Re: Serial IR receiver problem

[nobody@xxxxxxxxxxxx (Dave Houston)]

Erk <mrman_man@xxxxxxx> wrote:

>Thanks for yor reply.
>
>Yes it's a circuit from the winlirc web page: http://www.lirc.org/images/schematics.gif.
>
>I tried to use a longer cable to the skype adapter, separating them
>with about 3 meters - no change.
>
>I also tried to move the skype adapter to an externaly powered USB
>hub, but nothing changed.
>
>I also moved the skype adapter to another computer (a laptop) to rule
>out EMI interference. I put it close to the computer with the IR
>device and close to the IR device itself. This didn't affect the IR
>device at all, so it's some "internal"
>mayham with the com-port and USB.
>
>The error is very consistent in itself. Connect the skype adatper and
>the IR will only recognize one signal out of about 20 or so.
>Disconnect the skype adapter and the IR device will recognize all
>signals transmitted from the remote.
>
>I'm puzzled...

I've never heard of true USB interfering with a COM port. Is the Skype
device a true USB device or does it use a virtual comm port? Even with a
virtual port I can't see the driver messing with the COM port DCD line.

You can use your soundcard to see the IR signal but you'll need to attenuate
the signal since you're pulling the output up to DCD which I think is
10-12V. For a 5V signal see...

     http://davehouston.net/learn.htm

There's free soundcard oscilloscope software at...

     http://www.zelscope.com/

I would not entirely rule out EMI. You may need both devices using the same
ground and power to see it.