Rocode >> Hobbies >> Sensors

1-wire Temperature Sensor and LED Display

I have updated my temperature sensor using 1-wire technology with a LED Display.

I use a DS9490R-P 1-Wire USB Adaptor from Hobby Boards.
http://www.hobby-boards.com/store/products/1%252dWire-USB-Adaptor.html

Low Power PC and 1-wire USB Adaptor

I added a Digital Thermal Probe or Sensor DS18B20 from ebay for $3.

DS18B20 Temperature Sensor

Using a new crimping tool, a RJ12 connector and 1 meter of flat telephone wire. I connected the wire to the RJ12 connector and then soldered the other end to the lead of the DS18B20.

I added a mini speaker from ebay for $4.

Audio Speaker

Speaker

Hourly Temperature Report Hardware

Hourly Temperature Report Hardware

The temperature from the Thermal Probe is forward via Elvin notifications to the remote computer(s) running ticker or to remote LED display(s).

I have an hourly temperature report that is shown on the LED Display accompanied by a short audible message. Here is a video showing a temperature report at 3pm local time.

LED Display and Hourly Temperature

Hourly Temperature Graph A

Hourly Temperature Graph B

I installed owserver, owhttpd and owfs to my Fedora Linux computer.
http://sourceforge.net/projects/owfs/

I got them working using the follow instructions.
http://www.it-slav.net/blogs/2008/11/01/1-wire-getting-started/
I put the 3 commands from the above page into a service file called /etc/rc.d/init.d/owfs.
This starts the 1-wire system on boot and creates a /1-wire directory on the filesystem.

/1-wire/

I updated my /usr/local/bin/weatherchecker.sh script with code, to emit ticker and led display messages, as shown

/usr/local/bin/weatherchecker.sh

I then added a cron entry to call this script each hour. i.e in /etc/crontab:

/etc/crontab

Here is how the Elvin notification looks on my Windows 7 desktop.

This says that the recorded temperature at 4pm on the 1st was 24.0 degrees celsius.

Elvin Temperature Notification

Here is a brief history of readings as stored in Sticker.

The 85.0 degree readings are an intermittent error that I now filter out.

Sticker Message History

Here in the script that calls espeak to synthesize any messages that accompany the LED display output.

A curfew is programmed between 10pm and 8am.

/usr/local/bin/espeak