thank a lot for your reply.
how about samsung galaxy S2 that is running on android 2.3.4?
if i not wrong, usb host is only supported in android 3.1 onward. so in android 2.3.4 it is running in accessory mode.
since it running in accessory mode, this mean the accessory will be the USB host and the galaxy S2 will be the USB device. so the powering of the bus will be by the accessory. galaxy S2 support reading of flashdrive in android 2.3.4. if i am connecting the flashdrive to the galaxy S2, who is powering the bus? i know it will be the galaxy S2 but why is this so? arent in accessory mode, the accessory should be powering the bus instead?