Arduino and xbee development

Today i purchased xbee radio equipment which should arrive by Wednesday depending on the weather conditions to help in building an initial prototype to present to focus groups. I feel that this would allow them to get a 'feel' for the concept, and would allow me to see how they interact with the object.

I believe that the initial prototype would be built as a 'kit', where it could be transported easily. The reason why Ethernet connections are not be used is for portability and accessibility reasons: i would need to connect the arduino boards directly to the Ethernet connection which may be in an awkward place, configure them, and then run them which could take up users time, and force the tests to take place in an unsuitable location. Using xbee radios allows for greater flexibility, and the interactions could be up and running immediately.

This is the current shopping list:

2 x Breakout Board for Xbee Module	£3.24
1 x Buzzer - PC Mount 12mm - 2.048KHz	£1.02
4 x 2mm 10 Pin Xbee Socket	£1.60
1 x Infrared Emitters and Detectors Pair	£1.28
1 x Hall Effect Sensor	£0.86
2 x Break Away Headers - Straight	£1.28
1 x Arduino Uno - R3	£22.20
1 x Magnet Ring - 3/16"	£0.64
1 x 4-Digit 7-Segment Display - Kelly Green	£1.28
1 x Breadboard Clear Self-Adhesive	£4.80
2 x XBee 2mW Wire Antenna - Series 2 (ZB)	£46.96

It was complied with the help of 'Building wireless sensor networks'. I needed to buy an extra arduino board to control the second xbee radio. Two xbee radios are required as otherwise they'd have nothing to communicate with.

I selected the series two modules 'XB24-Z7WIT-004' as recommended by 'Building wireless sensor networks'.. These have an operating range of 40 metres indoors and 120 metres outdoors (line of sight), according to 'Building wireless sensor networks'. I selected wire, not chip antennas for stability and reliability.

I also bought a magnet ring and 'hall effect sensor': this is like a 'reed switch' but more reliable. These two together will become a prototype of my 'physical key', mentioned in a previous post.

The 7 segment display is to test screen displays within my project. I also bought an infrared sensor/emitter as an alternative way of detecting when someone is sitting down. They could be built into the arms of the chair to detect when someone is sitting down. This may be more reliable as environmental factors can very easily affects the light values in a room i.e. during the night.

This is a prototype model of an infrared sensor setup and how it would work.

Setting up and configuring the modules will come next. Robert Faludi describes the process of setting up the xbees in depth in his book.

It is also possible to use the xbee radios to upload code to the arduino board. This is explained here: http://www.faludi.com/itp_coursework/meshnetworking/XBee/XBee_program_Arduino_wireless.html

Rather than using an adapter i am going to use the adapter hack from pages 12-14 in 'BUilding wireless sensor networks'. If in future i do decide to purchase an adapter, i will most likely buy this one: http://proto-pic.co.uk/xbee-explorer-dongle/