Z86C72 Datasheet, PDF (26/71 Pages) Zilog, Inc. – IR MICROCONTROLLER

Z86C72/C92/L72/L92
IR Microcontroller
Zilog
PIN FUNCTIONS (Continued)
Port 3 (P37-P31). Port 3 is a 7-bit, CMOS compatible three
fixed input and four fixed output port. Port 3 consists of
three fixed input (P33-P31) and four fixed output (P37-
P34), and can be configured under software control for In-
put/Output, Interrupt, Port handshake, Data Memory func-
tions and output from the counter/timers. P31, P32, and
P33 are standard CMOS inputs; outputs are push-pull.
Two on-board comparators process analog signals on P31
and P32 with reference to the voltage on Pref1 and P33.
The analog function is enabled by programming the Port 3
Mode Register (bit 1). P31 and P32 are programmable as
rising, falling, or both edge triggered interrupts (IRQ regis-
ter bits 6 and 7). Pref1 and P33 are the comparator refer-
ence voltage inputs. Access to the Counter Timer edge de-
tection circuit is through P31 or P20 (see CTR1
description).
Port 3 provides the following control functions: handshake
for Ports 0, 1, and 2 (/DAV and RDY); three external inter-
rupt request signals (IRQ2-IRQ0); Data Memory Select
(/DM) (Table 2).
Port 3 also provides output for each of the counter/timers
and the AND/OR Logic. Control is performed by program-
ming bits D5-D4 of CTRI, bit 0 of CTR0 and bit 0 of CTR2.
Table 2. Pin Assignments
Pin
I/O
C/T
Comp.
Int.
P0 HS
P1 HS
P2 HS
Ext
Pref1 IN
RF1
P31
IN
IN
AN1
IRQ2
D/R
P32
IN
AN2
IRQ0
D/R
P33
IN
RF2
IRQ1
D/R
P34 OUT T8
A01
R/D
DM
P35 OUT T16
R/D
P36 OUT T8/16
R/D
P37 OUT
A02
P20 I/O
IN
Notes:
HS = Handshake Signals
D = /DAV
R = RDY
6-26
PRELIMINARY
DS97LVO0900