Duo not showing as usb serial device. A request for the USB device descriptor failed


Well, the title explains everything. Though it had firmware 0.3.1, on particle it was still shown as 0.2.4. I’ve attempted factory reset, but all it did is disconnecting duo from the network… Any way to fix it? Right now I would guess it’s an issue with downgrading from 0.3.0 if not for that I wasn’t downgrading my Duo… I don’t have RBLink so if it really is issue with bootloader I won’t be able to fix it :frowning:


Ok. Little update: I was able to connect it again to particle cloud by using android app to give Duo WiFi credentials. And I observed quite weird behavior. A) It connects and signal works, but when it’d disconnected it still appears connected on the website.
B) I can’t flash code. Website says that flashing was successful, but nothing happens to the Duo.
C) After some time it disconnects from the cloud (stops breathing cyan and starts breathing green)

I also reinstalled v0.3.1 using Duo CLI, but it didn’t change anything. And earlier I confirmed that Duo has v0.3.1 and current bootloader (r5), so I think it’s not the issue with downgrading.

But I think that reflashing bootloader might be at least worth trying. Any way to do that without RBLink?

And I think I saw somewhere that Duo has two more serial ports on pins (RX/TX and some other I don’t remember). Can I access one of them by hooking usb cable data pins or by using Arduino UNO (as this is the only spare board I have right now)?

Anyone has idea what could have happend and how to fix it if none of my ideas above will help? Is it hardware issue, or just broken software? And if it’s the hardware, then what can I do about it other than buying another Duo (if anything, of course)?


Anyone has at least idea how to flash code on Duo in this state? I will need it soon (I have different board capable of what I need on the way, but I’m not sure if I’ll get it on time, so I might need to use Redbear Duo).


Hi @opliko95, Try putting your Duo into safe mode, in which it will connect to the cloud without running the user application. Also you can make it enter Listening mode to verify the system firmware version using serial terminal. Remember that the Duo must not downgrade to v0.2.4 or below, otherwise, the bootloader will be destroyed.


I can’t check version in serial terminal, because my whole problem is that Duo is not recognised as serial device and I can’t use it with serial terminal. But I was able to check version using DuoSetupCLI:
“Release : 0.3.1
Bootloader : 5
System part1 : 9
System part2 : 9
User part : 9”
Everything seems ok.

And I was able to flash code while Duo was in safe mode, and now it doesn’t disconnect when I’m doing it while running user application (So I can work with it!), thanks for suggesting using safe mode.
But it still appears in device manager as unknown usb device, so I can flash code, but only using cloud.
And a new problem appeared since my last post: reset button sometimes gets “stuck” - led indicating that it’s pressed is still on, and Duo doesn’t turn on. Well I’ve found a solution - connecting it to positive side of any power source (including Duo’s 3V3 and VIN) “unstucks” it and Duo turns on normally.
So with that new issue in mind I think my problem might be issue with hardware, not firmware.


Please install the latest Windows driver.


Well, a long time has passed. I have almost forgotten about Duo, but it might prove useful to me once again. If I can just get it to work…
Although I kida doubt that I can. Installing the drivers (and I had to try it from the ZIP file, because the installer said I don’t need it on Windows 10…) didn’t change anything.
I mentioned in the earlier post that reset button sometimes gets “stuck” - so the LED stays on, and Duo isn’t doing anything until i remove power and connect it again. Now it does that every time.
It still isn’t recognized as a serial device, and now it isn’t even connected to wifi, so I essentially can’t do anything with it.
Any ideas? Or is it impossible to fix?

EDIT: Just after I added this post I tried to restore Duo to factory settings, but it ended up in an endless loop of blinking light. So I guess this is really bad if I can’t even do that…


Hi @opliko95,

To make sure the bootloader is working well to restore the system firmware, please try making the Duo entering the DFU Mode. If the bootloader is fine, please upgrade the system firmware to v0.3.2. I’ll follow up your case.

Best regards,


@guohui seems like bootloader is fine (Duo can enter safe mode and dfu mode), but even in dfu-mode it isn’t recognised by my computer (and not only mine - it took me so long to reply this time, because I was trying it with other pc’s. So I’m sure it’s not a problem with my computer).
So it seems that it’s just dead - i don’t have RBLink (and I’m not planning to buy one for the one Duo I have - instead, I will probably just use another board), and it a) doesn’t enter listening mode anymore, b) isn’t connected to any wi-fi network and c) isn’t detected as usb serial device (and as dfu device as well).


Did you install the DFU USB driver using the Zadig util?