Analog Buttons

// Provides a definition for each of the buttons
#define btnRIGHT   1
#define btnUP      2
#define btnDOWN    3
#define btnLEFT    4
#define btnSELECT  5
#define btnNONE    0


int inPin = A0;         // the number of the input pin
int outPin = 13;       // the number of the output pin

int state = HIGH;      // the current state of the output pin
int reading;           // the current reading from the input pin
int previous = LOW;    // the previous reading from the input pin

// the follow variables are long's because the time, measured in miliseconds,
// will quickly become a bigger number than can be stored in an int.
unsigned long time = 0;         // the last time the output pin was toggled
unsigned long debounce = 200;   // the debounce time, increase if the output flickers

void setup()
{
  pinMode(outPin, OUTPUT);
}

void loop()
{
  reading = read_LCD_buttons(inPin);  // checks to see which button is currently pressed, if any

  // if the input just went from LOW and HIGH and we've waited long enough
  // to ignore any noise on the circuit, toggle the output pin and remember
  // the time
  if ( (reading > 0) && (previous == LOW) && ((millis() - time) > debounce) ) {
    switch (reading) {
    case btnRIGHT:
      // the right button was pressed.
      // toggles the state of the LED pin
      state = !state;
      break;

    case btnUP:
      // Up button was pressed.
      break;

    default:
      // no button was pressed?
      break;
    }
    time = millis();
  }

  // Constantly "writing" the state of the pin
  digitalWrite(outPin, state);

  previous = reading;
}

int read_LCD_buttons(int pinToRead)
{
  int adc_key_in = analogRead(pinToRead);
  delay(5);
  if (5 < abs(adc_key_in)) return btnNONE;

  if (adc_key_in > 1000) return btnNONE;
  if (adc_key_in < 50)   return btnRIGHT;
  if (adc_key_in < 195)  return btnUP;
  if (adc_key_in < 380)  return btnDOWN;
  if (adc_key_in < 555)  return btnLEFT;
  if (adc_key_in < 790)  return btnSELECT;
  return btnNONE;
}