Project

Temperature & Humidity Log

13 Mar 2011 IT by Matt

The aim of this project started out with then need to know current temperature and humidity in my house and expanded into a little bit more. It started out as just one perl script to locally log the temperature and humidity but soon expanded to a log aggregator and a dynamic webpage that can be accessed from anywhere. Finally it was integrated as a page on a WordPress blog being used as a CMS for my homepage.

Hardware

The setup is based on five wireless temperature and humidity sensors, four S-300-TH units which are used indoors in the kitchen, living room, bedroom and bathroom and one special weather proof ASH-2200 unit, which is placed outdoors. The five sensors all connect to a USB-WDE1 receiver unit connected to a computer by USB.

S-300-TH
indoor sensor ASH-2200
outdoor sensor USB-WDE1
receiver
Software

Although off-the-shelf software is available (LogView) functionality was limited to only logging every minute. To enable extra functionality, and as a bit of a geek challenge, a custom software solution was created. This consist of the following parts:

A perl script (tempget.pl) run in the background that constantly gets reading from the receiver via a serial interface and writes out a log.

A shell script (templog.csh) run by cron every 15 mins that reads the log and writes out an hourly, daily and monthly logs.

A php script (tempweb.php) that reads the logs and dynamically creates a webpage with plots created using PHPlot.

None of these scripts is particularly pretty, nor efficient, but they work. As reading a serial interface and reporting results via a web interface was something I thought I would never be able to achieve with my basic programming knowledge I thought I would share this to encourage others to try such things. Although setup for Mac OS X 10.6 scripts should also work under Linux with appropriate modification. Note that PHP is not enabled by default in Mac OS X 10.6, PHP. To do this make a backup of the original http.conf file:
sudo cp /etc/apache2/httpd.conf /etc/apache2/httpd.conf.original

Then enabled PHP by editing the http.conf file:
sudo nano /etc/apache2/httpd.conf

and un-commenting the following line in /etc/apache2/httpd.conf and restarting the web server:
#LoadModule php5_module libexec/apache2/libphp5.so

Revision History

Over time a number of new features have been added:

created perl script

created shell script to create hourly, daily and monthly logs

added php script to real last log entry and display current values

added inside value as average of all four indoor sensors

added delta values to outside

added separate delta value between living room and bedroom

added room colour code to match plot

calculates daily maximum and minimum and reports it to daily log

added plot of last two hours by the minute

made las two hour plot only show one reading per minute to ignore two logs per minute

added date and time of last log read and current time

added reload button

added favicon and iphone icon

added plot of last two days by the hour

added plot of average temperature for last 28 day

added links to both raw logs and contracted logs used to plot

added automatic reload every minute

added javascript to remember current scroll location upon reload (3rd party code)

added css to harmonise look

added countdown till next reload using javascript (3rd party code)

added buttons to go directly to minute, hour and day plots

added links to plots to jump to next plot and then loop back

added plot of last month showing only inside and outside with max and min

added daily running max and min temperature to current values

made running max and min ignore sensor dropouts

made templog script ignore sensor dropouts

corrected averaging error that skewed averages (initiate counter as zero not 12!)

added plot of average temperature for last year

changed log location as Time Machine in Mac OS X does not backup ~/Library/Logs

added daily running average and plot it as day zero on day view.

added weekly and monthly running average and plot it as zero point on week and month view

tidyied up HTML of PHP output for easier debugging

added time of daily max and min temperature as mouse over in table

added plot of time of daily max and min temperature for last four weeks

made templog script record time of daily max and min

extended year plots to two year plots

fixed humidity axes to 0-100±20 %

calculate temperature axis based max and min values plotted and quantised with ±5°C.

corected wrong reading of bathroom humidity

transfered to wordpress usinf exec-php