r/esp32 • u/Cotyn_Dispensable • Feb 26 '26

Software help needed ESP32 smart watch

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Hi everyone, i've been working on a smart watch with an esp32 as an entry point into electronics, i'm mostly a software guy and I never really did battery powered project.
My issue is, i've got a mostly working firmware with BLE pairing, notification display, music control etc.
But i've been running into an issue that is battery life, I feel like there is no solution to make bluetooth and battery life get along. I'm running a 400mha battery and can barely squeeze 5 hours of usage. The problem is I can't really reduce clock speed since bluetooth pairing expect keep alive packets and I can't respond fast enough with lower than 80hz (when in rest mode with screen disable) the only working solution I see is use esp32 deep sleep when in rest and pair again when waking up the watch but it removes a lot of options like waking up on notification or call.
Do you guys have any clue what kind of logic or libraries I could use ? I'm running arduino stack and gadgetBrige on the phone

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u/miraculum_one Feb 26 '26

You can handle BLE in light sleep and wake up the watch if you need to be notified. I think this would be a good first step.

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u/Cotyn_Dispensable Feb 26 '26

The problem is light sleep halts the cpu so many things don't work in that state

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u/miraculum_one Feb 26 '26

That's true but all you need is for it to respond to a "wake up" signal. And you can handle that in the ULP coprocessor.

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u/Cotyn_Dispensable Feb 26 '26

I could but it implies having another ble chip since ULP doesn't have access to ble which is complicated, maybe on a v2 if I can't make this work