An Industry-oriented Mini-Project Report on

WIRELESS DC MOTOR SPEED AND DIRECTION CONTROL
USING RF COMMUNICATION
Submitted to
Department of Electronics and Communication Engineering
Mahaveer Institute of Science and Technology
(Approved by AICTE) and affiliated to
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY
Hyderabad, (A.P.). in partial fulfillment of the Requirement for the award of Degree of

BACHELOR OF TECHNOLOGY in Electronics & Communication Engineering
Submitted By

K. Vinay 08E31A04C8

GUIDE MINI-PROJECT COORDINATOR HEAD OF DEPT. Mr. Sridhar Chitta Mr. M. Nagaraju Naik Dr. B. Visvesvara Rao .

MAHAVEER INSTITUTE OF SCIENCE & TECHNOLOGY
Vyasapuri, Bandlaguda, Post: Keshavgiri, Hyderabad – 500 005
2011 - 2012

CERTIFICATE
This is to certify that the mini project work titled WIRELESS DC MOTOR SPEED AND DIRECTION CONTROL USING RF COMMUNICATION, which is being submitted
By
K. Vinay 08E31A04C8 in partial fulfilment for the award of Degree of Bachelor of Technology in Electronics and Communication Engineering to the Mahaveer Institute of Science and Technology, affiliated to Jawaharlal Nehru Technological University and is a bonafide record of work carried out by them under our supervision.
The results embodied in this mini-project report have not been submitted to any other University or Institute for the award of any degree or diploma.

Project Guide Project Coordinator Head of the Department Mr. Sridhar Chitta Mr. M. Nagaraju Naik Dr. B. Visvesvara Rao Associate Professor Associate Professor Professor

ACKNOWLEDGEMENT
This satisfaction and euphoria that accompany the successful completion of any task would be but incomplete without the mention of the people who made it possible and under whose constant guidance and encouragement, the task was completed.
We would like to express our sincere thanks to Mr. Sridhar Chitta, Associate Professor, Dept. of ECE, for his suggestion and support in successful completion of project.
We would like to express out profound gratitude to our Head of the department Dr. B. Visvesvara Rao, Dept. of ECE, and our project coordinator Mr. Nagaraju Naik, Department of ECE.
Finally, our sincere thanks to all our members who were helpful directly and in the completion of our project.

BY
K. Vinay 08E31A04C8
ABSTRACT
In recent years, due to a wide revolution in electronics, conventionally wired control circuits for motors are being replaced by controls using wireless connectivity.
By the summer of 1831, Joseph Henry improved on Michael Faraday’s experimental work in electromagnetism and built a simple device whose moving part was a straight electromagnet rocking on a horizontal axis. Its polarity was reversed automatically by its motion as pairs of wires projecting from its ends made connections alternately with two electrochemical cells. Two vertical permanent magnets alternately attracted and repelled the ends of the electromagnet, making it rock back and forth. A year after Henry’s motor was demonstrated, William Sturgeon invented the commutator which produces continuous rotary motion and this was the first rotary electric motor.
The basic principle behind the DC motor is the wires that carry current experience force, when placed in the regions of space that have magnetic field. The speed at which the rotor of a motor spins depend on the amount of current in the wire, the length of the wire and the strength of the magnetic field.
In the past several decades, the controllers for such motors were wired starters that used external resistors to control the currents to DC motor armatures and thereby the speed of its rotation and the power delivered to mechanical loads. With features like speed and direction control, this project aims to develop a circuit for controlling the motor using Radio Frequency (RF) signals. Such RF controlled motors can be quickly deployed for the actuation of hydraulic flow control valves, fire and irrigation controllers and a host of other applications where time to install and cost of wiring especially in areas that are not always easy to access are at a premium. INDEX S.No. CHAPTER NAME Page No. 1. INTRODUCTION 01 1.1 EMBEDDED SYSTEMS 03 1.2 WIRELESS TECHNOLOGIES 03 1.3 OVERVIEW OF EMBEDDED SYSTEM ARCHITECTURE 04 2. DC MOTOR AND MOTOR CONTROL 06 2.1 PRINCIPLES OF OPERATION 06 2.2 H-BRIDGE 09 2.2.1 OPERATION 10 2.2.2 DESCRIPTION 12 2.2.3 PIN CONNECTIONS 13 3. RADIO FREQUENCY 17 3.1 PROPERTIES OF RF 17 3.2 NEED FOR RF COMMUNICATION 17 3.3 RF COMMUNICATION AND ON-OFF 18 KEYING MODULATION 3.4 RF TRANSMITTER STT - 433MHZ 21 3.4.1 TRANSMITTER STT - 433MHZ 21 3.4.2 PIN DESCRIPTION OF RF TRANSMITTER 22 3.4.3 BC 557 TRANSISTOR 23 3.4.4 APPLICATION OF RF TRANSMITTER 24 3.5 ENCODER HT640 25 3.5.1 WORKING OF ENCODER 26 3.5.2 FLOWCHART 28 3.5.3 GRAPH SHOWING FREQUENCY VERSUS VOLTAGE 29 3.5.4 BASIC APPLICATION CIRCUIT OF HT640 ENCODER 30 3.6 RF RECEIVER STR - 433 MHZ 31 3.7 DECODER HT648L 33 3.7.1 WORKING FUNCTION OF A DECODER 34 3.7.2 FLOWCHART 35 3.7.3 BASIC APPLICATION CIRCUIT OF HT648L DECODER 36 4. POWER SUPPLY 37 4.1 TRANSFORMER 37 4.2 VOLTAGE REGULATOR 38 5. MICROCONTROLLER 40 5.1 DESCRIPTION 41 5.2 PIN DESCRIPTION 43 5.3 DATA MEMORY – EEPROM AND RAM 47 5.3.1 INSTRUCTIONS 47 5.3.2 PROGRAMMING THE FLASH AND EEPROM 49 5.4 MACHINE CYCLE FOR THE 8052 51 6. LIQUID CRYSTAL DISPLAY 53 6.1 LCD SCREEN 55 6.2 LCD CONNECTION 55 6.3 LCD INITIALIZATION 56 6.4 CONTRAST CONTROL 58 6.5 LCD INTERFACING WITH THE MICROCONTROLLER 59 7. IMPLEMENTATION 61 8. CODING 64 8.1 PROLOAD 64 8.2 CODE 65 CONCLUSION 74 REFERENCE 75

LIST OF FIGURES S.NO. FIGURE NAME PAGE NO. CHAPTER - 1 1.1 TRANSMITTER 01 1.2 RECEIVER 02 1.3 LAYERED ARCHITECTURE OF AN EMBEDDED SYSTEM 04 1.4 HARDWARE OF AN EMBEDDED SYSTEM 05 CHAPTER - 2 2.1 DC MOTOR 06 2.2 A SIMPLE 2-POLE DC ELECTRIC MOTOR 07 2.3 INTERNAL DIAGRAM OF MOTOR 07 2.4 FIELD FLOW IN DC MOTOR 08 2.5 H-BRIDGE 09 2.6 H-BRIDGE WITH L293D 11 2.7 L293D CHIP 12 2.8 PIN DESCRIPTION OF L293D 13 2.9 INTERNAL CONNECTIONS OF L293D 14 2.10 FREE WHEELING DIODES 15 CHAPTER - 3 3.1 RF CARRIER WAVEFORM 19 3.2 ON-OFF KEYED MORSE CODE CHARACTER 20 3.3 MODULATED CARRIER WAVE TRANSMITTED 20 3.4 RF TRANSMITTER 21 3.5 BLOCK DIAGRAM OF THE ST-433 TRANSMITTER 22 3.6 PIN DESCRIPTION ON RF TRANSMITTER 22 3.7 BC 557 TRANSISTOR 23 3.8 TRANSMITTER CIRCUIT WITH SWITCH 24 3.9 TYPICAL CONNECTION OF RF TRANSMITTER 24 3.10 ENCODER HT640 – 24 SOP/SDIP 25 3.11 TRANSMISSION TIMING OF ENCODER 26 3.12 DATA PIN PRESET 27 3.13 TRANSMITTER SECTION 27 3.14 FLOWCHART SHOWING ENABLING OF TRANSMITTER 28 3.15 FREQUENCY VS VOLTAGE GRAPH 29 3.16 APPLICATION CIRCUIT OF ENCODER 30 3.17 TRANSMISSION CIRCUIT 30 3.18 RF RECEIVER 31 3.19 PIN DESCRIPTION OF RECEIVER 31 3.20 TYPICAL CONNECTION OF RF RECEIVER 32 3.21 DECODER 33 3.22 RECEIVER SECTION 34 3.23 FLOWCHART SHOWING ENABLING OF RECEIVER 35 3.24 APPLICATION CIRCUIT OF DECODER 36 3.25 RECEPTION CIRCUIT 36 CHAPTER - 4 4.1 POWER SUPPLY CIRCUITRY 37 4.2 STEP DOWN TRANSFORMER 37 4.3 RECTIFIER CIRCUIT 38 4.4 VOLTAGE REGULATOR 7805 39 4.5 HEAT SINK 39 4.6 POWER SUPPLY SECTION 39 CHAPTER - 5 5.1 AT89S52 MICROCONTROLLER 42 5.2 PIN DIAGRAM OF AT89S52 43 5.3 MICROCONTROLLER PIN CONNECTIONS 52 CHAPTER - 6 6.1 LCD 16X2 53 6.2 LCD PIN CONNECTIONS 55 6.3 PROCEDURE ON 8-BIT INITIALIZATION 57 6.4 VARIABLE RESISTOR 58 6.5 POTENTIOMETER SYMBOL 58 6.6 PRESET SYMBOL 59 6.7 PRESET 59 6.8 LCD MODULE 59 6.9 LCD INTERFACE WITH MICROCONTROLLER 60 CHAPTER - 7 7.1 RECEIVER SECTION 61 7.2 TRANSMITTER SECTION 62

LIST OF TABLES S.No. TABLE NAME PAGE No. CHAPTER - 2 2.1 OPERATION OF MOTOR WHEN CONNECTED 10 WITH H-BRIDGE 2.2 ABSOLUTE MAXIMUM RATINGS OF L293D 13 CHAPTER - 3 3.1 PIN DESCRIPTION OF BC557 23 3.2 PIN DESCRIPTION OF ENCODER 26 3.3 PIN DESCRIPTION OF DECODER 33 CHAPTER - 5 5.1 PORT1 ALTERNATE FUNCTIONS 46 5.2 PORT3 ALTERNATE FUNCTIONS 47 5.3 MCON REGISTER 48 5.4 FUNCTIONING OF MCON REGISTER 48 CHAPTER - 6 6.1 PIN FUNCTION OF LCD 54