Reference > Language > Functions > External interrupts > Digitalpintointerrupt

digitalPinToInterrupt()

[External Interrupts]

Description

The digitalPinToInterrupt() function takes a pin as an argument, and returns the same pin if it can be used as an interrupt. For example, digitalPinToInterrupt(4) on an Arduino UNO will not work, as interrupts are only supported on pins 2,3.

See attachInterrupt() for a full list of supported interrupt pins on all boards.

Syntax

digitalPinToInterrupt(pin)

Parameters

pin - the pin we want to use for an interrupt.

Returns

The pin to interrupt (e.g. 2)+
If pin is not available for interrupt, returns -1.

Example Code

This example checks if a pin can be used as an interrupt.

int pin = 2;

void setup() {
  Serial.begin(9600);
  int checkPin = digitalPinToInterrupt(pin);

  if (checkPin == -1) {
    Serial.println("Not a valid interrupt pin!");
  } else {
    Serial.println("Valid interrupt pin.");
  }
}

void loop() {
}