Line Follower Using 89s52

by:-

Submitted

Ankur khurana (07EI407) Acknowledgement It is our privilege to express our sincerest regards to our project coordinator, Mr Jitender Singh Saggu for their valuable inputs, able guidance, encouragement, whole-hearted cooperation and constructive criticism throughout the duration of our project. We deeply express our sincere thanks to our teacher Dr Vishnu for encouraging and allowing us to present the project on the topic “Line Follower Robot “at our department premises for the partial fulfillment of the requirements leading to the award of B-Tech degree.We take this opportunity to thank all our lecturers who have directly or indirectly helped our project. We pay our respects and love to our parents and all other family members and friends for their love and encouragement through out our career. Last but not the least we express our thanks to ourfriends for their cooperation and support.

FOREWORD: The word robot was coined by the Czech writer Kapek in his play ‘Rossum's Universal Robots’. Since then countless devices have been created and have been associated with the word ‘Robot’. The works of Isaac Asimov have laid the foundation of sociology pertaining to the use of robots instead of humans and the word ‘Robotics’ was also coined by him. In today’s world, work on robots, that resemble and look almost human, and others which don’t resemble humans in any way, progresses in leaps and bounds. The world has forerunners in this technology like MIT, CMU, Sony, Honda etc. In this world of ASIMO, AIBO, Packbot etc., we have made an attempt to create machines which we dare call ‘Robots’. In this era where organizations like ABU – Asia Pacific Broadcasting Union are organizing robot contests like Robocon we have made an attempt to make robotic systems which could send and receive communication signal amongst them and complete the task assigned to them with coordinated efforts. Today when technology is developing faster then a blink of an eye and the competition is tough to win at any stage may it be national or international, we have put in tireless efforts to implement the technology in simpler and effective form to compete against some of the best in field of robotics in the country.

Table of contents:1: Introduction 2: Microcontroller 2.1: definition 2.2

ATMEL 89S52

2.3

FEATURES

2.4

DESCRIPTION

2.5

89S52 PROCESSOR ARCHITECTURE

2.6

PIN DESCRIPTION

2.7

PIN DIAGRAM OF AT89S52

2.8

DESIGN OF INFRARED SENSOR CIRCUIT

2.9

POSITIONING OF SENSORS

2.10 SENSOR ARRAY 2.11 MOTOR DRIVER:-L293D 2.12

COMPARATOR

2.13 DC MOTORS

2.14 BIPOLAR MOTOR DRIVER:2.15 PIN CONNECTIONS 2.16 Multipurpose Schematics and PCB Designs 2.17 Line Following and Turning 2.18 WHAT IS ISP? 2.19 BLOCK DIAGRAM OF LINE FOLLOWER ROBOT 2.20 ONBOARD PIN CONNECTIONS

2.21 SOFTWARE 2.22 SOURCE CODE 2.23 HEX CODE GENERATED FOR THE CODE 2.24 PROBLEMS ENCOUNTERED 2.25 REFERENCES AND RESOURCES

INTRODUCTION What is a line follower? Line follower is a machine that can follow a path. The path can be visible like a black line on a white surface (or viceversa) or it can be invisible like a magnetic field. Why build a line follower? Sensing a line and maneuvering the robot to stay on course, while constantly correcting wrong moves using feedback mechanism forms a simple yet effective closed loop system. As a programmer you get an opportunity to ‘teach’ the robot how to follow the line thus giving it a human-like property of responding to stimuli. Practical applications of a line follower: Automated cars running on roads with embedded magnets; guidance system for industrial robots moving on shop floor etc. Prerequisites: Knowledge of basic digital and analog electronics. Assembly Programming Sheer interest, an innovative brain and perseverance!

MICROCONTROLLER:-

2.1:-Defination A Microcontroller is a single-chip microcomputer that contains all the componentssuch as the CPU, RAM, some form of ROM, I/O ports, and timers. Unlike a generalpurpose computer, which also includes all of these components, a microcontroller is designed for a very specific task -- to control a particular system. Microcontrollers are sometimes called embedded microcontrollers, which just means that they are part of an embedded system. A microprocessor is a general-purpose digital computer with central processing unit (CPU), which contains arithmetic and logic unit (ALU), a program counter (PC), a stack pointer (SP), some working registers, a clock timing circuit, and interrupts circuits. The main disadvantage of microprocessor is that it has no on-chip memory. So we are going for micro controller since it has on-board programmable ROM and I/O that can be programmed for various control functions

2.2:- ATMEL 89S52 AT89S52 MICROCONTROLLER The microcontroller development effort resulted in the 8051 architecture, which was first introduced in 1980 and has gone on to be arguably the most popular micro controller architecture available. The 8051 is a very complete micro controller with a large amount of built in control store (ROM & EPROM) and

RAM, enhanced I/O ports, and the ability to access external memory. The maximum clock frequency with an 8051 micro controller can execute instructions is 20MHZ. Microcontroller is a true computer on chip. The design incorporates all of the features found in a microprocessor: CPU, ALU, PC, SP and registers. It also has the other features needed to, make complete computer: ROM, RAM, parallel I/O, serial I/O, counters and a clock circuit. The 89C51/89C52/89C54/89C58 contains a non-volatile FLASH program memory that is parallel programmable. For devices that are serial programmable (In-System Programmable (ISP) and In-Application Programmable (IAP) with a boot loader)All three families are Single-Chip 8-bit Microcontrollers manufactured in advanced CMOS process and are Derivatives of the 80C51 microcontroller family. All the devices have the same instruction set as the 80C51. 2.3 FEATURES • 8K Bytes of In-System Reprogrammable Flash Memory • Endurance: 1,000 Write/Erase Cycles • Fully Static Operation: 0 Hz to 33 MHz • Three-level Program Memory Lock • 256 x 8-bit Internal RAM • 32 Programmable I/O Lines • Three 16-bit Timer/Counters • Eight Interrupt Sources • Programmable Serial Channel • Low-power Idle and Power-down Modes

2.4 DESCRIPTION: The AT89s52 is a low power, high performance CMOS 8-bit micro computer with 8K bytes of flash programmable and erasable read only memory(PEROM).The device is manufactured using Atmel’s high density nonvolatile memory technology and is compatible with the industry standard 80c51 and 80C52 instruction set and pin out. The on-chip flash allows the program memory to be reprogrammed insystem or by a conventional nonvolatile memory programmer. By combining a versatile 8-bit CPU with flash on a monolithic chip, the Atmel AT89s52 Is a powerful microcomputer which provides a highly flexible and cost effective solution to many embedded control applications. The main advantages of 89s52 over 8051 are Software Compatibility Program Compatibility Rewritability The 89s52 microcontroller has an excellent software compatability, i.e. the software used can be applicable to any other microcontroller. The program written on this microcontroller can be carried to any base. Program compatibility is the major advantage in 89s52. The program can be used in any other advanced microcontroler. The program can be reloaded and changed for nearly 1000 times.

2.5:- 89S52 PROCESSOR ARCHITECTURE:

The AT89s52 provides the following standard features: 8K bytes of Flash, 256 bytes of RAM, 32 I/O lines, three 16-bit timer/counters, a six-vector two-level interrupt architecture, a full-duplex serial port, on-chip oscillator, and clock circuitry.

In addition, the AT89s52 is designed with static logic for operation down to zero frequency and supports two software selectable power saving modes. The Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port, and interrupt system to continue functioning. The Power-down mode saves the RAM contents but freezes the oscillator, disabling all other chip functions until the next hardware reset. 2.6:- PIN DESCRIPTION: VCC Supply voltage. GND Ground. Port 0 Port 0 is an 8-bit open drain bi-directional I/O port. As an output port, each pin can sink eight TTL inputs. When 1s are written to port 0 pins, the pins can be used as high impedance inputs. Port 0 can also be configured to be the multiplexed lower order address/data bus during accesses to external program and data memory. In this mode, P0 has internalpullups.Port 0 also receives the code bytes during Flash programming and outputs the code bytes during program verification. External pullups are required during program verification. Port 1

Port 1 is an 8-bit bi-directional I/O port with internal pull-ups. The Port 1 output buffers can sink/source four TTL inputs. When 1s are written to Port 1 pins, they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 1 pins that are externally being pulled low will source current (IIL) because of the internal pull-ups. In addition, P1.0 and P1.1 can be configured to be the timer/counter 2 external count input (P1.0/T2) and the timer/counter 2

2.7:- PIN DIAGRAM OF 89S52

2.8:- DESIGN OF INFRARED SENSOR CIRCUIT: Pr inciple of operation of the I.R L.E.D . and Phototransistor: -

A Photodiode is a p-n junction or p-i-n structure. When an infrared photon of sufficient energy strikes the diode, it excites an electron thereby creating a mobile electron and a positively charged electron hole. If the absorption occurs in the junction's depletion region, or one diffusion length away from it, these carriers are swept from the junction by the built-in field of the depletion region, producing a photocurrent. Photodiodes can be used under either zero bias (photovoltaic mode) or reverse bias (photoconductive mode). Reverse bias induces only little current (known as saturation or back current) along its direction. But a more important effect of reverse bias is widening of the depletion layer (therefore expanding the reaction volume) and strengthening the photocurrent when infrared falls on it. There is a limit on the distance between I.R. L.E.D. and infrared sensor for the pair to operate in the desired manner. In our case distance is about 5mm. Infra-Red emitter sends out IR pulses. Position calculation is done through intensity of reflected light received by the detector. Ambient interference is negligible

2.9:- POSITIONING OF SENSORS:-

The resistance of the sensor decreases when IR (infrared) light falls on it. A good sensor will have near zero resistance in presence of light and a very large resistance in absence of light. Whether the sensors are Light Dependent Resistors, laser diode, Infrared Sensors, Ultrasonic Sensors or anything else,the outputs of the sensor modules are fed to the Non-inverting input of a comparator . The reference voltage of the comparator is fed to the inverting input of the comparator by a trim pot or a tuning device connected between the supply lines.

LM339 is a comparator IC that digitizes the analog signal from the sensor array. Since the output of LM339 is TTL compatible it can be directly fed to the master microcontroller. The generalized connection diagram of Sensor Interfacing with microcontroller is shown below:-

CONNECTING INFRARED MODULE WITH MICROCONTROLLER MCS-51

When the sensor/emitter pair is on shining surface sensor is on i.e. in

low impedance mode which one can easily view as L.E.D. corresponding to that sensor doesn’t glow. The output of the opamp is HIGH SIGN AL and this HIGH SIGNAL is given to the microcontroller and when the sensor is on normal non-reflecting surface it’s off i.e. in HIGH IMPEDANCE state which one can easily view as L.E.D. corresponding to that sensor glows up and LOW SIG NAL is given to the microcontroller.

2.10:- Infra-Red Sensor Array

2.11:- MOTOR DRIVER:-L293D The L298 Motor Driver has 4 inputs to control the motion of the motors and two enable inputs which are used for switching the motors on and off. To control the speed of the motors a PWM waveform with variable duty cycle is applied to the enable pins. Rapidly switching the voltage between Vs and GND gives an effective voltage between Vs and GND whose value depends on the duty cycle of PWM. 100% duty cycle corresponds to voltage equal to Vs, 50 % corresponds to 0.5Vs and so on. The 1N4004 diodes are used to prevent back EMF of the motors from disturbing the remaining circuit. Many circuits use L293D for motor control, I chose L298 as it has current capacity of 2A per channel @ 45V compared to 0.6 A @ 36 V of a L293D. L293D’s package is not suitable for attaching a good heat sink, practically you can’t use it above 16V

2.12:-COMPARATOR

2.13:- DC MOTORS These are very commonly used in robotics. DC motors can rotate in both directions depending upon the polarity of current through the motor. These motors have free running torque and current ideally zero. These motors have high speed which can be reduced with the help of gears and traded off for torque. Speed Control of DC motors is done through Pulse Width Modulation techniques, i.e. sending the current in intermittent bursts. PWM can be generated by 555

timer IC with adjusted duty cycle. Varying current through the motor varies the torque.

PICTURE OF DC MOTOR USED

2.14:- BIPOLAR MOTOR DRIVER:L293D is a bipolar motor driver IC. This is a high voltage, high current pushpull four channel driver compatible to TTL logic levels and drive inductive loads. It has 600 mA output current capability per channel and internal clamp diodes. The L293 is designed to provide bidirectional drive currents of upto 1 A at voltages from 4.5 V to 36 V. The L293D is designed to provide bidirectional drive currents of up to 600-mA at voltages from 4.5 V to 36 V. Both devices are designed to drive inductive loads such as relays, solenoids, dc and bipolar stepping motors, as well as other high-current/high-voltage loads in positive supply applications. All inputs are TTL compatible. Each output is a complete totem-pole drive circuit, with a Darlington transistor sink and a pseudoDarlington source. Drivers are enabled in pairs, with drivers 1 and 2 enabled by 1,2EN and drivers 3 and 4 enabled by 3,4EN. When an enable input is high, the associated drivers are enabled, and their outputs are active and in phase with their inputs. When the

enable input is low, those drivers are disabled, and their outputs are off and in the high-impedance state. With the proper data inputs, each pair of drivers forms a full-H (or bridge) reversible drive suitable for solenoid or motor applications

2.15:-PIN CONNECTIONS

2.16:- Multipurpose Schematics and PCB Designs The Schematics and PCB Designs of the Electronic Circuits have been done such that the PCBs are multipurpose and just with the minute change in the number of components mounted on the PCB and some change in the interconnections between the PCBs, they could be used for all the robots. In fact the PCBs are made such that in most of the general robotic applications these PCBs could be used.

2.17:-Line Following and Turning The autonomous robots are required to perform their respective tasks without any manual guidance. Thus the technique used to make the robots reach the desired locations in order to perform their tasks is the white line following, cross detection and turning technique using the optoelectronic sensors. These optoelectronic sensors are actually developed during the project using light to voltage converter IC – OPT101 and LED. These sensors work on the principle of reflective light amplification. The IC – OPT101 comprised of a photodiode and amplifier. The light of LED reflects from the surface and falls on to the OPT101 which is amplified by the amplifier inbuilt the IC. The intensity of the light falling onto the photodiode of IC depends upon the color of the surface. Thus while the sensor is on the white line it gives the saturated output voltage where as while not on the white line it gives a low voltage. This voltage is converted into a digital signal using an analog comparator IC TLC324 where the second input to the IC is a fixed voltage. Thus when the output voltage of the sensor is

below certain level i.e. when the sensor is not on white line it gives ‘0’ as the output whereas if the output voltage of the sensor is above certain level i.e. when the sensor is on the white line it gives ‘1’ as the output. Using six such sensors divided into two rows on in front and one at the rear side the white line following is achieved. To make the robot follow the white line various sequences of the possible states of the sensors are considered and depending upon the same, position of the robot and correction required in the proper direction is analyzed. Finally on the basis of the required correction, PWM signal is applied to the H-Bridge drive circuit which uses LMD18200T IC, and the straight line is followed by the robot. For the motion of the robot high torque Maxon Motors are used with the gearbox having 1:18 ratio of gear reduction. While the robot follows the white line it is also required for the robot to take 90 degree turn in certain direction. For the same the cross detection is used in which the robot counts the number of crosses in the grid it passes and when this number matches with the number of cross where it has to turn or stop, the robot stops the straight line motion and the by rotating both the motors in the opposite directions it takes the turn in the desired direction till the desired sensor in the front line of the sensors come onto the white line.

2.18:- WHAT IS ISP? In-Syste m Programming (abbreviated ISP) is the ability of some programmable logic devices, microcontrollers, and other programmable electronic chips to be programmed while installed in a complete system, rather than requiring the chip to be programmed prior to installing it into the system. The primary advantage of this feature is that it allows manufacturers of electronic devices to integrate programming and testing into a single production phase, rather than requiring a separate programming stage prior to assembling the system. This may allow manufacturers to program the chips in their own system's production line instead of buying preprogrammed chips from a manufacturer or distributor, making it feasible to apply code or design changes in the middle of a production run. Typically, chips supporting ISP have internal circuitry to generate any necessary programming voltage from the system's normal supply voltage, and communicate with the programmer via a serial protocol. Most programmable logic devices use proprietary protocols or protocols defined by

older standards. In systems complex enough to require moderately large glue logic.

2.19:- BLOCK DIAGRAM OF LINE FOLLOWER ROBOT

2.20:- CIRCUIT DIAGRAM OF LINE FOLLOWER ROBOT:-

2.22:- ONBOARD PIN CONNECTIONS

2.23:- SOFTWARE The software programs for the microcontroller have been developed using Assembly Level Programming language. Microcontroller used in the project is 89S52 manufactured by atmel which is 8052 based microcontroller. Thus for microcontroller software programming Evaluation Version of Assembler – 8051IDE developed by AceBus has been used to assemble, compile and simulate the software programs. The benefit of using AT89S52 microcontroller is that the AT89S52 is a lowpower, high-performance CMOS 8-bit microcontroller with 8K bytes of in-system programmable Flash memory. The device is manufactured using Atmel’s high-density nonvolatile memory technology and is compatible with the industry- standard 80C51 instruction set and pinout. The on-chip Flash allows the program memory to be reprogrammed in-system or by a conventional nonvolatile memory programmer. By combining a versatile 8-bit CPU with insystem programmable Flash on a monolithic chip, the Atmel AT89S52 is a powerful microcontroller which provides a highly-flexible and costeffective solution to many embedded control applications. The AT89S52 provides the following standard features: 8K bytes of Flash, 256 bytes of RAM, 32 I/O lines, Watchdog timer, two data pointers, three 16-bit timer/counters, a six-vector two-level interrupt architecture, a full duplex serial port, on-chip oscillator, and clock circuitry. In addition, the AT89S52 is designed with static logic for operation down to zero frequency and supports two software selectable power saving modes. The Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port, and interrupt system to continue functioning. The Powerdown mode saves the RAM contents but freezes the oscillator, disabling all other chip functions until the next interrupt or hardware reset.

2.24:- SOURCE CODE PROGRAM FOR LINE FOLLOWER =======SYSTEM REGISTERS============== P0 EQU 080H P1 EQU 090H P2 EQU 0A0H P3 EQU 0B0H TH1 EQU 08DH TL1 EQU 08BH TCON EQU 088H TMOD EQU 089H IE EQU 0A8H SP EQU 081H FLAG1 EQU 0D0H ;======= PORT PIN DEFINITIONS ======== SENSOR1 EQU P1.0 SENSOR2 EQU P1.1 LED_RED EQU P0.6 LED_GREEN EQU P0.7 L_EN EQU P0.2 R_EN EQU P0.4 L_MO1 EQU P0.1 L_MO2 EQU P0.0 R_MO1 EQU P0.3 R_MO2 EQU P0.5 ;XXXXMXLR ; X X X X 1 X 0 0 - FWD -- 03 ; 0 1 - TR 01 ; 1 0 - TL 02

; 00 - STOP 00 ;========== HERE THE MAIN PROGRAM STARTS ========== ORG 0000H AJMP START ORG 0050H START: MOV R1,#0FFH MOV R2,#004H MOV P2,#000H LOOP: MOV C,SENSOR1 MOV LED_RED,C MOV C,SENSOR2 MOV LED_GREEN,C MOV A,P1 ANL A,#003H CJNE A,#000H,CHECK_LEFT ;////// GO FORWARD ///////// SETB R_MO1 CLR R_MO2 SETB L_MO1 CLR L_MO2 MOV R1,#0FFH MOV R2,#004H AJMP LOOP CHECK_LEFT: CJNE A,#001H,CHECK_RIGHT ;////// TURN LEFT /////////// SETB R_MO1 CLR R_MO2 CLR L_MO1 SETB L_MO2 MOV R1,#0FFH MOV R2,#004H

HERE_LEFT: MOV A,P1 ANL A,#003H CJNE A,#003H,LEFT_CONT DJNZ R1,LEFT_CONT DJNZ R2,LEFT_CONT AJMP STOP LEFT_CONT: JB P1.0,HERE_LEFT AJMP LOOP CHECK_RIGHT: CJNE A,#002H,CHECK_STOP ;/////// TURN RIGHT /////// CLR R_MO1 SETB R_MO2 SETB L_MO1 CLR L_MO2 MOV R1,#0FFH MOV R2,#004H HERE_RIGHT: MOV A,P1 ANL A,#003H CJNE A,#003H,RIGHT_CONT DJNZ R1,LEFT_CONT DJNZ R2,LEFT_CONT AJMP STOP RIGHT_CONT: JB P1.1,HERE_RIGHT AJMP LOOP CHECK_STOP: DJNZ R1,LOOP

STOP: SETB R_MO1 SETB R_MO2 SETB L_MO1 SETB L_MO2 HERE_STOP: AJMP HERE_STOP END

2.25:- HEX CODE GENERATED FOR THE CODE : 020000000150AD : 1000500079FF7A0475A000A2909286A2919287E51A : 10006000905403B4000ED283C285D281C28079FF3E : 100070007A040157B4011ED283C285C281D280792D : 10008000FF7A04E5905403B40306D904DA0201B8F8 : 100090002090F00157B4021EC283D285D281C28063 : 1000A00079FF7A04E5905403B40306D9E3DAE10159 : 1000B000B82091F00157D99FD283D285D281D280C6 : 0200C00001C07D : 00000001FF

2.26:- PROBLEMS ENCOUNTERED The ISP programmer requires dedicated supply of 9V from the USB of your P.C. Extern supply of other than 9V generates error while writing the HEX code to the Microcontroller. The programmer was soldered 3 times before it could successfully program the chip. • The program was difficult to implement as it was our first encounter with microcontroller programming in assembly. • The large number of interconnections in the circuit made it too difficult to solder. • The IR sensors burnt up on soldering so we have to use temperature controlled soldering iron. • In the model designed to show line follower robot, electric motors ought to be bidirectional and of low wattage i.e. should draw lesser current otherwise the motor can draw current to such a level to burn up the entire circuit.

2.27:- REFERENCES AND RESOURCES Books : 1) The 8051 Microcontroller and Embedded Systems Using Assembly and C By Muhammad Ali Mazidi, Janice Gillispie Mazidi & Ro lin D. McKinlay Webs ite s r ef er re d: 1) Atmel Corp. Makers of the AVR microcontroller www.atmel.com 2) One of the best sites AVR site www.avrfreaks.net 3) One of the best site for Microcontroller projects www.kmitl.ac.th 4) Keil™, the developer of Keilμvision www.keil.com 5) Information from www.wikipedia.com