8XC196NT
PIN DESCRIPTIONS (Continued)
Symbol
Name and Function
P5.2/WR/WRL/SLPWR
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. SLPWR is the
Slave Port Write Control Input
e
selects the bank of memory that is connected to the high byte of the data bus.
P5.5/BHE/WRH
Byte High Enable or Write High output, as selected by the CCR. BHE
0
e
A0 0 selects that bank of memory that is connected to the low byte. Thus
accesses to a 16-bit wide memory can be to the low byte only (A0 0,
e
e
e
e
e
BHE 1), to the high byte only (A0 1, BHE 0) or both bytes (A0 0,
BHE 0). If the WRH function is selected, the pin will go low if the bus cycle is
e
writing to an odd memory location. BHE/WRH is only valid during 16-bit
external memory read/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
P6.2/T1CLK
Dual function I/O pin. As a bidirectional port pin or as a system function. The
system function is a Slave Port Interrupt Output Pin.
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/O pin. 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
P6.0–6.1/EPA8–9
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
another function of T2CLK and T2DIR of the TIMER2 timer/counter.
PORT 0/ACH4–7
P6.3–6.7/SSIO
4-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 OTPROM parts to select the Programming Mode.
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.
EPORT
8-bit bidirectional standard and I/O port. These bits are shared with the
extended address bus, A16–A19. Pin function is selected on a per pin basis.
INTOUT
Interrupt Output. This active-low output indicates that a pending interrupt
requires use of the external bus.
SLP0–SLP7
Slave Port Address/Data Bus
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