/**
  Basic NTC Thermistor demo with LED indication
  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
const int LED_COLD = 2;  // Pin for the cold temperature LED
const int LED_NORMAL = 3;  // Pin for the normal temperature LED
const int LED_HOT = 4;  // Pin for the hot temperature LED

void setup() {
  Serial.begin(9600);
  pinMode(LED_COLD, OUTPUT);
  pinMode(LED_NORMAL, OUTPUT);
  pinMode(LED_HOT, OUTPUT);
}

void loop() {
  int analogValue = analogRead(A0);
  float celsius = 1 / (log(1 / (1023. / analogValue - 1)) / BETA + 1.0 / 298.15) - 273.15;
  
  Serial.print("Temperature: ");
  Serial.print(celsius);
  Serial.println(" ℃");

  // LED logic based on temperature
  if (celsius < 20.0) {
    digitalWrite(LED_COLD, HIGH);
    digitalWrite(LED_NORMAL, LOW);
    digitalWrite(LED_HOT, LOW);
  } else if (celsius >= 20.0 && celsius <= 25.0) {
    digitalWrite(LED_COLD, LOW);
    digitalWrite(LED_NORMAL, HIGH);
    digitalWrite(LED_HOT, LOW);
  } else {
    digitalWrite(LED_COLD, LOW);
    digitalWrite(LED_NORMAL, LOW);
    digitalWrite(LED_HOT, HIGH);
  }

  delay(1000);
}