Parallel port I/O problems

GENERAL Cafe
1

Hi!
I’ve used QNX 4 & many other OSs for years and used the parallel port
(0x378) for I/O. Under QNX 6 I have tried several programs that are intermittant at best an do not seem to operate at all in other cases.
I’m a newbie with QNX 6 so bear with me…

I have a scope on the outputs.

I have alread slayed devc-par.

Here is a code snippet:

int main( void )
{
if (-1 == ThreadCtl( _NTO_TCTL_IO, 0 ))
{
fprintf(stderr, “Failed to acquire hardware access privity.\n”);
exit (EXIT_FAILURE);
}
printf("\n\tNO mmap_device_io\n" );
out8(0x378, 0xff);
return (EXIT_SUCCESS);
}

The port works with a quick DOS Floppy boot with debug
out 378 1
out 378 0
etc.
so BIOS is OK.

Puzzled, HELP!!!

Thanks

2

It looks alright (not much can go wrong in 5 lines of code :slight_smile:.

This is x86 right ? (if not you’ll most likely need mmap_device_io).

Are you running as root ?

Didn’t call your program “test” did you ?

3

X86 is correct.
Running as root, (also setuid)
Compile command is:
qcc rout.cc -o ro
followed by
chmod 4755 ro
Both issued as root.

:confused:

What’s really puzzeling is it occassionally works. This is actually a simplified version that doesn’t work.

I originally had a more complicated version that repeated 20 times with 50ms between outputs of 0xff & 0x00.
Scope is on pins 4 & gnd. DC coupled.

I plan to try on another computer (swap drive).
Computer is a Dell. Port is on motherboard, and as previously stated
works when booted into DOS with debug.

Thanks again for any help.

4

Not that it should matter, but you could try renaming to rout.c (from rout.cc) in order to compile with the C compiler…

Are you slaying devc-par, or did you remove it from the enumeration (see /etc/system/enum/devices/char) ? It could be that if you are slaying it after it has started that it leaves the port in some funny state.

5

THANK YOU!!
Life is logical again. :wink:
It was the removal from the enumeration.

I find it VERY useful to use the parallel port. Low overhead, accurate
(real) timing of functions, etc. It’s almost always there, decoded, and hardly ever used for a printer!!

Mostly it was a mental block. It SHOULD work!

Thanks again,
Merle

6

Sorry to drag up this old thread. But what exactly is “remove it from the enumeration (see /etc/system/enum/devices/char)”

Do I remove the two section starting with devices and have something to do with parallel port or do I just delete the line that says enumerator…?

Thanks