Z86L78 Datasheet, PDF (16/59 Pages) Zilog, Inc. – IR/Low-Voltage Microcontroller

Z86L78
IR/Low-Voltage Microcontroller
Zilog
PIN FUNCTIONS (Continued)
Port 3 (P37-P31). Port 3 is a 6-bit, CMOS-compatible
three fixed input and four fixed output port. Port 3 and can
be configured under software control for Input/Output, In-
terrupt, and output from the counter/timers. P31, P32, and
P33 are standard CMOS inputs. Outputs P34, P35 are
push-pull or open-drain depending on P3M D0. P36 is
push-pull.
Two on-board comparators process analog signals on P31
and P32 with reference to the voltage on P33. The analog
function is enabled by programming the Port 3 Mode Reg-
ister (bit 1). P31 and P32 are programmable as rising, fall-
ing, or both edge triggered interrupts (IRQ register bits 6
and 7). P33 is the comparator reference voltage inputs.
Access to the edge detection circuit is through P31 or P20.
P33 will be in common to both comparators.
Port 3 provides output for each of the counter/timers and
the AND/OR Logic. Control is performed by programming
bits D5-D4 of CTRI, bit 0 of CTR0 and bit 0 of CTR2.
Table 2. Port 3 Pin Assignments
Pin
I/O
Pref1
P31
P32
P33
P34
P35
P36
P00
IN
IN
IN
IN
OUT
OUT
OUT
I/O
Notes:
HS = Handshake Signals
D = /DAV
R = RDY
C/T
ISP
T8
T16
T8/16
Comp.
RF1
AN1
AN2
RF2
A01
Int.
P0 HS P1 HS P2 HS
Ext
IRQ2
D/R
D/R
IRQ1
D/R
R/D
DM
R/D
R/D
Comparator Inputs. In Analog Mode, Port 3, P31 and P32
have a comparator front end. The comparator reference
voltages are on P33. The internal P33 register and its cor-
responding 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 9).
Notes: Comparators are powered down by entering STOP
Mode. For P33-P31 to be used as a STOP-mode recovery
source, these inputs must be placed into digital mode.
Comparator Outputs. Comparator output of COMP1 can
be programmed to output on P34 through the PCON reg-
ister (Figure 8).
/RESET (Input, active Low). Initializes the MCU. Reset is
accomplished either through Power-On, Watch-Dog Tim-
er; Stop-Mode Recovery, and Low Voltage detection. Dur-
ing Power-On Reset and Watch-Dog Timer Reset, the in-
ternally generated reset drives the internal reset Low for
the POR time.
2-16
DS97LVO0701