When the battery is low, the program freezes and the watchdog cannot be reset. J-link can't read the device

[SOK_LiWang]

hellow

I made a wearable device using nRF52840. 3.7V lithium battery power supply. The software adopts NCS V2.6.0. I found a problem that when my device is working at full speed and the battery level drops to 2.9V, the device stops working. nRF52840 will also stop working, after the battery is fully charged, nRF52840 will not restart work, it seems that the program is stuck somewhere. I want to use J-link to send nrfjprog.exe --reset, then J-link can't read the device either. The device will not reset until the battery is rewelded. A single channel EEG collection device I made, nRF52832, did not have this problem. Is there a problem with my device tree or config configuration? And please help me. Thank you so much.

sok

[Turbo J]

Redesign most likely.

In my opinion you need the protection/battery management circuitry to open the discharge FET below roughly 3.3V for normal LiPo chemistry. There is close to zero runtime left below that and it murders the battery. The internal resistance raises sharply, too.

Brownout behavior can vary wildly between µC samples. And its possible that a device self-destructs in a brownout condition by erasing/overwriting flash memory.