LCD Keypad Shield

http://dx.com/p/lcd-keypad-shield-for-arduino-duemilanove-lcd-1602-118059

http://www.nuelectronics.com/download/projects/LCDshield_v1_1.pdf

http://arduino.cc/en/Tutorial/LiquidCrystal

//From http://www.spcoast.com/wiki/index.php/DX_LCD_Keypad_Shield 

/*
The circuit:
* LCD RS pin to digital pin 8
* LCD Enable pin to digital pin 9
* LCD D4 pin to digital pin 4
* LCD D5 pin to digital pin 5
* LCD D6 pin to digital pin 6
* LCD D7 pin to digital pin 7
* LCD R/W pin to ground
* 10K resistor:
* ends to +5V and ground
* wiper to LCD VO pin (pin 3)

*/

// include the library code:
#include <LiquidCrystal.h>

// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(8, 9, 4, 5, 6, 7);
int ButtonVoltage = 0;
int ButtonPressed = 0;
int Backlight = 10;
int fadeValue = 255;

#define BUTTON_SELECT    5
#define BUTTON_LEFT      4
#define BUTTON_DOWN      3
#define BUTTON_UP        2
#define BUTTON_RIGHT     1
#define BUTTON_NONE      0


void printnum(int n) {
    if (n<1000) {
        lcd.print(" ");
        if (n<100) {
            lcd.print(" ");
            if (n<10) {
                lcd.print(" ");
            }
        }
    }
    lcd.print(n);

}


void setup() {
// set up the LCD's number of columns and rows:
lcd.begin(16, 2);
// Print a message to the LCD.
lcd.setCursor (0,0);
lcd.print("Key: ");
lcd.setCursor (7,1);
lcd.print("Time:");

}

void loop() {
// set the cursor to column 0, line 1
// (note: line 1 is the second row, since counting begins with 0):
lcd.setCursor(12, 1);
lcd.print (millis()/1000);

ButtonVoltage = analogRead(0);

lcd.setCursor (4,0);
// Observed values:
//     NONE:    1023
//     SELECT:  723
//     LEFT:    481
//     DOWN:    307
//     UP:      133
//     RIGHT:   0

if (ButtonVoltage > 800) ButtonPressed = BUTTON_NONE;    // No button pressed should be 1023
else if (ButtonVoltage > 500) ButtonPressed = BUTTON_SELECT;
else if (ButtonVoltage > 400) ButtonPressed = BUTTON_LEFT;
else if (ButtonVoltage > 250) ButtonPressed = BUTTON_DOWN;
else if (ButtonVoltage > 100) ButtonPressed = BUTTON_UP;
else ButtonPressed = BUTTON_RIGHT;

switch (ButtonPressed) {
case BUTTON_SELECT:
            lcd.print ("Select");
            break;
case BUTTON_LEFT:
            lcd.print ("Left  ");
            break;
case BUTTON_DOWN:     {
                lcd.print ("Down  ");
                fadeValue = fadeValue -5;
                if (fadeValue < 5) { fadeValue = 0; }
                analogWrite (Backlight, fadeValue);
                lcd.setCursor(12,0);
                printnum(fadeValue);
                delay (100);
            }
            break;
case BUTTON_UP:     {
                lcd.print ("Up    ");
                fadeValue = fadeValue +5;
                if (fadeValue > 254) { fadeValue = 255; }
                analogWrite (Backlight, fadeValue);
                lcd.setCursor(12,0);
                printnum(fadeValue);
                delay (100);
            }
            break;
case BUTTON_RIGHT:
            lcd.print ("Right ");
            break;
case BUTTON_NONE:
            lcd.print ("None  ");
            break;
}


// print the number of seconds since reset:
lcd.setCursor(0,1);
lcd.print("V:");

printnum(ButtonVoltage);
}