Thermostat

thermo.ino

/*
Thermo
  Seth
  
  It's a really hacky thermostat, getting cold outside

*/
#include <LiquidCrystal.h>
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);


#define RELAY1  6                      
#define RELAY2  7                       
#define RELAY3  8                        
#define RELAY4  9

const int sensorPin = A0;
const float baselineTemp = 20.0;
double averageTemp = 0;
int numReadings = 0;
double totalTemp = 0;
void setup()
{    
// Initialise the Arduino data pins for OUTPUT
  pinMode(RELAY1, OUTPUT);       
  pinMode(RELAY2, OUTPUT);
  pinMode(RELAY3, OUTPUT);
  pinMode(RELAY4, OUTPUT);
  
  Serial.begin(9600);
  lcd.begin(16, 2);
  lcd.clear();
  lcd.setCursor(0,0);
}
 
 void loop()
{
  lcd.setCursor(0,0);
  int sensorVal = analogRead(sensorPin);
  Serial.print("Sensor Value: ");
  Serial.print(sensorVal + '\n');
  
  float voltage = (sensorVal/1024.0) * 5.0;
  Serial.print(", Volts: ");
  Serial.print(voltage);
  
  Serial.print(", degrees F: ");
  
  float temperature = (voltage - .5) * 100;
  
  
  float tempFH = (temperature * 1.8) + 32;
  Serial.println(tempFH);
  lcd.print("Ambient: ");
  lcd.print(tempFH);
  lcd.print(" F");
  
  if (numReadings % 50 == 0) {
    numReadings = 0;
    totalTemp = 0; 
  }
  
  numReadings++;
  totalTemp += tempFH;
  averageTemp = totalTemp / numReadings;
  
  Serial.print("Average: ");
  Serial.println(averageTemp);
  lcd.setCursor(0,1);
  lcd.print("Average: ");
  lcd.print(averageTemp);
  lcd.print(" F");
  
  if (averageTemp < 68) {
    digitalWrite(RELAY1, LOW); //turn on relay
  } else {
    digitalWrite(RELAY1, HIGH); //turn off relay
  }
  delay(300);
 }

By "average" I really mean "somewhat stable-ish reading" since the single-wire sensor I have gives pretty erratic readings.