PROJECT REPORT ON WIRELESS CONTROL OF MOTOR USING ZIGBEE


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Introduction

The objective of this project is to design a simple, easy to install, microcontroller-based circuit to monitor and control the DC motor as required. We have two microcontrollers P89V51RD2 by Philips in the environment to optimize the maximum efficiency for control. The controller used is low cost, power efficient and flexible. An integrated Liquid crystal display (LCD) is also used for real time display of data acquired from the various sensors. Also, the use of easily available components reduces the manufacturing and maintenance costs. The design is quite flexible as the software can be changed any time. It can thus be tailor-made to the specific requirements of the user.
We also have use zigbee modules to send data wirelessly to an aquisition system for monitoring the parameters in the room.We have used two xbee nodes to send and receive data wirelessly over a range of 100m. One module acts as a receiver and other as a transmitter. The use of low cost components makes this project easy and efficient to afford.

What is Wireless Sensor Networking

Wireless sensor networks(WSN) consists of spatially distributed autonomous sensors to monitor physical environmental conditions such as temperature, sound, pressure, etc. and to cooperatively pass their data through the network to the main location. The more modern networks are bi-directional also enabling control of sensor activity.
The WSN is built of nodes from a few hundred to thousands, where each node is connected to one or several sensors. Each sensor has typically several parts, a radio transceiver with an internal antenna or connection to an external antenna, a microcontroller, an electronic circuit for interfacing with the sensors and an energy source usually a battery or an embedded form of energy harvesting. A sensor node might vary in size from that of a shoebox to a size of a grain. The cost of the sensor is similarly variable, ranging from a few to hundred rupees depending upon the complexity of the individual nodes. Size and cost constraints on sensor nodrs result in corresponding constraints on resources such as energy, memory, computational speed and communications bandwidth. The topology of WSN can vary from simple star network to an advanced multi hop wireless mesh network. The propagation technique between the hops of the network can be routing or flooding.

Why Use Zigbee?

Our project requires low power consumption. reduced latency, low cost and highly efficient data transfer rate over short range of distances. ZigBee is a specification for a suite of high level communication protocols using small, low-power digital radios based on an IEEE 802 standard for personal area networks. ZigBee devices are often used in mesh network form to transmit data over longer distances, passing data through intermediate devices to reach more distant ones. This allows ZigBee networks to be formed ad-hoc, with no centralized control or high-power transmitter/receiver able to reach all of the devices. Any ZigBee device can be tasked with running the network.

Advantages of XBee

When considering a wireless PICAXE application most users will compare the 2.4GHz XBee modem units with the slightly lower-cost 433MHz RF modules. Whilst the 433 modules are low cost and may be suitable for some very simple PICAXE applications, the XBee modules offer considerable advantages.
The primary advantage is that the XBee modules are ‘bi-directional’. Most budget 433 systems only transmit in one direction, so the transmitter has no idea whether the receiver is actually getting the data. The XBee modules transmit and receive in both directions, so you can easily test (at both ends) if the system is working correctly.
The second advantage is that of unique addressing. Each XBee unit has a unique serial number. This means two (or more) units can be set up to exclusively talk to each other, ignoring all signals from other modules. This is not easily achieved with 433 modules.
The third advantage is that the XBee module has in build ‘data-packet’ building and error-checking to ensure reliable data transmission. Finally the XBee protocol allows for a number of ‘channels’. By setting different units on different channels additional interference can be avoided.

Introduction to P89V51RD2

The P89V51RD2 microcontroller with 64KB Flash and 1024 bytes of data RAM. A key feature of the P89V51RD2 is its X2 mode option. The design engineer can choose to run the application with the conventional 80C51 clock rate ( 12 clocks per machine cycle) or select the X2 mode (6 clocks per machine cycle) to acheive twice the throughput at the same clock frequency. Another way to benefit from this feature is to keep the same performance reducing the EMI.
The Flash program memeory supports both parallel programming and in serial in system programming (ISP). Parallel programming mode offers gang programming to be re-programmed in the end product under software control. The capability to field/update the appkication firmware makes a wide range of applications possible.
The P89V51RD2 is also In-Application Orogrammable (IAP), allowing the flassh program memory to be reconfigured even whilr the application is running.

Rectifier:

A rectifier converts AC to DC, but the DC output is varying. There are several types of rectifiers; here we use a bridge rectifier.
The Bridge rectifier is a circuit, which converts an ac voltage to dc voltage using both half cycles of the input ac voltage. The Bridge rectifier circuit is shown in the figure. The circuit has four diodes connected to form a bridge. The ac input voltage is applied to the diagonally opposite ends of the bridge. The load resistance is connected between the other two ends of the bridge.
For the positive half cycle of the input ac voltage, diodes D1 and D3 conduct, whereas diodes D2 and D4 remain in the OFF state. The conducting diodes will be in series with the load resistance RL and hence the load current flows through RL.

LCD Module

To display interactive messages we are using LCD Module. We examine an intelligent LCD display of two lines,16 characters per line that is interfaced to the controllers. The protocol (handshaking) for the display is as shown. Whereas D0 to D7th bit is the Data lines, RS, RW and EN pins are the control pins and remaining pins are +5V, -5V and GND to provide supply. Where RS is the Register Select, RW is the Read Write and EN is the Enable pin.
The display contains two internal byte-wide registers, one for commands (RS=0) and the second for characters to be displayed (RS=1). It also contains a user-programmed RAM area (the character RAM) that can be programmed to generate any desired character that can be formed using a dot matrix. To distinguish between these two data areas, the hex command byte 80 will be used to signify that the display RAM address 00h will be chosen.Port1 is used to furnish the command or data type, and ports 3.2 to3.4 furnish register select and read/write levels.