PORTS Forum

Ports and Interfaces => USB => Topic started by: beandigital on February 27, 2013, 09:02:23 am

Title: USB descriptor checker
Post by: beandigital on February 27, 2013, 09:02:23 am

Is there such a program that will check a set of USB descriptors. The trouble is I am writing USB audio class 2.0 descriptors for an FX2LP processor,  and I am finding that Windows complains that it can't start the driver for the device. So is there a way to find out what it doesn't like or a program to check that the descriptors are OK.

Thanks

Jon   

Title: Re: USB descriptor checker
Post by: nvd on February 27, 2013, 09:13:26 am

Considering the variations possible in the descriptor information, I don't think there is any such program available.

The error could be because of improper values of VID,PID, bcdDevice.
If your device is bus powered, you should request for desired power withing spec limit and shouldnt exceed that value.

In case of Audio device, I guess rarely the host will refuse the device if the bandwidth your device desires is not available.

nvd

Title: Re: USB descriptor checker
Post by: beandigital on February 27, 2013, 09:27:24 am

But Windows must have some way to check the descriptor and then decide that it doesn't like it. So there must be a way to find out what it didn't like.

Title: Re: USB descriptor checker
Post by: Jan Axelson on February 27, 2013, 09:46:38 am

I would start by viewing the setupapi log files. Here is one tutorial:

http://sourcedaddy.com/windows-7/using-setupapi-log-file.html

A protocol analyzer is also useful for showing any problems in retrieving descriptors.