Z86L79 Datasheet, PDF (15/58 Pages) Zilog, Inc. – Low-Voltage Microcontroller

Zilog
Z86L79/80
Low-Voltage Microcontroller
Port 3 (P37-P31). Port 3 is a 7-bit, CMOS compatible three rising, falling, or both edge triggered interrupts (IRQ regis-
fixed input and four fixed output port. Port 3 consists of ter bits 6 and 7). Pref1 and P33 are the comparator refer-
1 ^{three fixed input (P33-P31) and four fixed output (P37- ence voltage inputs. Access to the edge detection circuit is}
P34), and can be configured under software control for In- through P31 or P20. Handshake lines Ports 0, 1, and 2 are
put/Output, Interrupt, Port handshake, Data Memory func- available on P31 through P36.
tions and output from the counter/timers. P31, P32, and
P33 are standard CMOS inputs; outputs are push-pull, ex- ^{Port 3 provides the following control functions: handshake}
cept for P34, 35 which are controlled by P3M, D0.
for Ports 0, and 2 (/DAV and RDY); four external interrupt
request signals (IRQ3-IRQ0). (See Table 2).
Two on-board comparators process analog signals on P31
and P32 with reference to the voltage on Pref1 and P33. ^{Port 3 also provides output for each of the counter/timers}
The analog function is enabled by programming the Port 3 ^{and the AND/OR Logic. Control is performed by program-}
Mode Register (bit 1). P31 and P32 are programmable as ^{ming bits D5-D4 of CTRI, bit 0 of CTR0 and bit 0 of CTR2.}
Table 2. Pin Assignments
Pin
I/O
Pref1
P31
P32
P33
P34
P35
P36
P37
IN
IN
IN
IN
OUT
OUT
OUT
OUT
Notes:
1. HS = Handshake Signals
2. D = /DAV
3. R = RDY
C/T
ISP
T8
T16
T8/16
Comp.
RF1
AN1
AN2
RF2
A01
A02
Int.
IRQ2
IRQ0
IRQ1
P0 HS
D/R
R/D
P2 HS
D/R
R/D
Comparator Inputs. Port 3, P31 and P32 all have a com-
parator front end. The comparator reference voltages are
on P33 and Pref1. The internal P33 register and its corre-
sponding IRQ1 is connected to the Stop-Mode Recovery
source selected by the SMR. In this mode, any of the Stop-
Mode Recovery sources can be used to toggle the P33 bit
or generate IRQ1. In digital mode, P33 can be used as a
Port 3 register input or IRQ1 for P33 (Figure 8).
Note: The comparators are disabled in STOP mode.
Comparator Outputs. These may be programmed to be
outputted on P34 and P37 through the PCON register (Fig-
ure 11).
PRELIMINARY
3-15