Rpm.rr

//***********************************************//
//******** Inductive Spark Plug Sensor***********//
//************ RPM Meter Shift Light ************//
//******************with Arduino*****************//
//***********************************************//
//**********Designed and Programmed**************//
//************by Kostas Kokoras******************//
//************kostas@kokoras.com*****************//

  
const int ignitionPin = 2;
const int ignitionInterrupt = 0;
const unsigned int pulsesPerRev = 1;

unsigned long lastPulseTime = 0;
unsigned long rpm = 0;
int rpm_int;
int rpm_to_disp;



void setup() {  

  Serial.begin(9600); 
  pinMode(ignitionPin, INPUT);
  attachInterrupt(ignitionInterrupt, &ignitionIsr, RISING);
  
}

void ignitionIsr()
{
  unsigned long now = micros();
  unsigned long interval = now - lastPulseTime;
  if (interval > 5000)
  {
     rpm = 60000000UL/(interval * pulsesPerRev);
     lastPulseTime = now;
     //rpm_int=int(rpm);
  }  
}


void loop() {
 
  noInterrupts();
  rpm_to_disp=int(rpm);
  interrupts();
    
}