Kegerator Controller.ino

#include <OneWire.h>
#include <SoftwareSerial.h>

float temp = -1;
float setTemp = 38;

boolean compressor = false;
boolean compressorDelayed = false;
float compressorOffTime = 0; // compressor should be off initially
const int compressorDelay = 300; // 5 minutes

const unsigned long MAX_LONG = 4294967265L;
unsigned long lastTimeMillis = 0;
float time;

SoftwareSerial mySerial(3, 13); // pin 2 = TX, pin 3 = RX (unused)
OneWire ds(5);

void setup(void) {
  Serial.begin(9600);

  setupLCD();
}

void setupLCD() {
  mySerial.begin(9600); // set up serial port for 9600 baud
  delay(500); // wait for display to boot up

  mySerial.write(254); // cursor to beginning of first line
  mySerial.write(128);

  mySerial.write("Temp:           ");
  mySerial.write("Compressor:     ");
}

void loop(void) {
  time = getTime();

  temp = getTemp() * 1.8 + 32;

  if (compressor) {
    // compressor currently on
    if (temp <= setTemp) {
      Serial.println("Compressor turned off!");
      compressor = false;
      compressorOffTime = time;
    }
  } else {
    // compressor currently off
    if (temp > setTemp) {
      Serial.println("Too warm!");
      if (time - compressorOffTime >= compressorDelay) {
        Serial.println("Compressor turned on!");
        compressor = true;
        compressorDelayed = false;
      } else {
        compressorDelayed = true;
        Serial.print("Compressor delay: ");
        Serial.print(time - compressorOffTime);
        Serial.print("/");
        Serial.println(compressorDelay);
      }
    } else {
      compressorDelayed = false;
    }
  }

  mySerial.write(254);
  mySerial.write(136);
  mySerial.write("        ");

  mySerial.write(254);
  mySerial.write(temp >= 100.0 ? 136 : temp >= 10.0 ? 137 : 138);
  mySerial.print(temp);
  mySerial.write(223); // degree symbol
  mySerial.print("F");

  mySerial.write(254);
  mySerial.write(204);
  mySerial.write("    ");

  mySerial.write(254);
  mySerial.write(204);
  mySerial.write(compressor ? "  ON" : (compressorDelayed ? "WAIT" : " OFF"));

  delay(1000);
  
  Serial.print("Time: ");
  Serial.println(getTime());

  Serial.print("Temp: ");
  Serial.print(temp);
  Serial.println(" degF");
}

float getTime() {
  unsigned long timeMillis = millis();
  if (timeMillis != lastTimeMillis) {
    if (timeMillis < lastTimeMillis) {
      time += (float)(MAX_LONG - lastTimeMillis + timeMillis) / 1000.0;
    } else {
      time += (float)(timeMillis - lastTimeMillis) / 1000.0;
    }
    lastTimeMillis = timeMillis;
  }
  return time;
}

float getTemp(){
 //returns the temperature from one DS18S20 in DEG Celsius

 byte data[12];
 byte addr[8];

 if ( !ds.search(addr)) {
   //no more sensors on chain, reset search
   ds.reset_search();
   return -1000;
 }

 if ( OneWire::crc8( addr, 7) != addr[7]) {
   Serial.println("CRC is not valid!");
   return -1000;
 }

 if ( addr[0] != 0x10 && addr[0] != 0x28) {
   Serial.print("Device is not recognized");
   return -1000;
 }

 ds.reset();
 ds.select(addr);
 ds.write(0x44,1); // start conversion, with parasite power on at the end

 byte present = ds.reset();
 ds.select(addr);  
 ds.write(0xBE); // Read Scratchpad

 
 for (int i = 0; i < 9; i++) { // we need 9 bytes
  data[i] = ds.read();
 }
 
 ds.reset_search();
 
 byte MSB = data[1];
 byte LSB = data[0];

 float tempRead = ((MSB << 8) | LSB); //using two's compliment
 float TemperatureSum = tempRead / 16;
 
 return TemperatureSum;
}