nRF52832 Custom Board - RESET stuck low

[phipi]

I'm just starting to bring up a custom board based on the nRF52832 and I am unable to program it using the J-link. It looks like my reset line gets stuck low when the JTAG is connected. I am able to program it sometimes, however most of the time (setup exactly the same), the orange light is on the JTAG. Can anyone suggest where to start debugging?

[Kenneth]

Hi, what likely has happened here is that you have programmed an application that enabled pin reset (CONFIG_GPIO_AS_PINRESET defined), and in addition you may have configured P0.21 (pin reset) as output low. This will cause the chip to stay continuously in reset state, preventing it to be re-programmed. The only way to get out of this situation is to force P0.21 high externally, by for instance connect it directly to VDD. This is not an ideal situation, since you are driving an output pin high, but should work for a short time while you can recover the chip using 'nrfjprog -f nrf52 --recover'.

[phipi]

I have been able to program it a few more times since then but it seems like it's very finicky. 90% of the time when I connect the J-Link the reset gets pulled low but the other 10% of the time it works and I am able to program. Without the J-Link the reset is high as expected.

[Kenneth]

Then I am not sure what the problem might be, I assume the board does operate as expected once you are able to program it? If yes, then maybe you should look at the programmer, how it's connected (GND, SWD pins, VDD), if the power supply range is supported by the programmer, try another programmer, and/or reduce programming speed.

[phipi]

I think I may have a bad connector. It seems like wiggling the 10pin ribbon cable can cause the issue to appear/disappear.

Thanks for the support.