Hi!

I want to acces a parallel port (in Linux) from FPC 1.0.4 to control a connected LCD display. I did such things in DOS with TP/BP by accessing the hardware of the port directly, but this seems to be a little bit too close to the hardware in linux. Instead, I would like to access the parallel port through its device (i.e. /dev/lp0) and with some ioctrl() calls to access the handshake lines, too.

Should normally be no problem, but I have no idea where to start.

Does anybody have a sample code for that? Also, a easy to understand documentation of all parallel-port ioctrl() functions would be helpful.

mfg

Ing. Rainer Hantsch

Does anybody have a sample code for that? Also, a easy to understand documentation of all parallel-port ioctrl() functions would be helpful.

I don't think the parport has any usable ioctrl(). In most cases using an user space program to control non-printer devices from userspace isn't possible at all due to timing problems.
The only solution that I am aware of is direct port access. But this is no easy task; for example have a look at the graphlcd patch for VDR. There is a small test program (written in C) for some parport dot-matrix displays.

- Sebastian

Hi Rainer!

I'm sorry that I can't help you out with ioctl()s. But: Some time ago I was searching for that (/dev/parport should be the right thing) but didn't find anything. Instead of that I had to directly program the ports.

Look up my K7103 Digital Storage Oscilloscope project at http://k7103.sourceforge.net/
and download the sources. In the source there is a file called osziaccess.pas which does parallel port programming. There is an "ioperm()" call too, this is important. Attention: you need root access to use this call. That is the drawback of that method.

Bye
Hansi