Build Instructions

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  Step 1

  
  // Temperature Controler for window fan
  // Written by mike, public domain
  
  /*--------------------------------------------------------------------------------------
  Includes
  --------------------------------------------------------------------------------------*/
  #include "DHT.h"
  #include <LiquidCrystal.h> // include LCD library
  
  /*--------------------------------------------------------------------------------------
  Defines
  --------------------------------------------------------------------------------------*/
  // Pins in use
  #define DHTPIN 2 // D2 is for DHT22
  #define OUTPUTPIN 3 // Relay pin
  #define BUTTON_ADC_PIN A0 // A0 is the button ADC input
  // ADC readings expected for the 5 buttons on the ADC input
  #define RIGHT_10BIT_ADC 0 // right
  #define UP_10BIT_ADC 131 // up
  #define DOWN_10BIT_ADC 305 // down
  #define LEFT_10BIT_ADC 476 // left
  #define SELECT_10BIT_ADC 718 // select
  #define BUTTONHYSTERESIS 20 // hysteresis for valid button sensing window
  
  //return values for ReadButtons()
  #define BUTTON_NONE 0 //
  #define BUTTON_RIGHT 1 //
  #define BUTTON_UP 2 //
  #define BUTTON_DOWN 3 //
  #define BUTTON_LEFT 4 //
  #define BUTTON_SELECT 5 //
  #define DHTTYPE DHT22 // DHT 22 (AM2302)
  // Define our states
  #define STATE_TITLE 00 // A title screen
  #define STATE_MODE 05 // Waiting for mode selection
  #define STATE_HEATING 10 // Heating Mode
  #define STATE_COOLING 20 // Cooling Mode
  
  DHT dht(DHTPIN, DHTTYPE);
  LiquidCrystal lcd( 8, 9, 4, 5, 6, 7 ); //Pins for the freetronics 16x2 LCD shield. LCD: ( RS, E, LCD-D4, LCD-D5, LCD-D6, LCD-D7 )
  
  
  /*--------------------------------------------------------------------------------------
  Variables
  --------------------------------------------------------------------------------------*/
  float hi = 0;
  float h = 0;
  float t = 0;
  float f = 0;
  byte buttonJustPressed = false; //this will be true after a ReadButtons() call if triggered
  byte buttonJustReleased = false; //this will be true after a ReadButtons() call if triggered
  byte buttonWas = BUTTON_NONE; //used by ReadButtons() for detection of button events
  byte button = BUTTON_NONE; // return no button pressed if the below checks don't write to btn
  byte state, nextstate;
  int Temperature_Set_Point = 71;
  unsigned int buttonVoltage;
  int relayState = LOW;
  int fanState = HIGH;
  
  void setup() {
  Serial.begin(9600);
  Serial.println("DHTxx test!");
  pinMode(BUTTON_ADC_PIN, INPUT ); // Analogue input for the LCD's buttons
  pinMode(OUTPUTPIN, OUTPUT );
  digitalWrite(OUTPUTPIN, relayState );
  dht.begin();
  lcd.begin( 16, 2 ); // Tell LCD library this is 16x2 display
  
  // TITLE
  
  lcd.clear();
  // 1234567890123456
  lcd.print( "THERMOSTAT" );
  lcd.setCursor( 0, 1 );
  // 1234567890123456
  lcd.print( "Version .3" );
  delay (2000);
  
  lcd.clear();
  }
  
  void loop() {
  h = dht.readHumidity();
  f = dht.readTemperature(true);
  hi = dht.computeHeatIndex(f, h);
  
  if (fanState && !relayState && Temperature_Set_Point < f - 1) {
  relayState = HIGH;
  digitalWrite(OUTPUTPIN, relayState);
  }
  if ((!fanState) || (relayState && Temperature_Set_Point >= f)) {
  relayState = LOW;
  digitalWrite(OUTPUTPIN, relayState);
  }
  
  lcd.setCursor( 0, 0 );
  lcd.print(Temperature_Set_Point);
  lcd.print("F");lcd.setCursor( 10, 0 );
  lcd.print(f);
  lcd.print("F");
  lcd.setCursor( 0, 1 );
  lcd.print(relayState);
  lcd.setCursor( 3, 1 );
  lcd.print(h);
  lcd.setCursor( 10, 1 );
  lcd.print(hi);
  lcd.print("F");
  
  delay(500); // Delay to stop buttons "jittering" false presses
  
  button = ReadButtons();
  
  while (button == BUTTON_UP) {
  Temperature_Set_Point = Temperature_Set_Point + 1;
  lcd.setCursor( 0, 0 );
  lcd.print(Temperature_Set_Point);
  lcd.print("F");
  delay(500); // Delay to stop buttons "jittering" false presses
  button = ReadButtons();
  }
  while (button == BUTTON_DOWN) {
  Temperature_Set_Point = Temperature_Set_Point - 1;
  lcd.setCursor( 0, 0 );
  lcd.print(Temperature_Set_Point);
  lcd.print("F");
  delay(500); // Delay to stop buttons "jittering" false presses
  button = ReadButtons();
  }
  while (fanState && button == BUTTON_SELECT) {
  fanState = LOW;
  delay(500); // Delay to stop buttons "jittering" false presses
  button = ReadButtons();
  }
  while (!fanState && button == BUTTON_SELECT) {
  fanState = HIGH;
  delay(500); // Delay to stop buttons "jittering" false presses
  button = ReadButtons();
  }
  
  //clear the buttonJustPressed & buttonJustReleased flags; they've already done their job
  if(buttonJustPressed) buttonJustPressed = false;
  if(buttonJustReleased) buttonJustReleased = false;
  
  Serial.print("Humidity: ");
  Serial.print(h);
  Serial.print(" %\t");
  Serial.print("Temperature: ");
  Serial.print(f);
  Serial.print(" *F\t");
  Serial.print("Heat index: ");
  Serial.print(hi);
  Serial.println(" *F");
  }
  
  /*--------------------------------------------------------------------------------------
  ReadButtons()
  Detect the button pressed and return the value
  Uses global values buttonWas, buttonJustPressed, buttonJustReleased.
  --------------------------------------------------------------------------------------*/
  byte ReadButtons() {
  unsigned int buttonVoltage;
  byte button = BUTTON_NONE; // return no button pressed if the below checks don't write to btn
  
  //read the button ADC pin voltage
  buttonVoltage = analogRead( BUTTON_ADC_PIN );
  //sense if the voltage falls within valid voltage windows
  if( buttonVoltage < ( RIGHT_10BIT_ADC + BUTTONHYSTERESIS ) )
  {
  button = BUTTON_RIGHT;
  }
  else if( buttonVoltage >= ( UP_10BIT_ADC - BUTTONHYSTERESIS )
  && buttonVoltage <= ( UP_10BIT_ADC + BUTTONHYSTERESIS ) )
  {
  button = BUTTON_UP;
  }
  else if( buttonVoltage >= ( DOWN_10BIT_ADC - BUTTONHYSTERESIS )
  && buttonVoltage <= ( DOWN_10BIT_ADC + BUTTONHYSTERESIS ) )
  {
  button = BUTTON_DOWN;
  }
  else if( buttonVoltage >= ( LEFT_10BIT_ADC - BUTTONHYSTERESIS )
  && buttonVoltage <= ( LEFT_10BIT_ADC + BUTTONHYSTERESIS ) )
  {
  button = BUTTON_LEFT;
  }
  else if( buttonVoltage >= ( SELECT_10BIT_ADC - BUTTONHYSTERESIS )
  && buttonVoltage <= ( SELECT_10BIT_ADC + BUTTONHYSTERESIS ) )
  {
  button = BUTTON_SELECT;
  }
  //handle button flags for just pressed and just released events
  if( ( buttonWas == BUTTON_NONE ) && ( button != BUTTON_NONE ) )
  {
  //the button was just pressed, set buttonJustPressed, this can optionally be used to trigger a once-off action for a button press event
  //it's the duty of the receiver to clear these flags if it wants to detect a new button change event
  buttonJustPressed = true;
  buttonJustReleased = false;
  }
  if( ( buttonWas != BUTTON_NONE ) && ( button == BUTTON_NONE ) )
  {
  buttonJustPressed = false;
  buttonJustReleased = true;
  }
  
  //save the latest button value, for change event detection next time round
  buttonWas = button;
  
  return( button );
  }
  
  

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