Reading from the parallelport (a/d Converter) Post: 20369

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Top Forums Programming Reading from the parallelport (a/d Converter) Post 20369 by fab102 on Thursday 25th of April 2002 08:25:43 AM

04-25-2002

Registered User

Reading from the parallelport (a/d Converter)

Hi all
For my Radio-astronomy project, I`d like to read from the parallel port. Signals are coming from a 8bit analog/digital converter over the parallelport.
I`d like to read the signal (endless) and print them out on the screen. I mean in a diagramm, with 2 axis. (Time,sec. and Voltage, V ). Like ploting. With enough bitrate and the putpixel function, that should be like a sinusfunction. (you know what I mean).
All this in Linux C code. The main problem for me, is to read and work with the signals over the port. The graphic part isn`t a problem , I will do that with the GNU g2 graphics Lib.
Here my code to read from the port and print it out on the screen. (very simple).

# include <asm/io.h> /* outb() und inb() */
# include <stdio.h> /* Standart I/O */
# include <unistd.h> /* ioperm() */

# define DATA 0x378 /*Paraport Adresse*/
# define STATUS DATA+1 /*Status Port*/
# define CONTROL DATA+2 /*Control Port*/

int main (void)

{

float x;
int h = 0;
if (ioperm(DATA,3,1))

{
printf("No permission to access the ports \n");
printf("You must be root\n");
exit (1);
}

for (h=1; h <= 10000 ; ++h )

{

x = inb(DATA);
printf(" Signal is %f Volts\n");

}
return (0);
}

But the code doesn`t work, I get allways 0 Volts , it doesn`t matter if the converter is attacht or not.
What I did wrong ????

Here is the orginal QBASIC sourcecode for the project. If someone can help me to port the code to C , that would be nice. Or explaind me each step of the code. (only the datacode, not the graphical stuff).
Here is the link
privat.eure.de/mora/balkonrt.htm

please help me , that would be nice.
Thanks

fab102

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outb_p

OUTB(2) 						     Linux Programmer's Manual							   OUTB(2)

NAME

       outb, outw, outl, outsb, outsw, outsl, inb, inw, inl, insb, insw, insl, outb_p, outw_p, outl_p, inb_p, inw_p, inl_p - port I/O

SYNOPSIS

       #include <sys/io.h>

       unsigned char inb(unsigned short int port);
       unsigned char inb_p(unsigned short int port);
       unsigned short int inw(unsigned short int port);
       unsigned short int inw_p(unsigned short int port);
       unsigned int inl(unsigned short int port);
       unsigned int inl_p(unsigned short int port);

       void outb(unsigned char value, unsigned short int port);
       void outb_p(unsigned char value, unsigned short int port);
       void outw(unsigned short int value, unsigned short int port);
       void outw_p(unsigned short int value, unsigned short int port);
       void outl(unsigned int value, unsigned short int port);
       void outl_p(unsigned int value, unsigned short int port);

       void insb(unsigned short int port, void *addr,
		  unsigned long int count);
       void insw(unsigned short int port, void *addr,
		  unsigned long int count);
       void insl(unsigned short int port, void *addr,
		  unsigned long int count);
       void outsb(unsigned short int port, const void *addr,
		  unsigned long int count);
       void outsw(unsigned short int port, const void *addr,
		  unsigned long int count);
       void outsl(unsigned short int port, const void *addr,
		  unsigned long int count);

DESCRIPTION

       This  family  of  functions  is	used  to do low-level port input and output.  The out* functions do port output, the in* functions do port
       input; the b-suffix functions are byte-width and the w-suffix functions word-width; the _p-suffix functions pause until the I/O completes.

       They are primarily designed for internal kernel use, but can be used from user space.

       You must compile with -O or -O2 or similar.  The functions are defined as inline macros, and will not be substituted in	without  optimiza-
       tion enabled, causing unresolved references at link time.

       You  use  ioperm(2)  or	alternatively  iopl(2) to tell the kernel to allow the user space application to access the I/O ports in question.
       Failure to do this will cause the application to receive a segmentation fault.

CONFORMING TO

       outb() and friends are hardware-specific.  The value argument is passed first and the port argument is passed second, which is the opposite
       order from most DOS implementations.

SEE ALSO

       ioperm(2), iopl(2)

COLOPHON

       This  page is part of release 3.53 of the Linux man-pages project.  A description of the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.

Linux								    2012-12-31								   OUTB(2)