Subject: Re: lost bytes in USB interrupt transfer
To: Edgar =?iso-8859-1?q?Fu=DF?= <>
From: Hans Petter Selasky <>
List: tech-kern
Date: 02/18/2007 20:36:53
On Sunday 18 February 2007 16:40, Edgar Fu=DF wrote:
> I've no idea whether this is in fact a problem with NetBSD's USB stack or
> rather a hardware problem or something else. However, I've also no idea h=
> to track that down and am hoping that knowledgeable people here will be
> able to teach me how to do that.
> I'm trying to communicate to a Mastergard A19 series UPS via USB. Thanks =
> extremly helpful people at Masterguard, I was able to find out that the
> protocol is rather simple. You issue a vendor specific write (bmRequestTy=
> UT_WRITE_VENDOR_ENDPOINT) to the control endpoint, bmRequest 0x0d, put the
> string you would send over the serial line in the data field and read back
> the response from endpoint 1.
> However, about half of the time, the response is missing a few (one to fo=
> or five) characters at the front. As that is an interrupt transfer, I've =
> idea how that may happen. I never experience any other mangling of the
> response string.
> That's on 4.0beta2. Any idea what's happening or how to debug it?
> After all, it's not impossible that the problem lies within the UPS's USB
> module.

How are you communicating with the device?

Using "ugen" ?