Author Topic: USB composite device  (Read 9636 times)

Massimo Manca

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USB composite device
« on: September 15, 2010, 04:51:21 pm »
Until now I designed some boards with USB connection with no more then one functions as HID and CDC.
Now I would experiment to make a composite USB device (HID + CDC + mass storage); so due to the fact that I have no mass storage working software ready I searched and found some examples from core red for LPC1768 (the mcu I am using).
To make a try I mixed the code of CDC with the code of mass storage example but it didn't work, so I supposed to didn't understand the correct way to make a compound device.
I wrote a device descriptor that is the CDC descriptor with added the interfaces of mass storage descriptor and the interrupt handler manages all commands of both, plus the installed handlers of both CDC and MSC.
When I execute the application I don't see any communication between the PC and the device related to the CDC but only related to MSC (that always fails).
So, just to understand better my mistakes:
1 is correct my approach to write the descriptor?
2 due to the fact that I don't see any communication related to CDC, is it possible that I missed something related to end point 0?
3 I suppose that for a composite device I may see on my usb sniffer/monitor communication for both CDC and MSC not necessarily in order but mixed, is this correct?
4 is there any application note or example related to composite usb device that my clarify the general situation?

Jan Axelson

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Re: USB composite device
« Reply #1 on: September 22, 2010, 11:48:50 pm »
See Composite CDC devices here:

http://lvr.com/serport.htm

Jan