From: Xam R. Time (xam_at_chalupa.wi2600.org)
Date: 2002-04-13 20:38:04 UTC
> More importantly, the USB 1.1 and 2.0 specs say that max length is 5.0
> meters (16.4 ft). I don't think you'll have a lot of luck pushing it
Hrm.. The way I read, is that they state the length limit as a function of time, not outright length of conductors. "The cable length was limited by a cable delay spec of 26ns to allow for reflections to settle at the transmitter before the next bit was sent." So, our cable can't add more than 26 nanoseconds of delay.. Hrm, if the speed of light is 186 miles per one hundred thousand nanoseconds, 26 ns wouldbe about 0.004836 miles. Assuming propogation velocity of 80% (good teflon cable), 20.4 ft of cable would present roughly 26 ns of delay. That's almost long enough for the ideas I had in mind.
Heh, we're never ones to actually follow recomended specs, are we? ;)
> See: http://www.usb.org/developers/usbfaq.html#cab_sol
Very informative for sure, thanks.
> And now you know why we use miniPCI @ Musenki. :-)
Yes, miniPCI is probably the best option for the boards you're working on with the applications you have in mind.
--Tk