Bricked nRF52840-dk

[Jerry Easley]

I had a pathological application running of my nRF52840 so I reset/power sequenced it; that procedure got rid of the pathological program but it also broke JLink, I think.  In any case it now connects as a usb serial device.  Apparently I need to reflash it in order to restore functionality,  There are other tickets on here concerning this issue and which I have reviewed.  I found the restorative procedures posited there to be incomprehensible; I am a newcomer to Nordic an I am not at all familiar with the tools used to do this,  So I need instructions in great detail.

Regards,

Jerry

[Simonr]

Hi

If you held the IF BOOT/RESET button while turning the nRF52840 DK on, you have likely put the MCU interface chip into bootloader mode, and will need to flash the Interface MCU firmware onto it again. When the DK shows up as a bootloader/USB serial device you can drag and drop this .bin file into the device that pops up. Make sure you only add the following .bin file, or you could be in danger of bricking the DK for good.

1346.j-link-ob-sam3u128-v2-nordicsemi-170724.bin

If this doesn't help. Please provide some more information as to what revision of the nRF52840 DK you have and what exactly happens when you power on the DK. Does any of the LEDs blink? Have you at any point cut or soldered any of the SB solder bridges that wasn't initially in that state?

Best regards,

Simon

[Jerry Easley]

Hi Simon, since posting this I have used J-Link commander to reflash with j-link-ob-sam3u128-v2-nordicsemi-170724.bin;

this did fix the connection problem; I now get two Jlink com ports showing up in my device manager.  I can program it with vscode and everything seems normal, However, I have an application that uses cdc_acm to create a console for printk statements.  Previous to bricking my dk this program worked on both my nrf52480-dk and my dongle.  When the program initializes it causes a virtual com port, COM11, to be created on my PC.  I can then use Putty to monitor the console traffic.  Now, the code still works on my dongle but not on the dk. When the program initializes on the dk nothing happens with respect to com ports. I have verified that the program is running as expected by stepping through the code with the debugger..  There must be something relisted to the dk's configuration causing it not to work correctly.. .