I bought these USB
powered lights from Woot! recently,
with grand plans of using them with a continuous build/test/install rig to
provide visual notification of when a build/test/install completed or failed
or something.
Somewhat to be expected for the price, they merely draw power from the USB
port, and have a physical switch on each light. I want something software
controlled though.
There's something in /sys/bus/usb/devices/*/power/level that looked
promising, but seems to be a red-herring (at least for non-devices. I was
able to turn off a USB mouse and a Bluetooth adapter this way)
What I'd like (and it probably exists, I just have to find it), is
a USB device that presents itself to the operating system, and its sole
purpose is providing pass-through power to a USB A-type receptacle on
itself. This would then be manageable by the operating system.
What I'm possibly trying to say here is a small, specialised, one port USB
hub. Hmm... I'll have to see if I can borrow a USB hub from someone to test
this theory. I've never had a need to own one.
Update: my adventures continue here.