STM32L431: Enable EXTI on a Pin Number Used as UART RX on a Different Port

Elliott99 · ‎2025-02-17

Hello,

I would like to configure PA11 as an EXTI pin. I know that there exists the hardware limitation that there cannot exist two pins with the same pin number in different ports configured as an EXTI pin (I.E., I could not configure both PB11 and PA11 as EXTI inputs). PB11 is already configured as a UART RX pin. Will there be any conflict if I now attempt to configure PA11 as an EXTI input pin, I.E. a low bit being received by PB11 triggers the EXTI interrupt on pin 11? Or does this conflict only occur when two pins of the same number are both configured as EXTI inputs?

SofLit · ‎2025-02-17

Hello,

No. There is no relation between UART Rx and EXTI interrupt. These lines are totally different. No risk to get EXTI triggered by the UART Rx.

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SofLit · ‎2025-02-17

Hello,

No. There is no relation between UART Rx and EXTI interrupt. These lines are totally different. No risk to get EXTI triggered by the UART Rx.

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.
PS:
1 - This is NOT an online support (https://ols.st.com) but a collaborative space.
2 - Please be polite in your reply. Otherwise, it will be reported as inappropriate and you will be permanently blacklisted from my help.

TDK · ‎2025-02-17

Furthermore, it is not possible to configure two pins of the same number as EXTI inputs.

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