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Associate II
August 29, 2025
Solved

Unable to connect to F103 MCU

  • August 29, 2025
  • 1 reply
  • 335 views

Hi, 
I forgot to add the  pins in my STM cube project and flashed my MCU. Now I am not able to connect to my MCU. I am working with the STMF103RCT6 MCU. I tried giving 3.3V to the boot pin and connect a UART to serial converter  to my board. But it still didn't connect with cube programmer. I am attaching the screenshot of the error for your reference. Please advise what to do.

 

Screenshot from 2025-08-29 12-07-26.png

Best answer by Peter BENSCH

You can only use USART1 with the integrated bootloader of the STM32F103. See also the data sheet, section 2.3.10 or AN2606, section 18.1. For other U(S)ARTs, you would need to use your own bootloader.

Regards
/Peter

1 reply

Peter BENSCH
Technical Moderator
August 29, 2025

Which of the 5 U(S)ARTs are you trying to use for the bootloader?

Have you also tried baud rates lower than 115200?

Regards
/Peter

Associate II
August 29, 2025

I am using UART 4. PC10 is the Tx pin and PC11 is the RX pin. I have only tried baud rates 115200 and 9600.

 

Peter BENSCH
Peter BENSCHBest answer
Technical Moderator
August 29, 2025

You can only use USART1 with the integrated bootloader of the STM32F103. See also the data sheet, section 2.3.10 or AN2606, section 18.1. For other U(S)ARTs, you would need to use your own bootloader.

Regards
/Peter