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Timer A

Mitsubishi microcomputer

M16C / 62A Grou

SINGLE-CHIP 16-BIT CMOS MICROCOMPUTE

2-4

(1) At reset, the count start flag is set to “0”. Set a value in the timer Ai register, then set the flag

to “1”.

(2) Setting the count start flag to “0” while a count is in progress causes as follows:

• The counter stops counting and a content of reload register is reloaded.

• The TAiOUT pin outputs “L” level.

• The interrupt request generated and the timer Ai interrupt request bit goes to “1”.

(3) The output from the one-shot timer synchronizes with the count source generated internally.

Therefore, when an external trigger has been selected, a delay of one cycle of the maximum

count source occurs between the trigger input to the TAiIN pin and the one-shot timer output.

(4) The timer Ai interrupt request bit goes to “1” if the timer's operation mode is set using any of

the following procedures:

• Selecting one-shot timer mode after reset.

• Changing operation mode from timer mode to one-shot timer mode.

• Changing operation mode from event counter mode to one-shot timer mode.

Therefore, to use timer Ai interrupt (interrupt request bit), set timer Ai interrupt request bit to

“0” after the above listed changes have been made.

(5) If a trigger occurs while a count is in progress, after the counter performs one down count

following the reoccurrence of a trigger, the reload register contents are reloaded, and the

count continues. To generate a trigger while a count is in progress, generate the second

trigger after an elapse longer than one cycle of the timer's count source after the previous

trigger occurred.

2.2.15 Precautions for Timer A (one-shot timer mode)

Note: The above applies when an external trigger (falling edge of TAiIN pin input signal) is selected.

TAi

IN pin input signal

“H”

“L”

Count source

Trigger input

Start one-shot pulse output

One-shot pulse

output from TAi

OUT pin

Figure 2.2.31. One-shot timer delay

1 2 ... 9 10 11 12 13 14 15 16 17 18 19 ... 56 57

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