// DECLARATION OF VARIABLES //
#include "digitalWriteFast.h"
//

// INPUT- OUTPUTS //
int COIL1    = 32;
int COIL2    = 36;
int COIL3    = 40;
int COIL4    = 44;
int LED      = 13;
int COILTR   = 11;
int SYNCTR1   = 9;
int SYNCTR4   = 3;


//INITIAL SYSTEM GLOBAL//
int OFFRET    = 0;
int SYNCNT1    = 0;
int SYNCNT4    = 0;
int NEXTCOIL  = 0; // 
int SYNCED    = 0;
int RUNNING   = 0;
int SPARKS    = 0;
int RPM       = 0;
unsigned long LASTMILLIS = 0;
unsigned long COILDUR;
unsigned long SYNCDUR1;
unsigned long SYNCDUR4;

//

// ** SETTINGS ** //
int FIRSTCOIL = 0;
int DWELL     = 1500; // INITIAL DWELL IN MICROSECONDS // 
//
int MAXDWELL  = 2750; // MAX DWELL IN MICROSECONDS FOR MAPPING WITH RPM //
int MINDWELL  = 2200; // MIN DWELL IN MICROSECONDS FOR MAPPING WITH RPM //
//
int MAXOFFRET = 0;  // MAX OFFSET RETARD MICROSECONDS FOR MAPPING WITH RPM //
int MINOFFRET = 0;    // MIN OFFSET RETARD IN MICROSECONDS FOR MAPPING WITH RPM //
//


void setup() {    
  //Serial.begin(115200); 
  pinModeFast(COIL1, OUTPUT);
  pinModeFast(COIL2, OUTPUT);
  pinModeFast(COIL3, OUTPUT);
  pinModeFast(COIL4, OUTPUT);
  pinModeFast(LED, OUTPUT);
  //
  pinModeFast(COILTR, INPUT);
  pinMode(SYNCTR1, INPUT_PULLUP);
  pinMode(SYNCTR4, INPUT_PULLUP);
  //  
}

// the loop routine runs over and over again forever:
void loop() {

  // SYNCHING ///
  if (SYNCED == 0){
   //
  //  SYNCDUR1 = pulseIn(SYNCTR1, LOW);
  //  SYNCDUR4 = pulseIn(SYNCTR4, LOW);
    SYNCDUR1 = digitalRead(SYNCTR1);
    SYNCDUR4 = digitalRead(SYNCTR4);
  // Serial.println(SYNCDUR);
   //
   if (SYNCDUR1 < HIGH){
    SYNCNT1++; 
   } else if (SYNCDUR4 < HIGH){
    SYNCNT4++;
   }
     
   if (SYNCDUR1 > 0 && SYNCNT1 > 1){ // AT LEAST 2 SYNCHS BEFORE SET AS SYNCED //
    FIRSTCOIL = 2;
    NEXTCOIL = FIRSTCOIL;
    SYNCED = 1;
    digitalWriteFast(LED, HIGH);
    SYNCNT1 = 0;
   } else if (SYNCDUR4 > 0 && SYNCNT4 > 1){ // AT LEAST 2 SYNCHS BEFORE SET AS SYNCED //
    FIRSTCOIL = 3;
    NEXTCOIL = FIRSTCOIL;
    SYNCED = 1;
    digitalWriteFast(LED, HIGH);
    SYNCNT4 = 0;
   }
 
  }
  //
  
  if (SYNCED == 1){
    COILDUR = pulseIn(COILTR, HIGH,500000);  
    //
    OFFRET = map(RPM,0,10000,MAXOFFRET,MINOFFRET);
    DWELL  = map(RPM,0,10000,MAXDWELL,MINDWELL);
    //
  }
  
  if (COILDUR > 0 && SYNCED == 1){
    // OFFSET RETART // 
    //delayMicroseconds(OFFRET);
    //
    if (NEXTCOIL == 1){
      FIRE_COIL1();
      NEXTCOIL = 3;
    }else if (NEXTCOIL == 3){
      FIRE_COIL3();
      NEXTCOIL = 4;
    }else if (NEXTCOIL == 4){
      FIRE_COIL4();
      NEXTCOIL = 2;
    }else if (NEXTCOIL == 2){
      FIRE_COIL2();
      NEXTCOIL = 1;
    }
    
    if (RPM > 200 && RUNNING == 0){
      RUNNING = 1; 
    }
    
  }

  // CALCULATES RPM //
  if (SPARKS >= 2) { 
     RPM = 30*1000/(millis() - LASTMILLIS)*SPARKS;
     LASTMILLIS = millis();
     SPARKS = 0;
  }

  // RPM IS LOWER OF 80 WILL DESYNCH //
  if (RPM < 200 && RUNNING == 1){
    SYNCED = 0;
    RUNNING = 0;
    digitalWriteFast(LED, LOW);
  } 
  
SPARKS++;

}

void FIRE_COIL1(){
  digitalWriteFast(COIL1, HIGH);
  delayMicroseconds(DWELL);
  digitalWriteFast(COIL1, LOW);
}

void FIRE_COIL2(){
  digitalWriteFast(COIL2, HIGH);
  delayMicroseconds(DWELL);
  digitalWriteFast(COIL2, LOW);
}

void FIRE_COIL3(){
  digitalWriteFast(COIL3, HIGH);
  delayMicroseconds(DWELL);
  digitalWriteFast(COIL3, LOW);
}

  void FIRE_COIL4(){
  digitalWriteFast(COIL4, HIGH);
  delayMicroseconds(DWELL);
  digitalWriteFast(COIL4, LOW);
}