8XC196MC
PIN DESCRIPTIONS (Alphabetically Ordered)
Symbol Function
ACH0–ACH12 Analog inputs to the on-chip A/D converter. ACH0–7 share the input pins
(P0.0–P0.7, P1.0 – P1.4)
with P0.0 – 7 and ACH8 –12 share pins with P1.0 – 4. If the A/D is not used,
the port pins can be used as standard input ports.
ANGND Reference ground for the A/D converter. Must be held at nominally the
same potential as V
SS
.
ALE/ADV(P5.0) Address Latch Enable or Address Valid output, as selected by CCR. Both
options allow a latch to demultiplex the address/data bus on the signal’s
falling edge. When the pin is ADV
, it goes inactive (high) at the end of the
bus cycle. ALE/ADV
is active only during external memory accesses. Can be
used as standard I/O when not used as ALE/ADV.
BHE/WRH (P5.5) Byte High Enable or Write High output, as selected by the CCR. BHE will go
low for external writes to the high byte of the data bus. WRH
will go low for
external writes where an odd byte is being written. BHE
/WRH is activated
only during external memory writes.
BUSWIDTH (P5.7) Input for bus width selection. If CCR bits 1 and 2e1, this pin dynamically
controls the bus width of the bus cycle in progress. If BUSWIDTH is low, an
8-bit cycle occurs. If it is high, a 16-bit cycle occurs. This pin can be used as
standard I/O when not used as BUSWIDTH.
CAPCOMP0–CAPCOMP3 The EPA Capture/Compare pins. These pins share P2.0 – P2.3. If not used
(P2.0–P2.3)
for the EPA, they can be configured as standard I/O pins.
CLKOUT Output of the internal clock generator. The frequency is (/2 of the oscillator
frequency. It has a 50% duty cycle.
COMPARE0–COMPARE3 The EPA Compare pins. These pins share P2.4 – P2.7. If not used for the
(P2.4–P2.7)
EPA, they can be configured as standard I/O pins.
EA External Access enable pin. EAe0 causes all memory accesses to be
external to the chip. EA
e
1 causes memory accesses from location 2000H
to 5FFFH to be from the on-chip OTPROM/QROM. EA
e
12.5V causes
execution to begin in the programming mode. EA
is latched at reset.
EXTINT A programmable input on this pin causes a maskable interrupt vector
through memory location 203CH. The input may be selected to be a
positive/negative edge or a high/low level using WGÐPROTECT (1FCEH).
INST (P5.1) INST is high during the instruction fetch from the external memory and
throughout the bus cycle. It is low otherwise. This pin can be configured as
standard I/O if not used as INST.
NMI A positive transition on this pin causes a non-maskable interrupt which
vectors to memory location 203EH. If not used, it should be tied to VSS. May
be used by Intel Evaluation boards.
PORT0 8-bit high impedance input-only port. Also used as A/D converter inputs.
Port0 pins should not be left floating. These pins also used to select
programming modes in the OTPROM devices.
PORT1 5-bit high impedance input-only port. P1.0–P1.4 are also used as A/D
converter inputs. In addition, P1.2 and P1.3 can be used as Timer 1 clock
input and direction select respectively.
PORT2 8-bit bidirectional I/O port. All of the Port2 pins are shared with the EPA I/O
pins (CAPCOMP0 – 3 and COMPARE0 –3).
PORT3 8-bit bidirectional I/O ports with open drain outputs. These pins are shared
PORT4
with the multiplexed address/data bus which uses strong internal pullups.
PORT5 8-bit bidirectional I/O port. 7 of the pins are shared with bus control signals
(ALE
, INST, WR,RD, BHE, READY, BUSWIDTH). Can be used as standard
I/O.
7