Re: Serial IR receiver problem

[andrew@xxxxxxxxxxxxxxxxxxxx (Andrew Gabriel)]

In article <1180175120.239232.39600@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
	mrman_man@xxxxxxx writes:
> Hello all
>
> I have a strange problem. I use a home built serial IR receiver
> attached to the com-port of my computer. I use Winlirc and Girder to
> perform different tasks from my remote control. It has worked very
> well for many years now.
>
> The other day I installed a Skype adapter, AU-600. I trhink this
> device works more or less as a modem with voice capablities. It
> enables me to use my regular phone with Skype, making and receiving
> calls.
>
> It's an USB device and after I installed it my IR receiver works very
> poorly. It seems that the signal received is very inconsistent. I've
> tried to re-learn some remote codes, but Winlirc reports inconsistent
> signal. When I pull the plug on the skype adapter, evereything is back
> to normal.
>
> Does anyone has any ideas what can cause this? I've tried to use
> different USB ports on the computer, different USB cables but no
> change. I tried to change the IRQ channel of the com port, but that
> didn't have any effect.

I suspect that the USB driver (or possibly the Skype application)
is preventing the serial port driver from emptying the 16550A FIFO
before it wraps, resulting in lost characters. At 115200, the serial
port driver must service a 16550A almost once every millisecond to
avoid character loss. What speed is your IR interface? Do you have
any flow control? Can you run it at a lower speed to see if that
helps? I'm not familiar with how Windows handles serial ports, but
on Unix systems, the serial port driver's interrupt handler is
normally one of the highest interrupt priority interrupt handlers,
and that's for a good reason, as 16550A type ports have more
taxing real-time demands than every other peripheral on a standard
PC system.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]