Adafruit STM32F405 Feather Express does not go into DFU bootloader

Just a heads up, it seems the Adafruit STM32F405 Feather Express boards will not enter DFU bootloader mode. The one I picked up from Core Electronics today certainly doesn’t.

See thread here: Adafruit customer service forums • View topic - STM32F405 Feather Express not entering bootloader mode

I was able to erase and re-program with micropython via ST-Link using the bottom SWD test points on the board but not everyone will have the ST-Link adapter to be able to do this.

Pulling B0 to 3.3v did not put it into DFU (it does halt the running program) nor does running the below from the REPL:


Following those support threads on the Adafruit forums for now. Just thought this may help anyone else having issues programming the board.

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Hmm it’ll be interesting to see what the root cause of this is.

Hi Brant,

I’ve followed up on this one a little further and it appears that there may be an issue with that particular board that you’ve got, as Adafruit has found that this is not the case for the majority of these boards. If you can please email us by replying to your order confirmation email, we’ll run through some troubleshooting with you to identify the issue and get this sorted out right away. If there’s anything else that you need please let us know! :grin:


Hi Bryce - I’ve sent through some more details. I’ll see what Adafruit come up with, for the moment I can upload to the board via ST-Link, not ideal but it works. My final project will have custom boards running the STM32F405 so for now this Adafruit board works well enough for prototyping. This post was more for your information as a few other people have had the same DFU issue and not everyone will have an ST-Link to get out of trouble.


Hey Brant,

Thanks for getting in contact with us about this and following up with the email. Our team will look into it ASAP to try and resolve this issue.

We’ll post any notable findings up on here too for other community members to see.