// https://forum.arduino.cc/t/sketch-to-compare-voltages-for-series-parallel-capacitor-switching-circuit/1046639

const int CHARGE1pin = 2;     // capacitor 1 in parallel
const int CHARGE2pin = 3;     // capacitor 2 in parallel
const int DISpin = 4;         // capacitors in series
const int VCCPin = A0;        // Voltage sensor 'S'
const int CAPpin = A1;        // Voltage sensor 'S'


int VCC = 0;
int CAPvolt = 0;

bool charging = false;
const int chargeLamp = A2;        // move the slider right to simulate charging
const int dischargeLamp = A3;     // move the slider left to simulate discharging

void setup () {
                          
 pinMode(CHARGE1pin, OUTPUT);     // mosfet
 pinMode(CHARGE2pin, OUTPUT);     // mosfet
 pinMode(DISpin, OUTPUT);         // mosfet

 pinMode(chargeLamp, OUTPUT);     // lamp
 pinMode(dischargeLamp, OUTPUT);  // lamp
}

void loop () {

// INPUT

  VCC = analogRead(VCCPin);       // read input voltage 
  CAPvolt = analogRead(CAPpin);   // read cap voltage
  int difference = VCC - CAPvolt;

// PROCESS

  if (charging) {
      if (CAPvolt > VCC - 30)
          charging = false;       // stop charging!
  }
  else { // (not charging)
      if (CAPvolt < VCC / 2)
          charging = true;        // start charging!
  }

// OUTPUT

  if (charging) {
    digitalWrite(DISpin,  LOW);       // discharge mosfet Off
    digitalWrite(CHARGE1pin, HIGH);   // charge mosfet ON
    digitalWrite(CHARGE2pin,  HIGH);  // charge mosfet ON

    digitalWrite(chargeLamp, 1);
    digitalWrite(dischargeLamp, 0); 
  }
  else {
    digitalWrite(CHARGE1pin, LOW);    // charge mosfet Off
    digitalWrite(CHARGE2pin,  LOW);   // charge mosfet Off
    digitalWrite(DISpin,  HIGH);    // discharge mosfet ON

    digitalWrite(chargeLamp, 0);
    digitalWrite(dischargeLamp, 1); 
  }
}