Z86L88 Datasheet, PDF (22/66 Pages) Zilog, Inc. – INFRARED REMOTE CONTROLLERS

Z86L88/81/86/87/89/73
IR/Low-Voltage Microcontroller
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). Other edge detect and IRQ modes are de-
scribed in Tables (3-6). Handshake lines Ports 0, 1, and 2
are available on P31 through P36.
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 3).
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 CTR1, bit 0 of CTR0 and bit 0 of CTR2.
Table 3. 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
AO1
R/D
DM
P35
OUT
T16
R/D
P36
OUT
T8/16
R/D
P37
OUT
AO2
P20
I/O
IN
Notes:
D = /DAV
R = RDY
HS = Handshake Signals
Comparator Inputs. In Analog Mode, Port 3 (P31 and
P32) have a comparator front end. The comparator refer-
ence is supplied to P33 and Pref1. In this mode, the P33
internal data latch and its corresponding IRQ1 is diverted
to the SMR sources (excluding P31,P32, and P33) as
shown in figure 41. In digital mode, P33 is used as D3 of
the Port 3 input register which then generates IRQ1 as
shown in Figure 17.
When P31 is used for counter timer input (demodulation
mode), input is always taken from the P31 digital input
buffer whether or not analog mode is enabled).
Notes: Comparators are powered down by entering STOP
mode. For P31-P33 to be used in a Stop-Mode Recovery
source, these inputs must be placed into digital mode.
Comparator Outputs. These may be programmed to be
outputted on P34 and P37 through the PCON register (Fig-
ures 16,38).
/RESET (Input, active Low). Initializes the MCU. Reset is
accomplished either through Power-On, Watch-Dog Tim-
er, Stop-Mode Recovery, Low Voltage detection, or exter-
nal reset. During Power-On Reset and Watch-Dog Timer
Reset, the internally generated reset drives the reset pin
Low for the POR time. Any devices driving the external re-
set line should be open-drain in order to avoid damage
from a possible conflict during reset conditions. Pull-up is
provided internally.
22
PRELIMINARY
DS96LV00800