7721 datasheet(133/577 Pages) RENESAS

tên linh kiện	7721

Giải thích chi tiết về linh kiện	16-BIT SINGLE-CHIP MICROCOMPUTER

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TIMER A

7721 Group User’s Manual

8–14

8.3 Timer mode

8.3.3 Operation in timer mode

When the count start bit is set to “1,” the counter starts counting of the count source.

When a counter underflow occurs, the reload register’s contents are reloaded, and counting continues.

The timer Ai interrupt request bit is set to “1” at the underflow in . The interrupt request bit remains

set to “1” until the interrupt request is accepted or the interrupt request bit is cleared to “0” by software.

Figure 8.3.4 shows an example of operation in the timer mode.

Stops counting.

Restarts counting.

FFFF16

000016

Time

Count start bit

Timer Ai interrupt

request bit

n = Reload register’s contents

Cleared to “0” when interrupt request is

accepted or cleared by software.

Set to “1” by software.

Starts counting.

1 / fi ! (n+1)

fi = frequency of count source

(f2, f16, f64, f512)

Cleared to “0” by software.

Set to “1” by software.

Fig. 8.3.4 Example of operation in timer mode (without pulse output and gate functions)

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