#include <PID_v1.h>
#include <LiquidCrystal_I2C.h>

#define THERMISTOR_PIN A0
#define RELAY_PIN 3

#define SERIES_RESISTOR 10000
#define NOMINAL_RESISTANCE 10000
#define NOMINAL_TEMP 25  
#define B_COEFFICIENT 3950 

double suhuInput, suhuOutput, suhuSetpoint;

double Kp = 2.0, Ki = 5.0, Kd = 1.0;
PID myPID(&suhuInput, &suhuOutput, &suhuSetpoint, Kp, Ki, Kd, DIRECT);

LiquidCrystal_I2C lcd(0x27, 16, 2);

double getTemperature(int rawValue) {
  double resistance = SERIES_RESISTOR / (1023.0 / rawValue - 1.0);
  double temperature = 1.0 / (log(resistance / NOMINAL_RESISTANCE) / B_COEFFICIENT + 1.0 / (NOMINAL_TEMP + 273.15)) - 273.15;  // Rumus untuk suhu
  return temperature;
}

void setup() {
  Serial.begin(9600);

  suhuSetpoint = 25.0; 
  
  myPID.SetMode(AUTOMATIC);

  lcd.begin(16, 2, LCD_5x8DOTS);
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("Suhu: ");
  
  pinMode(RELAY_PIN, OUTPUT);
  digitalWrite(RELAY_PIN, LOW);
}

void loop() {
  int rawValue = analogRead(THERMISTOR_PIN);
  suhuInput = getTemperature(rawValue);

  if (isnan(suhuInput)) {
    Serial.println("Gagal membaca suhu!");
    return;
  }

  myPID.Compute();
  
  Serial.print("Setpoint: ");
  Serial.println(suhuSetpoint);
  Serial.print("Suhu Input: ");
  Serial.println(suhuInput);
  Serial.print("PID Output: ");
  Serial.println(suhuOutput);
  
  lcd.setCursor(0, 1);
  lcd.print("                ");
  lcd.setCursor(0, 1);
  lcd.print(suhuInput);
  lcd.print(" C");
  
  if (suhuInput < suhuSetpoint) {
    digitalWrite(RELAY_PIN, HIGH);
  } else {
    digitalWrite(RELAY_PIN, LOW);
  }

  delay(2000);
}