Is it OK to configure two pins to have the same alternate function?

[dholth]

Posted on January 03, 2014 at 21:01

I noticed it is possible to configure two STM32[F051] pins to have the same alternate function but I couldn't find any documentation about what happens when you do so. Is it OK to use the chip this way? For example, what happens if the UART TX output is mappped to two pins? Or if the RX input is mapped to two external pins?

#stm32

[Mark Edwards]

Posted on January 03, 2014 at 23:47

Interesting, but why would you want to?

So far (thanks to the incomprehensible (to me) way that the designers allocate pins), I have found it a problem finding one spare suitable pin (which usually involves shuffling other pins around) to use for a function, why would you want to waste one?

[dholth]

Posted on January 05, 2014 at 04:41

Simple, I want to know whether it is harmful to the device, and also whether it might be useful. Maybe it is possible to drive two separate TX lines with the same signal and different GPIO configurations? I don't know because I couldn't find any mention of it in the datasheet.

[Tesla DeLorean]

Posted on January 05, 2014 at 05:23

Well I suspect there is no interlock on the hardware to stop you doing it, although the results may be undesirable. I'd expect outputs to work, and inputs to clash, you'd need to experiment.