Code used on demo project shown at (http://www.youtube.com/watch?v=a1M5kirA2_8) and (http://www.youtube.com/watch?v=epJ3aSzrsXQ) Includes climate sensing, logging to SD card, HTTP server with JSON output, LCD display with settings menus.

gistfile1.ino

/*
  Displays the current temperature and relative
  humidity on an LCD with an common cathode RGB
  backlight.
 */

// Include Standard Library
#include <stdlib.h>

// Include LCD Library Code
#include <LiquidCrystal.h>

// Include RHT Library Code
#include <DHT22.h>

// Include SPI and Ethernet Libraries
#include <SPI.h>
#include <Ethernet.h>

// Include SD for accessing the sd card
#include <SD.h>

// Include OneWire for reading the ds temperature sensor
#include <OneWire.h>

// Include Rotary Encoder Library
#include <QuadEncoder.h>

#include <Button.h>

// input
#define TEMP  27
#define SND1  28
#define PIR1  29
#define RHT   30
#define PIR2  31
#define LIGHT 15 // A15

// control
#define ROTENCA 43
#define ROTENCB 45
#define BUTTONR 2 // Intr 0 = Pin 2
#define BUTTON  1 // Intr 1 = Pin 3

// LCD
#define LCD_RS 42
#define LCD_EN 44
#define LCD_D1 46
#define LCD_D2 48
#define LCD_D3 47
#define LCD_D4 49
#define LCD_BLR 5
#define LCD_BLG 6
#define LCD_BLB 7

// OUTPUT
#define LED1  41
#define LED2  40
#define LED3  39
#define LED4  38
#define LED5  37
#define LED6  36
#define LED7  35
#define LED8  34
#define LED9  33
#define LED10 32

int leds[] = { LED1, LED2, LED3, LED4, LED5,
               LED6, LED7, LED8, LED9, LED10 };

// reserved
#define SD_SS     4
#define ETH_SS   10
#define SPI_MOSI 50
#define SPI_MISO 51
#define SPI_CLK  52
#define HW_SS    53

// modes
#define MODE_DISPLAY 0
#define MODE_COUNT 1
#define LAST_MODE 1

// Setup OneWire Temperature Sensor
byte tempAddr[] = { 0x28, 0x6C, 0xAC, 0x49, 0x03, 0x00, 0x00, 0x25 };
OneWire ds(TEMP);

// buffer for float to string conversion
char buffer[25];

// Setup MAC address and IP address for the Ethernet card
byte mac[] = { 0x90, 0xA2, 0xDA, 0x04, 0x00, 0xF1 };
IPAddress ip(192,168,1,5);

// Initialize the Ethernet server library
// with the IP address and port you want to use 
// (port 80 is default for HTTP):
EthernetServer server(80);

// initialize the LCD with the numbers of the interface pins
LiquidCrystal lcd(LCD_RS, LCD_EN, LCD_D1, LCD_D2, LCD_D3, LCD_D4);

// initialize RHT with data pin
DHT22 rht(RHT);

// initialize the encoder
QuadEncoder encoder(ROTENCA,ROTENCB); // initialize the encoder
// has the encoder moved on this loop?
boolean moved = false;

Button buttonR(BUTTONR);

// color levels for the backlight
int r_level = 255;
int g_level = 255;
int b_level = 255;

// data vars
int motionUp = LOW;
int motionDn = LOW;
int sound    = LOW;
double temperature;
double humidity;
double light;

unsigned long lastReading = 0;
int temperatureUnit = 'F';
boolean sdcard = false;

// last data vars
int lastMotionUp = motionUp;
int lastMotionDn = motionDn;
int lastsound = sound;
double lastTemperature = temperature;
double lastLight = light;

// other vars
int mode = MODE_DISPLAY;
int count = 0;
unsigned long timeSinceLastDisplay = 0;

boolean ledIsOn = false;

// Custom character for a degree sign
byte degree[8] = {
  B01100,
  B10010,
  B10010,
  B01100,
  B00000,
  B00000,
  B00000
};

void setup() {
  // setup interrupts
  attachInterrupt(BUTTON, displayMenu, RISING);
  
  // set the LCD's number of cols and lines
  lcd.begin(16, 2);
  lcd.createChar(0, degree);
  
  // turn on backlight
  ledOn();
  
  // Start Ethernet connection
  Ethernet.begin(mac, ip);
  
  // Start listening
  server.begin();
  
  // initialize pins for RGB backlight
  pinMode(LCD_BLR, OUTPUT);
  pinMode(LCD_BLG, OUTPUT);
  pinMode(LCD_BLB, OUTPUT);
  
  // initialize inputs
  pinMode(PIR1, INPUT);
  pinMode(PIR2, INPUT);
  pinMode(SND1, INPUT);
  
  // print a welcome message
  lcd.clear();
  lcd.print("*** WELCOME! ***");
  lcd.setCursor(0,1);
  lcd.print("Initializing");
  
  // initialize led bar while delaying 2000ms giving the rht time to warm up
  for (int i=0; i<10; ++i) {
    if (i%3 == 0) lcd.print(".");
    pinMode(leds[i], OUTPUT);
    digitalWrite(leds[i], HIGH);
    delay(100);
  }
  for (int i=0; i<10; ++i) {
    digitalWrite(leds[i], LOW);
    delay(100);
  }
  
  // Initialize sd card
  if (!SD.begin(SD_SS)) {
    Serial.println("Error initializing card");
    sdcard = false;
  } else {
    writeLog(",,,,,,");
  }
}

void loop() {
  ledStatus();
  populateData();
  displayData();
  runServer();
  if (!sound && !motionUp && !motionDn) autoBrightness();
  if (sound) ledColor(0,0,b_level);
  log();
  if (motionUp || motionDn) ledColor(r_level,0,0);  
}

void ledStatus() {
  if (sdcard) {
    digitalWrite(leds[0], HIGH);
    digitalWrite(leds[9], HIGH);
  } else {
    digitalWrite(leds[0], LOW);
    digitalWrite(leds[9], LOW);
  }
}

void log() {
  if (sdcard) {
    boolean logTemperature = (changed(lastTemperature,temperature));
    boolean logMotionUp = (changed(lastMotionUp, motionUp) && motionUp == HIGH);
    boolean logMotionDn = (changed(lastMotionDn, motionDn) && motionDn == HIGH);
    
    if (sound || logTemperature || logMotionUp || logMotionDn) {
      String data = String(millis(), DEC) + ", ";
      data += sound ? "1" : "0";
      data += ", ";
      data += motionUp ? "1" : "0";
      data += ", ";
      data += motionDn ? "1" : "0";
      data += ",";
      data += dtostrf(temperature, 6, 2, buffer);
      data += ",";
      data += dtostrf(humidity, 6, 2, buffer);
      data += ",";
      data += dtostrf(light, 6, 2, buffer);      
      writeLog(data);
      for (int j=1; j<9; ++j) {
        digitalWrite(leds[j], HIGH);
        delay(10);
        for (int i=1; i<9; ++i) digitalWrite(leds[i], LOW);
      }
    }
  } else delay(30);
}

void writeLog(String data) {
  if (sdcard) {
    File dataFile = SD.open("datalog.txt", FILE_WRITE);
    if (dataFile) {
      dataFile.println(data);
      dataFile.close();
    }
  }
}

boolean changed(int last, int current) {
  return (last != current);
}
boolean changed(double last, double current) {
  return (last != current);
}

// Displays the current values on the LCD
void displayData() {
  if (displayOk()) {
    lcd.clear();
    lcd.print("CLIMATE  L");
    lcd.print(light);
    lcd.print("%");
    lcd.setCursor(0,1);
    lcd.print("T");
    if (temperatureUnit == 'C') {
      lcd.print(temperature);
      lcd.write((uint8_t)0);
      lcd.print("C H");
    } else {
      lcd.print(c2f(temperature));
      lcd.write((uint8_t)0);
      lcd.print("F H");
    }
    lcd.print(humidity);
    lcd.print("%");
  }
}

// Check for requests
void runServer() {
  EthernetClient client = server.available();
  if (client) {
    // display something
    lcd.setCursor(0,0);
    lcd.print("CLIENT CONNECTED");
    ledColor(0,g_level,0);
    
    // an http request ends with a blank line
    boolean currentLineIsBlank = true;
    while (client.connected()) {
      if (client.available()) {
        char c = client.read();
        // if you've gotten to the end of the line (received a newline
        // character) and the line is blank, the http request has ended,
        // so you can send a reply
        if (c == '\n' && currentLineIsBlank) {
          // send a standard http response header
          client.println("HTTP/1.1 200 OK");
          client.println("Content-Type: application/json");
          client.println("Access-Control-Allow-Origin: *");
          client.println();
          client.print("{\"temperature\":");
          client.print(temperature);
          client.print(",\"humidity\":");
          client.print(humidity);
          client.print(",\"light\":");
          client.print(light);
          
          // fix these to return true if they have been activated in the last x time
          client.print(",\"motion_up\":");
          if (motionUp) client.print("true");
          else client.print("false");
          
          client.print(",\"motion_down\":");
          if (motionDn) client.print("true");
          else client.print("false");
          
          client.print(",\"sound\":");
          if (sound) client.print("true");
          else client.print("false");
          
          client.println("}");
          break;
        }
        if (c == '\n') {
          // you're starting a new line
          currentLineIsBlank = true;
        } else if (c != '\r') {
          // you've gotten a character on the current line
          currentLineIsBlank = false;
        }
      }
    }
    // give the web browser time to receive the data
    delay(1);
    client.stop();
    
    // display something
    lcd.setCursor(0,0);
    lcd.print("CLIENT FINISHED ");
    if (ledIsOn) {
      ledOn();
    } else {
      ledOff();
    }
  }
}

void displayMenu() {
  int selected = 3;
  
  lcd.clear();
  lcd.setCursor(0,0);
  lcd.print("Turn the knob to");
  lcd.setCursor(0,1);
  lcd.print("select an option");
  // display options
  while (!buttonR.pressed()) {
    selected += readEncoder();
    if (selected<0) selected=3;
    if (selected>3) selected=0;
    if (moved) {
      lcd.clear();
      lcd.setCursor(0,0);
      switch(selected) {
        case 0:
          lcd.print("Change Units    ");
          break;
        case 1:
          lcd.print("Backlight On/Off");
          break;
        case 2:
          lcd.print("Logging On/Off  ");
          break;
        case 3:
          lcd.print("Exit Settings   ");
          break;
      }
    }
  }
  // when button is pressed...
  lcd.clear();
  switch(selected) {
    case 0:
      settingsChangeUnits();
      break;
    case 1:
      settingsChangeBacklight();
      break;
    case 2:
      settingsChangeLogging();
  }
}

void settingsChangeUnits() {
  int selected = 2;
  lcd.clear();
  lcd.setCursor(0,0);
  lcd.print("Select Unit     ");
  lcd.setCursor(0,1);
  lcd.print("Currently it's ");
  lcd.write(temperatureUnit);
  while (!buttonR.pressed()) {
    selected += readEncoder();
    if (selected<0) selected=2;
    if (selected>2) selected=0;
    if (moved) {
      lcd.setCursor(0,1);
      switch(selected) {
        case 0:
          lcd.print("Celcius         ");
          break;
        case 1:
          lcd.print("Fahrenheit      ");
          break;
        case 2:
          lcd.print("Cancel          ");
          break;
      }
    }
  }
  // when button is pressed...
  switch(selected) {
    case 0:
      temperatureUnit = 'C';
      break;
    case 1:
      temperatureUnit = 'F';
      break;
  }
}

void settingsChangeBacklight() {
  boolean previousSetting = ledIsOn;
  int selected = 2;
  lcd.clear();
  lcd.setCursor(0,0);
  lcd.print("Backlight On/Off");
  while (!buttonR.pressed()) {
    selected += readEncoder();
    if (selected<0) selected=2;
    if (selected>2) selected=0;
    if (moved) {
      lcd.setCursor(0,1);
      lcd.print(" On  Off  Cancel");
      switch(selected) {
        case 0:
          lcd.setCursor(0,1);
          ledOn();
          break;
        case 1:
          lcd.setCursor(4,1);
          ledOff();
          break;
        case 2:
          lcd.setCursor(9,1);
          previousSetting ? ledOn() : ledOff();
          break;
      }
      lcd.write((uint8_t)126); // right arrow
    }
  }
}

void settingsChangeLogging() {
  int selected = 2;
  lcd.clear();
  lcd.setCursor(0,0);
  lcd.print("Logging to SD   ");
  lcd.setCursor(0,1);
  if (sdcard) lcd.print("card is: On     ");
  else lcd.print("card is: Off    ");
  while (!buttonR.pressed()) {
    selected += readEncoder();
    if (selected<0) selected=2;
    if (selected>2) selected=0;
    if (moved) {
      lcd.setCursor(0,1);
      switch(selected) {
        case 0:
          if (sdcard) lcd.print("Keep Logging On ");
          else lcd.print("Turn Logging On ");
          break;
        case 1:
          if (sdcard) lcd.print("Turn Logging Off");
          else lcd.print("Keep Logging Off");
          break;
        case 2:
          lcd.print("Cancel          ");
          break;
      }
    }
  }
  // when button is pressed...
  switch(selected) {
    case 0:
      sdcard = true;
      break;
    case 1:
      sdcard = false;
      break;
  }
}

// this function populates the global data variables temperature
// and humidity. it is safe to run as often as you'd like, it will
// only read the sensor every 2000ms.
void populateData() {
  // record last readings
  lastLight = light;
  lastTemperature = temperature;
  lastMotionUp = motionUp;
  lastMotionDn = motionDn;
  lastsound = sound;
  
  light = mapLight(analogRead(LIGHT));
  // temperature = readTemperature();
  motionDn = digitalRead(PIR1);
  motionUp = digitalRead(PIR2);
  sound = digitalRead(SND1);
  
  // is this useful in other places?
  unsigned long timeNow = millis();
  if (timeNow < lastReading) {
    // millis() has overflowed, reset lastReading time
    lastReading = timeNow;
  }
  
  if ((timeNow - lastReading) >= 2000) {
    DHT22_ERROR_t errorCode = rht.readData();
    if (errorCode == DHT_ERROR_NONE) {
      temperature = rht.getTemperatureC();
      humidity = rht.getHumidity();
    }
    lastReading = timeNow;
  }
}

// reads onewire ds temp sensor
double readTemperature() {
  byte data[12];
  ds.reset();
  ds.select(tempAddr);
  ds.write(0x44, 1); // start conversion, with parasite power on at the end
  byte present = ds.reset();
  ds.select(tempAddr);
  ds.write(0xBE); // Read Scratchpad
  for (int i=0; i<9; ++i) data[i] = ds.read();
  ds.reset_search();
  byte MSB = data[1];
  byte LSB = data[0];
  double tempRead = ((MSB << 8) | LSB); // using 2's compliment
  double tempSum = tempRead / 16;
  return tempSum;
}

// same as map(light, 0, 990, 0, 100), but with decimals
double mapLight(int lightIn) {
  return (double)lightIn * 100.0 / 990.0;
}

boolean displayOk() {
  unsigned long now = millis();
  if (now - timeSinceLastDisplay >= 500) {
    timeSinceLastDisplay = now;
    return true;
  } else return false;
}

// automatically adjusts backlight brightness depending on light sensor reading
void autoBrightness() {
  if (ledIsOn) {
    // adjust backlight based on ambient light
    double lightPercentage = (double)light/100.0;
    r_level = 255 - (255 * lightPercentage);
    g_level = 255 - (255 * lightPercentage);
    b_level = 255 - (255 * lightPercentage);
    ledOn();
  } else ledOff();
}

// returns 1 for right, -1 for left, or 0 for no movement
int readEncoder() {
  moved = true;
  switch(encoder.hb()) {
    case '>': return 1;
    case '<': return -1;
  }
  moved = false;
  return 0;
}

// converts celsius to fahrenheit
double c2f(double celsius) {
  return 1.8 * celsius + 32;
}

// toggles the backlight
void toggleBacklight() {
  ledIsOn ? ledOff() : ledOn();
}

// turns on the backlight
void ledOn() {
  ledIsOn = true;
  ledColor(r_level,g_level,b_level);
}

// turns off the backlight
void ledOff() {
  ledIsOn = false;
  ledColor(0,0,0);
}

// sets the color of the backlight
void ledColor(int r, int g, int b) {
  if (0 <= r && r <= 255) analogWrite(LCD_BLR, r);
  if (0 <= g && g <= 255) analogWrite(LCD_BLG, g);
  if (0 <= b && b <= 255) analogWrite(LCD_BLB, b);
}

QuadEncoder.cpp

/**
 * QuadEncoder.cpp - Library for reading moves from a quadrature rotary encoder
 * Created by Pedro Rodrigues ([email protected]) 9, January of 2010
 * Released into the public domain.
 */

#include "Arduino.h"
#include "QuadEncoder.h"

QuadEncoder::QuadEncoder(int pin1, int pin2)
{
  pinMode(pin1, INPUT);
  pinMode(pin2, INPUT);
  digitalWrite(pin1, HIGH);
  digitalWrite(pin2, HIGH);
  _inputPin1=pin1;
  _inputPin2=pin2;
  _val1=1;
  _val2=1;
  _oldVal1=1;
  _oldVal2=1;
  _pos=0;
  _oldPos=0;
  _turn=0;
  _turnCount=0;

}

char QuadEncoder::hb()
{  
  _val1 = digitalRead(_inputPin1);
  _val2 = digitalRead(_inputPin2);
    // Detect changes
  if ( _val1 != _oldVal1 || _val2 != _oldVal2) {
    _oldVal1=_val1;
    _oldVal2=_val2;
    
      //for each pair there's a position out of four
    if ( _val1 == 1 ) {// stationary position
      if (_val2 == 1)
        _pos = 0;
      else if (_val2 == 0)
        _pos = 3;
    } else if (_val1 == 0){
      if (_val2 == 1)
        _pos = 1;
      else if (_val2 == 0)
        _pos = 2;
    }
    
    _turn = _pos-_oldPos;
    _oldPos = _pos;
    if (abs(_turn) != 2) {
      if (_turn == 1 || _turn == -3)
        _turnCount++;
      else if (_turn == -1 || _turn == 3)
        _turnCount--;
    }
    if (_pos==0){
      if (_turnCount>0){
        _turnCount=0;
        return '>';
      } else if (_turnCount<0){
        _turnCount=0;
        return '<';
      } else {
        _turnCount=0;
        return '-';
      }
    }    
  }
}

QuadEncoder.h

/**
 * QuadEncoder.h - Library for reading moves from a quadrature rotary encoder
 * Created by Pedro Rodrigues ([email protected]) 9, January of 2010
 * Released into the public domain.
 */

#ifndef QuadEncoder_h
#define QuadEncoder_h

#include "Arduino.h"


class QuadEncoder
{
  public:
    QuadEncoder(int pin1, int pin2);
    char hb();
  private:
    int _inputPin1;
    int _inputPin2;
    int _val1;
    int _val2;
    int _oldVal1;
    int _oldVal2;
    int _pos;
    int _oldPos;
    int _turn;
    int _turnCount;  
  };

#endif