/**
  Basic NTC Thermistor demo
  https://wokwi.com/arduino/projects/299330254810382858

  Assumes a 10K@25℃ NTC thermistor connected in series with a 10K resistor.

  Copyright (C) 2021, Uri Shaked
*/

const float BETA = 3950; // should match the Beta Coefficient of the thermistor
int greenLED = 2; 
int yellowLED = 7; 
int redLED = 11;

void setup() {
  Serial.begin(9600);
  pinMode(greenLED, OUTPUT);
  pinMode(yellowLED, OUTPUT);
  pinMode(redLED, OUTPUT);
}

void loop() {
  int analogValue = analogRead(A0);
  float celsius = 1 / (log(1 / (1023. / analogValue - 1)) / BETA + 1.0 / 298.15) - 273.15;

  if (celsius < 30) {
    digitalWrite(greenLED, HIGH);
    digitalWrite(yellowLED, LOW);
    digitalWrite(redLED, LOW);
  } else if (celsius >= 30 && celsius <= 80) {
    digitalWrite(yellowLED, HIGH);
    digitalWrite(greenLED, LOW);
    digitalWrite(redLED, LOW);
  } else {
    digitalWrite(redLED, HIGH);
    digitalWrite(greenLED, LOW);
    digitalWrite(yellowLED, LOW);
  }

  Serial.print("Temperature: ");
  Serial.print(celsius);
  Serial.println(" ℃");
  delay(1000);
}