What does happen in STM32F4 if I configure an I/O as analog, but it is not an analog one? I mean, smith trigger and output buffer are disabled as well as pu and pd?

[Tesla DeLorean]

>>but it is not an analog one?

What does that mean?

The pin will just float in a Hi-Z state, it will track whatever external circuit you have attached to it, just don't exceed the min/max voltages specified in the data sheet.

[waclawek.jan]

I wouldn't bet on it - undefined combinations might have been optimized by the silicon compiler to a surprising result. For example, on 'F4, I've by mistake used an undefined AF for a particular pin, and it - for me quite surprisingly - turned the pin to output.

So, the short answer is "don't do it", and if you have the buying power as expressed in $M++, you can ask ST directly.

JW

[brazov22]

it means that analog switch is not present on that IO

[brazov22]

if I read the following application note AN4899 it's clearly stated on chapter 3.3.4 that configuring io as analog, disables input Schmitt trigger, output buffer and pu and pd.

[brazov22]

i.e. PB10 which has no analog function

[Tesla DeLorean]

Ok, so signal goes no where, and schmitt trigger disabled

[waclawek.jan]

Quick experiment on PC11 on 'F429 DISCO revealed that changing it to Analog indeed switched off pullup and IDR did not reflect the input level anymore (whether that means that ths Schmitt trigger was switched on and/or whether this means decreased leakage, I am not going to judge).

As much as experiments are worth...

JW

[brazov22]

the purpose is to configure it as analog pin before entering in stop2 in order to reduce consumption.