Skip to main content
EThom.3
Senior II
May 14, 2025
Solved

STM32G474, dual functionality on PD3, alternate function 2

I am confused.

On an STM32G474QE, I intend to use PD3 for TIM2_CH1. I'm running out of pins, so this is the only practical pin for me to use.

However, according to the datasheet (DS12288 Rev 6), this pin can be either TIM2_CH1 or TIM2_ETR when alternate function 2 is selected. It is mentioned in the pinout list, as well as the alternate functions table:

EThom3_1-1747210574894.png

EThom3_0-1747210511651.png

This confuses me. As far as I know, these two signals don't rule out each other. There shouldn't be anything preventing the developer from using ETR as a an external trigger or clock source, and at the same time use CH1 for input capture or output compare. Of course, I might be wrong about this.

I haven't found a description of this anywhere else in the datasheet. And not at all in the reference manual and the errata sheet. Nor have I been able to find a bit in the TIM2 registers that selects either CH1 or ETR for this pin.

Does anyone know what this is about? Have I missed something that should be obvious? Is it a typo that has somehow survived through numerous revisions?

Any help regarding this will be highly appreciated.

By the way, I see the exact same thing in the STM32G473 datasheet. No explanation there either.

This topic has been closed for replies.
Igor Cesko
Igor CeskoBest answer
ST Employee
May 14, 2025

Hello,

There are 2 TIM functions on the same pin - there depends only from software how this can be used.

More details:

https://community.st.com/t5/stm32-mcus-products/how-to-use-tim2-etr-and-tim2-ch1-at-the-same-time/td-p/188934

 

  Regards

                        Igor

6 replies

AScha.3
Super User
May 14, 2025

Just try to set both in CubeMx on this pin, then you see...

on some pins really 2 functions can work same time, something like  ADC1 input  and ADC2 input on a pin.

If you feel a post has answered your question, please click on " Best Answer ".
Igor Cesko
Igor CeskoBest answer
ST Employee
May 14, 2025

Hello,

There are 2 TIM functions on the same pin - there depends only from software how this can be used.

More details:

https://community.st.com/t5/stm32-mcus-products/how-to-use-tim2-etr-and-tim2-ch1-at-the-same-time/td-p/188934

 

  Regards

                        Igor

EThom.3
EThom.3Author
Senior II
May 14, 2025

Thank you. Reading now, and trying to comprehend...