hardware/arduino/sam/system/AndroidAccessory/examples/_01_digitalRead_adk/_01_digitalRead_adk.ino

/*
* ADK usb digitalRead
 *
 * TADA!
 *
 * (c) 2012 D. Cuartielles & A. Goransson
 * http://arduino.cc, http://1scale1.com
 *
 */

#include <Max3421e.h>
#include <Usb.h>
#include <AndroidAccessory.h>

// accessory descriptor. It's how Arduino identifies itself to Android
char applicationName[] = "Mega_ADK"; // the app on your phone
char accessoryName[] = "Mega_ADK"; // your Arduino board
char companyName[] = "Arduino SA";

// make up anything you want for these
char versionNumber[] = "1.0";
char serialNumber[] = "1";
char url[] = "http://labs.arduino.cc/adk/ADK_count"; // the URL of your app online

// button variables
int buttonPin = A1;
int buttonState = 0;
char letter = 'a';

// counters
long timer = millis();


// initialize the accessory:
AndroidAccessory usb(companyName, applicationName,
accessoryName,versionNumber,url,serialNumber);

void setup() {
  // start the connection to the device over the USB host:
  usb.powerOn();

  pinMode(buttonPin, INPUT);   
}

void loop() {
  /* Read button state */
  buttonState = digitalRead(buttonPin);
  
  /* Print to usb */
  if(millis()-timer>100) { // sending 10 times per second
    if (usb.isConnected()) { // isConnected makes sure the USB connection is ope
      if (buttonState == HIGH) {
        usb.write( 'a' );
      }
      else{
        usb.write( ' ' );
      }
    }
    timer = millis();
  }
}