//simplest, one relay

//define pins


#define Live_Relay 6
#define Pilot_Output 3
#define Prox_Output 2
#define Pilot_Read A1
#define Prox_Read A0
#define Charge_Pot A2
#define Cable_Connected 8
#define EV_Connected 9
#define Communicating 10
#define Charging 11
#define Tripped 12
#define Error 13

//define voltage levels

//Pilot voltages
//SAE_J1772 specifications allow +/- 0.5V from the +12V, and +/- 1V on the +9V, 6V 
#define Min_12V 909
#define Max_12V 950
#define Min_9V 805
#define Max_9V 867
#define Min_6V 712
#define Max_6V 778
#define Min_Neg12 162
#define Max_Neg12 203

//Proximity voltages
#define Min_13A 2.9
#define Max_13A 3.1
#define Min_20A 1.924
#define Max_20A 2.124
#define Min_32A 0.733
#define Max_32A 0.933
#define Min_63A 0.355
#define Max_63A 0.555

//global variables 

int findPilotVoltage();
float V_Max = 0;
float V_Min = 0;
float current_voltage;
int EVSE_State =1 ;
//int Charge_Req = 6; ///just placing this here temporaroily in stead of a selection medthod.
//int Charge_Level = 0;

//setup loop ( runs once)
void setup() {
        pinMode(Pilot_Read, INPUT);
        pinMode(Prox_Read, INPUT);
        pinMode(Pilot_Output, OUTPUT); 
        // pwm behavior 
        TCCR2B = TCCR2B & 0b11110000 | 0B00001011 ; //adjust prescaler and set counter mode to custom 
        OCR2A = 0xF8;  //tweak the PWM counter to get 1kHZ
        pinMode(Prox_Output, OUTPUT);
       
        pinMode(Live_Relay, OUTPUT);
      

}
//main loop (runs continuously)
void loop() {

        //local variables
        int Cable_rating = 0;
        int Charge_Req = 0 ;
        int Charge_Level = 0;

       
        // cable detection code 

        //the proximity detection 
        float prox_value = analogRead(Prox_Read);
        //1024 divisions of the arduino internal ADC so to calculate voltage;
        float prox_voltage = (prox_value * 5.0) / 1024.0;

        //cable rating detection
        if ((prox_voltage > Min_13A) && (prox_voltage < Max_13A)) {
                Cable_rating = 13;
        } else if ((prox_voltage > Min_20A) && (prox_voltage < Max_20A)) {
                Cable_rating = 20;
        } else if ((prox_voltage > Min_32A) && (prox_voltage < Max_32A)) {
                Cable_rating = 32;
        } else if ((prox_voltage > Min_63A) && (prox_voltage < Max_63A)) {
                Cable_rating = 63;
        } else {
                Cable_rating = 0;
        }

        
        // pilot detection code 

        //the pilot voltage
        float pilot_value = analogRead(Pilot_Read);
        //1024 divisions of the arduino internal ADC so to calculate voltage;
        float pilot_voltage = (pilot_value * 5.0) / 1024.0;

      
// deciding charge level

// input from pot to decide charge level
Charge_Req = analogRead(Charge_Pot) / 20 ;  //1024 steps, devided by 20 maxes a max value of 51.2A
Charge_Level = 4.25 * min(Charge_Req, Cable_rating); //this makes sure the requested charge is not higher than the cable rating, then converts it to the PWM scale



//use switch case to decide on charge state
switch (EVSE_State) {

case 1: //waiting for cable

         
       delay (1000);
       digitalWrite(Prox_Output,HIGH); //activate 5V prox signal
       delay (1000);
      if (Cable_rating > 10) {
          EVSE_State = 2;
          digitalWrite(Cable_Connected,HIGH);
        }
       
        break;
case 2: //waiting for car to connect
        
        digitalWrite(Live_Relay,LOW); //open live relay 
        analogWrite(Pilot_Output, 255); //activate PWM pilot pin (100% cycle to make continuous 12V signal )
        delay (3000);
        findPilotVoltage();

        if (Cable_rating < 10){
        EVSE_State = 1;}

        else if  ((Cable_rating > 10) && (V_Max > Min_9V) && (V_Max < Max_9V)) //&& (V_Min > Min_Neg12) && (V_Min <Max_Neg12)) 
        {
          EVSE_State = 3;
          digitalWrite(EV_Connected,HIGH);
        }        
        break;

case 3: // car connected
        delay (100);
        analogWrite(Pilot_Output, Charge_Level); //activate PWM pilot pin//activate pilot PWM (approriate cycle duty to cable rating and requested charge speed)
        delay (1000);
        findPilotVoltage();
        
         if (Cable_rating < 10)
         {
        EVSE_State = 1;
        }
        else if ((Cable_rating > 10) && (V_Max > Min_12V) && (V_Max < Max_12V)) //&& (V_Min > Min_Neg12) && (V_Min <Max_Neg12)) 
        {
          EVSE_State = 2;
        }  
        else if  ((Cable_rating > 10)  && (V_Max > Min_6V) && (V_Max < Max_6V)) //&& (V_Min > Min_Neg12) && (V_Min <Max_Neg12)) 
        {
          EVSE_State = 4;
          digitalWrite(Communicating,HIGH);
        }          
        break;
       
case 4:        
        delay (1000);
        
        digitalWrite(Live_Relay,HIGH); //close live relay
        delay (500);
        findPilotVoltage();
        if ((Cable_rating > 10)  && (V_Max > Min_6V) && (V_Max < Max_6V)) //&& (V_Min > Min_Neg12) && (V_Min <Max_Neg12))
        {
        digitalWrite(Charging,HIGH);
        } 
        else EVSE_State = 5;       
        break;

case 5:     //tripping
        
        digitalWrite(Live_Relay,LOW); //open live relay
        digitalWrite(Prox_Output,LOW); //swtich off prox signal
        delay (1000);
     
        digitalWrite(Tripped,HIGH);
        break;

default: //unknown condition
       
        digitalWrite(Live_Relay,LOW); //open live relay
        digitalWrite(Error,HIGH);
        break;

}
}
// function to find max and min voltages on pilot A1
int findPilotVoltage() {

        int i = 0;
        V_Max = 556;
        V_Min = 556;
        current_voltage = 556;   

        while (i < 99) {
                current_voltage = analogRead(Pilot_Read);
                if (current_voltage > V_Max) {
                        V_Max = current_voltage;
                }
                 if (current_voltage < V_Min) {
                        V_Min = current_voltage;
                }

                i++;
        }
       return V_Max;
       return V_Min;
}