7906 datasheet(180/531 Pages) RENESAS

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7906 Group User’s Manual Rev.2.0

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TIMER B

[Precautions for pulse period/pulse width measurement mode]

1. When the counter clear type is selected, a timer Bi interrupt request is generated by one of the following

sources:

q Valid edge input of measured pulse

q Counter overflow

When an overflow generates an interrupt request, the timer Bi overflow flag will be set to “1.”

2. When the free-run type is selected, the timer Bi interrupt request is generated only by the valid edge input

of the pulse to be measured.

3. After reset, the timer Bi overflow flag is undefined. When a value is written to the timer Bi mode register

after the next count timing of the count source with the count start bit = “1,” this flag will be cleared to

“0.”

4. An undefined value is transferred to the reload register at the first valid edge input after the count start.

In this case, no timer Bi interrupt request will occur.

5. The counter value at count start is undefined. Therefore, there is a possibility that a counter overflow

occurs immediately after the counting starts. In this case, the timer Bi overflow flag becomes “1”; and

when the counter clear type is selected, a timer Bi interrupt request is generated.

6. If the contents of the measurement mode select bits are changed after the count start, the timer Bi

interrupt request bit is set to “1.” When the value, which has been set in these bits before, are written

again, the timer Bi interrupt request bit will not change.

7. When using timer B2, be sure to clear the timer B2 clock source select bit (bit 6 at address 6316) to “0.”

8. If the input signal to the TBiIN pin is affected by noise, etc., there is a possibility that the counter cannot

perform the exact measurement. We recommend to verify, by software, that the measurement values are

within a constant range.

7906 Datasheet(PDF) 180 Page - Renesas Technology Corp