Remote USB switch

[Grey]

I have a high speed USB v2 widget which is a distance from my PC. I also run
different O/S (i.e. Linux) which don't like to see my widget and can cause
crashes. So I have to constantly plug/unplug my widget depending on what I'm
doing. I am concerned about the constant plugging/unplugging and the
mechanical wear/stresses on the connection - I have had a few memory sticks
fail as a result of this.

What I would like is a little circuit which sits in line with the USB widget
and I can turn it on and off via a simple switch. My first thought is
something like a tri-state bi-directional buffer with an enable facility -
or rough it and use a four-pole relay. Whatever, it must not interfere with
the data speed of the widget, so we are talking about something with a high
bandwidth.

Any ideas?

Graham

 

[Ian Stirling]

In sci.electronics.design Grey <grahame9@btinternet.com> wrote:

I have a high speed USB v2 widget which is a distance from my PC. I also run
different O/S (i.e. Linux) which don't like to see my widget and can cause
crashes. So I have to constantly plug/unplug my widget depending on what I'm
doing. I am concerned about the constant plugging/unplugging and the
mechanical wear/stresses on the connection - I have had a few memory sticks
fail as a result of this.

Buy a 1m extender cable.
Job done.

 

[Followups to sci.electronics.design]

In sci.electronics.design Grey <grahame9@btinternet.com> wrote:

What I would like is a little circuit which sits in line with the USB
widget and I can turn it on and off via a simple switch.

Two of the wires in USB are power (5 V and ground) and two are data. If
your widget draws power from USB, you could just leave the data wires
connected and disconnect the +5 V wire, effectively shutting the widget
down. I think USB devices can draw up to 500 mA, so your switch has to
be able to handle that much current.

The best option is probably to make Linux understand your widget - have
you checked for Linux drivers for it? Another option would be to get
Linux to stop probing the USB when it boots up. If you don't have any
other USB devices, you could unload the USB module or build a kernel
without USB support. Or, hack the USB drivers to give up when they see
your particular device type on the wire.

Matt Roberds