void timerAlarmWrite(hw_timer_t *timer, uint64_t alarm_value, bool autoreload);

Timer

About

The ESP32 SoCs contains from 2 to 4 hardware timers.

They are all 64-bit (54-bit for ESP32-C3) generic timers based on 16-bit pre-scalers and 64-bit (54-bit for ESP32-C3)

up / down counters which are capable of being auto-reloaded.

ESP32 SoC Number of timers

ESP32 4

ESP32-S2 4

ESP32-C3 2

ESP32-S3 4

Arduino-ESP32 Timer API

timerBegin

This function is used to configure the timer. After successful setup the timer will automatically start.

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* ``num`` select timer number.

* ``divider`` select timer divider.

* ``resolution`` select timer resolution.

* range is 1-14 bits (1-20 bits for ESP32).

This function will return ``timer`` structure if configuration is successful.

If ``NULL`` is returned, error occurs and the timer was not configured.

timerEnd

This function is used to end timer.

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* ``timer`` timer struct.

timerSetConfig

This function is used to configure initialized timer (timerBegin() called).

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* ``timer`` timer struct.

This function will return ``configuration`` as uint32_t number.

This can be translated by inserting it to struct ``timer_cfg_t.val``.

timerAttachInterrupt

This function is used to attach interrupt to timer.

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* ``timer`` timer struct.

* ``fn`` funtion to be called when interrupt is triggered.

* ``edge`` select edge to trigger interrupt (only LEVEL trigger is currently supported).

timerDetachInterrupt

This function is used to detach interrupt from timer.

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* ``timer`` timer struct.

timerStart

This function is used to start counter of the timer.

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* ``timer`` timer struct.

timerStop

This function is used to stop counter of the timer.

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* ``timer`` timer struct.

timerRestart

This function is used to restart counter of the timer.

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* ``timer`` timer struct.

timerWrite

This function is used to set counter value of the timer.

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* ``timer`` timer struct.

* ``val`` counter value to be set.

timerSetDivider

This function is used to set the divider of the timer.

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* ``timer`` timer struct.

* ``divider`` divider to be set.

timerSetCountUp

This function is used to configure counting direction of the timer.

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* ``timer`` timer struct.

* ``countUp`` select counting direction (``true`` = increment).

timerSetAutoReload

This function is used to set counter value of the timer.

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* ``timer`` timer struct.

* ``autoreload`` select autoreload (``true`` = enabled).

timerStarted

This function is used to get if the timer is running.

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* ``timer`` timer struct.

This function will return ``true`` if the timer is running. If ``false`` is returned, timer is stopped.

timerRead

This function is used to read counter value of the timer.

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* ``timer`` timer struct.

This function will return ``counter value`` of the timer.

timerReadMicros

This function is used to read counter value in microseconds of the timer.

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* ``timer`` timer struct.

This function will return ``counter value`` of the timer in microseconds.

timerReadMilis

This function is used to read counter value in miliseconds of the timer.

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* ``timer`` timer struct.

This function will return ``counter value`` of the timer in miliseconds.

timerReadSeconds

This function is used to read counter value in seconds of the timer.

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* ``timer`` timer struct.

This function will return ``counter value`` of the timer in seconds.

timerGetDivider

This function is used to get divider of the timer.

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* ``timer`` timer struct.

This function will return ``divider`` of the timer.

timerGetCountUp

This function is used get counting direction of the timer.

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* ``timer`` timer struct.

This function will return ``true`` if the timer counting direction is UP (incrementing).

If ``false`` returned, the timer counting direction is DOWN (decrementing).

timerGetAutoReload

This function is used to get configuration of auto reload of the timer.

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* ``timer`` timer struct.

This function will return ``true`` if the timer auto reload is enabled.

If ``false`` returned, the timer auto reload is disabled.

timerAlarmEnable

This function is used to enable generation of timer alarm events.

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* ``timer`` timer struct.

timerAlarmDisable

This function is used to disable generation of timer alarm events.

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* ``timer`` timer struct.

timerAlarmWrite

This function is used to configure alarm value and autoreload of the timer.

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* ``timer`` timer struct.

* ``alarm_value`` alarm value to generate event.

* ``autoreload`` enabled/disabled autorealod.

timerAlarmEnabled

This function is used to get status of timer alarm.

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* ``timer`` timer struct.

This function will return ``true`` if the timer alarm is enabled.

If ``false`` returned, the timer alarm is disabled.

timerAlarmRead

This function is used to read alarm value of the timer.

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* ``timer`` timer struct.

timerAlarmReadMicros

This function is used to read alarm value of the timer in microseconds.

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* ``timer`` timer struct.

This function will return ``alarm value`` of the timer in microseconds.

timerAlarmReadSeconds

This function is used to read alarm value of the timer in seconds.

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* ``timer`` timer struct.

This function will return ``alarm value`` of the timer in seconds.

Example Applications

There are 2 examples uses of Timer:

Repeat timer example:

.. literalinclude:: ../../../libraries/ESP32/examples/Timer/RepeatTimer/RepeatTimer.ino

:language: arduino

Watchdog timer example:

.. literalinclude:: ../../../libraries/ESP32/examples/Timer/WatchdogTimer/WatchdogTimer.ino

:language: arduino