RE: Known Problems with Deep Sleep on the NRF52840

Håkon Alseth — Thu, 11 Jan 2024 13:30:35 GMT

Hi,

The RESETREAS register, in the case of a full power on reset, will be 0x0.

Kind regards,

Håkon

RE: Known Problems with Deep Sleep on the NRF52840

Sami — Mon, 08 Jan 2024 23:51:00 GMT

So if a poor or intermittent battery contact is happening, which reset vector would be expect to see?

"RESETPIN" ?

"OFF" ?

RE: Known Problems with Deep Sleep on the NRF52840

Edvin — Fri, 05 Jan 2024 09:12:55 GMT

Hello,

Is this something you have been able to reproduce? What first comes to my mind is that if you have had a power cycle, the chip will turn on. This may happen if the battery has a bad contact, and the device is dropped, it may experience a power cycle.

If you are able to reproduce this, you can check the reset reason register (0x40000400).

You can add this to the start of your application to check:

uint32_t reset_reason = NRF_POWER->RESETREAS;
NRF_LOG_INFO("Reset reason: %08x", reset_reason);
NRF_POWER->RESETREAS = reset_reason; // write the bits that you want to reset, because this register is sticky between resets.

The reset reason register will either way give some hints on what started/reset the device. If the issue poor battery contact, causing some devices to experience power cycles during shipping, you may use this register to only power on if the reset reason is a button press. If it is something else, and perhaps particularly a power on reset, you can tell the application to go back to system off.

Best regards,

Edvin