TIMER A
7.5 One-shot pulse mode
7.5.2 Trigger
The counter is enabled for counting when the count start bit (addresses 4016, 4116) has been set to “1.” The
counter starts counting when a trigger is generated after counting has been enabled. An internal or external
trigger can be selected as that trigger.
An internal trigger is selected when the trigger select bits (bits 4 and 3 at addresses 5616 to 5A16, D616 to
DA16) are “00
2
” or “01
2
”; an external trigger is selected when the bits are “10
2
” or “11 .”
2
If a trigger is generated during counting, the reload register’s contents are reloaded and the counter
continues counting. If a trigger generated during counting, make sure that a certain time which is equivalent
to one cycle of the timer’s count source or more has passed between the previously trigger occurrence and
a new trigger occurrence.
(1) When selecting internal trigger
A trigger is generated when writing “1” to the one-shot start bit (addresses 4216, 4316). Figure 7.5.4
shows the structures of the one-shot start registers 0 and 1.
(2) When selecting external trigger
A trigger is generated at the falling edge of the TAiIN pin’s input signal when bit 3 at addresses 5616
to 5A16, D616 to DA16 is “0,” or at its rising edge when bit 3 is “1.”
When using an external trigger, set the port P6, port P2, and port P4 direction registers’ bits which
correspond to the TAiIN pins for the input mode.
7905 Group User’s Manual Rev.1.0
7-33
RENESAS [ RENESAS TECHNOLOGY CORP ]
