JLink disappeared on NRF52840DK after use

[LCYin]

Hi,

my PC stopped detecting the JLink debugger on my NRF52840DK board. This happened after I accidentally flipped the NRF only switch while I was handling the board. 

I have tried following the instructions from https://devzone.nordicsemi.com/f/nordic-q-a/24592/my-nrf52-nrf51-dk-kit-doesn-t-work/96836#96836, but I was not able to carry out step 4, as LED5 still blinks quickly when I power cycled the board while holding IF/RESET button. The BOOTLOADER drive does not apear on my computer either. I was able to verify that the NRF52840 SoC itself was functioning, as I could access the openThread CLI through the USB port.

Also, JLink Commander updated the firmware of the on board debugger while I was flashing a program. However, I am not sure if this is relevant.

Any help would be appreciated. 

[Priyanka]

Hi,

Did you change the switch from nRF Only to Default while performing Step 4? Also, what is your DK revision?

Best Regards,

Priyanka

[LCYin]

Hi Priyanka, 

It is currently in Default instead of nRF Only. I tried to enter the bootloader while it was set to nRF Only before this because I thought something happened to the Interface MCU.

The board I have is revision 3.0.0

I have also tried installing the mbed serial drivers, but the program says that no mbed microcontrollers were found.

Thank you

[LCYin]

I resolved the issue by using a different micro USB cable. It seems like certain cables prevent the detection of the onboard debugger or the USB serial port on the NRF SoC.

[Priyanka]

Glad to hear that it works now.

-Priyanka