The CargoNet active tag is a low-power and low-cost versatile platform with numerous sensors, processing, communication, and storage. The tag has the following sensors on-board:

• Piezoelectric shock sensor,
• Piezoelectric vibration dosimeter,
• Piezoelectric microphone,
• Tilt switch,
• Magnetic breach sensor,
• Phototransistor breach sensor,
• Temperature sensor,
• Humidity sensor.

System power consumption is minimized by using the energy of a stimulus---whenever possible---to power the sensor and alert the low-power MSP430 microcontroller. Slowly-changing environmental stimuli, such as humidity and temperature, are polled periodically.

The MSP430F135 microcontroller has a data-storage capacity of 8 kB, sufficient for logging events that exceed preset thresholds. An external SPI flash and ISM-band radio can also be used to log additional data or communicate them to other tags and readers, respectively.

The tag consumes only 23.7 microwatts of average power, resulting in a lifetime of over three years when running from a 235 mAh coin-cell lithium battery. Furthermore, this breadth of sensing capabilities and low power consumption has been achieved at a low-quantity cost of only USD 40. The low-cost sensors and components employed by CargoNet tags finally bring active RFID to the crate and pallet level.