PWM frequency below 1Hz

Q&A Forum › Category: ESP32 › PWM frequency below 1Hz

NUR AZLIN AIRUL AZLIN MOHAMED ZOHDI asked 3 years ago

Hi Rui & Sara,
I am trying to control my solid state relay using PWM, such that the relay stays ON for 5sec and OFF for 1sec but it seems that ESP32 LEDC function doesn’t allow for frequency below 1Hz.
I have tried using millis() to time the ON and OFF, but that is not as accurate as using PWM.
any idea?

Question Tags: PWM

6 Answers

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Best Answer

Steve Mercer answered 3 years ago

Have you looked into using hardware timers with interrupt?

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Sara Santos Staff answered 3 years ago

Hi.
I think this discussion answers your question: https://forum.arduino.cc/t/esp32-what-is-the-minimum-pwm-frequency/671077/4
Regards,
Sara

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NUR AZLIN AIRUL AZLIN MOHAMED ZOHDI answered 3 years ago

Tried that already before I posted my question here. Not working either.

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Sara Santos Staff answered 3 years ago

Have you tried using delay() to control the relay on and off for a determined number of seconds?
In some scenarios, you can use delay() if it doesn’t compromise the rest of the code.
Regards,
Sara

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NUR AZLIN AIRUL AZLIN MOHAMED ZOHDI answered 3 years ago

Hi.
Delay() is blocking function, just to many limitation by using it. Using millis() is much better approach, but that does not solve my problem either.
Anyway, based on my experimentation, frequency below 1Hz is possible by setting the resolution to 16-bit.
Testing it now. hopefully this is the solution to my problem

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NUR AZLIN AIRUL AZLIN MOHAMED ZOHDI answered 3 years ago

Thanks Steve Mercer for the info and link. Could be a solution to my problem also. Appreciate it.