Switching on/off 5V power to a USB port

[Devin Teske]

> -----Original Message-----
> From: owner-freebsd-current at freebsd.org [mailto:owner-freebsd-
> current at freebsd.org] On Behalf Of Ron McDowell
> Sent: Tuesday, April 03, 2012 3:14 PM
> To: freebsd-current
> Subject: Switching on/off 5V power to a USB port
> 
> I just got a little USB powered fan and it sure would be nice if I could
> have cron on my FreeBSD box turn it on or off at certain times by
> switching off the 5V line on a USB port.  Anyone know how I can do
> that?  Thanks.

Alternatively, you could just plug your USB fan into your monitor.

A fellow engineer and I discovered that most monitors power-down the USB ports
when entering power-save mode (with Dell, HP, and Viewsonic, this is whenever
the screen blanks due to inactivity; are you using DPMS and/or greensaver?).

Walking away from the PC will cause the fan to [eventually] turn off, while
waggling the mouse brings it back to life.


> BTW this is a pretty decent fan for the money. :)
> http://www.amazon.com/gp/product/B0033WSDOM/

We didn't have a USB powered fan, so we actually wired an internal case-fan to
the 5V lead and went that route. Nice fan though.
-- 
Devin

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