nrf52840DK not detected after flashing an external board

[j_sudria]

Hi all,

I recently bought an nrf52840DK, and yesterday I tried to program an external board through the p20 connector on the DK with the SWD pins. I was able to flash the code without any problems and verify that it worked.

Everything seemed to go well until today, when I connected the DK to the computer and it was no longer detected. It doesn't appear as a device in Windows Device Manager, in the nRF Connect extension for Visual Studio Code, or in the desktop version of nRF Connect. I also tried using the SEGGER J-Link Configurator, but it doesn't show up there either.

I assume the problem is with the DK since I have tried different cables and USB ports, and the result has been the same.

The external board contains an nrf52840, and the connections I made to flash it are:

nrf52840DK ----------    external board
SWDSEL     ----------          VCC
SWDIO        ----------        SWDIO
SWDCLK    ----------       SWDCLK
GND            ----------         GND
RESET        ----------     RESET_N

I'm using:

• nrf52840DK 3.0.2

• nRF Connect SDK v2.9.1

• SEGGER J-Link Configuration V8.28

Does anyone have any idea what the problem might be?

Thanks in advance,

Jaume

[Maria Gilje]

Hi Jaume, 

First, let's do a sanity check and make sure that the switches on the DK are in the correct positions and that you are using the correct USB connector. 

SW6 should be on DEFAULT 

SW9 (nRF power source) should be on VDD

The correct USB connector is J2. 

If you verify the above steps we can investigate more about what is going wrong. 

Best regards,

Maria

[j_sudria]

Hi Maria,
I checked and everything is connected as you indicated. I also tried measuring the voltage on the VDDnRF pins of the p20 connector and I get 0.4V. As far as I know I should measure a value close to 3V, right?