Code/tp-theft-basic

2007-04-10T16:41:29Z

OkdSog:

#!/usr/bin/perl
# tp-theft v0.1 (http://thinkwiki.org/wiki/Script_for_theft_alarm_using_HDAPS)
# This script uses the HDAPS accelerometer found on recent ThinkPad models
# to emit an audio alarm when the laptop is tilted. In sufficiently
# populated environments, it can be used as a laptop theft deterrent.
#
# This file is placed in the public domain and may be freely distributed.

use strict;
use warnings;

##############################
# Siren volume and content

# Audio volume (0..100)
my $volume = 70;

# Synthesize a siren for 1.0 seconds:
my $play_cmd = "sox -t nul /dev/null -t ossdsp /dev/dsp synth 1.0 sine 2000-4000 sine 4000-2000";

# Play a file:
# my $play_cmd = "play keep_your_hands_off_me.wav";

##############################
# Other tweakables

my $thresh = 0.20; # tilt threshold (increase value to decrease sensitivity)
my $interval = 0.1; # sampling interval in seconds
my $depth = 10; # number of recent samples to analyze
my $pos_file='/sys/devices/platform/hdaps/position';
my $verbose = 1;

##############################
# Code

sub get_pos {
open(POS,"<",$pos_file) or die "Can't open HDAPS file $pos_file: $!\n";
$_=<POS>;
m/^$(-?\d ),(-?\d )$$/ or die "Can't parse $pos_file content\n";
return ($1,$2);
}

sub stddev {
my $sum=0;
my $sumsq=0;
my $n=$#_ 1;
for my $v (@_) {
$sum = $v;
$sumsq = $v*$v;
}
return sqrt($n*$sumsq - $sum*$sum)/($n*($n-1));
}

my (@XHIST, @YHIST);
my ($x,$y) = get_pos;
for (1..$depth) {
push(@XHIST,$x);
push(@YHIST,$y);
}
my $alarm_file; # flags ongoing alarm (and stores saved mixer settings)

while (1) {
my ($x,$y) = get_pos;
shift(@XHIST); push(@XHIST,$x);
shift(@YHIST); push(@YHIST,$y);
my $xdev = stddev(@XHIST);
my $ydev = stddev(@YHIST);

# Print variance and history
print "X: v=$xdev (".join(',',@XHIST).") Y: v=$ydev (".join(",",@YHIST).")\n" if $verbose>1;

my $tilted = $xdev>$thresh || $ydev>$thresh;

if ($tilted

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Code/tp-theft-basic