How to get the 'System OFF' to work in nRF52840 XIAO BLE Sense?

[msfujino]

This link may be more useful.

Sleep Current of XIAO nRF52840, Deep Sleep vs. Light Sleep

I compared the sleep current between SystemOFFSleep(DeepSleep) and SystemONSleep(LightSleep). The board service package is “Seeed nRF52 Boards 1.1.1”. To enter sleep mode, I used NRF_POWER->SYSTEMOFF = 1; for DeepSleep and RTOS delay() function for LightSleep. The pppk2 was used to measure the sleep current by applying 3.6V to the BAT pad on the backside of XIAO. The measured results were 2.4uA and 5.4A, with no significant difference. Note that the quiescent current of the 3.3V LDO is measure…

If you want to keep the sleep current as low as possible, you need to use “Seeed nRF52 Boards 1.1.8” so called non-mbed for your BSP.