Pin Change Interrupt

/* Copyright 2011 Lex.V.Talionis at gmail This program is free software: */ #include <PinChangeInt.h> #include <PinChangeIntConfig.h> #define PIN 15  // the pin we are interested in volatile byte burp=0;    // a counter to see how many times the pin has changed byte cmd=0;     // a place to put our serial data void setup() {     Serial.begin(9600);     Serial.print("PinChangeInt test on pin ");     Serial.print(PIN);     Serial.println();     pinMode(PIN, INPUT);     //set the pin to input     digitalWrite(PIN, HIGH); //use the internal pullup resistor     PCintPort::attachInterrupt(PIN, burpcount,RISING);     // attach a PinChange Interrupt to our pin on the rising edge     // (RISING, FALLING and CHANGE all work with this library)     // and execute the function burpcount when that pin changes } void loop() {   cmd=Serial.read();    if (cmd=='p')   {     Serial.print("burpcount:\t");     Serial.println(burp, DEC);   }   cmd=0; } void burpcount() {   burp++; }