Android 4.1.2 Jelly Bean and Arduino Mega 2560 with USB Host Shield Communication

Few  weeks ago I wrote my first Android Jelly Bean App named ColorChanger. Since then I wanted to integrate it with Arduino and Control a physical RGB LED Light from the ColorChanger Android App. I finally managed to get it done using the following Items.

1. Arduino Mega 2560 Rev 3
2. DFRobot USB Host Shield 
3. Arduino IDE 0023
4. ADK Library
5. 1 RGB LED
6. 1 1k Resistor
7. Few Jumper Cables
8. One USB to Micro USB Cable

Few things changed from the original ColorChanger App starting from the AndroidManifest.xml where I had to allow my MainActivity to listen for USB_ACCESSORY_ATTACHED intent action and when my Accessory connects open the ColorChanger App.

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.shazin.colorchanger"
    android:versionCode="1"
    android:versionName="1.0" >
    
    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="17" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.shazin.colorchanger.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <action android:name="android.hardware.usb.action.USB_ACCESSORY_ATTACHED" />
                
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
            
            <meta-data android:name="android.hardware.usb.action.USB_ACCESSORY_ATTACHED"
                android:resource="@xml/accessory_filter" /> 
        </activity>
    </application>

</manifest>

The filtering criteria is placed in res/xml/accessory_filter.xml file which is as follows

<?xml version="1.0" encoding="utf-8"?>

<resources>
    <usb-accessory model="ColorChangerApp" manufacturer="Shazin Sadakath" version="1.0"/>
</resources>

Then my MainActivity class changed as follows

package com.shazin.colorchanger;

import java.io.FileDescriptor;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

import android.annotation.SuppressLint;
import android.app.Activity;
import android.app.PendingIntent;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.graphics.Color;
import android.hardware.usb.UsbAccessory;
import android.hardware.usb.UsbManager;
import android.os.Bundle;
import android.os.ParcelFileDescriptor;
import android.view.Menu;
import android.widget.LinearLayout;
import android.widget.SeekBar;
import android.widget.SeekBar.OnSeekBarChangeListener;
import android.widget.TextView;
import android.widget.Toast;


public class MainActivity extends Activity implements OnSeekBarChangeListener, Runnable {

    private TextView textViewColor;
    
    private SeekBar seekBarRed;
    
    private SeekBar seekBarGreen;
    
    private SeekBar seekBarBlue;
    
    private byte red, green, blue;
    
    private LinearLayout linearLayout;
    
    private UsbAccessory mAccessory;
    
    private ParcelFileDescriptor mFileDescriptor;
    
    private FileInputStream mInputStream;
    
    private FileOutputStream mOutputStream;
    
    private UsbManager mUsbManager;
    
    private static final String ACTION_USB_PERMISSION = "com.android.example.USB_PERMISSION";
        private final BroadcastReceiver mUsbReceiver = new BroadcastReceiver() {
         
            public void onReceive(Context context, Intent intent) {
                String action = intent.getAction();
                if (ACTION_USB_PERMISSION.equals(action)) {
                    synchronized (this) {
                        UsbAccessory accessory = (UsbAccessory) intent.getParcelableExtra(UsbManager.EXTRA_ACCESSORY);

                        if (intent.getBooleanExtra(UsbManager.EXTRA_PERMISSION_GRANTED, false)) {
                            if(accessory != null){
                                //call method to set up accessory communication
                                openAccessory();
                            }
                        }
                        else {
                            //Log.d(TAG, "permission denied for accessory " + accessory);
                            Toast.makeText(context, "permission denied for accessory "+accessory, 2).show();
                        }
                    }
                    unregisterReceiver(mUsbReceiver);
                }    
                
            }
        };
    
        public final BroadcastReceiver mUsbDetachReciever = new BroadcastReceiver() {

            @Override
            public void onReceive(Context context, Intent intent) {
                String action = intent.getAction();
                if (UsbManager.ACTION_USB_ACCESSORY_DETACHED.equals(action)) {
                    UsbAccessory accessory = (UsbAccessory)intent.getParcelableExtra(UsbManager.EXTRA_ACCESSORY);
                    if (accessory != null) {
                        cleanUp();                
                    }
                    unregisterReceiver(mUsbDetachReciever);
                }
                
            }
            
        };
        


        private boolean mPermissionRequestPending;        
        
        private void cleanUp() {
            try {
                if(mFileDescriptor != null)
                    mFileDescriptor.close();
                
                if(mInputStream != null) 
                    mInputStream.close();
                
                if(mOutputStream != null)
                    mOutputStream.close();
                mAccessory = null;
                mUsbManager = null;
                Toast.makeText(this, "Closed all resources", 2).show();
            } catch (IOException e) {
                Toast.makeText(this, "Error occured "+e, 2).show();
            }
        }
        
            
    @SuppressLint("NewApi")
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        linearLayout = (LinearLayout) findViewById(R.id.linearLayout);
        
        textViewColor = (TextView) findViewById(R.id.textViewColor);
                
        seekBarRed = (SeekBar) findViewById(R.id.seekBarRed);
        seekBarGreen = (SeekBar) findViewById(R.id.seekBarGreen);
        seekBarBlue = (SeekBar) findViewById(R.id.seekBarBlue);
        
        seekBarBlue.setOnSeekBarChangeListener(this);
        seekBarGreen.setOnSeekBarChangeListener(this);
        seekBarRed.setOnSeekBarChangeListener(this);
        
        textViewColor.setText(String.format("(%d, %d, %d)", red, green, blue));
        linearLayout.setBackgroundColor(Color.rgb(red, green, blue));
        
        
        mAccessory = (UsbAccessory) getIntent().getParcelableExtra(UsbManager.EXTRA_ACCESSORY);
        Toast.makeText(this, "USB Accessory = "+mAccessory, 2).show();
        
        mUsbManager = (UsbManager) getSystemService(Context.USB_SERVICE);
        Toast.makeText(this, "USB Manager = "+mUsbManager, 2).show();
        
        PendingIntent mPermissionIntent = PendingIntent.getBroadcast(this, 0, new Intent(ACTION_USB_PERMISSION), 0);
        IntentFilter filter = new IntentFilter(ACTION_USB_PERMISSION);
        registerReceiver(mUsbReceiver, filter);
        Toast.makeText(this, "Intent Registered", 2).show();
        
        if(mUsbManager.hasPermission(mAccessory)) {
            Toast.makeText(this, "Accessory has permission", 2).show();
            unregisterReceiver(mUsbReceiver);
            openAccessory();
        } else {            
            Toast.makeText(this, "Accessory has no permission", 2).show();
            synchronized (mUsbReceiver) {                
                if (!mPermissionRequestPending) {
                    mUsbManager.requestPermission(mAccessory, mPermissionIntent);
                    Toast.makeText(this, "Permission Request Sent", 2).show();
                    mPermissionRequestPending = true;
                }
            }
        }
        
        IntentFilter filter2 = new IntentFilter(ACTION_USB_PERMISSION);
        filter2.addAction(UsbManager.ACTION_USB_ACCESSORY_DETACHED);
        registerReceiver(mUsbDetachReciever, filter2);        
        
    }
    
    public void onDestroy() {
        super.onDestroy();
        cleanUp();
    }
    
    @SuppressLint("NewApi")
    private void openAccessory() {
        //Log.d(TAG, "openAccessory: " + accessory);
        mFileDescriptor = mUsbManager.openAccessory(mAccessory);
        Toast.makeText(this, "Accessory Opened", 2).show();
        if (mFileDescriptor != null) {
            FileDescriptor fd = mFileDescriptor.getFileDescriptor();
            Toast.makeText(this, "File Desc "+fd, 2).show();
            mInputStream = new FileInputStream(fd);
            mOutputStream = new FileOutputStream(fd);
            
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public void onProgressChanged(SeekBar seekBar, int value, boolean flag) {
        if(seekBar == seekBarRed) {
            red = (byte) value;
        } else if(seekBar == seekBarGreen) {
            green = (byte) value;
        } else if(seekBar == seekBarBlue) {
            blue = (byte) value;
        }
        linearLayout.setBackgroundColor(Color.rgb(red & 0xFF, green & 0xFF, blue & 0xFF));
        textViewColor.setText(String.format("(%d, %d, %d)", red & 0xFF, green & 0xFF, blue & 0xFF));
        if(mOutputStream != null) {
            try {
                byte[] data = new byte[4];
                data[0] = 0x2;
                data[1] = red;
                data[2] = green;
                data[3] = blue;
                mOutputStream.write(data);
                mOutputStream.flush();
            } catch (IOException e) {
                Toast.makeText(this, "Error "+e, 2).show();
            }
        }    
    }

    @Override
    public void onStartTrackingTouch(SeekBar arg0) {
        // TODO Auto-generated method stub
        
    }

    @Override
    public void onStopTrackingTouch(SeekBar arg0) {
        // TODO Auto-generated method stub
        
    }

    @Override
    public void run() {
    
    }

}

And the Arduino Sketch is as follows

#include <avrpins.h>
#include <max3421e.h>
#include <usbhost.h>
#include <usb_ch9.h>
#include <Usb.h>
#include <usbhub.h>
#include <avr/pgmspace.h>
#include <address.h>

#include <adk.h>

#include <printhex.h>
#include <message.h>
#include <hexdump.h>
#include <parsetools.h>

// For Arduino IDE 1.0.x Only following two is needed

#include <adk.h>
#include &ltusbhub.h>

USB Usb;
USBHub hub0(&Usb);
USBHub hub1(&Usb);
ADK adk(&Usb,"Shazin Sadakath",
            "ColorChangerApp", // This name Should match with xml/res/accessory_filter.xml name
            "Color Changer App",
            "1.0",
            "http://shazsterblog.blogspot.com",
            "0000000012345678");

#define  LED1_RED       5
#define  LED1_GREEN       4
#define  LED1_BLUE       3

void setup();
void loop();

void init_leds()
{
    digitalWrite(LED1_RED, 0);
    digitalWrite(LED1_GREEN, 0);
    digitalWrite(LED1_BLUE, 0);

    pinMode(LED1_RED, OUTPUT);
    pinMode(LED1_GREEN, OUTPUT);
    pinMode(LED1_BLUE, OUTPUT);
}

void setup()
{
    Serial.begin(115200);
    Serial.println("\r\nADK demo start");
        
        if (Usb.Init() == -1) {
          Serial.println("OSCOKIRQ failed to assert");
        while(1); //halt
        }//if (Usb.Init() == -1...


    init_leds();
}

void loop()
{
  uint8_t rcode;
  uint8_t msg[4] = { 0x00 };
   Usb.Task();
   
   if( adk.isReady() == false ) {
     analogWrite(LED1_RED, 255);
     return;
   }
   uint16_t len = sizeof(msg);
   
   rcode = adk.RcvData(&len, msg);
   if( rcode ) {
     USBTRACE2("Data rcv. :", rcode );
   } 
   if(len > 0) {
     if(msg[0] == 0x2) {
         USBTRACE("\r\nData Packet.");
         uint8_t r = (msg[1]) & 0xFF;
         uint8_t g = (msg[2]) & 0xFF;
         uint8_t b = (msg[3]) & 0xFF;
         analogWrite(LED1_RED, 255 - r);
         analogWrite(LED1_GREEN, 255 - g);
         analogWrite(LED1_BLUE, 255 - b);
     }
     

   }
   
   msg[0] = 0x1;
   
      delay( 10 );       
}

The video of the whole thing working together is available below.

 

References 

• http://www.circuitsathome.com/mcu/google-open-accessory-interface-for-usb-host-shield-library-2-0-released
• http://developer.android.com/tools/adk/adk2.html
• https://docs.google.com/file/d/0B9L9ONCpLAwGbU5Hd0pIVUlmMTQ/edit?usp=sharing