Z86C83 Datasheet, PDF (19/46 Pages) Zilog, Inc. – Z8 MCU MICROCONTROLLERS

Z86C83/C84
Z8^® MCU Microcontrollers
PIN FUNCTIONS (Continued)
Port 3 (P37-P30). Port 3 is a 6-bit, CMOS-compatible
port, with three fixed inputs (P33-P31) and three fixed
outputs (P34-P36), configured under software control for
Input/Output, Counter/Timers, interrupt, and port
handshake. P31, P32, and P33 are standard CMOS inputs
(no Auto Latches). Pins P34, P35, and P36 are push-pull
output lines (Figure 11). Low EMI output buffers can be
globally programmed by the software.
Two on-board comparators can process analog signals on
P31 and P32 with reference to the voltage on P33. The
analog function is enabled by programming Port 3 Mode
Register (P3M bit 1). For Interrupt functions, Port 3, pin 3
is falling-edge interrupt input. P31 and P32 are
programmable as rising, falling, or both edge triggered
interrupts (IRQ register bits 6 and bit 7). P33 is the
comparator reference voltage input when in Analog Mode.
Access to Counter/Timers 1 is made through P31 (T_IN) and
P36 (T_OUT). Handshake lines for Ports 0 and 2 are available
on P31/P36 and P32/P35 (Table 9).
Port 3 also provides the following control functions:
handshake for Ports 0 and 2 (/DAV and RDY); three
external interrupt request signals (IRQ2-IRQ0); timer input
and output signals (T_IN and T_OUT).
Table 9. Port 3 Pin Assignments
Pin I/O CTC1 Analog
P31 IN T_IN
P32 IN
AN1
AN2
P33 IN
REF
P34 OUT
AN1-OUT
P35 OUT
P36 OUT T_OUT
Notes:
HS = Handshake Signals
D = /DAV
R = RDY
Int.
IRQ2
IRQ0
IRQ1
P0 HS
D/R
R/D
P2 HS
D/R
R/D
Auto Latch. The Auto-Latch instruction puts valid CMOS
levels on all CMOS inputs (except P33-P31) that are not
externally driven. Whether this level is 0 or 1, cannot be
determined. A valid CMOS level, rather than a floating
node, reduces excessive supply current flow in the input
buffer.
Notes:
1. Deletion of Port Auto Latches is available as a ROM
mask option. The Auto Latch Delete option is selected
by the customer when the ROM code is submitted.
2. Ports 03, 04, 05, 07 have permanently enabled Auto
Latches.
Comparator Inputs. Port 3, P31 and P32, each have a
comparator front end. The comparator reference voltage,
P33, is common to both comparators. In analog mode, the
P33 input functions as a reference voltage to the
comparators. In Analog Mode, the internal P33 register
and its corresponding IRQ1 is connected to the Stop-Mode
Recovery source selected by the SMR register. In this
mode, any of the Stop-Mode Recovery sources are used
to toggle the P33 bit or generate IRQ1. In Digital Mode,
P33 can be used as a Port 3 register input or IRQ1 source.
P34 outputs the comparator outputs by software
programming the PCON Register bit D0 to 1.
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DS96DZ80203