Archive for January, 2011

During my testing of the Google visualization API I found that “Gauges” for some reason work ok in Safari, but do not work on the iPad.

This is already reported as a bug to the API team here.

Once I got the hand of AJAX calls in Rails3, it was easy enough to experiment with other graphics packages.

This is a test with Google’s visualisation tools – using their gauges to display (in real-time) the temperature from some of the now numerous Jeenodes around the house.


This is getting a lot more fun now that some of the base components are in place for this.

It has taken me 2 weeks of my precious spare time to get my home monitoring graphs to update smoothly and continuously from Ruby On Rails.

Of course this has meant that I (at the same time) is teaching myself

– Ruby on Rails 3

– Highcharts graphs library

– Javascript / AJAX

And I have to say that this has been a eyeopener. Rails3 has changed the way Rails use javascript to something called UJS (Unobtrusive Javascript) – and it does not seem to fit what I wanted to do – which was to update a graph in the background every x seconds. And as soon as I had that figured out, I discovered that Javascript (and Highcharts) needed the data presented in a very specific way – leading me to have to write a number of new event driven routines in Javascript.

All in all good fun – but there is a real lack of documentation on how to do this both for Highcharts and Rails3.

But now it works :


Got my first Jeenode graphics display in on Friday – and I have now connected it in to the house monitoring system. It’s pretty good – and contrary to what I believed I have been running it off 3 AA rechargeable cells since it arrived – I had not expected it to work so well off batteries.The software on the Jeenode is my own – as I wanted to use the same code as I already use to run the other LCD displays.IMHO this is (from a developer and debugging point of view) much easier to implement that the pre-written code for this display.At the moment I have the ability to send to a virtually unlimited number of display nodes from the house server, each one individually addressable.image897524315.jpg

For a long time I used to let our home monitoring system send out Twitter messages (ok – twits) – as long as all authentication was done using names and passwords.

Then Twitter changed their authentication mechanism to “oAuth” – which was considerably more complex for single programmers, and I let it lapse until I at long last found a easy way to generate all the necessary keys and tokens – using a command line client called twurl.

The steps are :

– Download twurl by “gem install twurl”

– Log in to the account you want to send twits from

– Log in to – and register a new appliction.

– Copy out the “consumer key” and “consumer secret” keys from the registration page and add them to the appropriate parts of the following command line command

“twurl authorize –consumer-key YOUR CONSUMER KEY –consumer-secret YOUR CONSUMER SECRET

follow the instructions….

after you have authorised the program and gotten the PIN

cat ~/.twurlrc

and her you will find the necessary oauth token and oauth secret to finish configuring your software.

I’m experimenting with the hot water heating to determine the most efficient way to heat it – without wasting too much energy heating up all the long metal pipes leading to the hot water storage cylinder.

The theory is that when I tried to keep the temperature in the cylinder within 1 degree celsius of the ideal temperature (51 degrees celsius).

At the moment I let the temperature vary between 48 and 51 degrees as can be seen from the monitoring chart


The old code is shown at the beginning of the week – a coding mistake at the middle of the week, and then I got it right at the end….

Hm! A commercial HDMI CEC control bridge you can access through f.x. telnet (it also seems to have a HTTP interface).

Access the control features of HDMI

In all HDMI connections, a channel is dedicated to a set of control functions collectively known as
Consumer Electronic Control (CEC).

kwikwai enables this control from anywhere!

[From kwikwai – HDMI-CEC bridge]

The sensor status page for the house is growing steadily :


and this is just part of it!

image1249001016.jpgis a large building site at the moment.

It’s quite interesting to see how the new central heating control system works in our house.

Currently we have 2 main zones – the main living room is one, and the conservatory the second one – as they have very different heating needs and characteristics, due to the very large expanse of glass (and inadequate insulation) in the conservatory, versus the quite controlled and well insulated nature of the main living room, which has a door that can cut it off from the rest of the fairly open plan house.

The “conservatory” zone also encompasses the kitchen – so there will be bursts of heating from the cooker, ovens etc.


You can quite clearly see the actuators (the green line on the graph) opening to make sure the temperature follows the setpoint in the livingroom going up for a brief time after 06:00 in the morning, and then down again , and the cycle in the conservatory to keep the temperature around a even 18 degrees celsius.