How to reinstall (restore) manufacturer`s bootloader on STM32F103C8T6 development board?

[AMelk]

I have STM32F103C8T6 development board (like this: https://www.rogerclark.net/wp-content/uploads/2014/11/STM32Mini.jpg) which can be programmed by USB interface. I programmed it several time before, but now I can't do this. When I connect it to the PC, I get a warning messege (pinned) and can't load firmware to the STM.

[Tesla DeLorean]

The ST boot loader is in ROM, strap BOOT0 high to enter it.

People call this the "Blue Pill"

Still doesn't work, perhaps review voltages on supplies, and behaviour of NRST pin. Try using a SWD/JTAG in "Connect Under Reset" mode, where you connect SWDIO, SWCLK, NRST, GND

[AMelk]

Thanks for reply. I can program my STM32 board by external ST-Link V2 programmer, but USB interface is doesn't working.

[Tesla DeLorean]

USB doesn't report as "STM32 DFU MODE" (or whatever) when BOOT0 is high at power on/reset, or your code running doesn't support USB?

You could have broken/damaged the port and or cable.

[turboscrew]

Blue pill can't be programmed with USB unless you put an USB-bootloader in it. I wonder if there has been STM32duino USB bootloader in it. The only manufacturer-made bootloader in it is RS-bootloader.

https://wiki.stm32duino.com/index.php?title=Burning_the_bootloader

[AMelk]

Thanks for reply. It's a new board. All that I was do - it load blink code (​then it worked). I did nothing with bootloader. I was try to connected board to the another PC, by another usb cable, but it's still not working:slightly_frowning_face:

[turboscrew]

Where did you got it? If it's from STM32DUINO-related place, it may have USB-bootloader preinstalled. STM doesn't put USB-bootloader in F103s.

Check table 3 here...

https://www.st.com/content/ccc/resource/technical/document/application_note/b9/9b/16/3a/12/1e/40/0c/CD00167594.pdf/files/CD00167594.pdf/jcr:content/translations/en.CD00167594.pdf

[Omeg18650]

I have some clue here.

But the solution is temporally.

The chip and board for me is stm32f411ec6

on the Blackpill board.

I have to touch the digital pin with fingers while the USB DFU boot loaders begin. If I don't do it. The 25 Mhz clock will show up for a small while, then fall flat. And the usb enumeration will fail on my computer. The error being reading product discriptor error.

[Omeg18650]

Ok I figured my problem out. The ripple from the circuit will trigger the USART1 RX pin to make it enter serial mode. by pulling the PA10 up to prevent accidental triggering, It can finally enumerate normally.

the dmesg -w report