Portable Wireless Sensors Network

Hello Readers

A recent wireless sensor network project has prompted the tech dept. to build a handy sensors platform. We snapped a couple of photos of the product and posted in our photo journal gallery. Here we are writing a blog about it, let’s examine it closer!

When it comes to wireless networking using Digi Xbee, it is considered as data communications within a personal area network (See Wiki on PAN). Xbee is a ZigBee protocol enabled RF module, two of more of these Xbee modules can form a unique, personal area network. Within this wireless PAN, you can have different kind of sensors, microcontrollers to communicate, send and receive data via the PAN established by the Xbee modules.
Our team put in a lot of time researching Xbee, this includes studying the ZigBee protocol standard, reviewed different Xbee product and more importantly, the communication methodology. Xbee offers two communication options and we opted to use the more robust and secure API mode for our project.
At the beginning of the project, our programmer is looking for a mock up device that can pump out data samples. That’s easy, we configured our Xbee to automatic sampling using sample rate (IR). This has lasted for less than a week. Further into data stream programming, we quickly discovered that a real, working device that can provide meaningful data is needed.
Head dive into the tool box and out came…

  • PIR motion sensor for triggering
  • IR Range sensor for analog input measurement
  • Push button for digital input
  • LED light for digital output from Xbee
  • Runs on battery for portability
  • Sparkfun SEN-09269 Triple axis Accelerometer breakout board for analog output with self-test
  • All sensors, LEDs are mounted securely on wooden plank with a dedicated breadboard.
  • All sensors’ outputs are connected to Xbee

Here is the finished product.

Notice the PIR motion sensor and IR range (Sharp 29 to 150cm) sensor are mounted on the side of the fixture.

Back of the fixture, we have everything on breadboard along with battery compartment.

4 x 1.2 (Rechargeable NiMh) a total 4.8V powers the setup, battery case features on/off switch.

Mounting of SEN-09269 Triple axis Accelerometer

Push button next to the Xbee for digital input, notice the 2 color LED is currently not hooked up.

The Xbee is sitting on Gravitech XBee-ADP5 5V Xbee adapter, this adapter features 3.3V 250mA voltage regulator, providing 3.3V power for Xbee and various sensors.


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