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[Lcdproc] cwlinux usb 12832

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  • From: dplatt AT (Dave Platt)
  • Subject: [Lcdproc] cwlinux usb 12832
  • Date: Thu Feb 14 18:43:01 2008

list-catcher wrote:
> Hello,
> This is probably a really noob question but I don't see it anywhere
> obvious in the docs. I've got a cwlinux usb 12832. In LCDd.conf
> model=12832 doesn't work but bumps back to 12232. Also I can't figure
> out what to set DEVICE to. I have no /dev/lcd.
> lsusb gives me
> Bus 003 Device 002: ID 067b:2303 Prolific Technology, Inc. PL2303 Serial
> Port
> Ok, it's a USB->Serial converter. So...what serial port?

Depends on your Linux distribution and whether you're using the "udev"
feature set.

In a non-udev environment it'll probably be /dev/ttyUSB0 or something
like that.

In a udev environment, the device may appear automagically in
/dev/usb/ (as /dev/usb/ttyUSB0) when the device is plugged in.

In both of the above cases, the specific TTY identifier will depend on
whether this is the only USB/serial converter attached, and (if not)
the order in which the devices are enumerated by the kernel.

I believe that some (or all?) PL2303 devices have a built-in unique
serial number. If so, you can add a customized rule to your udev
ruleset (probably in /etc/udev/rules.d/) to create a uniquely-named
device symlink for this device, based on the device serial number,
each time it's plugged in. Thus, you could have /dev/lcd created as
a symlink to the appropriate /dev/usb/whatever device. This will
eliminate possible problems if you have multiple USB serial adapters
connected, as the symlink will be created only for the adapter with the
correct serial number.

To do this you'll need to understand how to write udev rules for your
kernel revision and distribution.

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