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.. . 

[Simonr]

When using a DK and the USB example projects, you need to use the nRF USB connector (J3) instead of J2 that goes to the Interface MCU. Please check that the nRF USB is connected to the computer, and that the switches on the nRF52840 DK are in the correct position.

• SW9 to the middle position (VDD)
• ¨SW6 to DEFAULT
• SW10 to OFF

Best regards,

Simon

[Jerry Easley]

Hi Simon,

I have SW9 to mid pos (VDD)

I have SW6 to DEFAULT.

If I turn SW10 to OFF I lose all power to the board.  (are you sure it should be off; it is the power switch?)

If I turn SW10 to on, I get the ACM port, but no Jlink ports

This board seems to behave differently every time I touch it.

Yesterday, it would instantiate J-Link ports but would not instantiate ACM ports, today it will instantiate an ACM port but not J-Link ports.

In any case I have and have had the switches set as you direct, except SW10, which I have set to on.

I have both USB ports connected to my PC; my application is running and I can monitor the ACM port via Putty.

VSCODE cannot communicate with it because the J-Link ports are not instantiated.  

I am very confused.

Regards,

Jerry

[Jerry Easley]

Hi Simon,

I am such an idiot; I was confusing SW10 with the power switch. I believe I had SW10 set to the on position.

I have changed it to off. Now the board does not instantiate any virtual com ports at all; completely dysfunctional.  If I move sw10 back to on and try it, it’s still completely dysfunctional. For now I’ll I’ll leave it in the off position as you have directed.

I am now even more confused by this board’s behavior.

Regards,

Jerry