[plug] display

[Andrew McMeikan]

Hi all,
	I recently got sick of turning the monitor on in my computer room
just to see if my gateway/server was fully shutdown or not, just so I
could turn it all off again.  Having some vacuum fluorescent displays
lying around, I thought it would be a good status display.  If anyone is
desperately after one, I'm sure I can take small donations in exchange :)
 at the moment I have it using the parallel port, and feeding 5volts from
a separate supply.  I have attached the code in case anyone can think of a
better way (ie. games port has power out, but does it have 3 outgoing TTL
lines?)

	cya,	Andrew...

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-------------- next part --------------
/********************************************************
 *vfd.c  program to drive vacuum fluorescent display	*
 *(c) 31 May 1999  Andrew McMeikan GPL v2		*
 *andrewm at engineer.com ; andrew.mcmeikan at mitswa.com.au	*
 *toggles lines on the parallel port 			*
 *D0 is data						*
 *D1 is clock						*
 *D2 is reset line                                      *
 *this first version uses port at 0x378                 *
 *due to the use of outb macro you must compile with -O *
 *if you want non-root use remember to chmod +s it	*
 ********************************************************/
#define CLOCK 2
#define RESET 4
#define PORT 0x378

#include <unistd.h>
#include <asm/io.h>

void dochar( char);

int main (int argc, char *argv[])
{
int i;
if (argc!=2) 
	{
	printf("%s:must specify text to display (max 16chars)\n",argv[0]);
	printf("%s:eg. %s \"HELLO WORLD\"\n",argv[0],argv[0]);
	return(1);
	}

ioperm(PORT,1,255);
outb(RESET,PORT);
usleep(10);
outb(0,PORT);
usleep(10);
dochar(255);			/* set display mode and brightness */
for (i=0;i!=16;i++)
	dochar(' ');		/* clear all the @ after reset 	*/
for (i=0;(argv[1][i]!=0)&&(i!=16);i++)
	dochar(argv[1][i]);	/* display user string		*/
return(0);			/* exit happy			*/
}

void dochar(char d)		/* this function displays on char */
{
int i;
for (i=7;i>=0;i--)		/* MSB first 	*/
	{
	outb(CLOCK|((d>>i)&1),PORT);
	outb((d>>i)&1,PORT);	/* falling clock latches bit	*/
	}
}