On Mon, 4 Apr 2005, James Lamanna wrote: > I have some USB protocol questions about initial device setup. > I'm trying to write my own USB stack for an Atmel AT43USB355E microcontroller > (Atmel has a USB library but its binary only....). > This chip has 3 Functional Endpoints and 2 Hub ports.
By which I assume the controller includes a built-in hub with two external ports. Do the three function endpoints all belong to the same function, or are there multiple functions? > I noticed on device plug-in the GET_DESCRIPTOR control message is showing up > on the Hub endpoint 0 of the microcontroller, as opposed to function endpoint > 0. > Is this always what happens when plugging in a device with a hub? > Or is my hardware just weird? This is what always happens. Since the function is _behind_ the hub, obviously the host can't enumerate the function until it has enumerated the hub. > Also, the host sends my device a Get Descriptor request initially. > As far as I can tell, the device should only respond with the first 8 > bytes of the device descriptor (just to get maxPacketLength)? The device should respond with as many bytes of data as the host asks for (up to 18, the maximum size of a device descriptor). Why would you think you should only send 8 bytes? Is that what the host asks for? What host are you using (i.e., what OS and what version)? > This hardware is giving me fits trying to get past the initial stages, > either my linux box says reading the device descriptor timed out, or > it read 0 bytes (in hub.c). Does this occur when reading the device descriptor for the built-in hub or the device descriptor for another function? Does the controller already contain a built-in stack for running the built-in hub, or must you write that also? Alan Stern ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
