Using the serial port for GPIO.

Dave Johnson dave-gnhlug at davej.org
Sat May 13 11:17:01 EDT 2006


Scott Garman writes:
> Tom Buskey wrote:
> > People  usually use the parallel port for this kind of stuff.  8 outputs 
> > and  at least 5 inputs.  More inputs are possible w/ the newer 
> > bidirectional ports.
> > 
> > parpin on sourceforge lets you work on individual pins.  There's tons of 
> > info on using the parallel port for digital I/O out there.
> 
> Thanks Tom, this is extremely useful and exactly what I'm looking for 
> for some of the I/O I'll be doing!
>

/dev/parport0 is your friend.  No kernel work needed.  I use that for
controlling my LCD screen at work.  See http://centerclick.org/lcd/

Note that I've found that most modern PCs provide very poor voltages
on the parallel port (but still within the TTL ranges).  I've even
seen different voltages on the Data and Status Pins on the same port!.

Don't expect to draw very much current from it either.  After much
frustration I ended up adding some octal line drivers with a very wide
input range between the pport and device to boost everything to
acceptable levels.


-- 
Dave




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