#define vTestPin       0
#define chargePin      13
#define dischargePin   11
#define resistorValue  10000.0F
#define ADC_RES        1023.0F
#define V_HIGH         5

unsigned long startTime;
unsigned long elapsedTime;
float microFarads;
float nanoFarads;

void setup() {
  pinMode(chargePin, OUTPUT);
  digitalWrite(chargePin, LOW);
  Serial.begin(9600);
}

void loop() {
  // ---- Capacitance ----
  // start charging capacitor, and record time
  digitalWrite(chargePin, HIGH);
  startTime = millis();

  // wait for capacitor to charge ~63% (one T = RC)
  while (true) {
    float charge = analogRead(vTestPin);
    elapsedTime = millis() - startTime;

    if (charge > (ADC_RES * .63)) {
      microFarads = ((float)elapsedTime / resistorValue) * 1000;
      break;
    }

    if (elapsedTime > 2000) {
      microFarads = 0;
      break;
    }
  }

  // T = RC -> C = T / R
  elapsedTime = millis() - startTime;
  microFarads = ((float)elapsedTime / resistorValue) * 1000;

  if ((microFarads > 0) && (microFarads < 30)) {

    Serial.println("The electronic component is a capacitor");

    if (microFarads > 1) {
      Serial.print((long)microFarads);
      Serial.println(" microFarads is the value of the capacitor and");
      delay(1600);

      if (microFarads > 10) {
        Serial.println("falls into the category HIGH");
      }

      else if ((microFarads > 1) && (microFarads < 10)) {
        Serial.println("falls into the category MEDIUM");
      }

      else if (microFarads < 1) {
        Serial.println("falls into the category LOW");
      }

      else {
        nanoFarads = microFarads * 1000.0;
        Serial.print((long)nanoFarads);
        Serial.println(" nanoFarads");
        delay(1600);
      }
    }
  }

  if (microFarads > 100) {
    Serial.println("Please insert electronic component");
  }

  float vx = analogRead(vTestPin) * V_HIGH / ADC_RES;
  Serial.print("The electric component is a resistor \n");
  Serial.print("Voltage across the electronic component in Volts = ");
  Serial.println(vx);

  float ix = (V_HIGH - vx) / resistorValue;
  Serial.print("Resistance of the electronic component in Ohms = ");
  if ( ix > 0) {
    float rx = vx / ix;
    Serial.println(((int) rx));
  }

  else {
    Serial.println("infinite!");
  }

  // Allow capacitor to discharge
  digitalWrite(chargePin, LOW);
  pinMode(dischargePin, OUTPUT);
  digitalWrite(dischargePin, LOW);
  while (analogRead(vTestPin) > 0) {
  }
  pinMode(dischargePin, INPUT);
}