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PO
 

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  1. PO
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    <p>My guess is you're app probably establish the communication with a listener that looks for a connection just being made of the USB device. If the printer is already connected and your app is waiting on that listener, it will not happen since your call back function will not be called, the usb printer already being there before your app is running. This is a guess since I did not see your code but I saw that kind of behavior for that reason in other cases.</p> <p>EDIT after getting more info in the question. As I said in my comment, i believe the event lauching your app (the ...USB_DEVICE_ATTACHED) is not happenning if the device is already connected at boot time. To prove that, you should add a lot of traces with <a href="http://developer.android.com/tools/help/logcat.html" rel="nofollow">logcat (viewing)</a> and <a href="http://developer.android.com/tools/debugging/debugging-log.html" rel="nofollow">(writing)</a>in your code, inside your onCreate, onResume and may be elsewhere. Do that and you will see if each section perform what you expect. My guess is it's not executed at all when you boot and the USB device is already connected. If I understand what you want is this. When the device is being connected, you want to launch you app. But if the device is already there at boot time, you want your app to be launched anyway and connect to the USB. The way I would approach this is by having you app looking for the presence of the targeted USB device. The presence is different than the "USB_DEVICE_ATTACHED" which means it just got connected in the last few milliseconds. I would also register a listener on "USB_DEVICE_ATTACHED" that would launch your code on device connection and I would set also a listener on "BOOT_COMPLETED" to launch your app after your tablet booting sequence. </p>
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    1. POOpen USB host communication on a device already connected at the launch of the application
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    1. USSylvain Huard
    1. USSylvain Huard
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    1. COI don't understand precisely your answer :/. Could you explain me about the listener that you seak about ?
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      1. USMonkeyJLuffy
    2. COIn your first case when it works, it's because you registered a listener to the event of this USB device getting connected. This listener is launching your app on the occurance of that event and you make the connection. It's the same as when you want your app to be launch at boot time, you set-up a listener on "BOOT_COMPLETE". In your case, you have set it on the connection of that USB device. But, nothing prevents you from launching it manually and it should work. Look at the detail of what happen in the code triggered by the listener. It will show you how to establish the connection
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      1. PO
      1. USSylvain Huard
    3. COHere you are my code. Please, could you explain "But, nothing prevents you from launching it manually and it should work.". Because we try it, without succes. Maybe is the way to made it that it wrong. (Do you speack french ?)
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      1. USMonkeyJLuffy
 

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