Z86L972 Datasheet, PDF (32/91 Pages) Zilog, Inc. – Low-Voltage Microcontrollers

Z86L972/Z86L973/Z86L974
Low-Voltage Microcontrollers
25
Ports are read by specifying the port register as the source register of an instruc-
tion. When an output bit is read, data on the external pin is returned. Under normal
loading conditions, returning data on the external pin is equivalent to reading the
output register. However, if a bit is defined as an open-drain output, the data
returned is the value forced on the output pin by the external system. This value
might not be the same as the data in the output register. Reading input bits also
returns data on the external pins.
Special Functions
Table 7 defines the special functions of Ports 4 and 5.
Table 7. Special Port Pin Functions
Function
Pin
Analog Comparator Inputs
P51
P52
Analog Comparator
P50
References
P53
Analog Comparator Outputs P54
P55
External Interrupts
P52
P53
P51
T_IN External Clock Input
P52
Capture Timer Input
P51
T1 Timer Output
P56
T8 Output
P40
T16 Output
P41
Combined T8/T16 Output
P43
Controlled Current Output
ZiLOG Test Mode
P41
P42
Signal
Configuration Register
CIN1
P456CON
CIN2
P456CON
CREF1
CREF2
COUT1
COUT2
IRQ₀
IMR and IRQ
IRQ₁
IMR and IRQ
IRQ₂
IMR and IRQ
T_IN
TMR and PRE1
Demodulator_Input CTR1
T1OUT
TMR
P40_Out
CTR0
P41_Out
CTR2
P43_Out
CTR1
DSn Enable
ASn Enable
P456CON
P456CON
Peripherals
Analog Comparators
The Z86L972/Z86L973/Z86L974 family includes two independent on-chip gen-
eral-purpose analog comparators as shown in Figure 12. The comparators are
multiplexed with a digital input signal by the P456CON register. They can also be
used to generate interrupts IRQ0 and IRQ2. The comparators are turned off in
STOP mode.
PS010504-1002
PRELIMINARY