Thermostat RTC v4.0

/* Thermostat with Real Time Clock Module and web support using second Arduino with ethernet shield.
This sketch takes temp readings from three temp sensors and a door sensor and decides when to turn the heat on or off.
steve.a.mccluskey@gmail.com

This circuit uses a 2.04v analog reference by connecting the 3.3v pin to AREF through a 20k resistor. The internal 32k resistor creates a voltage divider.
The TMP36 temp sensor puts out 1750mV @ 125 degrees Celsius and 100mV @ -40. Since our voltage tops out at 1.75V, using a lower analog reference voltage
provides more resolution at the ADC.

To convert an anlog reading to C, we have to do some math:
0-2.04V over 1024 steps equals 1.992mV per step. At -40C, we should see 100mv, so we divide 100mV by 1.992 to get 50. This means at -40C, we
should see 50 as an analog reading. At 125C the sensor puts out 1750mV, so 1750mV / 1.992 = 878. We then map an analog range of 50 to 878 to a
Celsius range of -40 to 125: map(analogReading, 50, 878, -40, 125). See revision 2.8 for updated floating point math.

Revisions:
V2.2: Web support using second arduino with ethernet shield. Master sends single char commands over serial and thermostat responds accordingly.
V2.3: Added door and heater state to web page.
V2.4: Added EEPROM functionality to save settings to resume on startup.
V2.5: Added code to handle if one of the sensors is unplugged on the web page, 02/18/14.
V2.6: Rewrote button polling, bottom line display and ReadTimeDate() with switch/cases; consolidated door logic, rewrote average functions. 02/19/14.
V2.7: Added functionality to display negative temps down to -40. 02/20/14.
V2.8: Removed averageC(), removed unneccesary lcd.setCursor()'s, fixed average() to correctly return negative temps, changed tempAvgC calculation,
  sensorInterval variable added, C/F mode saved to EEPROM, tempHold limited to 12F minimum, getTemp() analog reading to tempC now uses floating point math and rounding. 03/02/14.
  Changed average() to use floating point math as well. 03/03/14.
V2.9: Changed how often ReadTimeDate() is called. 03/05/14.
V3.0: Added daylight savings time option menu and functionality. 02/23/15.
V3.1: Added doorState variable and only reads door once per loop instead of several times. 02/25/15.
V3.2: Changed ReadTimeDate() to only initialize one string instead of three. Added heaterDelay variable. 02/27/15.

V4.0: Added One-Wire Temp sensor support for outdoor temps and getOneWireTemp(). Changed temp variables to temp1, temp2, temp3 from tempNear/Far/Out.
Fixed closing parenthesis typo in getTemp(). Changed const uint8_t's to #define in pin declarations. Limited data[] to two slots in getOneWireTemp. 03/02/14.

Pin layout as follows:
0  : Hardware serial RX.
1  : Hardware serial TX.
2  : OneWire bus.
3 ~: Green LED.
4  :
5 ~: Yellow LED.
6 ~: Red LED.
7  : Door sensor.
8  : RTC CS.
9 ~: Heater relay.
10~:
11~: RTC MOSI.
12 : RTC MISO.
13 : RTC CLK
A0 : Sensor 1.
A1 : Sensor 2.
A2 : Sensor 3.
A3 :
A4 : LCD shield.
A5 : LCD shield.

Sketch outline:
Libraries.
Pin Declarations.
Global Variables.
setup().
loop() {
  Static variables.
  Poll buttons.
  Poll sensors.
  Print avg/hold to first line.
  Print menu to second line.
  Door closed: switch/case for second line.
  Door open: door open.
  Heater on/off logic.
}
getTemp().
getOneWireTemp().
heaterOn().
heaterOff().
clearLine().
average().
RTC_init().
ReadTimeDate().
serialEvent().
*/

#include <Wire.h>
#include <Adafruit_MCP23017.h>
#include <Adafruit_RGBLCDShield.h>
#include <SPI.h>
#include <EEPROM.h>
#include <OneWire.h>

#define sensorInterval 150 //interval between temp sensor readings.
#define heaterDelay 120000 //heater on or off for at least 2 min

Adafruit_RGBLCDShield lcd = Adafruit_RGBLCDShield();


//pin declarations:
#define oneWireBus 2 //OneWire bus.
#define greenLed 3
#define yellowLed 5
#define redLed 6
#define door 7
#define cs 8
#define relay 9

#define tempPin1 0
#define tempPin2 1
#define tempPin3 2

OneWire oneWire(oneWireBus);
byte addr[8]; //OneWire temp sensor address.

//global variables:
boolean celsius = EEPROM.read(5);
boolean doorLineCleared = false;
boolean daylightSavings = EEPROM.read(6);
uint8_t tempHold = EEPROM.read(0); // read saved tempHold value from EEPROM.
uint8_t tempReduction = EEPROM.read(1);
uint8_t menu = EEPROM.read(4);
int8_t temp1, temp2, temp3, tempOneWire, tempAvg; // variables to store temps.
unsigned long heaterOnTime = 0, heaterOffTime = 0, currentTime = 0, lastReadingTime = 0, lastClockCheck = 0;
uint8_t heaterState = 0;
uint8_t doorState = 0;
uint8_t reading = 0; //columns in matrix.

uint16_t val[3][10] = { //array to store analog reading values.
  {0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0 ,0, 0, 0, 0, 0}
}; //end val.

uint8_t hour;
uint8_t eveningHour = EEPROM.read(3);
uint8_t morningHour = EEPROM.read(2);

void setup() {
  analogReference(EXTERNAL); //AREF = 2.04v.
  pinMode(redLed, OUTPUT);
  pinMode(greenLed, OUTPUT);
  pinMode(yellowLed, OUTPUT);
  pinMode(door, INPUT_PULLUP); //door pin is pulled to ground while door is closed.
  pinMode(relay, OUTPUT);
  pinMode(cs, OUTPUT);
  Serial.begin(19200);
  lcd.begin(16, 2);
  lcd.setCursor(0, 0);
  lcd.print(F("RTC Thermostat"));
  lcd.setCursor(0, 1);
  lcd.print(F("V. 4.0"));
  RTC_init();
  delay(1000);
  lcd.clear();
  oneWire.search(addr); //get connected device's address.
} //end setup().

void loop() {
  uint8_t buttons = lcd.readButtons(); //MUST be in main loop. will not work if global.

  if (digitalRead(door) == HIGH) { //only read once per loop.
    doorState = 1;
  }
  else {
    doorState = 0;
  }

  currentTime = millis();
  String timeString;

  int8_t tempAvgC, temp1C, temp2C, temp3C, tempOneWireC;
  float convF = (5.0 * (tempHold - 32)) / 9.0;
  int8_t tempHoldC = round(convF);
  int8_t tempReductionC = tempReduction / 4;

  if (buttons) { //poll the buttons.
    if (buttons & BUTTON_SELECT) {
      celsius = !celsius;
      EEPROM.write(5, celsius); //only write to EEPROM when something is changed to reduce write cycles.
    } //end if.

    else if (buttons & BUTTON_UP) {
      switch (menu) { //update variables depending on which menu is selected.
        case 1:
          tempHold += 2;
          if (tempHold > 80) {
            tempHold = 80;
          } //end if.
          EEPROM.write(0, tempHold);
        break; //end case 1.

        case 2:
          tempReduction += 2;
          if (tempReduction > 12) {
            tempReduction = 12;
          } //end if.
          EEPROM.write(1, tempReduction);
        break; //end case 2.

        case 3:
          eveningHour ++;
          if (eveningHour > 24) {
            eveningHour = 24;
          } //end if.
          EEPROM.write(3, eveningHour);
        break; //end case 3.

        case 4:
          morningHour ++;
          if (morningHour > 11) {
            morningHour = 11;
          } //end if.
          EEPROM.write(2, morningHour);
        break; //end case 4.

        case 5:
        break; //end case 5.

        case 6:
        break; //end case 6.

        case 7:
          daylightSavings = !daylightSavings;
          EEPROM.write(6, daylightSavings);
        break; //end case 7.

        case 8:
        break; //end case 8.

        default:
        break;
      } //end switch.
    } //end if button_up.

    else if (buttons & BUTTON_DOWN) {
      switch (menu) {
        case 1:
          tempHold -= 2;
          if (tempHold < 12) {
            tempHold = 12;
          } //end if.
          EEPROM.write(0, tempHold);
        break; //end case 1.

        case 2:
          tempReduction -= 2;
          if (tempReduction < 0) {
            tempReduction = 0;
          } //end if.
          EEPROM.write(1, tempReduction);
        break; //end case 2.

        case 3:
          eveningHour --;
          if (eveningHour < 16) {
            eveningHour = 16;
          } //end if.
          EEPROM.write(3, eveningHour);
        break; //end case 3.

        case 4:
          morningHour --;
          if (morningHour < 3) {
            morningHour = 3;
          } //end if.
          EEPROM.write(2, morningHour);
        break; //end case 4.

        case 5:
        break; //end case 5.

        case 6:
        break; //end case 6.

        case 7:
          daylightSavings = !daylightSavings;
          EEPROM.write(6, daylightSavings);
        break; //end case 7.

        case 8:
        break;

        default:
        break;
      } //end switch
    } //end if button_down.

    else if (buttons & BUTTON_RIGHT) {
      menu ++;
      clearLine(); //clears 2nd line only when menu number is changed.
      if (menu > 8) {
        menu = 1;
      } //end if.
      EEPROM.write(4, menu);
    } //end if.

    else if (buttons & BUTTON_LEFT) {
      menu --;
      clearLine();
      if (menu < 1) {
        menu = 8;
      } //end if.
      EEPROM.write(4, menu);
    } //end if.
  } // end if buttons.

  if (currentTime - lastReadingTime > sensorInterval) { //only poll sensors every 150ms.
    timeString = ReadTimeDate(2);
    hour = timeString.toInt(); //gets hour of day.

    if (!celsius) {
      temp1 = getTemp(tempPin1); //poll the sensors.
      temp2 = getTemp(tempPin2);
      temp3 = getTemp(tempPin3);
      tempAvg = average(temp1, temp2, temp3);
      tempOneWire = getOneWireTemp();
    } //end if.
    else {
      temp1C = getTemp(tempPin1);
      temp2C = getTemp(tempPin2);
      temp3C = getTemp(tempPin3);
      tempAvgC = average(temp1C, temp2C, temp3C);
      tempOneWireC = getOneWireTemp();
    } //end else.

    lastReadingTime = currentTime;
    reading ++; //next column number in the matrix.
    if (reading > 9) { //reset reading counter every 10 readings.
      reading = 0;
    } //end if.
  } //end if.

  //print avg to screen:
  lcd.setCursor(0, 0);
  lcd.print(F("Avg:"));
  if (!celsius) {
    if (tempAvg >= -40 && tempAvg < 0) { //displays negative temps.
      lcd.print(tempAvg);
      lcd.print(F("F"));
    } //end if.
    else if (tempAvg >= 0) { //displays positive temps and clears last digit.
      lcd.print(tempAvg);
      lcd.print(F("F "));
    } //end else if.
    else {
      lcd.print(F("--F ")); //displays "--" if all 3 sensors are unplugged.
    } //end else.
  } //end if !celsius.

  else {
    if (tempAvgC >= -40 && tempAvgC < 0) {
      lcd.print(tempAvgC);
      lcd.print(F("C"));
    } //end if.
    else if (tempAvgC >= 0) {
      lcd.print(tempAvgC);
      lcd.print(F("C "));
    } //end else if.
    else {
      lcd.print(F("--C "));
    } //end else.
  } //end else.

  //print hold temp to screen:
  lcd.setCursor(8, 0);
  lcd.print(F("Hold:"));
  lcd.setCursor(13, 0);
  if (hour < morningHour || hour >= eveningHour) { //displays night temp hold at night.
    if (!celsius) {
      lcd.print(tempHold - tempReduction);
      lcd.print(F("*")); //star indicates night time temp reduction.
    } //end if.
    else {
      lcd.print(tempHoldC - tempReductionC);
      lcd.print(F("*"));
    } //end else.
  } //end if.

  else if (hour >= morningHour && hour < eveningHour) { //displays regular temp hold during day.
    if (!celsius) {
      lcd.print(tempHold);
      lcd.print(F("F"));
    } //end if.
    else {
      lcd.print(tempHoldC);
      lcd.print(F("C"));
    } //end else.
  } //end else if.

  lcd.setCursor(0, 1);
  lcd.print(F("M")); //displays menu number.
  lcd.print(menu);

  //bottom line display:
  if (doorState == 0) {
    analogWrite(redLed, 0);
    digitalWrite(greenLed, HIGH); //green led indicates system normal.
    if (!doorLineCleared) { //only clears line once when door is shut.
      clearLine();
      doorLineCleared = true;
    } //end if.

    switch (menu) {
      case 1: //displays sensors to screen and allows changing of temp hold.
        lcd.setCursor(2, 1);
        if (!celsius) { //sensor one:
          if (temp1 < -40) { //displays "--" if tempNear returns null and clears leading minus sign.
            lcd.print(F(" --"));
          } //end if.
          else if (temp1 >= -40 && temp1 < 0) { //negative temps.
            lcd.print(temp1);
          } //end else if.
          else {
            lcd.print(F(" ")); //positive temps and clears minus sign.
            lcd.print(temp1);
          } //end else.
          lcd.print(F("F "));
        } //end if.
        else {
          if (temp1C < -40) {
            lcd.print(F(" --"));
          } //end if.
          else if (temp1C >= 40 && temp1C < 0) {
            lcd.print(temp1C);
          } //end else if.
          else {
            lcd.print(F(" "));
            lcd.print(temp1C);
          } // end else.
          lcd.print(F("C "));
        } //end else.

        lcd.setCursor(7, 1);
        if (!celsius) { //sensor 2:
          if (temp2 < -40) {
            lcd.print(F(" --"));
          } //end if.
          else if (temp2 >= -40 && temp2 < 0) {
            lcd.print(temp2);
          } //end else if.
          else {
            lcd.print(F(" "));
            lcd.print(temp2);
          } //end else.
          lcd.print(F("F "));
        } //end if.
        else {
          if (temp2C < -40) {
            lcd.print(F(" --"));
          } //end if.
          else if (temp2C >= 40 && temp2C < 0) {
            lcd.print(temp2C);
          } //end else if.
          else {
            lcd.print(F(" "));
            lcd.print(temp2C);
          } // end else.
          lcd.print(F("C "));
        } //end else.

        lcd.setCursor(12, 1);
        if (!celsius) { //sensor 3:
          if (temp3 < -40) {
            lcd.print(F(" --"));
          } //end if.
          else if (temp3 >= -40 && temp3 < 0) {
            lcd.print(temp3);
          } //end else if.
          else {
            lcd.print(F(" "));
            lcd.print(temp3);
          } //end else.
          lcd.print(F("F "));
        } //end if.
        else {
          if (temp3C < -40) {
            lcd.print(F(" --"));
          } //end if.
          else if (temp3C >= 40 && temp3C < 0) {
            lcd.print(temp3C);
          } //end else if.
          else {
            lcd.print(F(" "));
            lcd.print(temp3C);
          } // end else.
          lcd.print(F("C "));
        } //end else.
      break; //end menu 1.

      case 2: //displays temp drop amount.
        lcd.setCursor(3, 1);
        lcd.print(F("Drop Temp:"));
        if (!celsius) {
          if (tempReduction < 10) {
            lcd.print(F(" "));
          } //end if.
          lcd.print(tempReduction);
          lcd.print(F("F"));
        } //end if.
        else {
          if (tempReductionC < 10) {
            lcd.print(F(" "));
          } //end if.
          lcd.print(tempReductionC);
          lcd.print(F("C"));
        } //end else.
      break; //end menu 2.

      case 3: //displays PM time to drop temp:
        lcd.setCursor(3, 1);
        lcd.print(F("Heat Dn: "));
        if (eveningHour < 22) {
          lcd.print(F(" "));
        } //end if.
        lcd.print(eveningHour - 12);
        lcd.print(F("pm"));
      break; //end menu 3.

      case 4: //displays AM time to raise temp:
        lcd.setCursor(3, 1);
        lcd.print(F("Heat Up: "));
        if (morningHour < 10) {
          lcd.print(F(" "));
        } //end if.
        lcd.print(morningHour);
        lcd.print(F("am"));
      break; //end menu 4.

      case 5: //display time to 2nd row:
        lcd.setCursor(4, 1);
        lcd.print(F("Tm: "));
        if (currentTime - lastClockCheck > sensorInterval) {
          lcd.print(ReadTimeDate(1)); //gets time only.
          lastClockCheck = currentTime;
        } //end if.
      break; //end menu 5.

      case 6: //display date to 2nd row:
        lcd.setCursor(4, 1);
        lcd.print(F("Dt: "));
        if (currentTime - lastClockCheck > sensorInterval) {
          lcd.print(ReadTimeDate(0)); //gets date only.
          lastClockCheck = currentTime;
        } //end if.
      break; //end menu 6.

      case 7: //daylight savings time enable/disable:
        lcd.setCursor(4, 1);
        lcd.print(F("DST:"));
        if (daylightSavings) {
          lcd.print(F("Active  "));
        } //end if.

        else {
          lcd.print(F("Inactive"));
        } //end else.
      break;  //end menu 7.

      case 8: //prints outside temp to screen.
        lcd.setCursor(4, 1);
        lcd.print(F("Out: "));
        if (!celsius) {
          if (tempOneWire > -51) {
            lcd.print(tempOneWire);
         } //end if.
          else {
            lcd.print("--");
          } //end else.
          lcd.print(F("F   "));
        } //end if celsius.
        else {
          if (tempOneWireC > -51) {
            lcd.print(tempOneWireC);
          } //end if.
          else {
            lcd.print("--");
          } //end else.
          lcd.print(F("C   "));
        } // else.
      break; //end case 8.
    } //end switch menu.
  } //end if door closed.

  else {
    doorLineCleared = false;
    lcd.setCursor(2, 1);
    lcd.print(F(" Door open!   "));
    digitalWrite(greenLed, LOW);
    digitalWrite(yellowLed, LOW);
    digitalWrite(relay, LOW);
    heaterState = 0;
    analogWrite(redLed, 180);
    heaterOffTime = currentTime;
  } //end else if.

  //decide when to turn heater on or off:
  if (hour >= morningHour && hour < eveningHour) { //day time
    if (((!celsius && tempAvg > -41 && tempAvg < tempHold) ||
    (celsius && tempAvgC > -41 && tempAvgC < tempHoldC)) && doorState == 0) {
      heaterOn();
    } //end if.
    else {
      heaterOff();
    } //end else.
  } //end if day time.

  else if (hour < morningHour || hour >= eveningHour) { //night time
    if (((!celsius && tempAvg > -41 && tempAvg < (tempHold - tempReduction)) ||
    (celsius && tempAvgC > -41 && tempAvgC < (tempHoldC - tempReductionC))) && doorState == 0) {
      heaterOn();
    } //end if.
    else {
      heaterOff();
    } //end else.
  } //end if night time.
} //end loop().

/* getTemp(): each time the function is called, a new reading is taken and stored to the 3x10 matrix. each row is then averaged and
returned as temp for each sensor. AREF = 2.04V.
*/
int8_t getTemp(uint8_t pin) {
  val[pin][reading] = analogRead(pin);
  delay(2); //delay between each analog pin is needed to reduce cross interferance between readings.
  if (val[pin][reading] < 50) { //sensor unplugged.
    return -41;
  } //end if.
  uint16_t sum = 0;
  for (uint8_t i = 0; i <= 9; i ++) { //adds up all the values in the row.
    sum += val[pin][i];
  } //end for.
  sum /= 10;
  float tempC = ((sum - 50.0) * (165.0) / (828.0)) - 40.0; //convert analog reading to celsius using floating point math instead of map(sum, 50, 878, -40, 125).
  if (celsius) {
    return round(tempC);
  } //end if.
  else {
    return round((1.8 * tempC) + 32.0);
  } // end else.
} //end getTemp().

int8_t getOneWireTemp() {
  byte data[2]; //array to store data retrieved from sensor.
  oneWire.reset();
  oneWire.select(addr);
  oneWire.write(0x44, 1); //start conversion.
  oneWire.reset();
  oneWire.select(addr);
  oneWire.write(0xBE); //read scratchpad.

  for (byte i = 0; i < 3; i ++) {
    data[i] = oneWire.read(); //collect data.
  } //end for.

  int16_t raw = (data[1] << 8) | data[0]; //convert raw data to C.

  if (celsius) {
    return round((float)raw / 16.0);
  } //end if.
  else {
    return round(((float)raw / 16.0) * 1.8 + 32.0);
  } //end else.
} //end getOneWireTemp().

void heaterOn() {
  if (currentTime - heaterOffTime > heaterDelay) { //check to see if heater has been off for at least 2 min.
    digitalWrite(relay, HIGH);
    analogWrite(yellowLed, 180);
    heaterOnTime = currentTime;
    heaterState = 1;
  } //end if.
} //end heaterOn().

void heaterOff() {
  if (currentTime - heaterOnTime > heaterDelay) { //check to see if heater has been on for at least 2 min.
    digitalWrite(relay, LOW);
    digitalWrite(yellowLed, LOW);
    heaterOffTime = currentTime;
    heaterState = 0;
  } //end if.
} //end heaterOff().

void clearLine() { //clears 2nd line past M#.
  lcd.setCursor(2, 1);
  lcd.print(F("              "));
} //end clearLine().

int8_t average(int8_t temp_1, int8_t temp_2, int8_t temp_3) { //averages 3 temps and knows how depending on which sensors are plugged in.
  uint8_t count = 0;
  float avg = 0.0;
  if (temp_1 > -41) { //sensor connected.
   count ++;
   avg += temp_1;
  } //end if.
  if (temp_2 > -41) {
    count ++;
    avg += temp_2;
  } //end if.
  if (temp_3 > -41) {
    count ++;
    avg += temp_3;
  } //end if.
  if (count != 0) {
    return round(avg / count);
  } //end if.
  else {
    return -41; //all three sensors unplugged.
  } //end else.
} //end average().

void RTC_init() { //start the RTC chip.
  SPI.begin();
  SPI.setBitOrder(MSBFIRST);
  SPI.setDataMode(SPI_MODE1); // both mode 1 & 3 should work.
  digitalWrite(cs, LOW); //set control register.
  SPI.transfer(0x8E);
  SPI.transfer(0x60); //60= disable Osciallator and Battery SQ wave @1hz, temp compensation, Alarms disabled.
  digitalWrite(cs, HIGH);
  delay(10);
} //end RTC_init().

String ReadTimeDate(uint8_t mode) { //gets time and date.
  String dateTime;
  uint8_t TimeDate [7]; //second,minute,hour,null,day,month,year
  for (uint8_t i = 0; i <= 6; i ++) {
    if (i == 3) {
      i ++;
    } //end if.
    digitalWrite(cs, LOW);
    SPI.transfer(i + 0x00);
    unsigned int n = SPI.transfer(0x00);
    digitalWrite(cs, HIGH);
    int a = n & B00001111;
    if (i == 2) {
      int b = (n & B00110000) >> 4; //24 hour mode
      if (b == B00000010) {
        b = 20;
      } //end if.
      else if (b == B00000001) {
        b = 10;
      } //end else.
      TimeDate[i] = a + b;
    } //end if.
    else if (i == 4) {
      int b = (n & B00110000) >> 4;
      TimeDate[i] = a + b * 10;
    } //end else.
    else if (i == 5) {
      int b = (n & B00010000) >> 4;
      TimeDate[i] = a + b * 10;
    } //end else.
    else if (i == 6) {
      int b = (n & B11110000) >> 4;
      TimeDate[i] = a + b * 10;
    } //end else.
    else {
      int b = (n & B01110000) >> 4;
      TimeDate[i] = a + b * 10;
    } //end else.
  } //end for.

  if (daylightSavings) { //reduce hour slot by 1.
        TimeDate[2] -= 1;
  } //end if.

  switch (mode) {
    case 0: //returns date only.
      if (TimeDate[5] < 10) {
        dateTime.concat("0"); //leading zero.
      } //end if.
      dateTime.concat(TimeDate[5]);
      dateTime.concat("/");
      if (TimeDate[4] < 10) {
        dateTime.concat("0");
      } //end if.
      dateTime.concat(TimeDate[4]);
      dateTime.concat("/");
      dateTime.concat(TimeDate[6]);
      return dateTime;
    break; //end mode 0.

    case 1: //returns time only.
      if (TimeDate[2] < 10) {
        dateTime.concat("0"); //leading zero
      } //end if.
      dateTime.concat(TimeDate[2]);
      dateTime.concat(":");
      if (TimeDate[1] < 10) {
        dateTime.concat("0");
      } //end if.
      dateTime.concat(TimeDate[1]);
      dateTime.concat(":");
      if (TimeDate[0] < 10) {
        dateTime.concat("0");
      } //end if.
      dateTime.concat(TimeDate[0]);
      return dateTime;
    break; //end mode 1.

    case 2: //returns hour of day only.
      dateTime.concat(TimeDate[2]);
      return dateTime;
    break; //end mode 2.
  } //end switch.
} //end ReadTimeDate().

void serialEvent() { //called any time serial data is available.
  char c = Serial.read();
  switch (c) {
    case '*': //all values requested. sends string of data to be served by other arduino. IE " 64h63a17j9e7m8t0d1f61x62y65z58w* "
      Serial.print(tempHold);
      Serial.print(F("h")); //indicates end of tempHold.

      if (tempAvg > -41) {
        Serial.print(tempAvg);
      } //end if.
      else {
        Serial.print(F("--"));
      } //end else.

      Serial.print(F("a"));
      Serial.print(hour);
      Serial.print(F("j"));
      Serial.print(eveningHour);
      Serial.print(F("e"));
      Serial.print(morningHour);
      Serial.print(F("m"));
      Serial.print(tempReduction);
      Serial.print(F("t"));
      Serial.print(doorState);
      Serial.print(F("d"));
      Serial.print(heaterState);
      Serial.print(F("f"));

      if (temp1 > -41) {
        Serial.print(temp1);
      } //end if.
      else {
        Serial.print(F("--"));
      } //end else.
      Serial.print(F("x"));

      if (temp2 > -41) {
        Serial.print(temp2);
      } //end if.
      else {
        Serial.print(F("--"));
      } //end else.
      Serial.print(F("y"));

      if (temp3 > -41) {
        Serial.print(temp3);
      } //end if.
      else {
        Serial.print(F("--"));
      } //end else.
      Serial.print(F("z"));

      if (tempOneWire > -51) {
        Serial.print(tempOneWire);
      }
      else {
        Serial.print(F("--"));
      }
      Serial.print(F("w"));

      Serial.println(F("*")); //end of data character.
    break; //end case '*'.

    case 'h': //increase hold temp.
      tempHold += 2;
      if (tempHold > 80) {
        tempHold = 80;
      } //end if.
      EEPROM.write(0, tempHold);
    break; //end case 'h'.

    case 'n': //decrease hold temp.
      tempHold -= 2;
      if (tempHold < 12) {
        tempHold = 12;
      } //end if.
      EEPROM.write(0, tempHold);
    break; //end case 'n'.

    case 'e': //heat off later.
      eveningHour ++;
      if (eveningHour > 24) {
        eveningHour = 24;
      } //end if.
      EEPROM.write(3, eveningHour);
    break; //end case 'e'.

    case 'd': //heat off earlier.
      eveningHour --;
      if (eveningHour < 16) {
        eveningHour = 16;
      } //end if.
      EEPROM.write(3, eveningHour);
    break; //end case 'd'.

    case 'm': //heat on later.
      morningHour ++;
      if (morningHour > 11) {
        morningHour = 11;
      } //end if.
      EEPROM.write(2, morningHour);
    break; //end case 'm'.

    case 'j': //heat on earlier.
      morningHour --;
      if (morningHour < 3) {
        morningHour = 3;
      } //end if.
      EEPROM.write(2, morningHour);
    break; //end case 'j'.

    case 't': //reduce temp more.
      tempReduction += 2;
      if (tempReduction > 12) {
        tempReduction = 12;
      } //end if.
      EEPROM.write(1, tempReduction);
    break; //end case 't'.

    case 'g': //reduce temp less.
      tempReduction -= 2;
      if (tempReduction < 0) {
        tempReduction = 0;
      } //end if.
      EEPROM.write(1, tempReduction);
    break; //end case 'g'.
  } //end switch.
} //end serialEvent().

/*
void printResults() { //for debugging.
  Serial.println(ReadTimeDate(0));
  Serial.println(ReadTimeDate(1));
  Serial.print(F("Menu #: "));
  Serial.println(menu);
  Serial.println();
  Serial.print(F("Hold temp: "));
  Serial.println(tempHold);
  Serial.println();
  Serial.print(F("Average temp: "));
  Serial.println(tempAvg);
  Serial.println();
  Serial.println(F("Sensor one: "));
  for (uint8_t i = 0; i <= 9; i ++) {
    Serial.print(val[0][i]);
    Serial.print(F(" "));
  } //end for.
  Serial.println();
  Serial.println(F("Sensor two: "));
  for (uint8_t i = 0; i <= 9; i ++) {
    Serial.print(val[1][i]);
    Serial.print(F(" "));
  } //end for.
  Serial.println();
  Serial.println(F("Sensor three: "));
  for (uint8_t i = 0; i <= 9; i ++) {
    Serial.print(val[2][i]);
    Serial.print(F(" "));
  } //end for.
  Serial.println();
} //end printResults().*/