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Author Topic: Low speed USB 2.0 device BOS descriptor  (Read 13541 times)

leeqm

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Low speed USB 2.0 device BOS descriptor
« on: January 16, 2013, 08:00:06 pm »
Hi,


We have a low speed USB HID device failed the BOS descriptor test recently, it turns out have to change in firmware, after reading the USB3.0 spec, still not sure , how to define a BOS descriptor to satisfy the USB2.0 CV test.

Can you help ?

Thanks

Leeqm
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Jan Axelson

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Re: Low speed USB 2.0 device BOS descriptor
« Reply #1 on: January 16, 2013, 10:15:40 pm »
If you can post your descriptor and provide the error message when it failed, someone might be able to help.
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Barry Twycross

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Re: Low speed USB 2.0 device BOS descriptor
« Reply #2 on: January 17, 2013, 04:52:50 pm »
You shouldn't need a BOS descriptor if you don't declare you have one.

A device should only have one if it declares its bcdUSB in the device descriptor is 0210H or greater. (Sec 9.2.6.6 of the USB 3 spec). So if you declare yourself as a plain old USB 2 device (bcdUSB 0200H), then you shouldn't get bothered for it.

Also if you don't support it and someone asks for it, the request should be STALLed. Does you device do that?
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