87C196KR/KQ 87C196JV/JT 87C196JR/JQ
PIN DESCRIPTIONS (Continued)
Symbol Name and Function
P5.3/RD Read signal output to external memory. RD is active only during external memory
reads or LSIO when not used as RD
.
P5.2/WR/WRL Write and Write Low output to external memory, as selected by the CCR, WR will
go low for every external write, while WRL
will go low only for external writes
where an even byte is being written. WR
/WRL is active during external memory
writes. Also an LSIO pin when not used as WR/WRL.
P5.5/BHE/WRH Byte High Enable or Write High output, as selected by the CCR. BHEe0 selects
the bank of memory that is connected to the high byte of the data bus. A0
e
0
selects that bank of memory that is connectd to the low byte. Thus accesses to a
16-bit wide memory can be to the low byte only (A0
e
0, BHE
e
1), to the high
byte only (A0
e
1, BHEe0) or both bytes (A0e0, BHEe0). If the WRH
function is selected, the pin will go low if the bus cycle is writing to an odd memory
location. BHE
/WRH is only valid during 16-bit external memory write cycles. Also
an LSIO pin when not BHE/WRH.
P5.6/READY Ready input to lengthen external memory cycles, for interfacing with slow or
dynamic memory, or for bus sharing. If the pin is high, CPU operation continues in
a normal manner. If the pin is low prior to the falling edge of CLKOUT, the memory
controller goes into a wait state mode until the next positive transition in CLKOUT
occurs with READY high. When external memory is not used, READY has no
effect. The max number of wait states inserted into the bus cycle is controlled by
the CCR/CCR1. Also an LSIO pin when READY is not selected.
P5.4/SLPINT Dual functional I/O pin. As a bidirectional port pin or as a system function. The
system function is a Slave Port Interrupt Output Pin.
P6.2/T1CLK Dual function I/O pin. Primary function is that of a bidirectional I/O pin, however it
may also be used as a TIMER1 Clock input. The TIMER1 will increment or
decrement on both positive and negative edges of this pin.
P6.3/T1DIR Dual function I/Opin. Primary function is that of a bidirectional I/O pin, however it
may also be used as a TIMER1 Direction input. The TIMER1 will increment when
this pin is high and decrements when this pin is low.
PORT1/EPA0–7 Dual function I/O port pins. Primary function is that of bidirectional I/O. System
function is that of High Speed capture and compare. EPA0 and EPA2 have yet
P6.0–6.1/EPA8– 9
another function of T2CLK and T2DIR of the TIMER2 timer/counter.
PORT 0/ACH0 – 7 8-bit high impedance input-only port. These pins can be used as digital inputs
and/or as analog inputs to the on-chip A/D converter. These pins are also used
as inputs to EPROM parts to select the Programming Mode.
P6.4–6.7/SSIO Dual function I/O ports that have a system function as Synchronous Serial I/O.
Two pins are clocks and two pins are data, providing full duplex capability.
PORT 2 8-bit multi-functional port. All of its pins are shared with other functions.
PORT 3 and 4 8-bit bidirectional I/O ports with open drain outputs. These pins are shared with
the multiplexed address/data bus which has strong internal pullups.
6