Regarding Android Accessory mode and normal usb connectivity

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I just started looking into OAPavailable in android.I came accros few doubts

  1. Is accessory mandatory my android phone/table for me to talk to an external device over usb?Cant I talk to my external hardware using normal usb mode?Accessory mode means the phone will always be USB device and my external device will be the USB host.My application in phone should be able to talk to the external hardware regardless whether its a host or a USB device

  2. What exactly are the difference between a USB host and device? Is it just that who powers the bus?When two devices connect how the device say "hey i will be the host and u be the device?"

In short my aim is I want to create an application that can talk to a usb device connected regardless its a usb device or a usb host.Can I acheive it using UsbManager apis without depending on OAP of Android

1
androidembeddedusb

1 Answers

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If you want to be able to work in either situation, you will basically have to write two communication subsystems, one using the APIs appropriate for each case.

It will be the external device and cabling which determines which mode is active (though if the phone cannot be a host, the connection of something external which requires that will be ignored, meaning no communication).