Hi,
I am newbie to USB protocol.I have read about basic working of USB, how it works, descriptors, endpoints and other related things. I have now taken a sample code for understanding how USB works. I am using the stellaries USB stack and the MSC example. In the stack there is a interrupt handler USB0HostIntHandler which is called continuously which in turn calls other handlers according to ulStatus. According to my reading USB is a polling mechanism.I am not understanding how the above mentioned handler is called continuously, even if there is no change on D+ and D- lines. This is really important for me to understand as it seems everything starts from here in the USB stack.
Regards Rajat