You say you can maintain one transaction per microframe -- what's the bottleneck?


How big are the buffer sizes in the URBs that you queue for your transfers? There's no reason for them to be limited to 512 bytes.

Alan Stern


Thanks for pointing that out Alan. I just tested it and I can
get up to 3 transactions per microframe with bigger buffers
which translates into 12Mb/sec. That's good enough for our
current camera.

What do you think determines this current limit of 3 transactions
per microframe? Is it primarily cpu speed that sets the amount
of time it takes to get another transaction going? I suspect it
is not the FX2 chip, but I haven't verified that yet.

It would still be nice to have high-bandwidth interrupt
packets (24Mb/sec guaranteed bandwidth) eventually. But for now
I'm happy with 12Mb/sec bulk transactions.

Alan and David, thanks for your help.

Richard

--
Richard Stover                       email: [EMAIL PROTECTED]
Detector Development Laboratory      http://www.ccd.ucolick.org
UCO/Lick Observatory
Natural Sciences Bldg. 2, Room 160
University of California
Santa Cruz, CA 95064  USA



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