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To: Ron McDowell <rcm@fuzzwad.org>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Tue, 03 Apr 2012 17:13:47 EST."
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Date: Tue, 03 Apr 2012 22:20:25 +0000
Message-ID: <57208.1333491625@critter.freebsd.dk>
Cc: freebsd-current <freebsd-current@freebsd.org>
Subject: Re: Switching on/off 5V power to a USB port
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In message <4F7B761B.4030104@fuzzwad.org>, Ron McDowell writes:

>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.

I have only found very few USB ports where it was possible to reliably
control power with a published interface.  Most USB-controllers support
doing it, but most motherboards don't mount the necessary FET.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.