6.2.3 Hardware Components
The following hardware components were used to instrument each parking lot:
14 Arduino Uno boards: 12 used on sensor nodes and 2 used in the sink nodes;
14 Arduino Xbee Shield: 12 used on sensor nodes and 2 used in the sink nodes;
12 ultrasonic sensors Maxbotix LV-EZ1;
2 laptop computers to host the sink nodes.
Arduino Uno (Fig. 6.5 ) is a microcontroller board based on the ATmega328 chip,
which has 14 digital inputs/outputs pins, 6 analog inputs, a 16MHz crystal oscilator,
a USB connection, a power jack, an ICSP header, and a button reset. The Arduino
Uno board can be powered via the USB connection or through an external battery
connected its power jack.
Arduino Xbee Shield (Fig. 6.6 ) can be plugged on top of the Arduino Uno to
allow it to communicate wirelessly using Zigbee. It is based on the Xbee module
fromMaxStream [ 5 ]. The Xbee module can communicate up to 30m indoors or 90m
outdoors (with direct line-of-sight).
Ultrasonic Distance SensorMaxbotix LV-EZ1 (Fig. 6.7 ) has a frequency of 42kHz
and reading rate of 20Hz. The LV-EZ1 has virtually no blind spots, detecting objects
up to 6.5m. The closest measured distance is 15 cm, meaning objects closer than this
distance are measured as being 15 cm apart. The ultrasonic distance sensor emits a
sound signal that travels up to a solid object, like a wall, and back to the source of
the sound. To determine the distance of a solid object, the travel time of the echo is
The laptops were used to host the SIM components responsible for processing the
data collected by the base station and transmit them over the Internet to the PEM.
The minimum required configuration is:
Fig. 6.5 Arduino Uno board