Your own wireless sensor network

Building your own wireless sensor network is easy!  Seriously, using the Sun SPOT you can deploy a data collection network capable of monitoring everything from your lights to the the movement of small animals in your yard.  I've written a complete guide to installing your own network.  Check it out:

The complete wireless network setup guide

Our own wireless sensor network at Sun labs has been built to the point of near completion.  It uses the same nodes we built for Panama, as detailed in previous blogs.  We will be using this network in the future to test and troubleshoot our software, hardware, and sensors.  You can find my presentation about the Sun SPOT, our test network, and Ecology our website:

Sensor Networks

This is my last day at Sun labs.  After my return to Asheville, NC, I will continue to investigate wireless sensor networks and how they can be used in science.  My professor David Abernathy and I will setup a test network at Warren Wilson College to work out bugs and prepare for future deployments in Panama.  The Sun SPOT has been instrumental in getting the Cocobolo Nature Reserve in Panama online, and breaking the disciplinary boundaries so that we might all share ideas.  The future of the SPOT and wireless sensor networks in general is somewhat unknown.  It's easy to speculate that we'll have higher quality data, transmitting over longer distances more often, but I feel that's only an upgrade.  The real developments in wireless sensor networks will depend on the creativity of those that deploy them, and how they use the data that becomes available.

Simple Solar SPOT

Regulating Your Power

Powering your Sun SPOT with solar energy makes sense linguistically.  Its also a great way to use a renewable energy source and free yourself from the ball and chain that is the USB port.

Interfacing your SPOT with a solar panel is fairly simple.  I used the schematic for interfacing an iPod charger with a solar panel that you can find here.  The circuit simply regulates the amount of voltage so you don't accidentally give your SPOT a tan.

Here we see the circuit regulating the power from 9 to 5 volts.  You can interface with your solar panel however you like.  We used a barrel connector to match the male plug that came with ours.

The Road to Panama

Building a Better Node

Before returning to the Cocobolo Nature Reserve in Panama, it is important we prototype everything we plan to deploy in the jungle.  The code and sensors having been mostly completed, it was time to build the structure that will house our data collection systems for an extended stay in the rain forest.

There were several goals in mind when building this node:

1. Keep the electronics dry.

2. Keep the photo radiation sensor level.

3. Keep the node where it is meant to be.

The finished node will be larger, about 5 feet in length, 2/3 of which will be driven deep within the soil.  In addition, we will be placing cages around the nodes (also driven into the ground), to prevent tampering by wildlife.

The internals of the node are very simple.  Below the junction is a seal to provide the SPOT a place to sit and protection from water.  Above the junction there is also a seal to keep the rain out.  Drain holes will be added above each seal to ensure water can flow outward because nothing is ever really sealed (thanks Keith).

Snorkel SPOT

Breaching The Surface

This week I have been focusing on interfacing external sensors with Spots.  Above a Precon hs-2000v Temp / Humidity sensor.  The power of the Spot lies in the simplicity of the code:

        EDemoBoard demo = EDemoBoard.getInstance();
        IScalarInput[] inputs = demo.getScalarInputs();

        //Get the values
        double extReference = inputs[EDemoBoard.A0].getValue();
        double extTemp = inputs[EDemoBoard.A1].getValue();
        double extHumidity = inputs[EDemoBoard.A2].getValue();

        //Deal with the data
        tempC = (((extTemp/extReference) * 130) - 30);
        humidity = ((extHumidity/extReference) * 100);

That's all there is to it!  Using Yggdrasil it was very simple to get the sensor taking and sending readings back to the host.

Powering your Sun SPOT

Alternative Energy - OR - How to Void Your Warranty

The best way to charge your Sun SPOT is via the USB port.  However, a pair of alligator clips will give your SPOT a little more powering flexibility, and a rugged new look.

 WARNING: Installing these clips will void your warranty.  Only connect to a power source +/- 10% 5V.

Locate the V_EXT connector (near the reset button or clamping screw hole depending on your board revision) on the main board and solder a high gauge wire to it (in this example, the red wire on the right).  Solder a grounding wire to a free ground connector.

You'll have to be creative about running the wire through the SPOT casing.  I dug a hole out and cut some plastic knobs to get the SPOT to fit back together.

But in the end everything snapped together nicely.  Attach some clips on the other end of the wires and your done!

With alligator clips, its easy to power your SPOT, but usually not safe.  To reiterate the warning above, only connect to a power source +/- 10% of 5V.  That said, have fun, and be creative!

Jungles, Petabytes, and Discoveries.

Yggdrasil - A Data Collection Framework

Trying to explain how a Sun SPOT works to a native Spanish speaker was proving more difficult than I had anticipated.  I had been attempting to explain to our guide, Joel, why I was standing in a clearing holding a blinking piece of hardware and looking pensive.  I had been trying my best to communicate using broken Spanish (which in truth, was mostly slow English) the concept of mesh routing.  Eventually I reverted to the what I thought must be the universal sign for wireless data transfer; holding the SPOT in one hand while wiggling the fingers of the other and moving the hands apart.  I may have confused the matter later in my explanation when I used the universal sign for rain (wiggling the fingers of one hand and dropping down to the SPOT) to indicate the Otter boxes we were using to keep the SPOTS safe were weather proof.

 Although I do not feel I was successful at breaking the language barrier during my trip to the Cocobolo Nature Reserve in Panama, we did do some pretty cool stuff with Sun SPOTS.  I was with my professor, David Abernathy who had co - written a grant to, among other things, install a wireless sensor network on the reserve.  We were bent on setting up a solar powered Sun SPOT, bouncing the data back to the thatch hut, and uploading it via satellite for visualization on Google Earth.  With us, we brought a special weather proof Sun SPOT.  The device had been constructed by Lawson Revan, my friend and neighbor at Warren Wilson College.  He had cleverly mounted a Sun SPOT inside an Otter box, and routed wire from the Vext port through a 5 volt regulator and to a cluster of solar panels harvested from garden lamps and mounted on a refrigerator panel.  The device performed very well under the Panamanian sun, outputting nearly 5 volts and up to 150 mA's.

I had written a simple Sun SPOT application to gather temperature, light, and power data and stream it back to the host.  From there, it was logged to MySQL.  The data was accessible via a simple Apache web server that interfaced the data with Google Earth.  On our second day in the Jungle, we had real time data streaming via satellite to the internet.

Since then the Sun SPOT data collection project has grown rapidly.  The Cocobolo Nature Reserve is one of several projects that seek to use SPOTS as data collection tools.  It is for this reason that Yggdrasil was developed, a data collection framework for Sun SPOTS.  The framework is currently in pre - beta, and is able to take sensor readings at a given time interval, relay the data back to the host, and interface with a database.  Throughout the process the Sun SPOT sleeps when it is not working, ensuring that no power is wasted.  The project is moving forward quickly.  Lachlan is working on the database component, John is building a 3D Node Browser, Robert is improving the underlying network code, and I am tying together a Configuration Manager.  We are planning a working deployment in Panama in late summer / early fall.

As a whole, our project is part of a growing cluster of projects that seek to collect data and store it.  Because of this, more and more data is becoming available on the cloud.  WIRED magazine has coined this the Petabyte age, in which scientific theory is taking a back seat to the investigation, interpretation, and visualization of vast quantities of data.  Technologies that make data collection and storage easy and rapid are changing the face of science.  Historically, researchers have hypothesized, collected data, and determined what it meant.  However with this new influx of information, we can design studies around the data we already have, or data that we expect to have.  In fact, we may find ourselves crunching data purely for the sake of crunching, and finding things we were never looking for in the first place.

As the cloud grows in size, and the speed at which it grows increases, the opportunity to find important trends in data grows exponentially.  It is essential that the scientific community not only be be equipped with the best tools technology has to offer, but also be free of technical problems so that they can spend their time exploring data, not debugging code.  This is a time in which our ecosystem is changing rapidly, for known and unknown reasons.  Data collection, storage, and interpretation is no longer a luxury, but a crisis discipline.  If we are indeed flapping the wings of a flying machine that was never meant to fly, as is postulated in Ishmael, now is our chance to rebuild in flight and ensure we make it to our destination safely.