...only if your interrupt from the turnstyle mechanism is fully debounced and ESD protected. If not (I'd assume not) then you need to use a interrupt initiated, polled event if you don't want spurious counts static discharges counted nor turnstyle switch bouncing counted as a quickly passing circus. :)

The advantage of having a micro do it rather than circuitry is you can add the intelligence to observe the input signal and classify it as good or bad before incrementing the count.

ESD (electro static discharge) protection is not too hard or costly and is often overlooked. That's the difference between the pros and the average job shops.

duh