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timer.rst

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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-S3 4
ESP32-C3 2
ESP32-C6 2
ESP32-H2 2

Arduino-ESP32 Timer API

timerBegin

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

hw_timer_t * timerBegin(uint32_t frequency);
  • frequency select timer frequency in Hz. Sets how quickly the timer counter is “ticking”.

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.

void timerEnd(hw_timer_t * timer);
  • timer timer struct.

timerStart

This function is used to start counter of the timer.

void timerStart(hw_timer_t * timer);
  • timer timer struct.

timerStop

This function is used to stop counter of the timer.

void timerStop(hw_timer_t * timer);
  • timer timer struct.

timerRestart

This function is used to restart counter of the timer.

void timerRestart(hw_timer_t * timer);
  • timer timer struct.

timerWrite

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

void timerWrite(hw_timer_t * timer, uint64_t val);
  • timer timer struct.
  • val counter value to be set.

timerRead

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

uint64_t timerRead(hw_timer_t * timer);
  • 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.

uint64_t timerReadMicros(hw_timer_t * timer);
  • 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.

uint64_t timerReadMilis(hw_timer_t * timer);
  • 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.

double timerReadSeconds(hw_timer_t * timer);
  • timer timer struct.

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

timerGetFrequency

This function is used to get resolution in Hz of the timer.

uint16_t timerGetFrequency(hw_timer_t * timer);
  • timer timer struct.

This function will return frequency in Hz of the timer.

timerAttachInterrupt

This function is used to attach interrupt to timer.

void timerAttachInterrupt(hw_timer_t * timer, void (*userFunc)(void));
  • timer timer struct.
  • userFunc funtion to be called when interrupt is triggered.

timerAttachInterruptArg

This function is used to attach interrupt to timer using arguments.

void timerAttachInterruptArg(hw_timer_t * timer, void (*userFunc)(void*), void * arg);
  • timer timer struct.
  • userFunc funtion to be called when interrupt is triggered.
  • arg pointer to the interrupt arguments.

timerDetachInterrupt

This function is used to detach interrupt from timer.

void timerDetachInterrupt(hw_timer_t * timer);
  • timer timer struct.

timerAlarm

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

void timerAlarm(hw_timer_t * timer, uint64_t alarm_value, bool autoreload, uint64_t reload_count);
  • timer timer struct.
  • alarm_value alarm value to generate event.
  • autoreload enabled/disabled autorealod.
  • reload_count number of autoreloads (0 = unlimited). Has no effect if autorealod is disabled.

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