I have been trying to handle the SPI and here is a problem: the u575zi processor datasheet says that both pins PA12 and PA7 have SPI1_MOSI as the alternate function 5 (AF5). When I configure PA7 as the AF5 - indeed, it outputs the MOSI signal. However, when I configure PA12 as AF5 - nothing happens! No signal output.
Could please someone explain why? And why multiple pins have the same alternate function? Does is mean that I have to do something else in order to have MOSI on PA12?
Check hardware connections (solder bridges, connection to some onboard device) in Nucleo's manual/schematics, and/or by setting PA12 as GPIO output and toggling it. Read out and check GPIO registers content.