NRF52 device not detected

[polly]

Hi, I'm having an issue with some PCBs I've designed with the NRF52832 on a module. When I first connect the board through a j-link, the device is not detected in NRFgo studio or by the command line tool. After trying for a while, seemingly randomly the device is detected and I can program the softdevice. From then on there are no issues re-programming.

The module is powered by a 3V coin cell. nReset is connected directly to the jtag connector with no pull-up. SWDIO and SWCLK are also connected directly to the jtag connector.

Any help would be greatly appreciated.

[MartinBL]

The randomness might suggest some sort of mechanical failure. Maybe a bad USB cable, bad soldering, bad wires, etc. Could that be it?

[polly]

I think I've resolved this but can't be sure as I ran out of boards to flash for the first time. There were a few things causing issues:

• On one board there was indeed a mechanical fault - a trace had been broken during assembly.
• The coin cell had dropped below 3V in some cases when I was trying to connect to the device for the first time
• With the above two issues resolved, the board could not be detected by nrfgo studio, however it could be programmed using the command line tool.