https://github.com/drbrain/temperature_monitor

Wireless Arduino Temperature Monitor
https://github.com/drbrain/temperature_monitor

Last synced: about 2 months ago
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Wireless Arduino Temperature Monitor

• Host: GitHub
• URL: https://github.com/drbrain/temperature_monitor
• Owner: drbrain
• Created: 2011-08-30T08:17:39.000Z (almost 15 years ago)
• Default Branch: master
• Last Pushed: 2018-06-19T22:39:00.000Z (about 8 years ago)
• Last Synced: 2025-01-26T04:44:16.983Z (over 1 year ago)
• Language: Ruby
• Homepage:
• Size: 31.3 KB
• Stars: 4
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.rdoc

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README

          
= Arduino + DHT22 + XBee + Indigo Temperature Monitor

This project is used to control a gas fireplace in my house to maintain a

constant temperature.

== Wireless Thermometer

The hardware for the thermometer includes:

* {Arduino Uno}[http://www.sparkfun.com/products/10356]

* {DHT22 Humidity & Temperature Sensor}[http://www.sparkfun.com/products/10167]

* Two series 2 {XBees}[http://www.sparkfun.com/products/10417]

  * {RP-SMA to U.FL cable}[http://www.sparkfun.com/products/662]

  * {RP-SMA antenna} [http://www.sparkfun.com/products/145]

* One {XBee Explorer}[http://www.sparkfun.com/products/8687]

* One {XBee Adapter Kit}[http://www.adafruit.com/products/126]

* {Jumper wires}[http://www.sparkfun.com/products/9387]

* One {Breadboard}[http://www.sparkfun.com/products/137]

The XBee Adapter Kit was my first soldering attempt and I'm told I did a great

job.  A PanaVise Junior and a Third Hand helped immensely, along with choosing

a 1/64" soldering iron tip over the 1/32" tip that came with my soldering

iron.

I also cut three jumper wires, stripped them and soldered them to the DHT22.

This was more difficult, but placing the sensor in the vise and using the Third

Hand to hold the wire with a folded up piece of paper to protect the insulation

helped line everything up.

I attached the XBee Adapter to the breadboard and wired up 5V power and ground.

I attached the TX pin of the adapter to digital pin 2 of the Arduino and the RX

pin of the adapter to digital pin 3 of the Arduino.  I attached the sensor's

data pin to port 7 (from the {DHT22

source}[https://github.com/nethoncho/Arduino-DHT22]) and the ground and power

to the proper pins on the breadboard.

I use X-CTU from Digi International to set up the XBees.  The destination

radio is using coordinator firmware while the monitor radio is using router

firmware.

Originally I bought XBees with the chip antennas, but they only had a range of

about 3m without careful alignment of the antennas.  I replaced these with

series 2 radios with U.FL connectors and antennas (even though that may be

over-compensating).

For the original series 1 antennas I used xbee_modem_setup.rb set up the to

XBees to communicate with each other.  Be sure to use the Arduino XBee's

serial number as the destination address of the XBee Explorer and vice versa.

`bin/watch` can be used to monitor the temperature the Arduino reads.

Excluding the cost of soldering equipment the wireless thermometer cost under

$150.

I plan to add two more thermometers to the setup which will cost another $250.

Instead of the Arduino Uno I'll be using the cheaper Arduino Pro Mini now that

my soldering skills are proven.

Most of the software used in this project was already written by third-parties

that I adapted to my needs.  The DHT22 library was changed from returning float

to int (that I can decode on the ruby side).  xbee_modem_setup.rb was updated

to work with a newer serialport gem for ruby and the documentation was

reformatted.

== Temperature Control

`bin/indigo_monitor` reads data from the thermometer and populates a variable

in Indigo.  Through Indigo's database support (I use Postgres) the values for

the temperature are recorded.

`bin/indigo_control` uses a PID controller (currently only Proportional

control, I and D gains are set to zero) to turn the fireplace on and off.

The desired temperature (set point) is controlled by a wall switch attached to

an event group that raises or lowers the set point by one degree per press.

Every minute the control loop reads the current temperature from Indigo, feeds

that into the PID controller, checks the output value and turns the fireplace

on if it is over 0.2 and off if it is under -0.2 (to avoid flutter in the

temperature measurement).  The current control position is also recorded in

Indigo for debugging purposes.

== Temperature Graph

For debugging purposes I also have `temperature_graph.r`.  This R script

graphs the last day's data from Indigo's Postgres database.  You can see a

sample graph here:  http://i.imgur.com/SDUUS.jpg