By Vasu Kilaru and Gayle Hagler, Ph.D.
Welcome back to the Village Green Project, an ongoing EPA research, development and demonstration project to build a solar-powered station to measure air pollutants.
This innovative new measurement system must: collect and send data; use minimal power; monitor instrument performance; and have remote on-and-off capabilities for several components to match changing conditions (off for dark and cloudy days, and then on again when the sun starts to shine).
The team searched far and wide for an on-board computer that would serve as the “brains” of the Village Green System. The computer needed to run on very little power, be flexible enough to handle all of our requirements, and ideally work using a free, publically available (“open source”) computer program.
We discovered Arduino—a microcontroller that is essentially a simple computer with an accompanying free programming tool. A wide group of people, including artists, designers and hobbyists, are already using it to build electronics like homemade clocks or robots. It works perfectly for our needs because it uses very low power and can fit in your hand.
A number of accessory electronic items allow the small circuit board to meet the requirements of the system. For example, one accessory adds a timestamp to the data being collected so anyone viewing it can see the amount of air pollutants measured at a particular time and day. Another accessory links the Arduino board with a cellular modem (similar to the “data” port of a cellphone), which then sends recorded air pollution data to our on-line database. These accessories are electronic boards that stack on top of the main Arduino board, making what looks like an electronics sandwich.
With a free programming tool available to the Arduino-user community, we are developing a custom computer program for the Village Green System—nearly 800 lines of code and counting.
So far, so good! Recently, North Carolina experienced several days of cloudy, overcast weather. The trusty Arduino board successfully handled the decrease in power—turning off several instruments during that time and then efficiently restarting them once the sun came back out.
About the Authors: Gayle Hagler is an environmental engineer who studies air pollutant emissions and measurement technologies. Vasu Kilaru works in EPA’s Office of Research and Development. He is currently working on the apps and sensors for air pollution initiative (ASAP) helping the Agency develop its strategic role and response to new sensor technology developments.
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