nRF52840 dongle not detected in device manager

[DavidXie]

Hi, one of my nRF52840 dongles cannot be detect in device manager. When I plugged it into a USB port on my pc, the red light slowly blinks and it didn't appeared in ports as the other dongle does. it is also cannot be detected in nRF Connect. I tried to reset the dongle by pressing the reset bottom on the side, holding the reset button and release after I plug it in, but it still doesn't work.

Any suggestions?

[frogrammer]

I had some issues with the dongle then I just reset the whole device with SWD pins and reuploaded the bootloader. 

[Einar Thorsrud]

Hi,

Unless you have used SWD with the dongle before, the bootloader should be intact. When you write that the red light slowly blinks, does it do that so tha the red light fades in and out, in the same way as other dongles do if you press the sideways button (reset)? This is the normal way to enter DFU mode, but there is no need to hold it while inserting it, imply pressing the sideways button should always make it enter DFU mode.

When you write device manager, do you mean nrfutil device or another application? Do you see the Dongle in the Programmer app?

[DavidXie]

By "device manager" I mean the device manager in windows. And no, I cannot see this dongle in the programmer app while I can find the other ones.

[Einar Thorsrud]

I see. It seems it is in a bad state, somehow. Can you elaborate on the red blinking. Is it the red blink fading in and out (indicateing that the device is in Bootloader mode) which you should see on the other/working dongle after pressing the sideways reset button, or is it blinking in a different way/pattern?

[DavidXie]

The first one,  the red blink fading in and out.