From: Russell Williams <russellw@...>
Date: 2006-12-03T03:34:06+09:00
Subject: Re: USB

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javra:
>
>Google for libusb.
>The first two hits are for the *nix project and the Windows port of it.
>Might help. You'd have to write a Ruby-C extension for it though.
>Might turn out to be easier/faster than writing your own USB driver, if
>that's what you meant.

Libusb is reasonably easy to use, but a big catch on *nix is that you =
have to be running as root.  Not a good idea for your entire =
application.  So I found it easier to write a small C daemon that =
listens to a *nix domain socket and send through what it gets to the USB =
device using appropriate libusb calls.  You could also write some =
Ruby-to-libusb wrappers and then write the daemon in Ruby instead of C =
if you wanted to learn the Ruby-to-C interfaces, but in my view that's =
adding needless complexity.  Depending on the type of USB device the =
amount of device control vs. data that you need to make to talk to it =
can be quite complex.  I'm happy to share the daemon source if you send =
me some private mail.
=20
The best way to figure out how to talk to your device is to reverse =
engineer what a manufacturer-provided Windows driver does unless you =
happen to have good device-level USB documentation.  You can do this by =
looking at logs snapped by SnoopyPro.
=20

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