Microclimate real-time monitoring based on ZigBee sensor network

Monitoring microenvironment at the farm level has recently become one of the hottest topics in precision agriculture. Zigbee technology is then the most prospective candidate for wirelessly networking those field sensors due to its low cost and power consumption and flexible architecture. The microclimate monitoring system in this research is a suit of equipments based on Zigbee networking to measure the air temperature and humidity in a vast area. Every sensor node works on a cluster tree topology which extends the point-topoint distance up to 1 mile (line of sight), allowing this system to cover large farm using less sensor nodes. A sensor node consists of a micro-controller unit connected with air temperature and humidity sensor chips which are packed in a cylindrical louvered housing to prevent fault air temperature and humidity data from solar radiation. Every sensor node uses energy from a solar cell charged by a charger circuit to a battery package that stores power for use during night time. An energy management scheme was implemented to optimize power use for sending and receiving data. The data from every node were sent to the receiver every 8-30 minutes, depending on backup energy status at each node. The humidity and temperature data are stored on a data-logging PC and only current data are displayed on website.