XIAO BLE Sense in deep sleep mode

[ybarigou]

@hichiaty & @turing-complete-labs, how did y’all manage to get down to 3-5uA ?? With sd_power_system_off(), it only reaches around 20uA for me (and some other folks here in this thread). I am using regular (not Sense) Xiao BLE.

I followed these steps:

1. Flashed this bootloader
   BLE_52840_Core/bootloader/Seeed_XIAO_nRF52840/update-Seeed_XIAO_nRF52840_bootloader-0.6.1_nosd.uf2 at main · 0hotpotman0/BLE_52840_Core · GitHub

2. Installed this library
   

   

3. Used this (minimal) code

void setup()
{
  suspendLoop();
  sd_power_system_off();
}

void loop()
{

}

4. Measured current using GND and 3V3 pins

What could I possibly be missing ??

Note that adding the following to setup did not improve the sleep current (since I am using sd_power_system_off() anyway)

  sd_power_mode_set(NRF_POWER_MODE_LOWPWR);
  sd_power_dcdc_mode_set(NRF_POWER_DCDC_ENABLE);
  __WFE();
  __WFI();