unable to enumerate USB device

[Mikkel L. Ellertson]

Jim wrote:
> To get a hub to work with all devices, hubs must have their own power
> source externally.
> Hubs that get there power source from the computer are the ones that
> give you problems, because of voltage drop across the cable to computer.
> 
Considering the amount of current we are talking about, I do not
think voltage drop is a problem. On the other hand, with a bus
powered hub, all the devices, plus the hub itself, are limited to
the max current of the port you are plugged into. A limit of
500ma/port is common, but it could be less.

Voltage drop = current x resistance
.5v = 500ma x 1 ohms.

Mikkel
-- 

  Do not meddle in the affairs of dragons,
for thou art crunchy and taste good with Ketchup!

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