Control USB Power based on temperature monitoring in Mac OS X

October 16, 2007 11:17 AM

I have a laptop cooling fan which runs on USB power. It works well but it's a fairly monotonous drone. The internal fans are linked to the cooling unit and the temperature monitor, so they operate based on the current temperature. Is there any way I can control the USB fan based on temperature as well?

MacBook Pro 2.16GHz 2GB RAM C2D running Mac OS X 10.4.10

I am really looking for an easy way to control power to the USB port based on temperature monitoring. At the most fundamental level, I'd like to do is write the following (in AppleScript, Cocoa Objective-C, Java, etc.):


temperature = TempMonitor.temp();

if (someUSBIdentifier == FAN) {
if (temperature <> someUpperLimit) {
USB.port(2).power = on;
}
}


I'd like to find some way to identify the fan through the port, so that I don't end up powering off an external laptop just because the machine heats up. I've looked through the System Profiler and can't find any identifying information for it, so I was wondering if there is some other profile or fingerprint I can pick up.

I've installed the Mac OS X USB SDK 1.8.7 for XCode and I will play around with that, but I was just looking to see if anyone had any ideas. Thanks.

posted by Mr. Banana Grabber to Computers & Internet (3 answers total)

You don't need active cooling - passive would be just fine... IMO

Basically the underside/back end of the machine typically simply needs to be lifted to get more airflow to it's in-built fan/intake(s).

(I have 3 Targus CoolPads - I swear by them)
posted by jkaczor at 11:24 AM on October 16, 2007

Response by poster: I'm using a Belkin F5L001 Cooling Stand - I like it so far, but when the enclosure temperature is down to 85?, there's no reason for the fans to be humming.

I definitely need the active cooling though, the temperature range before I started using it was 98? - 105? for the enclosure bottom and 140? to 160? for the CPU. Now it's down to 78? - 90? for the enclosure and 120? - 140? for the CPU. Much more comfortable when I'm using it.
posted by Mr. Banana Grabber at 11:38 AM on October 16, 2007

I have one of those kinda things too; the USB connection is just wired for power. if it's not showing up in System Profiler it's probably set up the same way. (mine's pretty obvious - the USB cable plugs in where the AC adapter plugs in.) you could build something (say, with a BASIC stamp or one of those Atmel things Make likes) with a USB port already on it to vary the voltage going into the fan, which would work, but would require soldering.
posted by mrg at 3:24 PM on October 16, 2007