gistfile1.ino

// name:     HVAC_Thermostat.ino

// -------------LIBRARIES----------------
#include <Wire.h>                   // Protocol to communicate with I2C devices
#include <Adafruit_MCP23017.h>      // LCD protocol
#include <Adafruit_RGBLCDShield.h>  // LCD + Button shield protocol
#include "DHT.h"                    // DHT11 Temp/Humidity Sensor 
// --------------PARAMETERS---------------------
int heat = 45;                    // This is the default heater trigger temp setting
int cool = 73;                    // This is the default cooling trigger temp setting
int buffer = 1;                   // This is the range away from the setpoint the heat or AC will overcool/heat to prevent shorter cycles
int heatPin = 7;                  // Digital pin used for turning on the heater relay
int coolPin = 8;                  // Digital pin used for turning on the AC relay
int fanPin = 9;                   // Digital pin used for turning on the fan relay
int cycleTime = 60000;               // The length of time to delay running the AC or heat to prevent short cycling
boolean heatRunning = false;      // Stores whether the heater is currently running or not
boolean coolRunning = false;      // Stores whether the AC is currently running or not
boolean fanRunning = false;       // Stores whether the Fan is currently running or not
float currentTemp = 70;           // Current room temperature

int serialSpeed = 9600;           // Default serial comm speed
float oldTemp = 0;                // Used to only update the currentTemp if the temp has changed
unsigned long timeOut;            // Backlight timeout variable
boolean editable = false;         // Determines whether or not button presses will do anything, used to avoid accidental changes
char* menu[] = {"Cooling", "Heating", "Fan"};  // Menu display for either setting the high point or the low point of the temp range
int menuPosition = 1;             // Current position in the setting menu
unsigned long heatLastRan;        // Stores the time the heater last ran
unsigned long coolLastRan;        // Stores the time the AC last ran
unsigned long TempLastCheck;      // Stores the last sensor reading ran

// -------------Library Interaction--------------
// Create our LCD Shield instance
Adafruit_RGBLCDShield lcd = Adafruit_RGBLCDShield();
#define ON 0x6            // For single color LCD, set on to white
#define OFF 0x0           // For single color LCD, set off to black

#define DHTTYPE DHT11   // DHT 11 
#define DHTPIN 4     // what pin we're connected to
DHT dht(DHTPIN, DHTTYPE);


// ----------------------------------------------------------------------------------------
// Function Name: setup()
// Parameters:    None
// Returns:       None
// Description:   This function executes housekeeping duties and staging for the loop() function; executed once
// ----------------------------------------------------------------------------------------
void setup() {

  // Leaves the relays "off" (no click until something is needed)
  digitalWrite(heatPin, HIGH);
  digitalWrite(coolPin, HIGH);
  digitalWrite(fanPin, HIGH);


  //  pinMode(busPin,INPUT);  // Designate temperature bus pin data direction
  pinMode(heatPin, OUTPUT);               // Heat circuit relay
  pinMode(coolPin, OUTPUT);               // Cooling circuit relay
  pinMode(fanPin, OUTPUT);                // Fan circuit relay
  Serial.begin(serialSpeed);


  lcd.begin(16, 2);       // set up the LCD's number of columns and rows
  lcd.setBacklight(ON);   // Start off with backlight on until time-out
  timeOut = millis();     // Set the initial backlight time
  TempLastCheck = millis();  // Set the initial sensor timing

  dht.begin();

}

// ----------------------------------------------------------------------------------------
// Function Name: loop()
// Parameters:    None
// Returns:       None
// Description:   This is the main executing block of the program, calling all ancillary functions to operate the Arduino
// ----------------------------------------------------------------------------------------
void loop() {
  if ((millis() - timeOut) > 30000) {                   // Turn on backlight for 30 seconds, else turn it off
    lcd.setBacklight(OFF);
    editable == false;
  } else {
    lcd.setBacklight(ON);
  }

  lcd.setCursor(0, 1);                  // Starting position of character printing

  uint8_t buttons = lcd.readButtons();  // Constantly check to see if something has been put on the bus

  // --------------Handle updating Temp Change Display---------------------
  if (getTemp()) {                      // Constantly check to see if the temperature has changed, and update appropriately
    lcd.clear();
    lcd.print("Temp: ");
    lcd.print(currentTemp);
    lcd.setCursor(0, 1);

    lcd.print("A:");
    lcd.print(coolRunning);
    lcd.print(" H:");
    lcd.print(heatRunning);
    lcd.print(" F:");
    lcd.print(fanRunning);
  }

  // --------------Handle Button Presses---------------------
  if (buttons) {
    timeOut = millis();
    lcd.setBacklight(ON);


    if (buttons & BUTTON_SELECT) {      // Allow parameters to be changed only if the Select button has been pressed first
      editable = true;
    }
    if (editable) {                     // go to buttonHandler to handle menu switching and parameter manipulations
      buttonHandler(buttons);
    }
  }

  // --------------Handle Heat and Cooling Cycles---------------------
  powerControl();

}

// ----------------------------------------------------------------------------------------
// Function Name: powerControlHandler()
// Parameters:    None
// Returns:       None
// Description:   This function will handle turning AC or Heat off and on based on current temp, timers, and setpoints
// ----------------------------------------------------------------------------------------
void powerControl() {

  // TODO: Add in fan relay control


  // This executes if the heater is running and it gets warm enough to turn off.
  if (heatRunning && (currentTemp > (heat + buffer))) {
    heatRunning = false;
    heatLastRan = millis();
    digitalWrite(heatPin, HIGH);
    return;
  }

  // This executes if the AC is running and it gets cool enough to turn off
  if (coolRunning && (currentTemp < (cool - buffer))) {
    coolRunning = false;
    coolLastRan = millis();
    digitalWrite(coolPin, HIGH);
    return;
  }

  // This executes if it gets cold enough and the heater has not run for a minimum time (short cycle protection)
  if ((currentTemp < heat) && ((millis() - heatLastRan) > cycleTime)) {
    digitalWrite(heatPin, LOW);
    heatRunning = true;
    return;
  }

  // This executes if it gets hot enough and the AC has not run for 10 minutes (short cycle protection)
  if ((currentTemp > cool) && ((millis() - coolLastRan) > 60)) {
    digitalWrite(coolPin, LOW);
    coolRunning = true;
    return;
  }

  return;
}


// ----------------------------------------------------------------------------------------
// Function Name: buttonHandler()
// Parameters:    None
// Returns:       Boolean, True if the temperature has changed, else False
// Description:   This function polls the temp sensors, retrieves the values, and then returns
// ----------------------------------------------------------------------------------------
boolean buttonHandler(uint8_t buttons) {

  // --------------PARAMETERS---------------------
  int heatModifier = 0;
  int coolModifier = 0;
  // --------------SETUP---------------------
  lcd.clear();

  // If the UP Button is pushed, increasing the setpoint
  if (buttons & BUTTON_UP) {
    if (menuPosition == 0) {
      coolModifier = 1;
    }
    if (menuPosition == 1) {
      heatModifier = 1;
    }
  }

  // If the Down Button is pushed, decreasing the setpoint
  if (buttons & BUTTON_DOWN) {
    if (menuPosition == 0) {
      coolModifier = -1;
    }
    if (menuPosition == 1) {
      heatModifier = -1;
    }
  }


// If the Left Button is pushed, change the menu context
if (buttons & BUTTON_LEFT) {
  menuPosition--;  // decrement the variable
  if ( menuPosition < 0 ) {
    menuPosition = 0;          // don't let it decrement too much 
  }
}

// If the Right Button is pushed, change the menu context
if (buttons & BUTTON_RIGHT) {
  menuPosition++;  // increment the variable
  if ( menuPosition <= 2 ) {
    menuPosition = 2;          // don't let it increment too much 
  }
}



  // If anything has been modified, update accordingly
  heat = heat + heatModifier;
  cool = cool + coolModifier;

  // Print proper menu title and setpoint
  lcd.setCursor(0, 0);
  lcd.print(menu[menuPosition]);
  lcd.setCursor(0, 1);
  lcd.print("Setting: ");

  if (menuPosition == 0) {
    lcd.print(cool);
  }
  if (menuPosition == 1) {
    lcd.print(heat);
  }
  if (menuPosition == 2) {
    lcd.print(fanRunning);
  }

}

// ----------------------------------------------------------------------------------------
// Function Name: getTemp()
// Parameters:    None
// Returns:       Boolean, True if the temperature has changed, else False
// Description:   This function polls the temp sensors, retrieves the values, and then returns
// ----------------------------------------------------------------------------------------
boolean getTemp() {

  //currentTemp = 0;
  float temp = 0;

  if ((millis() - TempLastCheck) > 2000) {
    TempLastCheck = millis();
    temp = dht.readTemperature(true);


    /*

    Serial.println("");
    Serial.print("temp:        ");
    Serial.println(temp);
    Serial.print("CurrentTemp: ");
    Serial.println(currentTemp);
    Serial.print("OldTemp:     ");
    Serial.println(oldTemp);
    Serial.print("cool:        ");
    Serial.println(cool);
    Serial.print("heat:        ");
    Serial.println(heat);

    Serial.println("");
    Serial.print("heat running: ");
    Serial.println(heatRunning);
    Serial.print("cool running: ");
    Serial.println(coolRunning);

    */
    if (temp != currentTemp) {
      currentTemp = temp;
    }
  }


  // Check to see if temperature has changed
  if (currentTemp != oldTemp) {
    oldTemp = currentTemp;
    return true;
  }
  else {
    return false;
  }
}