[kwlug-disc] USB Webcam curious behaviour

[Chris Irwin]

On Sat, 2010-08-14 at 09:20 -0700, Raul Suarez wrote:
> When I plug just the usb webcam it works, when I have the wireless mouse plugged it stops working.

It could also be a power issue. From my limited understanding of USB
(and a quick check of wikipedia appears to confirm this), devices can
accept power in 1 to 5 units of 100mA, where 500mA is the maximum the
bus supports. So if your camera required higher power (say 4 or 5
units), and your wireless mouse dongle required enough power to push
them over the limit (say 2 units), there would be insufficient power to
run both.

http://en.wikipedia.org/wiki/Universal_Serial_Bus#Power

Usually USB ports are in pairs on the same bus. If you had four ports,
two would probably be on a separate bus, which should allow you to run
the devices together. Assuming it is a power issue.

-- 
Chris Irwin <chris at chrisirwin.ca>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 198 bytes
Desc: This is a digitally signed message part
URL: <http://kwlug.org/pipermail/kwlug-disc_kwlug.org/attachments/20100815/f0be41e2/attachment.sig>