7733 datasheet(148/940 Pages) RENESAS

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TIMER A

7733 Group User’s Manual

6–37

6.5.3 Trigger

The counter enters the count enable state when the count start flag (address 4016) is set to “1.” And then,

the counter starts counting when a trigger occurs. An internal or external trigger can be selected as this

trigger.

An internal trigger is selected when the trigger selection bits (bits 4 and 3 at addresses 5616 to 5A16) are

“002” or “012”; an external trigger is selected when the trigger selection bits are “102” or “112.”

When a trigger occurs during counting, the reload register’s contents is reloaded and the counter continues

counting. When generating a trigger during counting, make sure that a certain time which is equivalent to

two cycles of the timer’s count source or more has passed between the trigger previously generated and

a new trigger.

(1) When internal trigger is selected

A trigger is generated when the one-shot start flag (address 4216) is set to “1.” Figure 6.5.4 shows

the structure of the one-shot start flag.

(2) When external trigger is selected

A trigger is generated at the falling edge of pin TAiIN’s input signal when bit 3 at addresses 5616 to

5A16 = “0” or at the rising edge of pin TAiIN’s input signal when bit 3 = “1.”

When using an external trigger, set the port P5 or P6 direction register’s bit which corresponds to pin

TAiIN’s for the input mode.

6.5 One-shot pulse mode

Fig. 6.5.4 Structure of one-shot start flag

Bit

7 to 5

Not implemented.

Timer A4 one-shot start flag

Timer A3 one-shot start flag

Timer A2 one-shot start flag

Timer A1 one-shot start flag

Timer A0 one-shot start flag

Bit name

At reset

Undefined

Functions

One-shot start flag (address 4216)

1: One-shot pulse output is started.

(Valid when the internal trigger

is selected).

“0” at reading.

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