nRf52840 unseen under Device Manager. How to restore?

[wendytang2000]

My nRF52840 was recently corrupted. I was able to run through reset and downloaded the latest MCU 'J-Link OB-SAM3U128-V2-NordicSemi 170724.bin' onto the board. So now it shows up in bootloader mode when connected to my PC. However, under Device Manager, it showed up under USB controller, but not under Ports (COM & LPT). The J-link was broken. 

I have tried the following things to fix J-link. None of them worked.

1. Used a different cable;

2. Connected to a different USB port;

3. Uninstalled device under Device Manager and reset the board;

4. Disabled the device and updated the device driver;

5. Drag-and-dropped an application hex onto the board during bootloader mode. The board remained in bootloader and didn't go to app; 

6. reinstalled 'J-Link OB-SAM3U128-V2-NordicSemi 170724.bin';

7. Tried nrfjprog -- recover. The error message was 'no debug device connected'.

Please help. Thanks in advance. 

[Edvin]

Hello,

What USB port on the DK are you using? If you expect it to show up as a DK (JLink), you should use the port on the short side of the DK. 

I am not sure where you found your 1-7 guide, but try this:

1: connect the USB port on the short side of the DK to your computer.

2: Power off the DK using the power switch.

3: Hold the IF BOOT/RESET button while you power on the DK

4: It should appear as BOOTLOADER, drag and drop the file that you are using (OB-SAM3...).

5: After a few seconds, LED 5 should blink a bit faster than it did

6: Power off the DK using the power switch.

7: Power on the DK without holding IF BOOT/RESET.

It should appear as JLink. NB: You don't have to do this every time you want to program your nRF. This is only if the programmer chip on the DK has crashed.

The USB port on the long side of the DK is the nRF USB Peripheral. It is used only if your application uses USB. Right now it looks like it is programmed with the mass storage device (MSD) example. It has nothing to do with the programmer on the DK, or the OB Segger chip.

BR,

Edvin

[wendytang2000]

It worked. Thanks.