[clug] how to configure a second keyboard

Michael Cohen scudette at gmail.com
Sun Nov 11 23:15:06 GMT 2007

On Mon, Nov 12, 2007 at 09:22:36AM +1100, Robert Edwards wrote:
> Michael,
> More details on your serial IR receiver - please!
> Cheers,
> Bob Edwards.

  The serial receiver i built was the one described in
http://lirc.org/receivers.html and the layout I used was in
http://lirc.org/images/irrcv_board.gif. It probably took about 20
minutes to build the first one the next one took 10 minutes etc... (I
built 3) I think the total cost was less than $10 - the IR component
- most expensive part - cost about $2.60 from RS.

There are other references like
http://lnx.manoweb.com/lirc/?partType=section&partName=circuit which try
to build it into the connector but thats just silly because the serial
connector is at the back of the computer and the receiver has to be in
the front so you need to make a serial cable anyway. That reference is
excellent for the software configuration part though (i.e. using xmode2
and irrecord).

I find that you need to be quite specific with the lirc driver (which
you need to compile from source as explained in the lirc reference) -
and set stuff which may be autodetected wrongly. This is what I do in
rc.local: (btw by setting the io and irq you dont need to recompile if
you change them later - most lirc packages have a gui for configuration
but that only configures the defaults and is not needed if you
explicitely set it like this).

setserial /dev/ttyS0 uart none
modprobe lirc_serial io=0x3f8 irq=4 sense=0
/etc/init.d/lirc restart

I find that it takes a little while for the receiver to become ready
(i.e. respond properly) maybe 10 seconds or so - that might be due to
the RC factor on the power regulator taking a while to bring the supply
voltage up if the serial port current is too low (this might be specific
to my mobo).

If your receiver has the sense autodetected wrong it will work really
badly - i.e. you can train it but the training will not be that stable
and will miss many signals which is why I force it now. Often I find
that stray light does affect the receiver (I think it might increase the
voltage bias) so try to put it in a reasonably dark spot. The workable
range with my remote is about 10-15 meters.

This receiver works well - but your mobo _has_ to have real serial ports
not usb/serial - that wont work. One of my new mobos doesnt even have
any serial ports at all - so that makes life more difficult.

You can use a PIC to build a usb receiver but thats beyond the time i
care to invest on it atm. There is a reference for an IR receiver which
uses the sound card which might be nice if anyone got that one to work?


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