
Z8 Microcontrollers
Counter/Timers
ZiLOG
6-8
UM001600-Z8X0599
It is suggested that P31 be configured as an input line by
setting P3M Register bit 5 to 0, although T
IN
is still function-
al if P31 is configured as a handshake input.
Each High-to-Low transition on T
IN
generates an interrupt
request IRQ2, regardless of the selected T
IN
mode or
the enabled/disabled state of T1. IRQ2 must therefore be
masked or enabled according to the needs of the applica-
tion.
6.5.1 External Clock Input Mode
The T
IN
External Clock Input Mode (TMR bit 5 and bit 4
both set to 0) supports counting of external events, where
an event is considered to be a High-to-Low transition on
T
IN
(Figure 6-15).
Note:
See the product data sheet for the minimum
allowed T
IN
external clock input period (T
P
T
IN
).
Figure 6-15. External Clock Input Mode
D
P3
1
Internal
Clock
IRQ
2
TMR
D
5
- D
4
= 00
T
Clock
D
PRE1
T1
IRQ
5