const byte cam_pin = 2;   //Interrupt pin for camshaft position (pin3) [datarange 0-255]
const byte tdc_pin = 3;   //Interrupt pin for camshaft reference (pin2) [datarange 0-255]
const byte ign_pin = 13;  //Interrupt pin for ignition (pin28) [datarange 0-255]
const byte led = 16;
const byte coil1=8;
const byte coil2=9;
const byte coil3=17;
const byte coil4=19;

volatile int out_count = 0;
volatile bool sync_achieve = 0, ign_on = 0;

void setup() {
  // put your setup code here, to run once:
  pinMode(led, OUTPUT);
  pinMode(cam_pin, INPUT_PULLUP);
  pinMode(tdc_pin, INPUT_PULLUP);
  pinMode(ign_pin, INPUT_PULLUP);
  pinMode(coil1, OUTPUT);
  pinMode(coil2, OUTPUT);
  pinMode(coil3, OUTPUT);
  pinMode(coil4, OUTPUT);
  all_off();
  attachInterrupt(digitalPinToInterrupt(tdc_pin), tdc_detect, RISING);
}

void loop() {
  while (sync_achieve == 0) {
    digitalWrite(led, !digitalRead(led));
    delay(300);
  }
  delay(500);
}

void tdc_detect() {
  if (digitalRead(tdc_pin) == 1) {
    sync_achieve = 1;
    out_count = 3;
    detachInterrupt(digitalPinToInterrupt(tdc_pin));
    delayMicroseconds(500);
    attachInterrupt(digitalPinToInterrupt(ign_pin), ign_detect, CHANGE);
  }
}

void ign_detect() {
  if (digitalRead(ign_pin) == 1 && ign_on == 0) {
    ign_on = 1;
  } else if (digitalRead(ign_pin) == 0 && ign_on == 1) {
    ign_on = 0;
    out_count += 1;
    if (out_count > 3)
      out_count = 0;
    coil_out(out_count);
  }
}

void all_off(){
  digitalWrite(coil1,0);
  digitalWrite(coil2,0);
  digitalWrite(coil3,0);
  digitalWrite(coil4,0);
}

void coil_out(int val){
  all_off();
  if(val==0)
    digitalWrite(coil1,1);
  else if(val==1)
    digitalWrite(coil3,1);
  else if(val==2)
    digitalWrite(coil4,1);
  else if(val==3)
    digitalWrite(coil2,1);
  digitalWrite(led, !digitalRead(led));
}