analogRead takes about 0.1ms, so it should be fast enough assuming no/little contact-bounce. But with a single pin there is the problem of recognising contact bounce in the first place, which I have glossed over.
analogRead takes about 0.1ms, so it should be fast enough assuming no/little contact-bounce. But with a single pin there is the problem of recognising contact bounce in the first place, which I have glossed over.