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

Alexander McKinney alex_mckinney at net.com
Wed Oct 1 15:48:13 EDT 2003


>> > 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

Actually, this is something that I hope MythLCD does or will do.  Or I will
have to make it do!  :)

ARM




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