USB host for android

Question

I am trying to communicate with my freeduino board which is similar to arduino uno via usb through android device 'nexus 7' which has 4.2 (jelly beans) in it.

I used the developers guide to communicate with the device from a couple of months but with no result. I think i am missing something minute in it. I am trying to simply display the vendor id of my freeduino board. My manifest file look like this.

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.usb_host_final_try"
    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.example.usb_host_final_try.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
            <intent-filter>
        <action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" />
    </intent-filter>

    <meta-data android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED"
        android:resource="@xml/device_filter" />
        </activity>
    </application>

</manifest>

I have created a file device_filter in res/xml dir. which look like this

 <?xml version="1.0" encoding="utf-8"?>
<resources>
    <usb-device vendor-id="0403" product-id="07d7" />
</resources>

and my MainActivity.java has the following code.

package com.example.usb_host_final_try;

import java.util.HashMap;

import android.hardware.usb.UsbDevice;
import android.hardware.usb.UsbManager;
import android.os.Build;
import android.os.Bundle;
import android.annotation.TargetApi;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.view.Menu;
import android.widget.TextView;

public class MainActivity extends Activity {

    @TargetApi(Build.VERSION_CODES.HONEYCOMB_MR1)
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Intent intent = new Intent();
        UsbManager manager = (UsbManager) getSystemService(Context.USB_SERVICE);
        HashMap<String, UsbDevice> deviceList = manager.getDeviceList();
        UsbDevice device = deviceList.get("deviceName");
        int vid=device.getVendorId();
        TextView tv = (TextView) findViewById(R.id.textview);
        tv.setText(Integer.toString(vid));
    }

please help me out i am screwed up over it from past few months now. I have tried doing this but it is also not working.

link

link

Stack overfolow question

stack overflow question

I have tried all these and still haven't been able to succeed. I also tried to use an if else loop to see if enumeration works where i set the text to device not found if no device is else settext to vendor id. On emulator is showed no device found but on my tablet wen i connect the device it force closes or else it still shows no device found wen nothing is connected.

The stack trace is here..

01-05 09:10:35.364: W/Trace(1658): Unexpected value from nativeGetEnabledTags: 0 01-05 09:10:35.364: W/Trace(1658): Unexpected value from nativeGetEnabledTags: 0 01-05 09:10:35.464: W/Trace(1658): Unexpected value from nativeGetEnabledTags: 0 01-05 09:10:35.464: W/Trace(1658): Unexpected value from nativeGetEnabledTags: 0 01-05 09:10:35.624: D/AndroidRuntime(1658): Shutting down VM 01-05 09:10:35.624: W/dalvikvm(1658): threadid=1: thread exiting with uncaught exception (group=0x40a70930) 01-05 09:10:35.644: E/AndroidRuntime(1658): FATAL EXCEPTION: main 01-05 09:10:35.644: E/AndroidRuntime(1658): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.usb_host_final_try/com.example.usb_host_final_try.MainActivity}: java.lang.NullPointerException 01-05 09:10:35.644: E/AndroidRuntime(1658): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180) 01-05 09:10:35.644: E/AndroidRuntime(1658): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230) 01-05 09:10:35.644: E/AndroidRuntime(1658): at android.app.ActivityThread.access$600(ActivityThread.java:141) 01-05 09:10:35.644: E/AndroidRuntime(1658): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234) 01-05 09:10:35.644: E/AndroidRuntime(1658): at android.os.Handler.dispatchMessage(Handler.java:99) 01-05 09:10:35.644: E/AndroidRuntime(1658): at android.os.Looper.loop(Looper.java:137) 01-05 09:10:35.644: E/AndroidRuntime(1658): at android.app.ActivityThread.main(ActivityThread.java:5039) 01-05 09:10:35.644: E/AndroidRuntime(1658): at java.lang.reflect.Method.invokeNative(Native Method) 01-05 09:10:35.644: E/AndroidRuntime(1658): at java.lang.reflect.Method.invoke(Method.java:511) 01-05 09:10:35.644: E/AndroidRuntime(1658): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 01-05 09:10:35.644: E/AndroidRuntime(1658): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 01-05 09:10:35.644: E/AndroidRuntime(1658): at dalvik.system.NativeStart.main(Native Method) 01-05 09:10:35.644: E/AndroidRuntime(1658): Caused by: java.lang.NullPointerException 01-05 09:10:35.644: E/AndroidRuntime(1658): at com.example.usb_host_final_try.MainActivity.onCreate(MainActivity.java:35) 01-05 09:10:35.644: E/AndroidRuntime(1658): at android.app.Activity.performCreate(Activity.java:5104) 01-05 09:10:35.644: E/AndroidRuntime(1658): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080) 01-05 09:10:35.644: E/AndroidRuntime(1658): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144) 01-05 09:10:35.644: E/AndroidRuntime(1658): ... 11 more 01-05 09:10:46.074: W/Trace(1712): Unexpected value from nativeGetEnabledTags: 0 01-05 09:10:46.074: W/Trace(1712): Unexpected value from nativeGetEnabledTags: 0 01-05 09:10:46.754: D/AndroidRuntime(1712): Shutting down VM 01-05 09:10:46.754: W/dalvikvm(1712): threadid=1: thread exiting with uncaught exception (group=0x40a70930) 01-05 09:10:46.766: E/AndroidRuntime(1712): FATAL EXCEPTION: main 01-05 09:10:46.766: E/AndroidRuntime(1712): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.usb_host_final_try/com.example.usb_host_final_try.MainActivity}: java.lang.NullPointerException 01-05 09:10:46.766: E/AndroidRuntime(1712): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180) 01-05 09:10:46.766: E/AndroidRuntime(1712): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230) 01-05 09:10:46.766: E/AndroidRuntime(1712): at android.app.ActivityThread.access$600(ActivityThread.java:141) 01-05 09:10:46.766: E/AndroidRuntime(1712): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234) 01-05 09:10:46.766: E/AndroidRuntime(1712): at android.os.Handler.dispatchMessage(Handler.java:99) 01-05 09:10:46.766: E/AndroidRuntime(1712): at android.os.Looper.loop(Looper.java:137) 01-05 09:10:46.766: E/AndroidRuntime(1712): at android.app.ActivityThread.main(ActivityThread.java:5039) 01-05 09:10:46.766: E/AndroidRuntime(1712): at java.lang.reflect.Method.invokeNative(Native Method) 01-05 09:10:46.766: E/AndroidRuntime(1712): at java.lang.reflect.Method.invoke(Method.java:511) 01-05 09:10:46.766: E/AndroidRuntime(1712): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 01-05 09:10:46.766: E/AndroidRuntime(1712): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 01-05 09:10:46.766: E/AndroidRuntime(1712): at dalvik.system.NativeStart.main(Native Method) 01-05 09:10:46.766: E/AndroidRuntime(1712): Caused by: java.lang.NullPointerException 01-05 09:10:46.766: E/AndroidRuntime(1712): at com.example.usb_host_final_try.MainActivity.onCreate(MainActivity.java:35) 01-05 09:10:46.766: E/AndroidRuntime(1712): at android.app.Activity.performCreate(Activity.java:5104) 01-05 09:10:46.766: E/AndroidRuntime(1712): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080) 01-05 09:10:46.766: E/AndroidRuntime(1712): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144) 01-05 09:10:46.766: E/AndroidRuntime(1712): ... 11 more 01-05 09:10:49.104: I/Process(1712): Sending signal. PID: 1712 SIG: 9

Answer 1

EDIT: Permissions aren't actually needed if defined in XML, so the answer below does not apply. The issue was an NPE - no such device "deviceName" existed in the code.

---

It looks like you are not obtaining permission to use the USB accessory, as described here in the docs and in this answer.

In your onCreate():

UsbManager mUsbManager = (UsbManager) getSystemService(Context.USB_SERVICE);
private static final String ACTION_USB_PERMISSION =
    "com.android.example.USB_PERMISSION";
...
mPermissionIntent = PendingIntent.getBroadcast(this, 0, new Intent(ACTION_USB_PERMISSION), 0);
IntentFilter filter = new IntentFilter(ACTION_USB_PERMISSION);
registerReceiver(mUsbReceiver, filter);

In your Activity:

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
                    }
                }
                else {
                    Log.d(TAG, "permission denied for accessory " + accessory);
                }
            }
        }
    }
};

To show the dialog to get permission:

UsbAccessory accessory;
...
mUsbManager.requestPermission(accessory, mPermissionIntent);

Answer 2

the main activity will now become like this and rest of it remains the same

    package com.example.usb_host_final_try;

import java.util.HashMap;
import java.util.Iterator;

import android.hardware.usb.UsbAccessory;
import android.hardware.usb.UsbDevice;
import android.hardware.usb.UsbManager;
import android.os.Build;
import android.os.Bundle;
import android.annotation.TargetApi;
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.util.Log;
import android.view.Menu;
import android.widget.TextView;

public class MainActivity extends Activity {

    protected static final String TAG = null;

    @TargetApi(Build.VERSION_CODES.HONEYCOMB_MR1)
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        UsbManager manager = (UsbManager) getSystemService(Context.USB_SERVICE);
        HashMap<String, UsbDevice> deviceList = manager.getDeviceList();
        Iterator<UsbDevice> deviceIterator = deviceList.values().iterator();
        while(deviceIterator.hasNext()){
            UsbDevice device = deviceIterator.next();
            String s=device.getDeviceName();
            int pid= device.getProductId();
            int vid = device.getVendorId();
            TextView tv = (TextView) findViewById(R.id.textview);
            tv.setText(s+"\n"+Integer.toString(pid)+"\n"+Integer.toString(vid));
        }

    }

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

}

All thanks to oleg Vaskevich!!