Hi I have a coinslot project and connected with a fingerprint sensor it was stated in the ardiuno forum that it will work on pin 2 and 3 , but it is already used pins of the finger print sensor .

Coinslot signal is in pin 9 and the in2,3 is for the rx and tx of the fingerprint sensor.

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  • 4
    So... change the RX and TX of the fingerprint sensor to some other pins...?
    – Majenko
    May 21 at 14:00

If you can't rearrange the pins like Majenko suggests in the their comment, something you can do is is use pin change interrupts rather than the regular "external" interrupts. On the UNO, these are available on all of the "digital" capable pins, which also includes most of the "analog" pins if you have an SMT UNO, or all of them if you have a DIP model.

NiceHood's PinChangeInterrupt library is modeled after the regular attachInterrupt function, so it should be familiar looking to you. It's in the library manager; you don't need to get it from github.

NOTE: The O.P. opened a another question which seems to be this same thing, only with different context and specific code. There I've given more details on what's outlined above but in relation to that that specific code in an answer there.


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