#include <LiquidCrystal.h>
 
// Create An LCD Object. Signals: [ RS, EN, D4, D5, D6, D7 ]
LiquidCrystal My_LCD(13, 12, 14, 27, 26, 25);
const float BETA = 3950; // should match the Beta Coefficient of the thermistor
const int NTC_PIN = 15;
const int BUZZER_PIN = 2;
int freq = 2000;
int channel = 0;
int resolution = 8;

 
void setup()
{
  Serial.begin(115200);
  ledcSetup(channel, freq, resolution);
  ledcAttachPin(BUZZER_PIN, channel);
}
 
void loop()
{
  int analogValue = analogRead(NTC_PIN);
  float celsius = 1 / (log(1 / (1023. / (analogValue / (465/115)) - 1)) / BETA + 1.0 / 298.15) - 273.15;

  My_LCD.begin(16, 2);
  My_LCD.clear();
  if (celsius > 20)
  {
    My_LCD.print("High temperature");
    tone(BUZZER_PIN, 800);
  }
  else
  {
    if (celsius < -5)
    {
      My_LCD.print("Low temperature");
      tone(BUZZER_PIN, 800);
    }
    else
    {
      My_LCD.print("OK");
      noTone(BUZZER_PIN);
    }
  }
  My_LCD.setCursor(0, 1);
  My_LCD.print("Temp: " + String(celsius) + char(223) + "C");

  delay(1000);
}