I noticed that, ignoring supply pins, every pin on an STM32F1xx device is 5V-tolerant except:
- special-purpose inputs nRST and BOOT0
- backup-domain pins: PC13-15
- pins with analog (ADC/DAC/oscillator) functionality on at least one F1xx device: PA0-7, PB0-1, PC0-5, PF6-10
- and finally... PB5.
So what's up with PB5 ? As far as I can tell from the documentation it is a wholly unremarkable digital I/O pin. Is there some non-obvious reason it isn't 5V-tolerant?