#include <OneWire.h>
#include <DallasTemperature.h>
float RT = 100000;// the potentiometer value
float R;// the unknow R value
const int TEMP_THRESHOLD_UPPER = 30; // upper threshold of temperature
int sensorValue ;

const int SENSOR_PIN    = 2; // Arduino pin connected to DS18B20 sensor's DQ pin
const int RELAY_PIN = 9; // Arduino pin connected to relay which connected to fan
OneWire oneWire(SENSOR_PIN);         // setup a oneWire instance
DallasTemperature sensors(&oneWire); // pass oneWire to DallasTemperature library

float room_temperature;    // temperature in Celsius

void setup() {
  sensorValue = analogRead(A3);
  Serial.begin(9600); // initialize serial
  sensors.begin();    // initialize the sensor
  pinMode(RELAY_PIN, OUTPUT); // initialize digital pin as an output

}


void loop()
{
  sensors.requestTemperatures();             // send the command to get temperatures
  room_temperature = sensors.getTempCByIndex(0);  // read temperature in Celsius
  sensorValue = analogRead(A3);
  float voltage = sensorValue * (5 / 1023.0);
  R = ( voltage * RT) / 5;
  Serial.print("Voltage =");// pritns the text "Voltage =
  Serial.print(voltage);
  Serial.print("V R=");
  Serial.print(R);
  Serial.print(" ohms");
  Serial.println();
  delay(1000);
  digitalWrite(RELAY_PIN, LOW);
  if (( R <= 100000 ) && (R > 80000) && (room_temperature >= 25 ) && (room_temperature <= 30)) {
    Serial.println("A\C Temp is between 25 and 30 and room temp also");
    digitalWrite(RELAY_PIN, LOW); // turn off
    delay(2000);
  }
  else if (( R <= 100000 ) && (R > 80000) && (room_temperature > 30 ) && (room_temperature <= 35)) {
    digitalWrite(RELAY_PIN, HIGH); // turn on
    Serial.println("A\C Temp is between 25 and 30 and room temp is between 31 and 35 so the A\C is broken");
    delay(2000);
  }
  else if ((R == 100000) && (room_temperature == 25)) {
    digitalWrite(RELAY_PIN, LOW); // turn off
    Serial.println("A\C Temp is 25 and room temp is 25");
  }
}