Z86C04 Datasheet, PDF (20/34 Pages) Zilog, Inc. – CMOS 8-BIT LOW-COST 1K/2K-ROM MICROCONTROLLERS

Z86C04/C08
CMOS 8-Bit Low-Cost 1K/2K-ROM Microcontrollers
PIN DESCRIPTION (Continued)
Port 3 (P33-P31). Port 3 is a 3-bit, Schmitt-triggered
CMOS compatible port with three fixed input (P33-P31)
lines. These three input lines can be configured under soft-
Zilog
ware control as digital inputs or analog inputs. These three
input lines can also be used as the interrupt sources IRQ0-
IRQ3 and as the timer input signal (T_IN) (Figure 9).
MCU
Port 3
PAD
P31 (AN1)
PAD
P32 (AN2)
P33 (REF)
PAD
R247 = P3M
D1
1 = Analog
0 = Digital
DIG.
+
AN.
-
+
-
P31
Data Latch
IRQ, Tin
IRQ3
P32
Data Latch
IRQ0
P33
Data Latch
Vcc
IRQ1
IRQ 0,1,2 = Falling Edge Detection
IRQ 3 = Rising Edge Detection
Figure 8. Port 3 Configuration
Comparator Inputs. Two analog comparators are added to
Port 3 inputs for interface flexibility. Typical applications for
these on-board comparators are: Zero crossing detection,
A/D conversion, voltage scaling, and threshold detection.
The dual comparator (common inverting terminal) features
a single power supply which discontinues power in STOP
mode. The common voltage range is 0-4V when the V_CC is
5.0V.
Interrupts are generated on either edge of Comparator 2’s
output, or on the falling edge of Comparator 1’s output.
The comparator output may be used for interrupt genera-
tion, Port 3 data inputs, or T_IN through P31. Alternately, the
comparators may be disabled, freeing the reference input
(P33) for use as IRQ1 and/or P33 input.
20
PRELIMINARY
DS97DZ80502