ESP32 boards Low Power mode including M5StickC and M5stack

The ESP32 boards can now run on low power modes when configured as BLE scanners.
Between each scan instead of waiting and be ON, if set the ESP32 will go to deep sleep. The current in this configuration will go down to milli amps.

This mode enable to save energy if you are on a power plug and allow also to run on a battery for days, you could also alternatively and if you need to cover outdoor area add a solar panel to the battery.
This give the opportunity to have a fully wireless gateway retrieving BLE sensors data.

Current in sleep mode with M5stickC

Current in sleep mode with M5stack

By default the low power mode is disabled, to enable it you have several possibilities:

  • press the button B of the M5 devices (center button of M5Stack or top button of M5StickC)
  • set it by MQTT
  • change it on user_config.h

There is 3 power modes available:

  • 0 standard mode
  • 1 only for M5 boards, display is ON only when processing, the rest of the time low power
  • 2 for all ESP32 based boards, a led can be used to know when processing, the rest of the time low power

Here is a current measurement done on ESP32 DEV KIT in low power mode:

After removing the LED we are at 1.7mA

Note that you see mV on the multumeter due ti the fact that I mnusing a converter mA to mV to read low current.