USB

USB Drives under Windows

Some references:

• http://www.uwe-sieber.de/usbtrouble_e.html
• http://www.uwe-sieber.de/usbstick_e.html
• http://www.ghacks.net/2008/10/16/how-to-create-multiple-usb-stick-partitions/

Creating multiple partitions on a single USB drives

From [1], Nearly all USB flash drives pretend to have a removable media (even it's a lie), so Windows detects them as 'removable'. On drives with a removable media Windows 2000 and higher supports only one partition. Finally it's a single bit in the device's device descriptor, the removable media bit (RMB). If you take away the RMB then Windows sees the drive as local disk and multiple partitions work.

To have Windows not to handle USB drives as removable media, just install a filter driver that will remove the RMB flag. Check here.

USB Power Control

Reference

• USB power switch
• Use Linux to control outlet (hub-ctrl.c)

wget http://www.gniibe.org/oitoite/ac-power-control-by-USB-hub/hub-ctrl.c
sudo apt-get install libusb-dev
gcc -lusb hub-ctrl.c -o hub-ctrl

#Get info on USB devices:
lsusb -t
sudo ./hub-ctrl -v
# Hub #0 at 001:056
#  INFO: individual power switching.
#  WARN: Port indicators are NOT supported.
#  Hub Port Status:
#    Port 1: 0000.0100 power
#    Port 2: 0000.0303 lowspeed power enable connect
#    Port 3: 0000.0100 power
# Hub #1 at 001:055
#  INFO: individual power switching.
#  WARN: Port indicators are NOT supported.
#  Hub Port Status:
#    Port 1: 0000.0103 power enable connect
#    Port 2: 0000.0100 power
#    Port 3: 0000.0103 power enable connect

Let's for instance cut device on port 3 at 001:055 (i.e. bus 1, dev 55):

beq06659@nxl67002ux ~/tmp/hub-ctrl (master)
sudo ./hub-ctrl -b 1 -d 55 -P 3 -p 0
# Hub #0 at 001:056
#  INFO: individual power switching.
#  WARN: Port indicators are NOT supported.
#  Hub Port Status:
#    Port 1: 0000.0100 power
#    Port 2: 0000.0303 lowspeed power enable connect
#    Port 3: 0000.0100 power
# Hub #1 at 001:055
#  INFO: individual power switching.
#  WARN: Port indicators are NOT supported.
#  Hub Port Status:
#    Port 1: 0000.0103 power enable connect
#    Port 2: 0000.0100 power
#    Port 3: 0000.0000

• Controlling Power on a USB Hub

Advices:

• Avoid hub with cheap Genesys Logic chip inside.
• Good hub is Linksys 4-port hub, with external power cable.