Chris Schumann wrote:
> Hey guys,
> 
> I've got a little electronics project I'm working on, and I
> need to send pulses out from a PC that's got Red Hat 9.
> 
> I thought the data strobe on the parallel port would be a
> perfect way to do this, and I'd like to avoid writing "real"
> program, so I'd like to do it using a shell command.
> 
> The external device takes TTL levels, which are abundant
> on the parallel port. I'm hoping to use just two wires.
> 
> I tried changing permissions on /dev/lp0 to a+wr and
> doing "echo > /dev/lp0", but it didn't work.
> "echo > file" puts just a newline in file. One byte.
> 
> Echoing to the port hangs, perhaps waiting for an
> acknowledgement.
> 
> I've also tried looking around for a HOWTO, but it's
> so involved and requires programming (which I can do,
> but would like to avoid).
> 
> I'd appreciate it a lot if someone would point me to
> a site I can read to knock this out. Thanks.
> 
> Chris Schumann
> 
> (Hmmm... maybe I can connect the STROBE to ACK pin...)
> 
> 
My guess is that you don't have the parallel port drivers loaded - do an lsmod 
to see.  If you do, try echo'ing to /dev/lp and /dev/lp1.

You can probably poke around in /proc and figure out where your parallel port is.


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