by Vipul Gupta

February 24, 2009 - Sun SPOTs are small, battery-powered, wireless embedded devices that can autonomically sense and respond to their environment. These and similar devices represent the next wave in the continuing evolution of computing devices -- mainframes to minicomputers to desktops to laptops to PDAs and mobile phones. As these devices get smaller, simpler and cheaper, they will become more ubiquitous and end up woven tightly into the fabric of our daily lives. Project Sun SPOT at Sun Microsystems Laboratories aims to develop a better understanding around the operation and management of these devices.

Sun SPOTs have the potential to revolutionize a broad spectrum of applications — environmental monitoring, asset tracking, proactive healthcare, intelligent agriculture, military surveillance, etc. Many of these require the device to run for long periods (months) using a combination of duty cycling and renewable energy sources (e.g., solar panels). This technical report is the first comprehensive study of end-to-end data collection from a solar-powered Sun SPOT over a period of multiple weeks.

We ran our experiment for nearly a month and collected sensor data into a mySQL database for later analysis and visualization. This experiment helped us uncover and fix several issues that caused disruptions in data collection -- the occasional inability of the device to enter deep sleep, the resulting clock reset due to premature battery exhaustion, and loss of connectivity to the database after long periods of inactivity. The report offers important lessons in the design of a sensor data collection framework and lists both recommended best practices as well as potential pitfalls to avoid.