+++ /dev/null
->From joev@mikasa.WPI.EDU Sun Jan 1 18:34:40 EST 1995
-Article: 144 of comp.os.linux.development.system
-Path: bigblue.oit.unc.edu!concert!gatech!bloom-beacon.mit.edu!news2.near.net!news.mathworks.com!bigboote.WPI.EDU!mikasa.WPI.EDU!joev
-From: joev@mikasa.WPI.EDU (Joseph W. Vigneau)
-Newsgroups: comp.os.linux.development.system
-Subject: My LED performance meter thing...
-Date: 1 Jan 1995 23:18:28 GMT
-Organization: Worcester Polytechnic Institute
-Lines: 147
-Message-ID: <3e7d84$or5@bigboote.WPI.EDU>
-NNTP-Posting-Host: mikasa.wpi.edu
-
-Last week, someone wrote here asking about robotic contol via Linux... I
-responded explaining how I used the parallel port to control a sort-of
-"performance meter". I've recieved a lot of requests on how I did this.
-Here's the story:
-
-Last year, at school (WPI), Silicon Graphics brought this huge 18-wheel
-truck that is basically a demonstrationmobile. Inside it had Indys,
-Crimsons, and some of their big machines like a couple of Onyxes and an
-*monsterous* Power Challenge.. I'm relatively young (17 at the time), and
-I'd never seen a computer this big before: It looked like an oversized
-refrigerator, with cooling ducts running in and out of it! On the front of
-this beast, was a little LCD backlit readout about the size of my HP-48G's
-display. It was labeled "CPU Activity", and had a little bar chart showing
-how hard each processor was working. I thought it would be cool to have one
-of these mounted on my Linux box :)
-
-I finally got a computer of my own this past November, and finally got to run
-Linux on my own, instead of administering it for a number of people on my
-floor. I had a Shack attack, and went to Radio Shack, and picked up the
-following items: a breadboard, a 10-bar LED, breadboard wires, and a
-package of assorted resistors. [Side note: While at the Shack with a few of
-my suitemates, we were way in back in the component section (the only good
-part of the store any more), and were approached by a lady who thought we
-were employees there :). Back to the project.]
-
-It was wired up like this, via the parallel port:
-
- pin 20 (ground)
- |
- 150ohm LED |
-pin 2 (D0) ----/\/\/------|>|-----+
- |
-pin 3 (D1) ----/\/\/------|>|-----+
- |
-pin 4 (D2) ----/\/\/------|>|-----+
-
- [...]
- |
-pin 9 (D7) ----/\/\/------|>|-----+
-
-Note: 2 of the LEDs weren't connected.
-
-Now, the software part:
-
-Two files were used: the first is a routine written by a roomate
-(damianf@wpi.edu) used to blast raw bytes at a port, and read them. Please
-contact him for more info, or if you want to use it in a progrm of your own.
-
-static inline int port_in( int port )
-{
- unsigned char value;
- __asm__ volatile ("inb %1,%0"
- : "=a" (value)
- : "d" ((unsigned short)port));
- return value;
-}
-
-static inline void port_out( unsigned short int port, unsigned char val )
-{
- __asm__ volatile (
- "outb %0,%1\n"
- :
- : "a" (val), "d" (port)
- );
-}
-
-I originally wanted to use the load average to determine how many of the
-LEDs lit up, but realized that it was only updated every minute.. I wanted a
-display similar to xload or xosview, but I really coun't figure out how they
-were determined.. What I ended up doing was reading the output of 'ps aux',
-and summing up the %CPU column. I then converted that into a number
-representing how many LEDs should light, and blast it at the printer port.
-
-NOTE: I wrote and built this thing in a bout 90 minutes, so it's quick and
-dirty, and not at all as elegant as I hoped it to be.
-
-Here's the program:
-
-/* meter.c by Joseph W. Vigneau (joev@wpi.edu) (c)1994.
- This program is covered under the GNU copyleft agreement.
-*/
-
-#include <stdio.h>
-#include <unistd.h>
-#include <errno.h>
-#include <time.h>
-#include "port.h"
-
-float loadavg(void)
-{
- FILE *f;
- char line[80];
- float cpu = 0.0, totalcpu = 0.0;
-
- if((f = popen("/bin/ps -aux","r"))==NULL) {
- fprintf(stderr,"Couldn't fork /bin/ps.\n");
- exit(1);
- }
-
- fgets(line, 80, f);
- while(!feof(f)) {
- sscanf(line,"%*s %*d %f",&cpu);
- totalcpu += cpu;
- fgets(line, 80, f);
- }
-/* printf("TOTAL: %f\n",totalcpu); */
- pclose(f);
- return totalcpu/100.0;
-}
-
-
-main()
-{
- unsigned char lights;
- float ave;
- char dir = 0;
- char foo[10];
- register unsigned char numlights, i;
-
- if(ioperm(0x378,1,1)) {
- fprintf(stderr,"ioperm error.\n");
- exit(1);
- }
-
- while(1) {
- ave = loadavg();
- numlights = (int)(ave*8.0);
-/* printf("ave = %f, numlights = %d\n",ave, numlights); */
-
- lights = 0;
- for(i=0;i<numlights;i++)
- lights |= (1<<i);
-
- port_out(0x378, lights);
- usleep(750000L);
- }
-}
-
-This program has to be suid root, due to the ioperm call.
-
-Good luck, and have fun! Your mileage may vary.. If this makes your computer
-explode or something, I'm not responsible, etc.. If you improve upon this,
-post it here, so everyone else can see!
-
---
-joev@wpi.edu WPI Computer Science '97 Linux!
- <a href="http://www.wpi.edu/~joev"> Click Here! </a>
-
-
-
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projects / svn42.git / blobdiff