Adds onto existing partially erasable pins, allowing a pin to be downgraded once to remove its number (as exists today), and then a second time to then remove its port as well (new).
let generic_pa_pin = gpioa.pa0.into_push_pull().downgrade(); // PAx<Output>
let generic_pin = generic_pa_pin.downgrade(); // PXx<Output>
PR to add fully erasable pins (#104)
Borrows heavily from https://github.com/stm32-rs/stm32f0xx-hal
Adds onto existing partially erasable pins, allowing a pin to be downgraded once to remove its number (as exists today), and then a second time to then remove its port as well (new).