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Unable to connect to F103 MCU

Akshat_codes_
Associate

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

1 ACCEPTED SOLUTION

Accepted Solutions

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

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5 REPLIES 5
Peter BENSCH
ST Employee

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

In order to give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

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.

 

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

In order to give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

Thank you for the support. I'll try this out and let you know if I face any issue.

 

Hello,

For a new question regarding the usage of the bootloader over UASRT1, please open a new thread.

Thank you.

To give better visibility on the answered topics, please click on "Accept as Solution" on the reply which solved your issue or answered your question.