[mythtv-users] How about a "Now Recording" red light?

[Christian Hack]

> -----Original Message-----
> From: mythtv-users-bounces at mythtv.org 
> [mailto:mythtv-users-bounces at mythtv.org] On Behalf Of Jim Paris
> Sent: Tuesday, 30 September 2003 4:38 AM
> To: jason at axtools.com; Discussion about mythtv
> Subject: Re: [mythtv-users] How about a "Now Recording" red light?
> 
> 
> > I've not personally done it from myth or Linux for that 
> matter, but I
> > suspect that with a little work that the parallel port 
> would work well.
> 
> 	 ioperm(0x378,1,1);
> 	 outb(inb(0x378)^1,0x378);
> 
> will toggle pin D0 on the parallel port at 0x378.  ioperm() 
> requires uid=0.
> 
> > It outputs TLL voltage levels with sufficient current to 
> drive an LED
> > (with a small series resistor so that you aren't just shorting 5V to
> > ground when it's on).  Under Windows this isn't difficult.  
> 
> Some modern parallel ports use 3.3V signalling.  Also, they can
> typically only source about 2mA, but sink around 24mA, so the 
> best would be to flip the LED and connect one side to +5
> (from an internal connector or ps2/usb/firewire port).
> 

Any average serial port can drive a small LED easily (use a series
resistor of around 1k). You don't even have to worry about setting pins
in most cases. Simply open the port and DTR (and probably RTS too)
become active.

Just another way to do it I guess..

CH