STM32F411CEU6 Black Pill – DFU Mode "USB device not recognized"

[DRIFTYY777]

STM32F411CEU6 Minimum System Board Microcomputer STM32 ARM Core Board

I'm unable to flash my board using USB DFU mode. When I enter DFU mode, Windows fails to recognize the device and shows a USB error. However, UART flashing works correctly using PA9 (TX) and PA10 (RX)

- Hold the BOOT0 button
- Pressed and released RESET button
- Then released BOOT0
- Windows shows a popup:
_USB device not recognized. The last USB device you connected to this computer malfunctioned
- Device Manager says "USB Device Descriptor Failed"
- STM32CubeProgrammer and dfu-util do not detect the device

And also I installed STM32CubeProgrammer, Drivers and more but still cant enter dfu mode 
On the other hand Im unable to flash board with UART which I dosent like 

Note- Im new to STM boards

I'd appreciate help in diagnosing and fixing the USB DFU issue on my STM32F411CEU6 Black Pill board.

[Andrew Neil · Accepted solution]

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@DRIFTYY777 wrote:

Note- I'm new to STM boards

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Note that Black Pill is not an ST Product - you need to go to the manufacturer for support with it.

I would suggest that you start with a genuine ST board - such as the NUCLEO-F411RE:

https://www.st.com/en/evaluation-tools/nucleo-f411re.html

This not only gives you a fully documented and supported board - with plenty of ready-to-go tutorials and examples - but also includes a free, genuine ST-Link.

PS:

I have a feeling that Black Pills may not use the ST USB Bootloader - it might be their own, proprietary one?

[DRIFTYY777]

As I mention "Im new to STM" and that's my first STM board I just randomly picked this board not knowing much about it but I worked with pic, avr, and esp. After some digging I found out its called black pill but still dont know its clone. Thanks for letting me know its not STM product.

[kaosad]

If you bought the WeAct STM32F411CEU6 Black Pill, I'm fairly confident it's a genuine STM32 MCU. You can see their claim here. (I've purchased several of their products and have been happy with them.) They seem aware of the issue, and amusingly, their suggested fix is to heat it up.

The actual problem stems from the UART1 RX pin (PA10) being left floating, which makes it susceptible to random noise. This can cause the MCU to mistakenly enter UART ISP mode on power-up. To prevent this, simply add a pull-up or pull-down resistor (preferably a high-value one) to either 3.3V or GND. This stabilizes the pin and prevents unwanted fluctuations during startup. More details can be found here.