Resolved! Pristine STM32L431 PA6 turned to hard output
When switching on a new, unprogrammed STM32L431, PA6 turns hard to output high.This is SPI1 MOSI.AN2606 should say this out aloud.I know the 'G0 have this too, and AN2606 says this for them, although quite quietly and confusingly in a footnote.There ...