int IGBT_out = 3; // output for IGBT to pin 3
int delays[14] = {e1000, e2000, e3000, e4000, e5000, e6000, e7000, e8000, e9000, e10000, e11000, e12000, e13000, e14000}; // delays in uS. Points 1000-14000rpm.
float rpm;
float timeold;
int dwell; // time to charge the coil
float pulse_number; //variable to store pulses from trigger

void setup()
{
  // put your setup code here, to run once:
  Serial.begin(9600);

pinMode(IGBT_out, OUTPUT);
digitalWrite(IGBT_out, LOW);
attachInterrupt(0, pulse, RISING);
dwell = 2000;
}

void pulse()
{
  pulse_number++;
}

void loop() {

if (pulse_number >= 5)
  {
  rpm = 60.0f*1000000/(micros() - timeold)*pulse_number;
   timeold = micros();

   pulse_number = 0;
    Serial.println(rpm, 0);