Pressure monitoring in wireless sensor network using Zigbee transceiver module

Wireless Sensor Networks (WSNs) are spreading around in multiple fields of applications because they perform measuring tasks in a flexible way [1]. In this presented work IEEE 802.15.4 protocol based Zigbee transceivers module are used to make the wireless sensor network. The sensor node will acquire and internally store data periodically. Starting times as well as the time intervals for the measurements can be freely programmed over the network system [2]. As soon as a mobile network is detected in its proximity the node will automatically transfer data. Optionally sensor data can be delivered on demand. When in its idle state the node remains in power-down mode in order to minimize power consumption. The system is based on an AVR microcontroller coupled to an RF-transceiver. In a sample application the system is interfaced to a piezoresistive pressure sensor, typically used to determine water levels in closed tanks or open aquaculture systems. Possible applications in the area of environmental monitoring will be presented (including tidal range measurements).

I. Introduction

WSN is a term used to describe an emerging class of embedded communication products that provide redundant, fault-tolerant wireless connections between sensors, actuators, and controllers. The large amount of research projects in this area allows for the existence of better tiny hardware devices with reduced cost/size, and improvements in software performance. WSNs are typically formed by groups of several sensor nodes, the so-called motes, whose individual constitution is based on actually combining sensor radios and CPUs into an effective robust secure and flexible network, with low power consumption, and advanced communication and computation capabilities, one or more sensors, a communication device (typically a radio), a microcontroller (with memory), and a power supply (battery)[3], [5], [8]. These motes exchange messages among each other in order to efficiently monitor an environment/process. The power of wireless sensor networks lies in the ability to deploy large numbers of tiny wireless nodes that assemble and configure themselves. For large number of sensors adequate measures are necessary to keep fewer efforts in data acquisition system. As far as the cost and complexity concern of a data acquisition system, a wireless sensor network seems to be a convenient option. For this reason, wireless network standard ZigBee is appropriate. ZigBee has been developed for low-cost applications with little amount of data in wireless local area networks. In addition, sensors might be difficult to access in some cases, as they might be placed in hard-to-reach areas with no electricity being available, e.g. in the countryside, the mountains or at sea. So power consumption of a sensor node and network-independent functionality appear to be other critical factors [4], [6], [7]. Data might be stored internally until demanded by the network host. Each sensor node can be programmed by a coordinator. Figure 1. Basic block diagram of wireless measurement and control system