Changing ESP32 CPU clock frequency

ESPHome
1

I’m speculating that if I reduce the CPU clock frequency on an ESP32 board, it will reduce the power draw. Am I right about that?

I can see that ESPHome has a way to pass an option to platformio to give a different clock frequency, but there is a clear warning there that it only affects how the firmware is built. It doesn’t actually change the hardware clock. I’m pretty sure I know how to do this (actually change the clock frequency) with the native Espressif IDF, but I’m not sure how to do it when using ESPHome. I know I can do an onboot lambda to make native calls, but I don’t know if there are any “gotchas”. Can someone clue me in?

2

Hi Bill, wondering if you had made any progress in changing the clock freq within ESPHome?
As you indicate, I am hoping to set the ESP32 to 80Mhz to save battery on a remote sensor, but don’t know how to do that within ESPHome…
Were you able to make it work? can you explain the on boot lambda solution?

Thanks in advance,
ET

3

No, I never figured it out. (And I’ve also kind of forgotten what I was trying to do when I asked the question.:frowning: )

4

I used the board_build.f_cpu property in platformio_options described here: Slowing down an ESP32 with ESPHome
When I flash to the device, it tells me it’s running at 80mhz, so I think it’s working.

1 Like
5

Yes, I’m using this too.

Seems to work.

  board: wemos_d1_mini32
  platformio_options:
    board_build.f_cpu: 80000000L # Reduce CPU speed to match HX711 sample rate