Low-tech door monitoring with ICQ
Submitted by zany on Wed, 02/18/2009 - 15:38
Do you want to monitor some door? Get notified when it opens/closes? This is low-tech solution for the trusty old parallel port.
Just solder a Reed-switch and protective resistor to a DB-25 connector. Then run this simple program as daemon to monitor the switch. (This project is about 10 years old. You might consider fancy things like DBUS today...)
I my case the program runs scripts which controls the status of a running ICQ client. The door in question is the front door of our club room. Yeah!
#include <stdio.h> #include <unistd.h> /* needed for ioperm() */ #include <asm/io.h> /* for outb() and inb() */ #include <fcntl.h> #define DATA 0x378 #define STATUS DATA+1 #define CONTROL DATA+2 #define LP_PE 0x04 /* shifted */ int runscript(char *cmd) { int ret; if((ret=fork())==-1) { perror("Fork Failed"); return 1; } if(ret==0) // child { char *args[] = { NULL }; execve(cmd, args, NULL); perror("Exec Failed"); return 1; } wait(&ret); // wait for child return 0; } int main(void) { int v, v0; if (ioperm(DATA,3,1)) { printf("Sorry, you were not able to gain access to the ports\n"); printf("You must be root to run this program\n"); exit(1); } for (;;) { v = ((inb(STATUS)^0x80) >> 3); if (v != v0) if ((v & LP_PE) != 0) { //printf("Status: opening\n"); runscript("/root/bin/opendoor"); } else { //printf("Status: closing\n"); runscript("/root/bin/closedoor"); } v0 = v; sleep(1); //usleep(100000); } return 0; }
The script should run some commands (also consider dropping the privileges) but must not stay in the foreground (i.e. needs to terminate). Simple example:
#!/bin/sh exec su someuser -l -c /usr/local/bin/opendoor-user
Where opendoor-user would set the status in licq, micq, pidgin, ...
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