M32CSLASH86 datasheet(488/505 Pages) RENESAS

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27.9.2.3 Timer A (One-shot Timer Mode)

• The TAiS (i=0 to 4) bit in the TABSR register is set to "0" (stops counting) after reset. Set the TAiS

bit to "1" (starts counting) after selecting an operating mode and setting the TAi register.

• The followings occur when the TABSR register is set to "0" (stops counting) while counting:

- The counter stops counting and the microcomputer reloads contents of the reload register.

- The TAiOUT pin becomes low ("L").

- The IR bit in the TAiIC register is set to "1" (interrupt requested) after one CPU clock cycle.

• The output of the one-shot timer is synchronized with an internal count source. When set to an

external trigger, there is a delay of one count source cycle maximum, from trigger input to the TAiIN

pin to the one-shot timer output.

• The IR bit is set to "1" when the following procedures are performed to set timer mode:

- selecting one-shot timer mode after reset.

- switching from timer mode to one-shot timer mode.

- switching from event counter mode to one-shot timer mode.

Therefore, set the IR bit to "0" to generate a timer Ai interrupt (IR bit) after performing these proce-

dures.

• When a trigger is generated while counting, the reload register reloads and continues counting

after the counter has decremented once following a re-trigger. To generate a trigger while counting,

wait at least 1 count source cycle after the previous trigger has been generated and generate a re-

trigger.

• If an external trigger input is selected to start counting in timer A one-shot timer mode, do not

provide another external trigger input again for 300 ns before the timer A counter value reaches

"000016". One-shot timer may stop counting.

27.9.2.4 Timer A (Pulse Width Modulation Mode)

• The TAiS(i=0 to 4) bit in the TABSR register is set to "0" (stops counting) after reset. Set the TAiS bit

to "1" (starts counting) after selecting an operating mode and setting the TAi register.

• The IR bit is set to "1" when the following procedures are performed to set timer mode:

- Selecting PWM mode after reset

- Switching from timer mode to PWM mode

- Switching from event counter mode to PWM mode

Therefore, set the IR bit to "0" by program to generate a timer Ai interrupt (IR bit) after performing

these procedures.

• The followings occur when the TAiS bit is set to "0" (stops counting) while PWM pulse is output:

- The counter stops counting

- Output level changes to low ("L") and the IR bit changes to "1" when the TAiOUT pin is held high ("H")

- The IR bit and the output level remain unchanged when TAiOUT pin is held "L"

27. Precautions (Timer)

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