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TIMER A

7721 Group User’s Manual

8–19

8.4 Event counter mode

Table 8.4.2 Specifications of event counter mode (when using two-phase pulse signal processing function)

Item

Count source

Count operation

Division ratio

Count start condition

Count stop condition

Interrupt request occurrence timing

TAjIN, TAjOUT pin function

Read from timer Aj register

Write to timer Aj register

(n + 1)

Specifications

External signal (two-phase pulse) input to the TAjIN or TAjOUT pin

q Countup or countdown can be switched by external signal (two-

phase pulse).

q When a counter overflow or underflow occurs, reload register’s contents

are reloaded, and counting continues.

q For countdown

q For countup

When the count start bit is set to “1.”

When the count start bit is cleared to “0.”

When a counter overflow or underflow occurs.

Two-phase pulse input

Counter value can be read out.

q While counting is stopped

When a value is written to the timer Aj register, it is written to both

of the reload register and counter.

q While counting is in progress

When a value is written to the timer Aj register, it is written only to

the reload register. (Transferred to the counter at the next reload

time.)

(FFFF16 – n + 1)

n : Timer Aj register’s set value

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