7906 datasheet(121/531 Pages) RENESAS

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TIMER A

7906 Group User’s Manual Rev.2.0

7-18

Item

Count source

Count operation

Division ratio

Count start condition

Count stop condition

Interrupt request occurrence timing

TAjIN pin’s function

TAjOUT pin’s function

Read from timer Aj register

Write to timer Aj register

Specifications

q External signal input to the TAjIN pin

q The count source’s valid edge can be selected from the falling edge

and the rising edge by software.

q Countup or countdown can be switched by external signal or software.

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

tents 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.

Count source input

Programmable I/O port pin, pulse output pin, or countup/countdown

switch signal input pin

Counter value can be read out.

q While counting is stopped

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

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

7.4 Event counter mode

Timer Aj (j = 0 to 2, 4, 9) is equipped with the event counter mode. In this mode, the timer counts an external

signal.

Tables 7.4.1 and 7.4.2 list the specifications of the event counter mode. Figure 7.4.1 shows the structures

of the timer Aj register and timer Aj mode register in the event counter mode.

Each of timers A3, A5 to A8 is not equipped with this mode.

Table 7.4.1 Specifications of event counter mode (when not using two-phase pulse signal processing

function)

(n + 1)

(FFFF16 – n + 1)

n: Timer Aj register’s set value

7.4 Event counter mode

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