(This page is currently work-in-progress.)

Introduction

The information here is about being able to use Ubuntu to switch real world appliances using the USB interface on your computer.

The technical details can be found here: http://www.gniibe.org/ac-power-by-usb/ac-power-control.html

Part of the process is finding USB hubs which allow the power on their ports to be switched. Many USB hubs have chips that support this, but are not necessarity wired up.

Checking your hardware

The following requires use of the command line interface (Accessories->Terminal). Before plugging in your USB hub and do the following:

$ lsusb > a.txt

Plug in you USB hub and use the above command again to see how you hub has been detected.

$ lsusb > b.txt
$ diff a.txt b.txt | tail -n 1 | awk '{print $7}' > usbhub.txt
$ rm a.txt b.txt
$ cat usbhub.txt | xargs lsusb -d

This chould report something like

Bus 003 Device 010: ID 05e3:0605 Genesys Logic, Inc. USB 2.0 Hub [ednet]

or

Bus 003 Device 007: ID 0409:0059 NEC Corp. HighSpeed Hub

The following can be used to get the full details on the hub hardware (administration password required):

cat usbhub.txt | xargs sudo lsusb -v -d

Under the 'Hub Descriptor' heading you should expect something like the following..

  wHubCharacteristic 0x00a9
    Per-port power switching
    Per-port overcurrent protection
    TT think time 16 FS bits
    Port indicators
  bPwrOn2PwrGood       50 * 2 milli seconds
  bHubContrCurrent    100 milli Ampere
  DeviceRemovable    0x48
  PortPwrCtrlMask    0xc0
 Hub Port Status:
   Port 1: 0000.0100 power
   Port 2: 0000.0100 power
   Port 3: 0000.0100 power
   Port 4: 0000.0100 power