Hi In the STM32L053R8 Datasheet, I cannot figure out the default alternative function AF0, AF1... I'm using the UART TX RX on PA10 PA9 is that the correct choice?

[Foued_KH]

Hello @BEKABEN​ ,

Correct, for UART instance 1 : PA9/PB6 -> UART1_TX and PA10/PB7 -> UART1_RX

For LPUART : PB10/PC4/PC10 -> LPUART1_TX and PC5/PC11 -> LPUART1_RX

Also, for UART instance 2 : PA2/PA14 -> UART2_TX and PA3/PA15 -> UART2_RX

Foued

[waclawek.jan]

 

JW

[BEKABEN]

Yes

is AF4 the default setting on the stm32l053r8?

[waclawek.jan]

No.

Default setting of all AF is AF0 - see GPIO_AFR registers description in the GPIO chapte of Reference Manual.

JW

[BEKABEN]

If I design my schematic based on AF4 and I'm accessing the UART from PA9 PA10 is it possible to do updates in the future?

[Tesla DeLorean · Accepted solution]

AF4 is set by software.

If you used PA9/PA10 for a UART connection in your design it will be usable as such.

F​or the System Loader see App Note AN2606 for supported PINS and METHODS.