From owner-freebsd-hackers  Mon Oct 28  5:56:45 2002
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Date: Mon, 28 Oct 2002 08:56:35 -0500
From: Joe Sunday <sunday@csh.rit.edu>
To: David Nicholas Kayal <davek@saturn5.com>
Cc: freebsd-hackers@FreeBSD.ORG
Subject: Re: i am looking for a 5 volt signal
Message-ID: <20021028135635.GA28293@csh.rit.edu>
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On Sun, Oct 27, 2002 at 09:12:33AM -0800, David Nicholas Kayal wrote:

> I'm looking for a 5 volt signal.
> 
> I have wires plugged into pins 2 and 25 of the parallel port.
> 
> I have written a small program:
> 
> #include <stdio.h>
> #include <dev/ppbus/ppi.h>
> #include <dev/ppbus/ppbconf.h>
> 
> int main()
> {
>   int fd;
>   while(1)
>     {
>       ioctl(fd, PPISDATA, 255);
>     }
> }

PPISDATA actually takes an int* argument. (The man page may be a tad
confusing here.)

Try
int main() {
    int fd;
    int d = 255;
    fd = open( "/dev/ppi0", O_RDWR );

    ioctl( fd, PPISDATA, &d );

    return 0;
}

The port should hold the last value you send to it, there's no need
to continually refresh it.

--Joe

-- 
Joe Sunday <sunday@csh.rit.edu>  http://www.csh.rit.edu/~sunday/
Computer Science House, Rochester Inst. Of Technology

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