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?

[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.

[Einar Thorsrud]

Hi,

Can you elaborate what you mean by the first one? I assume you see a red LED fading in and out on the working dongle after pressing the reset button. Is it different on the failing one? If it is, that may give an indication. If not, the dongle should be in DFU mode and it should show up. As it does not it seems it is damaged somehow.

[Healthnut]

I have a nrf52840 dongle that seems to be in the same state directly out of the packaging. With the pulsing red light but no dfu device detected in windows device manager or the NRF desktop programmer app. A second dongle is recognized fine so it seems to be a problem with the first dongle. 

Did you figure out a method to recover yours? I’m currently planning to see if a j-link edu mini could recover it, but haven’t done this before and still need to find the original bootloader and figure out how to flash it. 

[Einar Thorsrud]

Hi,

I do not have an explanation for this yet, so we may continue to look into it. However, the dongle should enumerate when it is new (and unless it has been used with an external debugger when you may have deleted the USB bootloader, it should always enumerate after the reset button has been pressed).

As there are several contributors in this thread now I suggest you create separate private tickets if you need the dongles replaced. Please refer to this ticket and include your shipping address. It would also be good if you can include a photo of the failing dongle (particularly the back side with the white sticker.