STM32F401 Can't enter DFU mode

[hautamak]

Hello everybody

I have following board:

https://www.amazon.in/SunRobotics-STM32 ... B08Q3RNKFP

I got it working with st-link, but I want to use it with usb (mainly to get serial communication, St-link seems to be really hard to get working with serial).

However, When i put 3 headers to boot position, the device don't show up in device manager, nor stm32cube, nor arduino ide.
I did try another board, but with no luck.

Could somebody guide me to correct direction. I'm open to installing other bootloader for my blackpill.

Thank you all.
Hautamak.

[ag123]

The usual thing is set boot0 and press reset.
And that is provided that you board is properly wired for USB, e.g. that D+ is pulled up with a 1k resistor etc
And that a crystal of preferably 8 Mhz is needed for HSE running on the external crystal clock
in short, USB needs to be working properly

and that make sure nothing is connected to PA9, PA10 Serial1, otherwise it is flashing from uart

[STM32ardui]

I got it working with st-link, but I want to use it with usb (mainly to get serial communication, St-link seems to be really hard to get working with serial).

ST Link is made for uploading (and debugging?), but you can't get output from a Serial.print() over it. For this you need an USB/Serial-adapter too.
If you connect ST Link to SWD connector, you don't need t put board into boot mode, STM32CubeProgrammer does it.

However, When i put 3 headers to boot position, the device don't show up in device manager, nor stm32cube, nor arduino ide.

I don't know this board. Normally there are two buttons or two jumpers (on BluePill-boards).
For what your board needs 3 switches? I see a button on the picture, so 1 switch should be enough ...
Do you get any instructions from dealer or manufacturer how to set board to boot mode?