what input pin is it using?

Using Arduino Programming Questions
11

hi thanks for your replies on that link Gammon Forum : Electronics : Microprocessors : Interrupts there is a lot of stuff on that website to get your head wrapped around lol i have come up with this compiles fine but somethings telling me im missing something here?

volatile int rpmcount;
int sensorState = 0;
unsigned int rpm;
unsigned long timeold;


ISR (PCINT2_vect)
 {
 // handle pin change interrupt for D0 to D7 here
 }  // end of PCINT2_vect


void setup ()
  { 
  Serial.begin(9600);  
  // pin change interrupt (example for D0)
  PCMSK2 |= _BV (PCINT16);  // want pin 0
  PCIFR  |= _BV (PCIF2);   // clear any outstanding interrupts
  PCICR  |= _BV (PCIE2);   // enable pin change interrupts for D0 to D7
  }

void loop(){
  
   if(rpmcount>=5) {
      rpm=(60000*rpmcount)/(8*(millis()-timeold)); //the 8 changes to 4 if 4 magnets are used.
      timeold = millis();
      //Serial.println(rpmcount,DEC);
      rpmcount = 0;
      Serial.println(rpm,DEC);
   }
}

p.s i dont wont the led output