Hacking@CDTM – First time

by Raphael Haase

Just recently, I started an initiative called Hacking@CDTM. In the announcement at the Inspire & Dine I briefly explained what hacking is: It is about exploring the boundaries of anything that is programmable or that you can put together in some way. For example, building spaceships with Lego is hacking. Building a sensor box that has a temperature and a motion sensor and that transmits all the data wirelessly to another box which uploads it to the internet is hacking as well. So hacking really is about creatively exploring what can be done with technology. It’s sort of like Star Trek: “Going where no one has gone before.”

In our first iteration on May 21st, we hacked a Wireless Sensor Network (WiSeNet) together. A WiSeNet is a network of multiple nodes that contain sensors and transmit all their readings over the air. We used the robust and established industry standard ZigBee for this. ZigBee is a really great invention: It’s very power efficient, designed with the goal in mind of having thousands of equal sensor nodes over large areas (e.g. a rainforest) and it’s extremely robust. A typical use case could be detecting fires in a big forest: You build a large amount of these small ZigBee-equipped sensor boxes that work for years with just one battery. Then you distribute the boxes from an airplane over that wide area just like food supplies are sometimes distributed from the air in disaster zones. All you then have to do is constantly monitor all the readings from the sensor nodes. If there is a sudden high temperature reading from node, one can immediately go there and stop the fire before it spreads.

We had another use case in mind this time: Having sensors in your household to monitor your home. We played around with a number of sensors: temperature sensor, motions sensors, light intensity sensor, humidity sensors and a magnetic sensor (which can be used to detect an opened window if you place a magnet on the window and the sensor on the wall).

For those interested in the implementation: We used a netduino (compatible to Arduinos in many aspects, but it runs on an ARM7 core and comes with the .NET Micro Framework) and the XBee Series 2.5 modules from Digi. The XBee modules are relatively easy to use: You simply connect one of the serial buses of the netduino to the XBee module. ZigBee handles all the securing communications work for you and you just have to tell the module the address of the other module that it’s supposed to connect to in the beginning via some special commands that also go over the serial bus.

Within just a few hours we had calibrated one of the sensors and were able to transmit values from the sensor box to a laptop (we plugged a USB ZigBee module into that laptop). This required us to solder a little and find out how some of the sensors work. For me, being a computer scientist, this was an interesting new thing to learn. But it was great fun. Another guy also tried to play a little with the brand new Android Accessory Development Kit that we got right away from the Google I/O. But apparently one needs an android device to really do something with it, so we have to do that again next time.
We also want to continue working on this and maybe one day we can install our own home automation technology at the CDTM!

I would like to thank all who participated and Anas and Ronnie who helped me organize it and Christian Menkens for supporting us. Thanks also to Nils Hitze for providing the Accessory Development Kit.

Check out our website for updates and the next upcoming event! Go to hackingatcdtm.eu.