#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27, 16, 2); // I2C address 0x27, 16 column and 2 rows

// Initialize Pins
int capPin = A1;
int resPin = A0;
int sw_cap = 12;
int sw_res = 11;

int raw = 0;

int Vin = 5;
float Vout = 0; // unknown voltage, we have to measure
float R1 = 1000;
float R2 = 0; // Unknown resistance, we have to measure
float buffer = 0;

int chargePin = 5;
int dischargePin = 3; //speeds up discharging process, not necessary though

// Initialize Resistor
int resistorValue = 10000;

// Initialize Timer
unsigned long startTime;
unsigned long elapsedTime;

// Initialize Capacitance Variables
float microFarads;
float nanoFarads;

void setup()
{
  Serial.begin(9600); // Necessary to print data to serial monitor over USB
  pinMode(chargePin, OUTPUT);
  pinMode(sw_cap, INPUT_PULLUP);
  pinMode(sw_res, INPUT_PULLUP);
  digitalWrite(chargePin, LOW);
  lcd.init(); // initialize the lcd
  lcd.backlight();
    lcd.clear();                 // clear display
    lcd.setCursor(0, 0);         // move cursor to   (0, 0)
    lcd.print("WELCOME TO");        // print message at (0, 0)
    lcd.setCursor(2, 1);         // move cursor to   (2, 1)
    lcd.print("COMPONENT TEST"); // print message at (2, 1)
}

void loop()
{
  int sw_capread = digitalRead(sw_cap);
  int sw_resread = digitalRead(sw_res);

  Serial.print("RES:");
  Serial.println(sw_resread);
  Serial.print("CAP:");
  Serial.println(sw_capread );
  ////////////////////////////////////////////////////////////////////////
  ////////////////////////////////////////////////////////////////////////
  ////////////////////////////////////////////////////////////////////////
  if (sw_resread == 1 && sw_capread == 0) {
    digitalWrite(chargePin, HIGH); // Begins charging the capacitor
    startTime = millis(); // Begins the timer
    

    while (analogRead(capPin) < 648)
    {
      // Does nothing until capacitor reaches 63.2% of total voltage
      lcd.clear();                 // clear display
      lcd.setCursor(0, 0);         // move cursor to   (0, 0)
      lcd.print("Capacitor Test");        // print message at (0, 0)
      lcd.setCursor(0, 1);         // move cursor to   (2, 1)
      lcd.print("Make selection"); // print message at (2, 1)
      //delay(1000);
    }

    elapsedTime = millis() - startTime; // Determines how much time it took to charge capacitor
    microFarads = ((float)elapsedTime / resistorValue) * 1000;
    Serial.print(elapsedTime);
    Serial.print(" mS    ");

    if (microFarads > 1) // Determines if units should be micro or nano and prints accordingly
    {
      Serial.print((long)microFarads);
      Serial.println(" microFarads");
      lcd.clear();                 // clear display
      lcd.setCursor(0, 0);         // move cursor to   (0, 0)
      lcd.print("Capacitance(uF):");        // print message at (0, 0)
      lcd.setCursor(0, 1);         // move cursor to   (2, 1)
      lcd.print((long)microFarads);
      delay(1000);
    }

    else
    {
      nanoFarads = microFarads * 1000.0;
      Serial.print((long)nanoFarads);
      Serial.println(" nanoFarads");
      lcd.clear();                 // clear display
      lcd.setCursor(0, 0);         // move cursor to   (0, 0)
      lcd.print("Capacitance(nF):");        // print message at (0, 0)
      lcd.setCursor(0, 1);         // move cursor to   (2, 1)
      lcd.print((long)nanoFarads);
      delay(1000);
    }

    digitalWrite(chargePin, LOW); // Stops charging capacitor
    pinMode(dischargePin, OUTPUT);
    digitalWrite(dischargePin, LOW); // Allows capacitor to discharge

    while (analogRead(capPin) > 0)
    {
      // Do nothing until capacitor is discharged
      lcd.clear();                 // clear display
      lcd.setCursor(0, 0);         // move cursor to   (0, 0)
      lcd.print("Capacitor Test");        // print message at (0, 0)
      lcd.setCursor(0, 1);         // move cursor to   (2, 1)
      lcd.print("Make selection"); // print message at (2, 1)
      //delay(1000);
    }

    pinMode(dischargePin, INPUT); // Prevents capacitor from discharging

  }
  ////////////////////////////////////////////////////////////////////////
  ////////////////////////////////////////////////////////////////////////
  ////////////////////////////////////////////////////////////////////////
  if (sw_resread == 0 && sw_capread == 1) {
    raw = analogRead(resPin);
    lcd.clear();                 // clear display
    lcd.setCursor(0, 0);         // move cursor to   (0, 0)
    lcd.print("Resistor Test");        // print message at (0, 0)
    lcd.setCursor(0, 1);         // move cursor to   (2, 1)
    lcd.print("Make selection"); // print message at (2, 1)
    if (raw)

    {

      buffer = raw * Vin;

      Vout = (buffer) / 1024.0;

      buffer = (Vin / Vout) - 1;

      R2 = R1 * buffer;

      Serial.print("Vout: ");

      Serial.println(Vout);

      Serial.print("R2:");

      Serial.print(R2);

      Serial.print("ohm");
      lcd.clear();                 // clear display
      lcd.setCursor(0, 0);         // move cursor to   (0, 0)
      lcd.print("Resistance(ohm)");        // print message at (0, 0)
      lcd.setCursor(0, 1);         // move cursor to   (2, 1)
      lcd.print(R2); // print message at (2, 1)
      delay(1000); // resistance value is measured per second

    }
  }

  if (sw_cap == 1 && sw_res == 1) {
    lcd.clear();                 // clear display
    lcd.setCursor(0, 0);         // move cursor to   (0, 0)
    lcd.print("WELCOME TO");        // print message at (0, 0)
    lcd.setCursor(2, 1);         // move cursor to   (2, 1)
    lcd.print("COMPONENT TEST"); // print message at (2, 1)
    delay(1000); // resistance value is measured per second
  }
  ////////////////////////////////////////////////////////////////////////
  ////////////////////////////////////////////////////////////////////////
  ////////////////////////////////////////////////////////////////////////
delay(1000);
}