Thermostat RTC I2C for Mega! V6.6

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

Hardware used:
Arduino Mega 2560 R3.    http://arduino.cc/en/Main/ArduinoBoardMega2560
Arduino Ethernet Shield.    http://arduino.cc/en/Main/ArduinoEthernetShield
Arduino ProtoShield.    http://arduino.cc/en/Main/ArduinoProtoShield
Adafruit I2C RGB/LCD Shield.    https://www.adafruit.com/products/772
Adafruit MCP9808 I2C temp sensor breakout board (3).    https://www.adafruit.com/products/1782
DS18B20 OneWire digital waterproof temp sensor.    https://www.adafruit.com/products/381
Adafruit DS1307 I2C Real Time Clock breakout board.    https://www.adafruit.com/products/264
5Vdc relay.
Magnetic door sensor.
5V voltage regulator.

Web page and server code modified from sketch found at
http://startingelectronics.com/tutorials/arduino/ethernet-shield-web-server-tutorial/SD-card-AJAX-XML-web-server/
Original Author:  W.A. Smith, http://startingelectronics.com
References:   - WebServer example by David A. Mellis and
                modified by Tom Igoe
              - SD card examples by David A. Mellis and
                Tom Igoe

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.
Version 4.0 which uses analog TMP36 temp sensors can be found here: http://pastebin.com/YxKFUr2y

V5.0: Rewrote entire sketch to use I2C temp sensors and I2C clock module. 03/04/14.
V5.1: TempHold is now changeable on M8 (temp Out) screen. Added RTC_Interval and changed sensorInterval. Added lastClockCheck variable. 03/09/14.

V6.0: Combined I2C and Ajax Server to run on a Mega. 03/10/14.
V6.1: Shortened strings sent to and from client to save clock cycles. Combined lines in XML_Response() to eliminate cl.print()'s by butting successive HTML tags on the same line.
Eliminated RTC_Interval check on Menu 5 and 6 since the RTC is being updated during loop(), eliminated lastClockCheck2. Misc clock cycle savings. 03/17/15.
V6.2: Made C temp variables global because sketch initializes them every loop and it caused errors with web server. sendCommands() only called if there is a button pushed
on web page. 03/18/15.
V6.3: All temps are updated every sensor interval in celsius then converted to F regardless of celsius mode. getOneWireTemp() now only returns temp in C. 03/19/15.
V6.4: Consolidated a few client.println()'s and index.htm is sent in 64 byte packets instead of byte by byte (thanks SurferTim!). Temps are read as floats then rounded. 03/20/15.
V6.5: Button presses are executed as nested switch/cases instead of if/else if/else. 03/21/15.
V6.6: Button presses and web commands now execute a specific function instead of identical code. IE tempHoldUp(), tempHoldDn(), etc.
sendCommands() is now a switch/case, using char after "%" in HTTP_req as its argument to reduce calls to StrContains(). 03/25/15.


Pin layout as follows:
0  : Hardware serial RX.
1  : Hardware serial TX.
2 ~: OneWire bus.
3 ~: Green LED.
4 ~: SD CS.
5 ~: Yellow LED.
6 ~: Red LED.
7 ~: Door sensor.
8 ~: Heater relay.
9 ~:
10~: Ethernet CS.
11~:
12~:
13~:
14 ... 19 : N/C.
20 : SDA.
21 : SCL.
22 ... 49 : N/C.
50 : SPI MISO.
51 : SPI MOSI.
52 : SPI SCK.
53 :
A0 ... A15: N/C.

Sketch outline:
Libraries.
Pin Declarations.
Global Variables.
setup().
loop() {
  Web server.
  Poll door.
  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.
}
cToF().
getOneWireTemp().
heaterOn().
heaterOff().
clearLine().
average().
XML_Response().
StrClear().
StrContains().
sendCommands().
tempHoldUp().
tempHoldDn().
tempReductionUp().
tempReductionDn().
eveningHourUp().
eveningHourDn().
morningHourUp().
morningHourDn().
dayLightSavings().
*/

#include <Wire.h>
#include "RTClib.h"
#include <RTC_DS1307.h>
#include "Adafruit_MCP9808.h"
#include <Adafruit_MCP23017.h>
#include <Adafruit_RGBLCDShield.h>
#include <EEPROM.h>
#include <OneWire.h>
#include <SPI.h>
#include <Ethernet.h>
#include <SD.h>

#define RTC_Interval 150 //delay between RTC updates.
#define sensorInterval 1000 //delay between sensor readings.
#define heaterDelay 120000 //heater on/off delay.

#define REQ_BUF_SZ 60 // size of buffer used to capture HTTP requests.

//pin declarations:
#define oneWireBus 2
#define greenLed 3
#define yellowLed 5
#define redLed 6
#define door 7
#define relay 8

byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xFD };
IPAddress ip(192, 168, 1, 177); // IP address, may need to change depending on network.
EthernetServer server(80); // create a server at port 80.
File webFile;
char HTTP_req[REQ_BUF_SZ] = {0}; // buffered HTTP request stored as null terminated string.
char req_index = 0; // index into HTTP_req buffer.

OneWire oneWire(oneWireBus);
byte addr[8]; //array to store OneWire device's address.

//objects:
Adafruit_RGBLCDShield lcd = Adafruit_RGBLCDShield();
RTC_DS1307 rtc;
Adafruit_MCP9808 tempSensor1 = Adafruit_MCP9808();
Adafruit_MCP9808 tempSensor2 = Adafruit_MCP9808();
Adafruit_MCP9808 tempSensor3 = Adafruit_MCP9808();

//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 menu = EEPROM.read(4);
uint8_t heaterState = 0, doorState = 0;
int8_t tempReduction = EEPROM.read(1);
int8_t temp1, temp2, temp3, tempOneWire, tempAvg; // variables to store temps.
int8_t tempAvgC, temp1C, temp2C, temp3C, tempOneWireC, tempHoldC, tempReductionC;
unsigned long heaterOnTime = 0, heaterOffTime = 0, currentTime = 0, lastReadingTime = 0, lastClockCheck = 0;

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

void setup() {
  pinMode(10, OUTPUT);
  digitalWrite(10, HIGH); // disable Ethernet chip.
  Serial.begin(19200);
  Wire.begin();
  lcd.begin(16, 2);
  lcd.setCursor(0, 0);
  lcd.print(F("RTC Thermostat"));
  lcd.setCursor(0, 1);
  lcd.print(F("V 6.6 for Mega!"));
  delay(1000);
  lcd.clear();
  lcd.setCursor(0, 0);

  if (!SD.begin(4)) { // initialize SD card.
    lcd.print(F("No SD Card!"));    // init failed.
    while(true);
  } //end if.

  if (!SD.exists("index.htm")) { // check for index.htm file.
    lcd.print(F("index.htm"));
    lcd.setCursor(0, 1);
    lcd.print(F("not found!"));
    while(true);  // can't find index file.
  } //end if.

  digitalWrite(10, LOW);
  Ethernet.begin(mac, ip);
  server.begin();
  lcd.print(F("IP Address:"));
  lcd.setCursor(0, 1);
  lcd.print(Ethernet.localIP());
  Serial.println(F("IP Address is:  "));
  Serial.println(Ethernet.localIP());

  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);

  tempSensor1.begin(0x18); //I2C address.
  tempSensor2.begin(0x19);
  tempSensor3.begin(0x1A);
  oneWire.search(addr); //get connected OneWire device address.
  rtc.begin();
  //rtc.adjust(DateTime(__DATE__, __TIME__)); //set RTC to time of compile, will revert to that time every time arduino is reset. run once and then comment out and reload.
  delay(1000);
  lcd.clear();
} //end setup().

void loop() {
  float convF = (5.0 * (tempHold - 32)) / 9.0;
  tempHoldC = round(convF);
  tempReductionC = tempReduction / 4;

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

  EthernetClient client = server.available();  // try to get client.

  if (client) {  // got client?
    boolean currentLineIsBlank = true;
    boolean commandRecieved = false;
    uint8_t index = 0;

    while (client.connected()) {
      if (client.available()) {
        char c = client.read(); // read 1 byte (character) from client.
        if (c == '%') {
          commandRecieved = true; //"%" recieved indicating a web button was pressed.
          index = req_index; //save slot of "%".
        } //end if.

        // limit the size of the stored received HTTP request.
        // buffer first part of HTTP request in HTTP_req array (string),
        // leave last element in array as 0 to null terminate string (REQ_BUF_SZ - 1).
        if (req_index < (REQ_BUF_SZ - 1)) {
          HTTP_req[req_index] = c; // save HTTP request character.
          req_index ++;
        } //end if.

        // last line of client request is blank and ends with \n
        // respond to client only after last line received:
        if (c == '\n' && currentLineIsBlank) { // send a standard http response header.
          client.println(F("HTTP/1.1 200 OK"));
          // remainder of header follows below, depending on if
          // web page or XML page is requested.
          // Ajax request - send XML file:
          if (StrContains(HTTP_req, "getIO")) { //send rest of HTTP header.
            client.println(F("Content-Type: text/xml\r\nConnection: keep-alive\r\n"));
            if (commandRecieved) {
              sendCommands(HTTP_req[index + 1]); //send char after "%".
            }
            XML_response(client); //send XML file containing input states.
          } //end if.
          else { // web page request.
            // send rest of HTTP header:
            client.println(F("Content-Type: text/html\r\nConnection: keep-alive\r\n\r\n"));
            // send web page:
            char tBuf[64];
            uint8_t clientCount;
            webFile = SD.open("index.htm");
            if (webFile) {
              while(webFile.available()) {
                clientCount = webFile.read(tBuf, 64);
                client.write((byte*)tBuf, clientCount); //send web page to client 64 bytes at a time.
              } //end while.
              webFile.close();
            } //end if.
          } //end else.

          //Serial.println(HTTP_req); // display received HTTP request on serial port.

          // reset buffer index and all buffer elements to 0:
          req_index = 0;
          StrClear(HTTP_req, REQ_BUF_SZ); //clear the buffer.
          break;
        } //end if.

        // every line of text received from the client ends with \r\n.
        if (c == '\n') {
        // last character on line of received text.
        // starting new line with next character read.
          currentLineIsBlank = true;
        }  //end if.
        else if (c != '\r') { // a text character was received from client.
          currentLineIsBlank = false;
        } //end if.
      } // end if client.available().
    } // end while client.connected().
    commandRecieved = false;
    client.stop(); // close the connection.
  } // end if (client).

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

  currentTime = millis();

  if (buttons) { //poll the buttons.
    switch (buttons) {
      case 1: //select:
        celsius = !celsius;
        EEPROM.write(5, celsius); //only write to EEPROM when something is changed to reduce write cycles.
      break; // end select.

      case 8: //up:
        switch (menu) { //update variables depending on which menu is selected.
          case 1:
            tempHoldUp();
          break; //end case 1.

          case 2:
            tempReductionUp();
          break; //end case 2.

          case 3:
            eveningHourUp();
          break; //end case 3.

          case 4:
            morningHourUp();
          break; //end case 4.

          case 5:
          break; //end case 5.

          case 6:
          break; //end case 6.

          case 7:
            dayLightSavings();
          break; //end case 7.

          case 8:
            tempHoldUp();
          break; //end case 8.

          default:
          break;
        } //end switch.
      break; //end up.

      case 4: //down:
        switch (menu) {
          case 1:
            tempHoldDn();
          break; //end case 1.

          case 2:
            tempReductionDn();
          break; //end case 2.

          case 3:
            eveningHourDn();
          break; //end case 3.

          case 4:
            morningHourDn();
          break; //end case 4.

          case 5:
          break; //end case 5.

          case 6:
          break; //end case 6.

          case 7:
            dayLightSavings();
          break; //end case 7.

          case 8:
            tempHoldDn();
          break; //end case 8.

          default:
          break;
        } //end switch.
      break; //end down.

      case 2: //right:
        menu ++; //advances menu.
        clearLine(); //clears 2nd line only when menu number is changed.
        if (menu > 8) {
          menu = 1;
        } //end if.
        EEPROM.write(4, menu);
      break; //end right.

      case 16: //left:
        menu --; //retreats menu.
        clearLine();
        if (menu < 1) {
          menu = 8;
        } //end if.
        EEPROM.write(4, menu);
      break; //end left

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

  if (currentTime - lastClockCheck > RTC_Interval) { //get hour of day from RTC.
    now = rtc.now();
    hour = now.hour();
    if (daylightSavings) {
      hour += 1;
    } //end if.
    lastClockCheck = currentTime;
  } //end if.

  if (currentTime - lastReadingTime > sensorInterval) { //only poll sensors every interval
    float t1 = tempSensor1.readTempC();
    float t2 = tempSensor2.readTempC();
    float t3 = tempSensor3.readTempC();

    temp1C = round(t1);
    temp2C = round(t2);
    temp3C = round(t3);
    tempAvgC = average(temp1C, temp2C, temp3C);

    temp1 = cToF(t1);
    temp2 = cToF(t2);
    temp3 = cToF(t3);
    tempAvg = average(temp1, temp2, temp3);

    tempOneWireC = getOneWireTemp(addr);
    tempOneWire = cToF(tempOneWireC);

    lastReadingTime = currentTime;
  } //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 (hour < 10) {
          lcd.print(F(" "));
        } //end if.
        lcd.print(now.hour());
        lcd.print(F(":"));
        if (now.minute() < 10) {
          lcd.print(F("0"));
        } //end if.
        lcd.print(now.minute());
        lcd.print(F(":"));
        if (now.second() < 10) {
          lcd.print(F("0"));
        } //end if.
        lcd.print(now.second());
      break; //end menu 5.

      case 6: //display date to 2nd row:
        lcd.setCursor(4, 1);
        lcd.print(F("Dt: "));
        if (now.month() < 10) {
          lcd.print(F(" "));
        } //end if.
        lcd.print(now.month());
        lcd.print(F("/"));
        if (now.day() < 10) {
          lcd.print(F("0"));
        } //end if.
        lcd.print(now.day());
        lcd.print(F("/"));
        lcd.print(now.year() - 2000);
      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().

int8_t cToF(float c) { //convert float C to int F.
  return round((1.8 * c) + 32.0);
} //end cToF().

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

  for (byte i = 0; i < 2; i ++) {
    data[i] = oneWire.read(); //collect data.
  } //end for.

  int16_t raw = (data[1] << 8) | data[0]; //convert raw data to C.
  return round((float)raw / 16.0);
} //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 XML_response(EthernetClient cl) {
  cl.print(F("<?xml version = \"1.0\" ?><inputs><tAvg>"));
  cl.print(tempAvg);
  cl.print(F("</tAvg><tHold>"));

  cl.print(tempHold);
  cl.print(F("</tHold><eHour>"));

  cl.print(eveningHour - 12);
  cl.print(F("</eHour><mHour>"));

  cl.print(morningHour);
  cl.print(F("</mHour><tReduct>"));

  cl.print(tempReduction);
  cl.print(F("</tReduct><dState>"));

  cl.print(doorState);
  cl.print(F("</dState><hState>"));

  cl.print(heaterState);
  cl.print(F("</hState><sensors>"));

  if (temp1 >= -40) { //sensor 1.
    cl.print(temp1);
  } //end if.
  else {
    cl.print(F("--"));
  } //end else.
  cl.print(F("</sensors><sensors>"));

  if (temp2 >= -40) { //sensor 2.
    cl.print(temp2);
  } //end if.
  else {
    cl.print(F("--"));
  } //end else.
  cl.print(F("</sensors><sensors>"));

  if (temp3 >= -40) { //sensor 3.
    cl.print(temp3);
  } //end if.
  else {
    cl.print(F("--"));
  } //end else.
  cl.print(F("</sensors><sensors>"));

  if (tempOneWire >= -40) { //outdoor sensor.
    cl.print(tempOneWire);
  } //end if.
  else {
    cl.print(F("--"));
  } //end else.
  cl.print(F("</sensors><dateTime>"));

  if (now.hour() < 10) {
    cl.print(F("0"));
  }
  cl.print(now.hour());
  cl.print(F(":"));
  if (now.minute() < 10) {
    cl.print(F("0"));
  }
  cl.print(now.minute());
  cl.print(F(":"));
  if (now.second() < 10) {
    cl.print(F("0"));
  }
  cl.print(now.second());
  cl.print(F("</dateTime><dateTime>"));
  if (now.month() < 10) {
    cl.print(F("0"));
  }
  cl.print(now.month());
  cl.print(F("/"));
  if (now.day() < 10) {
    cl.print(F("0"));
  }
  cl.print(now.day());
  cl.print(F("/"));
  cl.print(now.year());
  cl.print(F("</dateTime></inputs>"));
} //end XML_response().

// sets every element of str to 0 (clears array)
void StrClear(char *str, char length) {
  for (uint8_t i = 0; i < length; i ++) {
    str[i] = 0;
  } //end for.
} //end StrClear().

// searches for the string sfind in the string str
// returns 1 if string found
// returns 0 if string not found
char StrContains(char *str, char *sfind) {
  char found = 0;
  char index = 0;
  char len;

  len = strlen(str);

  if (strlen(sfind) > len) {
    return 0;
  } //end if.
  while (index < len) {
    if (str[index] == sfind[found]) {
      found ++;
      if (strlen(sfind) == found) {
        return 1;
      } //end if.
    } //end if.
    else {
      found = 0;
    } //end else.
    index ++;
  } //end while.
  return 0;
} //end StrContains().

//issues commands according to HTTP_req char after "%".
void sendCommands(char index) {
  switch (index) {
    case '1':
      tempHoldUp();
    break;

    case '2':
      tempHoldDn();
    break;

    case '3':
      tempReductionUp();
    break;

    case '4':
      tempReductionDn();
    break;

    case '5':
      eveningHourUp();
    break;

    case '6':
      eveningHourDn();
    break;

    case '7':
      morningHourUp();
    break;

    case '8':
      morningHourDn();
    break;

    default:
    break;
  } //end switch.
} //end sendCommands().

void tempHoldUp() {
  tempHold += 2;
  if (tempHold > 80) {
    tempHold = 80;
  } //end if.
  EEPROM.write(0, tempHold);
} //end tempHoldUp().

void tempHoldDn() {
  tempHold -= 2;
  if (tempHold < 12) {
    tempHold = 12;
  } //end if.
  EEPROM.write(0, tempHold);
} //end tempHoldDn().

void tempReductionUp() {
  tempReduction += 2;
  if (tempReduction > 12) {
    tempReduction = 12;
  } //end if.
  EEPROM.write(1, tempReduction);
} //end tempReductionUp().

void tempReductionDn() {
  tempReduction -= 2;
  if (tempReduction < 0) {
    tempReduction = 0;
  } //end if.
  EEPROM.write(1, tempReduction);
} //end tempReductionDn().

void eveningHourUp() {
  eveningHour ++;
  if (eveningHour > 24) {
    eveningHour = 24;
  } //end if.
  EEPROM.write(3, eveningHour);
} //end eveningHourUp().

void eveningHourDn() {
  eveningHour --;
   if (eveningHour < 16) {
     eveningHour = 16;
   } //end if.
   EEPROM.write(3, eveningHour);
} //end eveningHourDn().

void morningHourUp() {
  morningHour ++;
  if (morningHour > 11) {
    morningHour = 11;
  } //end if.
  EEPROM.write(2, morningHour);
} //end morningHourUp().

void morningHourDn() {
  morningHour --;
  if (morningHour < 3) {
    morningHour = 3;
  } //end if.
  EEPROM.write(2, morningHour);
} //end morningHourDn().

void dayLightSavings() {
  daylightSavings = !daylightSavings;
  EEPROM.write(6, daylightSavings);
} //end dayLightSavings().