20 Jan

TechGirlz Tackle Arduino

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On Saturday, more than 20 middle-school girls gave up an unseasonably sunny afternoon to hack with Arduinos. Philadelphia Water’s greenSTEM project hosted a free TechGirlz workshop at Moore College of Art to explain how low-cost electronics and sensors can be used to help the environment, improve our cities and neighborhoods, and connect the real world to the virtual world.

We hit the ground running by setting up with Codebender, a browser-based Arduino programmer that takes much of the pain out of installing software, drivers and libraries on two dozen different computers. We quickly moved to a modified version of the Arduino blink activity and then tackled an art project: programming designs onto a 16×32 LED matrix sign using an x,y grid, geometric shape codes and color codes. This was hard work—many lines of code were written with intense focus.

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Thanks to the girls for attending, to our TechGirlz volunteers, and to Moore College for providing the space.

27 Apr

Thinking Outside of the (Cardboard) Box

Ninth grade students at Science Leadership Academy’s Beeber campus began the challenge this week of creating their own solar-powered, video-capturing, soil-moisture monitoring bird houses—and maybe even a few bat boxes. Each unit will be equipped with its own Arduino/Raspberry Pi  device that will harness the solar power and use WiFi to transmit soil-moisture data and a live “peep show” (get it, because they’re birds?) courtesy of the infrared camera, allowing students to observe the birds inside. As if all of the technical aspects weren’t enough to consider, the students also have to be aware of what kind of birds they’re building for, and choose their houses’ specifications accordingly.

So this week, in becoming aware of their tenants, the students crafted cardboard to scale models of their birds of choice with the help of Alex Gilliam, director of the organization Public Workshop (which collaborates with youths and their communities to help them shape the design of their cities through workshops and leadership programs). And check out the results!

Photo credit: Matthew Fritch

Here we have a few American Robins, a few House Sparrows, and one American Chickadee. Some students also scaled cardboard models of starlings, bluebirds, and bats.

Gilliam encouraged the students to account for both the size of their birds with their wings at their sides and fully spread. They’re each taped to a cardboard sheet inscribed with pertinent information—things like diet, preferred habitat, and how they prefer to nest.

Next week the students will start modeling cardboard prototypes of their birdhouses/bat boxes for their cardboard creatures in order to get the designs perfect for the final products.

16 Apr

Welcome to the Matrix

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In our last post, we detailed how soil moisture sensors and datalogging are not exactly the cure for dead plants (or neglectful students). The next step at SLA Beeber was to give students blindingly bright visual cues as to when their plants required watering. Along with taking soil moisture readings and determining a wet or dry state, students programmed their own designs onto an Arduino-powered LED matrix. Remember Lite-Brite? It’s kind of like that, except it’s coded in Arduino using an x-y coordinate system, geometric shape commands and color codes. Students began by sketching their designs onto a 16×32 grid, then breaking the grid into rectangles, lines, and pixels as lines of code:

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Adafruit has an excellent tutorial on how to wire this to the Arduino and program it. We put the display inside a Pelican case to keep it dry and set it up in the school’s hallway, where one can only hope the plants’ occasional pleas for water will catch someone’s eye.

05 Jan

Bigger, Better and Brighter LED Display

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Our previous post detailed the simple soil moisture sensor with an LCD display that has been keeping track of our plant’s watering needs at the Fairmount Water Works.  We decided the project could use a little more flair—plus, our original LCD display got a little wet.  Luckily, our new 16×32 LED Matrix has its own waterproof case. The setup uses an Arduino Uno ($25), a Grove base shield ($10), a Vegetronix VH400 soil moisture sensor ($37), and a 16×32 RBG LED matrix panel ($25). All of the electronics are safely tucked into a waterproof Pelican case.

We decided to display more information with our LED matrix.  Now, it will display the words “Water me!” when the soil moisture level falls below a voltage of 1.2, or “Don’t Water” when the moisture level is greater than 1.2 V. It then displays the voltage, followed by “Water Works,” and repeats.

We found that with RGB (red-blue-green) matrices like this one, certain colors require more power.  When using solely the power coming through the computer to the Arduino to power the matrix, we were limited to basic red, blue, and green colors.  Any other colors would be displayed as one of the tree.

We decided this was a little too boring, and experimented with supplying power from the wall directly to the matrix, in addition to the power coming from the wall to Arduino.  This got us very bright, vibrant colors. However, the LEDs were glitchy and flashing.  We think the matrix was getting just a little too much power, and it was distracting.  In the end, we stuck with the additional wall power, but used lower power colors.  This gave us the brightness we wanted, without all the flashing.

View the code after the jump.

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