6 years, 5 months ago.

Serial problem - no Tx to PB_10


I wish to use USART 3 on the STM32F302 Nucleo board.

I initialise using

Serial usart3(PB_10, PB_11);

but there is no response from the Tx pin on PB_10. It just sits at high level.

I have successfully used USART1 as follows, but USART3 does not appear to initialise

Serial usart1(PA_9, PA_10);

Any help appreciated


Question relating to:

Affordable and flexible platform to ease prototyping using a STM32F302R8T6 microcontroller.
posted by toshiki goto 31 May 2016

3 Answers

4 years, 10 months ago.

Hello, I have validated that replacing UART3_BASE by USART3_BASE in the file : targets/hal/TARGET_STM/TARGET_STM32F3/serial_api.c fixes the issue for PB_9 and PB_10

I have done a Pull request in github, you should be able to use it soon. Thank you for the issue notification.

Accepted Answer

Hello. Thank you Adu.

I will wait for the pull request is merged.

posted by toshiki goto 31 May 2016


Hello.Adu. I checked your fix code.(code of github)

I have succeeded in using the Port PB_10 as UART.

Thank you.

posted by toshiki goto 01 Jun 2016
4 years, 10 months ago.

I also got up the same problem.


4 years, 10 months ago.


Could you please add the following define and let me know if it is working as expected or not:


Thank you for reply. But it did not work even if you add it.(I checked with an oscilloscope.)

The results are below.

Serial SIRIAL(PB_9, PB_8); ->NG

Serial SIRIAL(PB_10, PB_8); -> NG

Serial SIRIAL(PA_9, PA_10); -> OK

Signal of Pin PB_9 PB_10 is always "H".

We will continue to investigate. If you have same tips, please tell me.


posted by toshiki goto 30 May 2016