Is there a way to make ESP32 or ESP8266 wake up from sleep using code?

Question

Good morning everyone,

I know that waking up an ESP32 or ESP8266 can be done either by setting the RTC timer or by an external event which can be generally pushing a button. My question is can an ESP32 for example wakes up another ESP32 or ESP8266 by sending a message or a wake up signal ? of course I mean using source code. I'm working on a battery management system using duty cycling approach for my PhD and I thought I can use one ESP as controller and it will have the responsibility to wake one of the ESP slaves I should call and every slave is connected to the controller by the mean of ESP-NOW protocol or Bluetooth. Thanks in advance

I didn't find a solution from the beginning and any hint will be useful

Answer 1

You basically just answered your own question. The wakeup signal from one ESP device to another can just be the changing state of a GPIO pin (one device's GPIO pin connected to the other device's GPIO pin).

The sleep power when using the internal wakeup RTC is much lower (4-10uA) versus setting up a pin change to wake up (100-200uA). You will have to decide which uses less total power:

• waking up with the internal RTC on a regular schedule to check status
• setting a pin change to wake up