recovering NRF52DK with bootloader

RE: recovering NRF52DK with bootloader

Vidar Berg — Wed, 03 Aug 2022 09:16:34 GMT

Thanks for the update!

RE: recovering NRF52DK with bootloader

danmcb — Wed, 03 Aug 2022 09:14:05 GMT

seemed to be some kind of hardware/wiring issue. The problem went away of its own accord. You may close this ticket, sorry for wasting your time with it.

RE: recovering NRF52DK with bootloader

Vidar Berg — Fri, 17 Jun 2022 12:10:07 GMT

Hello,

You should not be able to brick the device even if you are playing around with the startup files. The only known configuration/condition that can cause the chip to become in an unrecoverable state is the one described in the errata here: [176] System: Flash erase through CTRL-AP fails due to watchdog time-out.

[quote user=""]Initially, the jLink wa sno longer visible from my host system.[/quote]

Sounds like it could have been a temporary bad USB connection? The FW running on the nRF should definitely not affect how the Jlink FW runs on the interface MCU.

[quote user="danmcb"]the code was playing with SWO interface somehow, which mine does not).[/quote]

The SWD interface is always available regardless of SWO/trace settings.

[quote user="danmcb"]I've seen a number of these tickets where people could not recover and most have not had a reply from Nordic. It would be great to get, at least, some explanation of why this has happened and perhaps how to avoid it.[/quote]

It's usually a bad connection somewhere or wrong logic levels (i.e. mismatch between programmer and target). But there seems to seems to be some communication between the Jlink and nrf in your case at least.

[quote user="danmcb"]I also tried with a Segger JLink unit, still no success.[/quote]

Could you try with the latest version of nrfjprog as well?

RE: recovering NRF52DK with bootloader

danmcb — Fri, 17 Jun 2022 08:07:40 GMT

I also tried with a Segger JLink unit, still no success.

Trashing a single dev board is not that big of a deal for us, but what is annoying is not knowing why. I understand that modifying asm startup code is a delicate matter, but it should not brick the board so that FLASH cannot be erased any more (unless maybe the code was playing with SWO interface somehow, which mine does not).

I've seen a number of these tickets where people could not recover and most have not had a reply from Nordic. It would be great to get, at least, some explanation of why this has happened and perhaps how to avoid it.