Ninja-TeCo Part2 – The ONE WIRE

To get the necesary Temperature Information i used several DS18S20 and a OneWire to USB Adapter.

As i want to use several Scripts to work with the same Temperature Data i wrote a small Deamon to get the Temperature Data via digitemp and save it in “sensor” files under /tmp/sensorN. OneWire Fs only gave wrong Temperature Data (85°C) and the nodejs script got some serious problems with digitemp.

NOTE: I created two UDEV rules to get a “static” path for the two serial devices(Outlet and 1Wire Adapter)

cat /etc/udev/rules.d/44-ttyusb.rules
ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6001", ATTRS{serial}=="A6XDT7AO", SYMLINK+="steckdose", ACTION=="add"
ATTRS{idVendor}=="0403", ATTRS{idProduct}=="ea90", ATTRS{serial}=="10TK4WX6", SYMLINK+="onewire", ACTION=="add"

At first you need to initialize your digitemp config file:

digitemp -i -s /dev/onewire -c /etc/digitemp.conf 

The next step is to create the Daemon under /usr/local/bin/onewire/onewire.pl:

#!/usr/bin/perl

use strict;
use warnings;

use Proc::Daemon;
use Proc::PID::File;

MAIN:
{
	# Daemonize
	Proc::Daemon::Init;

	# If already running, then exit
	if (Proc::PID::File->running()) {
		exit(0);
	}

	my $continue = 1;
	$SIG{TERM} = sub { $continue = 0 };
	
	my $temperature;
	my $c = 0;
	my $sensor_count = 0;
	
	# Get Sensor #
	open DIGITEMPCONF, "<", '/etc/digitemp.conf' || die "Can't open /etc/digitemp.conf: $!";
	while() {
	        if($_ =~ m/SENSORS/) {
	                my @tmp = split(' ',$_);
	                $sensor_count = $tmp[1];
	        }
	}
	
	# filling sensor files arra<
	my @sensorfiles;
	
	for(my $i = 0; $i ", $sensorfile || die "Can't open $sensorfile: $!";
			$temperature = 85;
			while ($temperature == 	85) {
				$temperature = `/usr/bin/digitemp -c /etc/digitemp.conf -t$c -q -o"%.2C" -r1000`;
			}
			print $temp_sensorfile $temperature;
			print $temperature;
			close $temp_sensorfile;
			$c++;
		}
		$c = 0;
		sleep(15);
	}
	close DIGITEMPCONF;
}

And a start stop script under /etc/init.d/onewire (install it with update-rc.d onewire defaults)

#!/bin/sh
### BEGIN INIT INFO
# Provides:          onewire
# Required-Start:    
# Required-Stop:
# Should-Start:
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6 
# Short-Description: Starts the onewire "daemon" to provide onewire sensor datat under /tmp/sensorN
# Description: Starts the onewire "daemon" to provide onewire sensor datat under /tmp/sensorN       
### END INIT INFO

PATH=/sbin:/usr/sbin:/bin:/usr/bin
. /lib/init/vars.sh

do_start () {
	/usr/local/bin/onewire/onewire.pl
}

do_status () {
	if [ -f /var/run/onewire.pl.pid ] ; then
		echo "onewire is running";
		return 0
	else
		echo "onewire is not running";
		return 4
	fi
}
do_stop () {
	killall onewire.pl
}

case "$1" in
  start|"")
	do_start
	;;
  restart|reload|force-reload)
	do_stop
	rm /tmp/sensor*
	do_start
	;;
  stop)
	do_stop
	;;
  status)
	do_status
	exit $?
	;;
  *)
	echo "Usage: onewire [start|stop|status]" >&2
	exit 3
	;;
esac

:

After a lovely /etc/init.d/onewire restart you go the sensor data for each sensor under /tmp/sensorN
for example:

cat /tmp/sensor0
24.19

The sensor data will be updated every 15 seconds and the N in the sensor file is the same number you can find in the digitemp config (/etc/digitemp.conf).

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