Associate III

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USART3 selection disabled in CubeMx

I need UART to use printf, but it's showing as disabled. How can I enable it, and I also need an example code for printf.

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mƎALLEmBest answer

ST Technical Moderator

If you pass the mouse on USART3, you will get the warning and the information about the issue:

There are IO conflicts with FMC or/and LTDC.

So you need to go to the pinout view and type USART3. All USART3 pins will toggle. Then select the pin that you need to use for UART3.

Attached a project where I configured USART3 on PB10 and PB11.

But becarefull, for this discovery you need to use USART1 not USART3 over STLINK Virtual comport as said in this thread for printf:

And if you need to use USART3 you need to check the HW and manage the conflicts on the board by referring to the schematics.

Hope that answers your question.

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ST Technical Moderator

Again, please put a correct title for your posts. "uart" doesn't make any sense.

For your question: Look at the warning. It seems there is a GPIO conflict between USART3 and something else ..

Please share your ioc file.

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Associate III

hello iam using stm32f429i-disc1 in this how to enable usart1?

ST Technical Moderator

I've already said there is a conflict in your config and I've requested to share your ioc file.

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