7906 datasheet(164/531 Pages) RENESAS

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7906 Group User’s Manual Rev.2.0

8-13

TIMER B

8.4 Event counter mode

In this mode, the timer counts an external signal. Table 8.4.1 lists the specifications of the event counter

mode. Figure 8.4.1 shows the structures of the timer Bi register and the timer Bi mode register in the event

counter mode.

Table 8.4.1 Specifications of event counter mode

Item

Count source

Count operation

Division ratio

Count start condition

Count stop condition

Interrupt request occurrence timing

TBiIN pin’s function

Read from timer Bi register

Write to timer Bi register

Specifications

•External signal input to the TBiIN pin, or fX32 (Note 1)

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

the rising edge, and both of the falling and rising edges by software.

•Countdown

•When a counter underflow occurs, reload register’s contents are

reloaded, and counting continues.

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

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

When the counter underflow occurs.

Count source input pin (Note 2)

Counter value can be read out.

q While counting is stopped

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

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

(n + 1)

n: Timer Bi register’s set value

Notes 1: Only for timer B2, fX32 can be selected.

2: When fX32 is selected as the count source in timer B2, the TB2IN pin can be used as a programmable

I/O port pin or as I/O pins of other internal peripheral devices, which are multiplexed.

7906 Datasheet(PDF) 164 Page - Renesas Technology Corp