7906 参数 Datasheet PDF下载

TIMER A

7.2 Block description

7.2.1 Counter and Reload register (timer Ai register)

Each of timer Ai counter and reload register consists of 16 bits.

Countdown in the counter is performed each time the count source is input. In the event counter mode,

it can also function as an up-counter.

The reload register is used to store the initial value of the counter. When a counter underflow or overflow

occurs, the reload register’s contents are reloaded into the counter.

A value is set to the counter and reload register by writing the value to the timer Ai register. Table 7.2.1

lists the memory assignment of the timer Ai register.

The value written into the timer Ai register while counting is not in progress is set to the counter and reload

register. The value written into the timer Ai register while counting is in progress is set only to the reload

register. In this case, the reload register’s updated contents are transferred to the counter at the next

reload time. The value obtained when reading out the timer Ai register varies according to the operating

mode. Table 7.2.2 lists reading from and writing to the timer Ai register.

Table 7.2.1 Memory assignment of timer Ai register

Timer Ai

Timer A0

Timer A1

Timer A2

Timer A3

Timer A4

Timer A5

Timer A6

Timer A7

Timer A8

Timer A9

register

register

register

register

register

register

register

register

register

register

register

High-order byte

Address 47

16

Address 49

16

Address 4B

16

Address 4D

16

Address 4F

16

Address C7

16

Address C9

16

Address CB

16

Address CD

16

Address CF

16

Low-order byte

Address 46

16

Address 48

16

Address 4A

16

Address 4C

16

Address 4E

16

Address C6

16

Address C8

16

Address CA

16

Address CC

16

Address CE

16

Note:

At reset, the contents of the timer Ai register

are undefined.

Table 7.2.2 Reading from and writing to timer Ai register

Operating mode

Timer mode

Event counter mode

One-shot pulse mode

Pulse width modulation (PWM) mode

(Note

1)

Undefined value is read out.

Read

Counter value is read out.

Write

<While counting>

Written only to reload register.

<While not counting>

Written to both of the counter

and reload register.

Notes 1:

Also refer to sections

“[Precautions for timer mode]”

and

“[Precautions for event counter

mode].”

2:

When reading from and writing to the timer Ai register, perform it in a unit of 16 bits.

3:

Each of timers A3 and A5 to A8 is equipped with the timer mode only.

7906 Group User’s Manual Rev.2.0

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