Detecting when a USB device is detached on Android

Question

I've got an Android app that needs to detect when a USB peripheral is attached or detached. It works fine when the peripheral is first attached, but I don't receive any notification (i.e., I don't receive an Intent whose action is ACTION_USB_DEVICE_DETACHED) when it is subsequently detached.

Here's the relevant part of my AndroidManifest.xml:

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

It may also be worth noting that LauncherActivity only exists to start a Service when the device is attached, and to stop the service when it is detached. In either case, LauncherActivity always finishes itself immediately. All of this occurs in LauncherActivity.onCreate.

Any ideas?

Answer 1

USB_DEVICE_DETACHED is a broadcast intent, thus you may want to declare the BroadcastReceiver in manifest with the appropriate intent-filter for detached action, also with meta-data attached. Same goes for USB_ACCESSORY_DETACHED, for who is interested.

Summary:
USB_XXX_ATTACHED is an activity intent
USB_XXX_DETACHED is a broadcast intent

(where XXX = DEVICE | ACCESSORY)

See: http://developer.android.com/guide/components/intents-filters.html

"There is no overlap within these messaging systems: Broadcast intents are delivered only to broadcast receivers, never to activities or services"