Z87C33 Datasheet, PDF (14/72 Pages) Zilog, Inc. – CMOS Z8® MCU Consumer Controller Processor

Z87C33
CMOS Z8“ MCU Consumer Controller Processor
8
Mode Register (P3M bit 1). For interrupt functions, Port 3, bit 0 and pin 3 are fall-
ing-edge interrupt inputs. P31 and P32 are programmable as rising, falling, or
both edge-triggered interrupts (IRQ register bits 6 and 7). P33 is the comparator
reference voltage input when in Analog mode. Access to Counter/Timer 1 is made
through P31 (T_IN) and P36 (T_OUT). Handshake lines for Ports 0, 1, and 2 are avail-
able on P31 through P36.
Port 3 also provides the following control functions: four external interrupt request
signals (IRQ3–IRQ0) and timer input and output signals (T_IN and T_OUT).
Table 3. Port 3 Pin Assignments
Pin
I/O
Control
Timer Analog
Interrupt
P30 IN
IRQ3
P31 IN
T_IN
P32 IN
AN1
AN2
IRQ2
IRQ0
P33 IN
REF
IRQ1
P34 OUT
AN1–OUT
P35 OUT
P36
OUT T_OUT
P37 OUT
AN2–OUT
Comparator Inputs and Outputs. Port 3, pins P31 and P32 each feature a compar-
ator front end. The comparator reference voltage, pin P33, is common to both
comparators. In ANALOG mode, the P31 and P32 are the positive inputs to the
comparators, and P33 is the reference voltage supplied to both comparators. In
DIGITAL mode, pin P33 is used as a P33 register input or IRQ1 source. P34 and
P37 can provide the comparator output directly by software-programming the
PCON register bit D0 to 1 (see Figure 5).
Note: ^{The user must add a two-NOP delay after setting the P3M bit}
D1 to 1 before the comparator output is valid. IRQ0, IRQ1, and
IRQ2 must be cleared in the IRQ register when the comparator
is enabled or disabled.
PS015601-1003