16-03-2011, 10:41 AM
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Introduction
The technological drive for smaller devices using less power with greater
functionality has created new potential applications in the sensor and data
acquisition sectors. Low-power microcontrollers with RF transceivers and
various digital and analog sensors allow a wireless, battery-operated network of sensor modules (“motes”) to acquire a wide range of data. The TinyOS is a real-time operating system to address the priorities of such a sensor network using low power, hard real-time constraints, and robust communications.
The first goal of WISENET is to create a new hardware platform
to take advantage of newer microcontrollers with greater functionality and
more features.This involves selecting the hardware, designing the motes, and porting TinyOS.Once the platform is completed and TinyOS was ported to it, the next stage is to use this platform to create a small-scale system of wireless networked sensors.
wisenet
WISENET is a wireless sensor network that monitors the environmental
conditions such as light, temperature, and humidity. This network is
comprised of nodes called “motes” that form an ad-hoc network to transmit is data to a computer that function as a server. The server stores the data in a database where it can later be retrieved and analyzed via a webbased interface.
The network works successfully with an implementation of one sensor mote.
System Description
There are two primary subsystems (Data Analysis and Data Acquisition)
comprised of three major components (Client, Server, Sensor Mote Network).
Primary Subsystems:
There are two top-level subsystems –
Data Analysis
Data Acquisition.
Data Analysis:
This subsystem is software-only (relative to WISENET). It relied on existing
Internet and web (HTTP) infrastructure to provide communications between the client and server components. The focus of this subsystem was to selectively present the collected environmental data to the end user in a graphical manner.
Data Acquisition:
The purpose of this subsystem is to collect and store environmental data for later processing by the Data Analysis subsystem. This is a mix of both PC & embedded system software, as well as embedded system hardware. It is composed of both the Server and Sensor Mote Network components.
System Components
System components are Client, Server, and Sensor Mote Network.
Client:
The Client component is necessary but external to the development of
WISENET.That is, any computer with a web browser and Internet access could be a Client. It served only as a user interface to the Data Analysis subsystem.
Server:
The Server is a critical component as the link between the Data Acquisition and Data Analysis subsystems. On the Data Analysis side, an web (HTTP) server hosting a web application. When a page request came in, the web server executes the web application, which retrieved data from the database, processes it, and returns a web page that the web server transmitted to the Client. For the data acquisition system there is a daemon (WiseDB) running to facilitate
communication with the Sensor Mote Network. This daemon is responsible for collecting raw data packets from the Sensor Mote Network. These packets are then processed to convert the raw data into meaningful environmental data. This processed data is then inserted into the database. Thus the database is the link between the Data Analysis and Data Acquisition subsystems. The Server also had the potential to send commands to the Sensor Mote Network (via the gateway mote), although this functionality was not explored in WISENET.It should be noted that since the SQL database connections can be made via TCP/IP, only the web server and web-program needed to be located on the same physical machine.
The web server, the database, and WiseDB could all be on different physical
machines connected via a LAN or the Internet. This allows a flexible Server
component implementation that is useful during WISENET development.