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POHow to communicate with a USB device?
 

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  1. POHow to communicate with a USB device?
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    <p>I am trying to establish USB communication as host. I am following the examples here <a href="http://developer.android.com/guide/topics/usb/host.html">http://developer.android.com/guide/topics/usb/host.html</a> but I cannot get this working. Here is my code:</p> <pre><code>private static final String ACTION_USB_PERMISSION = "com.multitools.andres.LCView"; UsbDevice device; //Pide permisos al usuario para comunicacion con el dispositivo USB private final BroadcastReceiver mUsbReceiver = new BroadcastReceiver() { @Override public void onReceive(Context context, Intent intent) { String action = intent.getAction(); if (ACTION_USB_PERMISSION.equals(action)) { synchronized (this) { UsbDevice device = (UsbDevice)intent.getParcelableExtra(UsbManager.EXTRA_DEVICE); if (intent.getBooleanExtra(UsbManager.EXTRA_PERMISSION_GRANTED, false)) { if(device != null){ //call method to set up device communication } } else { Log.d(TAG, "permission denied for device " + device); } } } } }; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); if(DEBUG) Log.i(TAG, "onCreate() -&gt; MainMenu"); actionBar = getActionBar(); //obtengo el ActionBar actionBar.setDisplayHomeAsUpEnabled(true); //el icono de la aplicacion funciona como boton HOME //Menu setListAdapter(new ArrayAdapter&lt;String&gt;(MainMenu.this, android.R.layout.simple_list_item_1, MenuNames)); //USB if(DEBUG) Log.i(TAG, "Setting UsbManager -&gt; MainMenu"); UsbManager mUsbManager = (UsbManager) getSystemService(Context.USB_SERVICE); PendingIntent mPermissionIntent; if(DEBUG) Log.i(TAG, "Setting PermissionIntent -&gt; MainMenu"); mPermissionIntent = PendingIntent.getBroadcast(this, 0, new Intent(ACTION_USB_PERMISSION), 0); if(DEBUG) Log.i(TAG, "Setting IntentFilter -&gt; MainMenu"); IntentFilter filter = new IntentFilter(ACTION_USB_PERMISSION); if(DEBUG) Log.i(TAG, "Setting registerReceiver -&gt; MainMenu"); registerReceiver(mUsbReceiver, filter); if(DEBUG) Log.i(TAG, "Setting requestPermission -&gt; MainMenu"); mUsbManager.requestPermission(device, mPermissionIntent); } </code></pre> <p>I get the Force Close dialog when I uncomment the line <code>mUsbManager.requestPermission(device, mPermissionIntent);</code> If I comment it, I don't get the force close but it doesnt work. I think the problem is in:</p> <pre><code>private static final String ACTION_USB_PERMISSION = "com.multitools.andres.LCView"; </code></pre> <p>On Google's example it is as:</p> <pre><code>private static final String ACTION_USB_PERMISSION = "com.android.example.USB_PERMISSION"; </code></pre> <p>But I dont know what exactly I have to put there and i could not find any explanation about that. What i have to put there or where is my error ? Here is the LogCat i am getting when i start my application:</p> <pre><code>04-17 00:57:50.944: I/dalvikvm(1362): threadid=3: reacting to signal 3 04-17 00:57:51.331: I/dalvikvm(1362): Wrote stack traces to '/data/anr/traces.txt' 04-17 00:57:51.981: I/(1362): onCreate() -&gt; MainMenu 04-17 00:57:52.013: I/dalvikvm(1362): threadid=3: reacting to signal 3 04-17 00:57:52.151: I/dalvikvm(1362): Wrote stack traces to '/data/anr/traces.txt' 04-17 00:57:52.570: I/dalvikvm(1362): threadid=3: reacting to signal 3 04-17 00:57:52.731: I/dalvikvm(1362): Wrote stack traces to '/data/anr/traces.txt' 04-17 00:57:53.122: I/dalvikvm(1362): threadid=3: reacting to signal 3 04-17 00:57:53.231: I/dalvikvm(1362): Wrote stack traces to '/data/anr/traces.txt' 04-17 00:57:53.390: I/(1362): Setting UsbManager -&gt; MainMenu 04-17 00:57:53.451: I/(1362): Setting PermissionIntent -&gt; MainMenu 04-17 00:57:53.470: I/(1362): Setting IntentFilter -&gt; MainMenu 04-17 00:57:53.470: I/(1362): Setting registerReceiver -&gt; MainMenu 04-17 00:57:53.511: I/(1362): Setting requestPermission -&gt; MainMenu 04-17 00:57:53.660: I/dalvikvm(1362): threadid=3: reacting to signal 3 04-17 00:57:53.791: I/dalvikvm(1362): Wrote stack traces to '/data/anr/traces.txt' 04-17 00:57:54.311: I/dalvikvm(1362): threadid=3: reacting to signal 3 04-17 00:57:54.401: I/dalvikvm(1362): Wrote stack traces to '/data/anr/traces.txt' 04-17 00:57:54.531: I/(1362): onCreateOptionsMenu() -&gt; MainMenu 04-17 00:57:54.683: I/dalvikvm(1362): threadid=3: reacting to signal 3 04-17 00:57:54.772: I/dalvikvm(1362): Wrote stack traces to '/data/anr/traces.txt' 04-17 00:57:55.186: I/dalvikvm(1362): threadid=3: reacting to signal 3 04-17 00:57:55.291: I/dalvikvm(1362): Wrote stack traces to '/data/anr/traces.txt' 04-17 00:57:55.661: I/dalvikvm(1362): threadid=3: reacting to signal 3 04-17 00:57:55.751: I/dalvikvm(1362): Wrote stack traces to '/data/anr/traces.txt' 04-17 00:57:55.791: D/gralloc_goldfish(1362): Emulator without GPU emulation detected. 04-17 01:11:47.323: I/dalvikvm(1459): threadid=3: reacting to signal 3 04-17 01:11:47.720: I/dalvikvm(1459): Wrote stack traces to '/data/anr/traces.txt' 04-17 01:11:48.124: I/dalvikvm(1459): threadid=3: reacting to signal 3 04-17 01:11:48.291: I/dalvikvm(1459): Wrote stack traces to '/data/anr/traces.txt' 04-17 01:11:48.452: I/(1459): onCreate() -&gt; MainMenu 04-17 01:11:48.691: I/dalvikvm(1459): threadid=3: reacting to signal 3 04-17 01:11:48.813: I/dalvikvm(1459): Wrote stack traces to '/data/anr/traces.txt' 04-17 01:11:49.172: I/dalvikvm(1459): threadid=3: reacting to signal 3 04-17 01:11:49.321: I/dalvikvm(1459): Wrote stack traces to '/data/anr/traces.txt' 04-17 01:11:49.653: I/dalvikvm(1459): threadid=3: reacting to signal 3 04-17 01:11:49.821: I/dalvikvm(1459): Wrote stack traces to '/data/anr/traces.txt' 04-17 01:11:49.901: I/(1459): Setting UsbManager -&gt; MainMenu 04-17 01:11:49.931: I/(1459): Setting PermissionIntent -&gt; MainMenu 04-17 01:11:50.021: I/(1459): Setting IntentFilter -&gt; MainMenu 04-17 01:11:50.031: I/(1459): Setting registerReceiver -&gt; MainMenu 04-17 01:11:50.051: I/(1459): Setting requestPermission -&gt; MainMenu 04-17 01:11:50.071: D/AndroidRuntime(1459): Shutting down VM 04-17 01:11:50.133: W/dalvikvm(1459): threadid=1: thread exiting with uncaught exception (group=0x409c01f8) 04-17 01:11:50.231: I/dalvikvm(1459): threadid=3: reacting to signal 3 04-17 01:11:50.331: I/dalvikvm(1459): Wrote stack traces to '/data/anr/traces.txt' 04-17 01:11:50.401: E/AndroidRuntime(1459): FATAL EXCEPTION: main 04-17 01:11:50.401: E/AndroidRuntime(1459): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.multitools.andres/com.multitools.andres.MainMenu}: java.lang.NullPointerException 04-17 01:11:50.401: E/AndroidRuntime(1459): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956) 04-17 01:11:50.401: E/AndroidRuntime(1459): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981) 04-17 01:11:50.401: E/AndroidRuntime(1459): at android.app.ActivityThread.access$600(ActivityThread.java:123) 04-17 01:11:50.401: E/AndroidRuntime(1459): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147) 04-17 01:11:50.401: E/AndroidRuntime(1459): at android.os.Handler.dispatchMessage(Handler.java:99) 04-17 01:11:50.401: E/AndroidRuntime(1459): at android.os.Looper.loop(Looper.java:137) 04-17 01:11:50.401: E/AndroidRuntime(1459): at android.app.ActivityThread.main(ActivityThread.java:4424) 04-17 01:11:50.401: E/AndroidRuntime(1459): at java.lang.reflect.Method.invokeNative(Native Method) 04-17 01:11:50.401: E/AndroidRuntime(1459): at java.lang.reflect.Method.invoke(Method.java:511) 04-17 01:11:50.401: E/AndroidRuntime(1459): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784) 04-17 01:11:50.401: E/AndroidRuntime(1459): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551) 04-17 01:11:50.401: E/AndroidRuntime(1459): at dalvik.system.NativeStart.main(Native Method) 04-17 01:11:50.401: E/AndroidRuntime(1459): Caused by: java.lang.NullPointerException 04-17 01:11:50.401: E/AndroidRuntime(1459): at android.os.Parcel.readException(Parcel.java:1333) 04-17 01:11:50.401: E/AndroidRuntime(1459): at android.os.Parcel.readException(Parcel.java:1281) 04-17 01:11:50.401: E/AndroidRuntime(1459): at android.hardware.usb.IUsbManager$Stub$Proxy.requestDevicePermission(IUsbManager.java:535) 04-17 01:11:50.401: E/AndroidRuntime(1459): at android.hardware.usb.UsbManager.requestPermission(UsbManager.java:361) 04-17 01:11:50.401: E/AndroidRuntime(1459): at com.multitools.andres.MainMenu.onCreate(MainMenu.java:80) 04-17 01:11:50.401: E/AndroidRuntime(1459): at android.app.Activity.performCreate(Activity.java:4465) 04-17 01:11:50.401: E/AndroidRuntime(1459): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049) 04-17 01:11:50.401: E/AndroidRuntime(1459): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920) 04-17 01:11:50.401: E/AndroidRuntime(1459): ... 11 more 04-17 01:11:50.751: I/dalvikvm(1459): threadid=3: reacting to signal 3 04-17 01:11:50.851: I/dalvikvm(1459): Wrote stack traces to '/data/anr/traces.txt' 04-17 01:11:51.331: I/dalvikvm(1459): threadid=3: reacting to signal 3 04-17 01:11:51.403: I/dalvikvm(1459): Wrote stack traces to '/data/anr/traces.txt' 04-17 01:11:51.774: I/dalvikvm(1459): threadid=3: reacting to signal 3 04-17 01:11:51.961: I/dalvikvm(1459): Wrote stack traces to '/data/anr/traces.txt' </code></pre> <p>Thanks you :)</p>
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    2. COmUsbManager.requestPermission(device, mPermissionIntent); the line that if a comment it the application does not FC and i think is because of private static final String ACTION_USB_PERMISSION = "com.multitools.andres.LCView"; because i dont know what to put there
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