Lab 1: Becoming familiar
with the Java-programmable Sun SPOT technology.
Introduction:
The goal of this lab is to introduce you to Sun’s new Sun SPOT (which stands for Small Programmable Object Technology) wireless sensor network technology. Unlike most motes that run TinyOS and require applications to be written in NesC, Sun’s new motes are programmed in Java. For people with experience in Java, learning to program applications for the Sun SPOTs should be relatively easy. Sun makes use of familiar techniques in the design of the SPOT API ; communication between motes, for example, should be reasonably intuitive for anyone that has used Java sockets before. The Sun SPOT software comes with a number of fun example applications that show off some of what the motes are capable of. We will explore a couple of these, learning how to deploy applications on the SPOTs as we go, and ultimately start looking at the code to see how the programs work.
Let’s get started.
1. Check your equipment. You should have been provided with a Sun SPOT development kit. This includes two motes and a basestation. You can tell the basestation apart from the free-range SPOTs by the fact that it does not have a detachable semi-transparent plastic cover on top and is not as tall off the table. You will also need at least one USB cable to hook your SPOTs up to the computer.
2. Open Netbeans. Sun has made programming and deploying applications to the SPOTs extremely simple by incorporating the functionality into Netbeans, the Integrated Development Environment (IDE) that Sun offers with their free version of the Java Development Kit (jdk). The Netbeans modules that allow for this come with the SunSPOT sdk. In this lab, we will be learning how to work with the SPOTs through Netbeans. You may already have another favorite IDE of your own, or even already dislike Netbeans for whatever reason, however we will make use of it in these labs to take advantage of the ease of developing and deploying SunSPOT applications that it provides.
a. Double-click the Netbeans icon on your desktop to start it.
3.
“Short tour of a Sun
SPOT”. When you first open
Netbeans, you should see a tab open called “SunSPOTs info”, with a heading that
reads: “Welcome to the
World of Sun Small Programmable Object Technology - Sun SPOTs.” A little farther down the page, you will see a link to
the Sun SPOT Quick Start Tutorial.
Click this. From there click on
either the link at the end of the introduction or on the sidebar to the “short
tour of a Sun SPOT.” Quickly read over
this page. This will get your familiar
with the basics of the SPOTs. Try taking
the lids off and locating the switches next to the LED’s (under the lid) and
the control (power) button. The tour
will teach you about turning a SPOT on, how to reset a SPOT, and how to
interpret the power/activity LED.
Now that you’ve got the basics, let’s see what these things can do. The SPOTs come preloaded with a very cool demo that utilizes the on-board three-axis accelerometer, one of a number of sensors that the free-range SPOTs are equipped with, and the eight tri-color LED’s under the lid. This demo is also covered in the next section of the Quick Start Tutorial. You are welcome to refer the tutorial in addition to—or instead of—the steps below (if anything is unclear, the tutorial has pictures).
1.
Turn the SPOT on. Most likely in the last step you pressed the
power button on one of the motes at some point and noticed a few of the LED’s
on top (there are eight total) light up. If not, turn one of the free-range
SPOTs on now. The two lights on the ends
will be red, and there will be a blue light somewhere that acts like a bouncing
ball if you tilt or shake the mote back and forth. NOTE:
if your SPOT doesn’t respond and refuses to power-up, it may not be charged. In
this case, request a new kit (you can also use the USB cable to plug it into
the computer and charge it, but it may take a minute or two before it will have
enough power for the demo to run)
2. Play with the bouncing ball. Take a moment to get a feel for the bouncing ball application. Shake the SPOT furiously to get the ball bouncing between the two ends at lightning speed and then hold it still and watch the ball gradually lose speed and settle back down to a final resting place. When the ball is on one end, try tilting the mote gradually just until the ball falls and watch it bounce back a few times (most likely ending up on the other end; though sometimes if you just barely tilt it, the ball will go back to where it started). Try to get the ball to stop in the very middle (without spending too much time trying). Once you’ve had enough fun, go on to the next step.
3.
Introduce the second
SPOT. If you haven’t already, start up the second
free-range SPOT, which should also have the bouncing ball application
running. This time you will see a ball
that is green. Now turn both motes off
(hold the control button for a couple seconds; if you just press it without
holding, it will reset and not shut down) and then turn the one that previously
had the green ball back on again. Notice
that it will now have a blue ball. This
means that the SPOTs, true to the spirit of wireless sensor networks, are aware
of each others’ presence. We will
investigate this further when we look at the code later. NOTE: if you are doing this lab in close proximity to other groups, the
colors may not match what is described here since all the motes will be
communicating and trying to assign themselves a unique color at startup. There
is a maximum of three motes (and thus three unique colors) per self-assigning
group, though.
4. Break down the walls. Make sure both your motes are on. Now go ahead and take both the lids off. If you were wondering earlier what the control switches do, the answer is: it depends on what the application developer wants them to. It just so happens that the developers at Sun were nice enough to make bouncing ball demo even cooler by letting us use the control switches to share multiple balls in one arena that spans more than one SPOT. If that wording is confusing to you, try it yourself and see what happens.
a. Press one of the control switches. The red light on that end of the mote will start to blink. While that light is still blinking, press a switch on another mote. The two “walls” should disappear. Now you can have both balls going back and forth between SPOTs! Unless you’re really good, the balls will probably quickly combine into one. You can even put the walls back up and isolate both balls on one mote, or take all the walls out altogether.
b. Play with this for awhile, taking walls down and passing balls back and forth between multiple motes.
Conclusion: The point of the lab so far was to get you familiar with the basics and layout of the Sun SPOTs and hopefully get you excited about working with them by giving you a glimpse at some of the fun, cool things that can be done with them.
Questions:
1. What are some fun, useful, or interesting applications that you would like to see made to run on the SunSPOTs?