condition the edge sense network. If the interrupt flag has
been enabled and the edge sense circuit has been properly
conditioned, the interrupt flag will be set on the next active
transition of the interrupt input pin.
PIA PERIPHERAL INTERFACE LINES
The Pl~.~~~~~~s two 8-bit bidirectional data buses and
four in~~m$&control lines for interfacing to peripheral
de$sq&+
*\~,$\>\<Jt~>~\~ *
~~~~~on A Peripheral Data (PAO-PA71 - Each of the
petrpheral data lines can be programmed to act as an input or
output. This is accomplished by setting a “1” in the cor-
responding Data Direction Register bit for those lines which
are to be outputs. A “0” in a bit of the Data Direction
Register causes the corresponding peripheral data line to act
as an input. During an MPU Read Peripheral Data Operation,
the data on peripheral lines programmed to act as inputs ap-
pears directly on the corresponding MPU Data Bus lines. In
the input mode, the internal pullup resistor on these lines
represents a maximum of 1.5 standard TTL loads.
The data in Output Register A will appear on the data lines
that are programmed to be outputs. A logical “1” written in-
to the register will cause a “high” on the corresponding data
-
line while a “0” results in a “low.” Data in Output Register A
may be read by an MPU “Read Peripheral Data A” operation
when the corresponding lines are programmed as outputs.
This data will be read properly if the voltage on the
peripheral data lines is greater than 2.0 volts for a logic “I”
output and less than 0.8 volt for a logic “0” output. Loading
the output lines such that the voltage on these lines does not
reach full voltage causes the data transferred into the MPU
on a Read operation to differ from that contained in the
respective bit of Output Register A.
Section B Peripheral Data (PBO-PB7) - The peripheral
data lines in the B Section of the PIA can be programmed to
act as either inputs or outputs in a similar manner to PAO-
PA7. They have three-state capabiity, allowing them to enter
a high-impedance state when the peripheral data line is used
as an input. In addition, data on the peripheral data lines
‘BO-PB7 will be read properly from those lines programmed
IS outputs even if the voltages are below 2.0 volts for a
‘high” or above 0.8 V for a “low”. As outputs, these lines
Ire compatible with standard TTL and may also be used as a
source of at least 1 milliampere at 1.5 volts to directly drive
the base of a transistor switch.
Interrupt Input (CA1 and CBI) - Peripheral input lines
3A1 and CBI are input only lines that set the interrupt flags
If the control registers. The active transition for these
;ignals is also programmed by the two control registers.
Peripheral Control (C/G!) - The peripheral control line
CA2 can be programmed to act as an interrupt input or as a
INTERNAL
INITIALIZATION
A RESET has the effect of zeroing all PIA registers. This
NilI set PAO-PA7, PBO-PB7, CA2 and CB2 as inputs, and all
nterrupts disabled. The PIA must be configured during the
restart program which follows the reset.
There are six locations within the PIA accessible to the
MPU data bus: two Peripheral Registers, two Data Direction
Registers, and two Control Registers. Selection of these
locations is controlled by the RSO and RSl inputs together
Gth bit 2 in the Control Register, as shown in Table 1.
Details of possible configurations of the Data Direction
3nd Control Register are as follows: <a<
\.P’ ‘-&
*$\ -+‘S.
‘FZ..
,,*+\,.. ‘“\,
““pi:. ., \
TABLE 1 - INTERNAL ADDRESSING ,~~~~~‘~~~~~~~‘~~~~
PORT~$&&~ARDWARE CHARACTERISTICS
~~~~~~n in Figure 17, the MC6821 has a pair of I/O ports
wh&$?haracteristics differ greatly. The A side is designed
to drive CMOS logic to normal 30% to 70% levels, and incor-
porates an internal pullup device that remains connected
even in the input mode. Because of this, the A side requires
more drive current in the input mode than Port B. In con-
trast, the B side uses a normal three-state NMOS buffer
which cannot pullup to CMOS levels without external
resistors. The B side can drive extra loads such as Darl-
ingtons without problem. When the PIA comes out of reset,
the A port represents inputs with pullup resistors, whereas
the B side (input mode also) will float high or low, depending
upon the load connected to it.
peripheral control output. As an output, this line is compati-
ble with standard TTL; as an input the internal pullup resistor
on this line represents 1.5 standard TTL loads. The function
of this signal line is programmed with Control Register A.
Peripheral Control (CB2) - Peripheral Control line CB2
may also be programmed to act as an interrupt input or
peripheral control output. As an input, this line has higQn-
put impedance and is compatible with standard TT~.~~~~:~~
output it is compatible with standard TTL and rn~~~~~ be
used as a source of up to 1 milliampere at 1.5 v~~~~~~~~ectly
drive the base of a transistor switch. This line&QrQgrammed
by Control Register B. ??<>$ >tv; Xb&
” *&
*f*.**s” \,
Notice the diffe&r+c&between a Port A and Port B read
operation whe~.~~~~~~~~utput mode. When reading Port A,
the actual pi~~~~~~~~, whereas the B side read comes from an
output la@hk&$d of the actual pin.
COb$@Ol?kGISTERS (CRA and CRB)
,~~~~~~~~~o Control Registers (CRA and CRB) allow the MPU
LsX,& c@trol the operation of the four peripheral control lines
-GC:?@?, CA2, CBI, and CB2. In addition they allow the MPU to
‘q&..*,
bs;&ehable the interrupt lines and monitor the status of the inter-
,:& “rupt flags. Bits 0 through 5 of the two registers may be writ-
ten or read by the MPU when the proper chip select and
register select signals are applied. Bits 6 and 7 of the two
registers are read only and are modified by external interrupts
occurring on control lines CAI, CA2, CBI, or CB2. The for-
mat of the control words is shown in Figure 18.
DATA DIRECTION ACCESS CONTROL BIT (CRA-2 and
CRB-2)
Bit 2, in each Control Register lCRA and CRB), deter-
mines selection of either a Peripheral Output Register or the
corresponding Data Direction E Register when the proper
register select signals are applied to RSO and RSI. A “1” in
bit 2 allows access of the Peripheral Interface Register, while
a “0” causes the Data Direction Register to be addressed.
Interrupt Flags (CRAB, CRA-7, CRBB, and CRB-7) -
The four interrupt flag bits are set by active transitions of
signals on the four Interrupt and Peripheral Control lines
when those lines are programmed to be inputs. These bits
cannot be set directly from the MPU Data Bus and are reset
indirectly by a Read Peripheral Data Operation on the ap-
propriate section.
Control of CA2 and CB2 Peripheral Control Lines (CRA-3,
CRA-4, CRA-5, CRB-3, CRB-4, and CRB-5) - Bits 3,4, and
5 of the two control registers are used to control the CA2 and
CB2 Peripheral Control lines. These bits determine if the con-
trol lines will be an interrupt input or an output control
signal. If bit CRA-5 (CRB-5) is low, CA2 (CB2) is an interrupt
input line similar to CA1 (CBI). When CRA-5 (CRB-5) is
high, CA2 (CB2) becomes an output signal that may be used
to control peripheral data transfers. When in the output
mode, CA2 and CB2 have slightly different loading
characteristics.
Control of CA1 and CBI Interrupt Input Lines (CRA-0,
CRB-0,
CRA-1, and CRB-1)
- The two lowest-order bits of
the control registers are used to control the interrupt input
lines CA1 and CBI. Bits CRA-0 and CRB-0 are used to
enable the MPU interrupt signals IRQA and Im, respec-
tively. Bits CRA-1 and CRB-1 determine the active transition
of the interrupt input signals CA1 and CBI.
FIGURE 17 - PORT A AND PORT B EQUIVALENT CIRCUITS
Port A
in
(I -Output Pin1 I I
(04nput PinI
To External
Bus A
Port R
Data DIrection
DATA
Read of B
Data when
in Input Mode
A= 1.5 MHz
8=2.0 MHz
Device Designation
In M6800 Famllv
Temperature Range
Blank=OO- +70°C
C= -4O’=- +85”C
Package
P = Plastic
S = Cerdlp
L = Ceram7lc
BETTER PROGRAM
Better program processing IS available on all types llsted. Adc
suffix letters to part number.
Level 1 add “S” Level 2 add “D” Level 3 add “DS”
Level 1 “S” = 10 Temp Cycles - (-25 to 150°C);
HI Temp testing at TA max
Level 2 “D” = 168 Hour Burn-In at 125°C
Level 3 “DS” = Comblnatlon of Level 1 and 2
1
Determine Active CA1 (Cl311 Transition for Setting
Interrupt Flag IRQA(B)l - (bit 7)
bl=O: IRQA(B)l set by high-to-low transition on CA1
(CBII
bl = 1: IRQA(B)l set by low-to-high transition on CA1
(CBII.
I
I I
FIGURE 18 - CONTROL WORD FORMAT
CA1 (CBI) Interrupt Request Enable/Disable
bO=O: Disables IRQAIB) MPU Interrupt by CA1
(CBI) active transition.’
bO= 1: Enable IRQA(BI MPU Interrupt by CA1 (CBli
active transition.
1. IRQA(B) will occur on next (MPU generated) posmve
transition of b0 if CA1 tCBl1 active transltion oc-
curred while interrupt was disabled.
IRQA(B) 1 Interrupt Flag (bit 7)
Goes high on active transition of CA1 ICBI); Automa-
tically cleared by MPU Read of Output Register A(B).
May also be cleared by hardware Reset.
Control Register IRQA(B)l IRQA(Bj2 CA2 lCB2)
Flag Flag Control Access
I
IRQA(B)Z Interrupt Flag (bit 6)
When CA2 (CB2) is an input, IRQAlBl goes high on ac-
tive transition CA2 (CB21; Automatically cleared by
MPU Read of Output Register AIB). May also be
cleared by hardware Reset.
CA2 (CB2) Established as Output (b5=1): IRQA(B)
2=0, not affected by CA2 (CB2) transitions.
I
L
L
CA2 (CB2) Established as Output by b5= 1
b5 b4 t
--_
1 0
INote that operation of CA2 and CB2 output
functions are not identical)
--e CA2 $3
b3 = 0: Read Strobe with CA1 Restore -i“$
CA2 goes low on first high:t?kw
E transition following an ~~~~
of Output Register A; re&&c&gh
by next active CA1 ?~~~~~, as
“~>*~ ~‘$k “I
specified by bit I+\ ,~+&% :;
b3 = 1: Read Strobe w&th &@&ore
CA2 goes l~~‘~~~~~~st high-to-low
E transitio~~follr&ving an MPU read
of Out~~~~~~er A; returned high
by n,e&&$$to-low E transition dur-
,?~~~~~~ect,
+ CB2 :*+ “>@
b3~&&&ite Strobe with CBI Restore
ST,a,%,, ‘+@2 goes low on first low-to-high
?b<,~ “&&” ‘V?h
.< k,\ 9
sSF E transition following an MPU write
:QL& into Output Register 8; returned
6‘ f ;-i‘;
~<$P
*$:
‘&$S high by the next active CBl transi-
‘,Lk
- -\ \’ tion as specified by bit 1. CRB-b7
I_ ‘\&<?>, ,>d
&$, %Q,\S must first be cleared by a read of
“~@w~ ” data.
?&#,, %$$
$>, \‘\* ;\* > b3= 1: Write Strobe with E Restore
<$:$*
rt. CB2 goes low on first low-to-high
E transition following an MPU write
into Output Register B; returned
b5 b4 b3 high by the next low-to-high E tran-
--
L
sition following an E pulse which
occurred while the part was de-
selected.
1 1 Set/Reset CA2 (CB2)
CA2 lCB2) goes low as MPU writes
b3= 0 into Control Register.
CA2 lCB2) goes high as MPU writes
b3= 1 into Control Register.
:$.@ (CB2) Established as Input by b5= 0
CA2 (CB2) Interrupt Request Enable/Disable
b3=0: Disables IRQA(B) MPU Interrupt by
CA2 ICB2) active transition.*
b3= 1: Enables IRQAlB) MPU Interrupt by
CA2 lCB2) active transition.
‘IRQA(B) WIII occur on next (MPL! generat-
ted) positive transition of b3 if CA2 lCB21
active transition occurred while interrupt
was disabled.
Determines Active CA2 (CB2) Transition for
Setting Interrupt Flag IRQA(B)P - (Bit b6)
b4=0: IRQA(B)2 set by high-to-low transi-
tion on CA2 (CB2).
b4= 1: IRQA(B)Z set by low-to-high transi-
tion on CA2 (CB2).
PACKAGE DIMENSIONS
3501 ED BLUESTEIN BLVD, AUSTIN, TEXAS 78721 0 A SUBSIDIARY OF MOTOROLA INC -
