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Message
From: "Kirill 'Big K' Katsnelson" <kkm@d...>
Date: Fri, 12 Sep 2003 17:24:18 -0700
Subject: Re: [usb] usb FPGA test
Some time ago, Jimmy wrote...
>hello, would someone tell me how to send a single packet from the usb host
>of computer to the device of FPGA in order to testing core, or which
>software can do it?
Do you mean - send a packet to a device that is not yet enumerated
or addressed? If so, you may use the USB test suite, USBCV, available
for free from usb.org. Select "Debug" option and "Chapter 9 tests", and
you may attempt to talk to you device in separate transactions. However,
there is a catch #22: it needs to be able to enumerate your device, i.e.
retrieve device descriptor over the default pipe.
If you are talking about an enumerated and addressed device that the OS
can see, then, as a rule of thumb (it's true in Linux and Windows with
EHCI controllers, but the scope must be broader than that) the HC sends
packets to the device only when there are any IO pending, and does not
if the host does not do I/O. So, to generate a single IN or OUT packet
you may generate an URB and quickly cancel it - or simply leave it pending
to receive IN or OUT packets every (micro)frame.
-kkm
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