simple script to read ds18b20 on ntc chip, requires 4.4.13 kernel for w1_therm module

ds18b20.pl

#!/usr/bin/perl

# "ds18b20.pl" collect data from ds18b20 via one-wire modules
#  and save in mysql and mqtt

use strict;
use warnings;

# most logic lifted from http://webshed.org/wiki/RaspberryPI_DS1820
# required mysql permissions like:
#     GRANT ALL ON environ.* to rh@'192.168.1.XXX' IDENTIFIED BY 'rh';

use DBI;
use Net::MQTT::Simple "192.168.1.91";

 my $user="rh";
 my $password="rh";
 my $dsn = "DBI:mysql:database=environ;host=192.168.1.91";
 my $dbh = DBI->connect($dsn, $user, $password);
      die( "Unable to connect:\n $DBI::errstr\n") unless $dbh;

 my $dt = `date '+%Y-%m-%d %H:%M:%S'`; chomp $dt;

 my $mods = `cat /proc/modules`;
 if ($mods =~ /w1_gpio/ && $mods =~ /w1_therm/) {
    #print STDERR "w1 modules already loaded \n";
   } else {
    `logger w1 modules not loaded`;
    die "w1 modules not loaded\n";
 }

 my @devices = `cat /sys/bus/w1/devices/w1_bus_master1/w1_master_slaves`;
   chomp @devices;

 for my $device ( @devices ){

   next unless ( $device =~ m/^28-/ );

   my $sensor_temp = `cat /sys/bus/w1/devices/${device}/w1_slave 2>&1`;

   if ($sensor_temp !~ /No such file or directory/) {
     if ($sensor_temp !~ /NO/) {
         $sensor_temp =~ /t=(\d+)/i;
         my $tempInC = sprintf("%3.2f",($1/1000));
         my $tempInF = sprintf("%3.1f",  ( $tempInC *  1.8)  + 32 ) ;

         #-- persist to mysql -----------------
         my $insertSQL = qq[insert into measures
                 (evtime,sernum,meas,val)
                 values (?,?,?,?)];
         my $insertCursor = $dbh->prepare( $insertSQL ) || die DBI::errstr;
             $insertCursor->execute( $dt,$device,'temperature',$tempInF);

         #-- persist to mqtt -------------------
         retain "temperature/study" => "$tempInF";

         #-- save to /var/log/messages ---------
         `logger $0 temperature/study $tempInF `;

         exit;
     }
     die "Error locating sensor file or sensor CRC was invalid\n";
   }
 }