ESP32 Forum

Hi everyone,

I am currently trying to implement a low power mode on my custom board to reduce as much as possible its consumption because it runs with a battery. My device needs to maintain the BLE connection at all times. I am developing with ESP-IDF v5.2.3 and VSCode on an ESP32-C3-Mini.

With the Power Save example (https://github.com/espressif/esp-idf/tr ... power_save) I managed to reduce as much as possible the consumption, especially by using the Modem Sleep mode and Dynamic Frequency Scaling.
However, I only reached 8 mA which is still high. I have already adjusted the advertising interval and connection parameters and TX power.

It seems I cannot use : because it disables all peripherals and so cuts the BLE connection and even with : my device connects, disconnects, connects, etc.

Is there a way to keep the BLE modem enabled AND the BLE connection active while still reducing the consumption ?

Best regards,

After deeper researches, all the use cases for BLE and sleep mode are about :
- wake up the chip
- connect to a device via BLE
- get some data via BLE
- execute the main task
- (disconnect and) go into sleep mode (which disconnects)

Nothing about maintaining the connection

Using an external 32kHz crystal you should be able to keep Bluetooth 'connected' during light sleep.

After added an external 32kHz crystal on my custom board, and flashed the "power_save" (https://github.com/espressif/esp-idf/tr ... power_save) example, I get :

• with the External 32 kHz crystal :
  • Disconnected : 8 mA
    Connected : 6.5 mA
  with the Main crystal :
  • Disconnected : 10 mA
    Connected :8 mA
  with the External 32 kHz crystal and all GPIO disabled :
  • Disconnected : 7.5 mA
    Connected : 6 mA

Does this mean I cannot reduce the consumption because of my custom board ?