Z86L972 Datasheet, PDF (44/91 Pages) Zilog, Inc. – Low-Voltage Microcontrollers

D₅ D₄
Z86L972/Z86L973/Z86L974
Low-Voltage Microcontrollers
37
R241 TMR
Timer Mode Register
(F1h; Read/Write)
T_IN modes
External clock input = 00
Gate input = 01
Trigger input = 10
(non-retriggerable)
Trigger input = 11
(retriggerable)
Figure 25. Timer Mode Register T_IN Operation
R243 PRE1
Prescaler 1 Register
(F3h; Write Only)
D₁
Figure 26. Prescaler 1 T_IN Operation
Clock source
1 = T₁ internal
0 = T₁ external (T_IN)
The T₁ counter/timer clock source must be configured for external by setting
PRE₁ bit D₂ to 0. The Timer Mode register bits D₅ and D₄ can then be used to
select the T_IN operation.
For T₁ to start counting as a result of a T_IN input, the Enable Count bit D₃ in TMR
must be set to 1. When using T_IN as an external clock or a gate input, the initial
values must be loaded into the down-counters by setting the Load bit D₂ in TMR
to 1 before counting begins. Initial values are automatically loaded in Trigger and
Retrigger modes, so software loading is unnecessary.
Configure P5₂ as an input line by setting P5M bit D₂ to 1.
PS010504-1002
PRELIMINARY