USART2 of STM32 Nucleo-L053R8

BSalt.1 · ‎2022-03-30

When using USART2 of STM32 Nucleo-L053R8, if I try to use PA0 and PA1 that are not used for flow control as GPIO, a warning appears as shown in the attached picture. How to resolve this conflict?

Artur IWANICKI · ‎2022-03-30

Hello,

In case you do not plan to use hardware flow control (neither RTS/CTS nor DE) there is no issue and you can use USART2 in asynchronous mode (on RX/TX lines), PA0 as external interrupt line and PA1 as output line. This warning is just in case you would decide to turn on HW flow control.

PA0 and PA1 can be used as flow control pins for USART2. There is no alternate location of those, this is why there is this warning and marked on red fields related to hardware flow control.

In case you would like to use hardware flow control you would need to release PA0 and PA1 and select different pins for external interrupt and output.

Peter BENSCH · ‎2022-03-31

This is not an irresolvable conflict, but a warning, as CubeMX also signals with the small yellow triangle next to USART2. As soon as you assign functions to PA0 and/or PA1 on the NUCLEO, where USART2 is used for the Virtual COM Port, PA0 and PA1 are no longer available for hardware flow control on USART2.

However, this is not a problem, as hardware flow control is not used with the VCP anyway.

Does it answer your question?

Regards

/Peter

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BSalt.1 · ‎2022-03-31

@Artur IWANICKI, @Peter BENSCH

Thanks for your help.

I'm testing BLE with L053 and F401 Nuc64 boards and X-NUCLEO-IDB05A1 boards.

I used X-CUBE-BLE1 for the software pack.

The F401 was well tested, but the L053 board didn't.

So, I'll have to look into what I'm doing wrong.

I don't think it's a USART2 problem.