Why my nrf52840 dongle is recognized as "nRF52 SDFU USB" not nRF Connect USB CDC ACM

[dongxu0827]

I use c# write a server to monitor the com  whether the dongle plug.

At begin the dongle was recognized as nRF Connect USB CDC ACM

But yesterday, it was changed to "nRF52 SDFU USB"

That is awful, is there any solution to change nRF Connect USB CDC ACM?

[Hung Bui]

Hi, 
Could you let me know which SDK did you use ? I assume you were developing your application on nRF Connect SDK ? 
The name  "nRF52 SDFU USB" suggests that the dongle has entered the bootloader mode. This is the bootloader from NRF5 SDK, it is activated when you put the dongle to bootloader mode (press reset button on the dongle). 
You should see the LED breathing red color. 
In your case there could be a chance that the dongle entered bootloader mode because it detect invalid application. This can happen if you modify the flash content of the application (so CRC doesn't match) 

Or if you do a pin reset for some reason. 

Please try to upload your image again and see if the issue persist. 
Note that you can solder the header to P1 port and can erase/program the dongle from a DK.

[dongxu0827]

I install the nRF Connect for Desktop v4.1.2 and the Programmer version is v3.0.9. So is that mean the SDK?

Oh, yeah, maybe I press the button sometime by mistake so that put the dongle to bootloader mode and the led actually breathing right.

So how can i do can change the dongle name to the nRF Connect USB CDC ACM？

what is mean "solder the header to p1 port"

[Hung Bui]

Hi Xu Dong, 

Do you have other dongle to test ? 

I suspect it may have hardware defect on the chip that it couldn't run the connectivity firmware. 
Could you try flashing the sniffer firmware that I attached here, just to see if the board can get out of the bootloader mode. 

sniffer_nrf52840dongle_nrf52840_4.1.1.hex

[dongxu0827]

i  install the hex you give me, it stop blink.

but when i install the connectivity hex again, it occurs the same problems

[Hung Bui]

Hi, 
How did you generate the .hex file ? 
Could you try the following hex. 
After you program, please make sure you unplug and plug the dongle again. 

8424.connectivity_4.1.2_usb_with_s132_5.1.0.hex

I did a quick test here and the dongle worked fine after that. 

[dongxu0827]

I try this but no effect. also show the nrf52 sdfu usb.

yesterday i use a new dongle and i plugin the pc first time and install the same program, it success.

and I can see the nordic semidimtor dfu in device management but the old don't have. maybe the old is broken? 

[Hung Bui]

Hi Xu Dong, 
Most likely it's an issue with the dongle. 
One of the solution is to solder the header on P1. It should look like this: 

After that you can use a development kit to reprogram it. Please take a look here:  RE: Is it possible to program the nRF52840 dongle using the nRF52832-DK using SWD?