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I have a project where I'd like to have two esp32s communicate using ESP-NOW, but both running on battery. I'd like for both to be in deep sleep, wake up and communicate, and go back to sleep, repeat.

What's the best way to handle this? Would trying to coordinate waking and sleeping with the RTC be possible? Should I have the wake up more frequently and wait a bit for a message from the other? Other ideas?

In the absolute worst case scenario I could potentially have one running on an outlet which would make this easy, but it's highly preferable for both to run on battery power.

Thanks!

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  • Perhaps ESPNow software features have changed since I had last done this. But IIRC, there is a receiver and many transmitters. The receiver always has to be listening. The transmitters can sleep. There was no guaranteed delivery. It was meant to be quick & fast. Unlike WIFI where there is a lot of negotiations going on before data is sent. Which takes more time and likely cuts your battery life considerably.
    – st2000
    Commented Nov 13 at 13:21
  • (I should just turn these comments into an answer.) Also, again, IIRC, the sleep timers were not accurate and were influenced by temperature. Likely to sleep both the transmitter and receiver, you would have to write clever code on the receiver to synchronizing it (calculate the receiver's next sleep timer value) with the transmitter's short messages.
    – st2000
    Commented Nov 13 at 13:29
  • how far apart are the two devices? ... you could add another ESP32 that is powered from an outlet to act as a synchronizer
    – jsotola
    Commented Nov 13 at 16:18
  • @st2000 Oh, that is is a lot of great info, thanks!! Sounds like my approach might not be the best route to go. I was trying to avoid wifi since from my research it looked like ESP-Now was more power efficient. But if I end up using wifi I guess I could use a web bucket as an intermediary, way it doesn't matter who's awake or asleep.
    – user1661890
    Commented Nov 14 at 4:53
  • @jsotola About 30 ft. Oh interesting! That might be a viable solution. Thanks!
    – user1661890
    Commented Nov 14 at 4:54

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