Block Diagram Chapter 3: List

CONTENTS

List of Figures III List of Tables V Abstract VI Chapter 1: Introduction 1  Introduction 1  Problem Definition 2 Chapter 2: Block Diagram 3  Solar Panel 3  Battery 4  Microcontroller 4  Motor Driver IC (L293D) 4  12V DC Motor 5 Chapter 3: List of Components and Costing 6 Chapter 4: Circuit Diagram and Explanation 7  Microcontroller (AT89S51) 8  Solar panel 13  Battery 14  Motor 15  L293D 17  Resistor 19  Capacitor 20  LED 22 Chapter 5: Algorithm, Flowchart & Program 22  Algorithm of Project 22

 Flowchart of Project 23

 Program of Project 24

Chapter 6: PCB Fabrication & Soldering 29  Description 29

 PCB Materials 30

 PCB Layout Designing Software 30

 Software used For PCB Designing 31

 Making an EAGLE Schematic 32

 Making Layout using EAGLE 35

 Precautions taken during PCB Designing 37

 PCB Layouts 38

 PCB Etching 40

 PCB Drilling 43

 PCB Soldering 45 Chapter 7: Troubleshooting and Testing 48  Troubleshooting 48  Description 48  Need of Troubleshooting 48  Steps Prior to Troubleshooting 49  Steps for Troubleshooting 49

 Practical Troubleshooting 51

 Testing the board with various tools 52 Chapter 8: Datasheet 56  Microcontroller AT89S51 56

 L293D 56

 Solar Panel 58

 Rechargeable Battery 59

Chapter 9: Advantages, Limitations, Future scope, 60 Applications and Conclusion  Advantages 60

 Limitations 60

 Future Scope 61

 Applications 61

 Conclusion 61 Chapter 10: Bibliography 62

III

LIST OF FIGURES

Fig 1.1: Industry 1

Fig 1.2: Solar panel to battery 2

Fig 2.1: Block diagram of solar grass cutter 3

Fig 4.1: Circuit diagram 7

Fig 4.2: Microcontroller 89S51 8

Fig 4.3: Microcontroller mounted on a PCB 9

Fig 4.4: Pin diagram of 89S51 10

Fig 4.5: Microcontroller oscillator section 13

Fig 4.6: Solar panel 14

Fig 4.7: Battery 14

Fig 4.8: Basic principle of DC motor 15

Fig 4.9: Fleming’s left hand rule 16

Fig 4.10: 12V DC motor 16

Fig 4.11: Pin diagram of L293D 17

Fig 4.12: Resistor 19

Fig 4.13: Capacitor 20

Fig 4.14: LED 21

Fig 6.1: Control panel of eagle 33

Fig 6.2: Schematic editor of eagle 34

Fig 6.3: Board editor of eagle 34

Fig 6.4: Layout of microcontroller section 38

III

Fig 6.5: Layout of motor section 39

Fig 6.6: PCB cutter 40

Fig 6.7: Cleaning of PCB 40

Fig 6.8: DIP coat 41

Fig 6.9: PCB oven 41

Fig 6.10: UV exposure 42

Fig 6.11: AGITATING PCB 42

Fig 6.12: Easy etcher 43

Fig 6.13: Drill machines 45

Fig 6.14: Soldering of PCB 46

Fig 6.15: Dry soldering 47

Fig 7.1: Multi meter 53

Fig 7.2: Cathode ray oscilloscope 54

Fig 7.3: IC tester 55

Fig 8.1: Pinout of L293D 57

Fig 8.2: Internal Block Diagram of L293D 58

LIST OF TABLES

Table 3.1: Component list and costing 4 Table 4.1: Alternate functions of port 3 11 Table 4.2: Pin description of L293D 19

ABSTRACT

A Solar grass cutter is a machine that uses circular blades to cut a lawn at an even length. Even more sophisticated devices are there in every field. Power consumption becomes essential for future. Solar grass cutter is a very useful device which is very simple in construction. It is used to maintain and upkeep lawns in gardens, schools, college’s etc. We have made some changes in the existing machine to make its application easier at reduced cost. Our main aim in pollution control is attained through this. Unskilled operation can operate easily and maintain the lawn very fine and uniform surface look. In our project, solar grass cutter is used to cut the different grasses for the different application. Unlike commercial grass cutter this grass cutter works on the solar supply so it is very much energy efficient. There is no question of air getting polluted. The reason of using solar energy is solar energy is natural resource which is available in plenty. If we go for fuels like petrol, diesel it will cause pollution plus to this fuel causes lot of pollution of air. The grass cutter and vehicle motors are interfaced to an 8051 family microcontroller that controls the working of all the motors. The motor driver IC L293D is to boost the current which is given to the microcontroller to drive the motor. The current from microcontroller is very less so it cannot drive the motor so L293D must be used.

CHAPTER-1

INTRODUCTION

1.1 INTRODUCTION

The commercial grass cutter are very bulky in size and large amount of power consumption but the solar power grass cutter would be a good replace option of that. We have designed a “SOLAR GRASS CUTTER” which will be very useful in today’s industries. The grass cutter is powered by a solar panel and 12V DC rechargeable Lead-acid battery. The main component of the project is the microcontroller which will be driving the motors. The input coming from solar panel will be given to battery for charging purpose. The output from battery will be given to all part of the circuits.

Figure 1.1 Industry

Our project will meet all the requirements of need of industry. Here we are going to use a solar panel which will be converting all the energy coming from sun’s radiation directly in electrical equivalent DC voltage that will the overall power consumption and the battery needs to be recharged for less amount of time.

Figure 1.2 Solar panel to battery

1.2 PROBLEM DEFINATION

In today’s modern world there is a lot a drastic change in amount of industries that we are seeing in our everyday life. At every day the amount of industry is growing like anything. India is sixth largest country in the world with most number of industries. When an industry is build it normally build in a very large area around 10,000 to 12,000 acres. But this total space is not completely occupied by the infrastructure of the industry but only ¼ part that is only 25% of land is used to build the infrastructure and the rest of the land is remain unused so grass starts coming on it.

CHAPTER 2 BLOCK DIAGRAM

Fig 2.1: Block diagram of Solar Grass Cuter

2.1 Solar Panel:

Solar panel refers to a panel designed to absorb the sun's rays as a source of energy for generating electricity or heating. Solar Photovoltaic panels constitute the solar array of a photovoltaic system that generates and supplies solar electricity in commercial and residential applications. Each module is rated by its DC output power under standard test conditions, and typically ranges from 100 to 365 watts. The efficiency of a module determines the area of a module given the same output.

2.2 Battery:

The rechargeable batteries are lead-lead dioxide systems. The dilute sulphuric acid electrolyte is absorbed by separators and plates and thus immobilized. Should the battery be accidentally overcharged producing hydrogen and oxygen, special one way valves allow the gases to escape thus avoiding excessive pressure build-up, otherwise, the battery is completely sealed and is, therefore, maintenance-free, leak proof and usable in any condition.

2.3 Microcontroller:

The AT89S51 is a low-power, high-performance CMOS 8-bit microcontroller with 4K Bytes of In-System Programmable Flash memory. The device is manufactured using Atmel’s high-density non-volatile 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 non-volatile memory programmer. By combining a versatile 8-bit CPU with In-System Programmable Flash on a monolithic chip, the Atmel AT89S51 is a powerful microcontroller which provides a highly-flexible and cost- effective solution to many embedded control applications. The AT89S51 provides the following standard f0eatures: 4K bytes of Flash, 128 bytes of RAM, 32 I/O lines, Watchdog timer, two data pointers, two 16-bit timer/counters, a five-vector two-level interrupt architecture, a full duplex serial port, on-chip oscillator, and clock circuitry. In addition, the AT89S51 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 external interrupt or hardware reset.

2.4 Motor Driver IC (L293D):

L293D is a dual H-bridge motor driver integrated circuit (IC). Motor drivers act as current amplifiers since they take a low-current control signal and provide a higher-current signal. This higher current signal is used to drive the motors. L293D contains two inbuilt H-bridge driver circuits. In its common mode of operation, two

DC motors can be driven simultaneously, both in forward and reverse direction. The motor operations of two motors can be controlled by input logic at pins 2 & 7 and 10 & 15. Input logic 00 or 11 will stop the corresponding motor. Logic 01 and 10 will rotate it in clockwise and anticlockwise directions, respectively. Enable pins 1 and 9 (corresponding to the two motors) must be high for motors to start operating. When an enable input is high, the associated driver gets enabled. As a result, the outputs become active and work in phase with their inputs. Similarly, when the enable input is low, that driver is disabled, and their outputs are off and in the high-impedance state.

2.5 12V DC Motor:

A DC motor is any of a class of electrical machines that converts direct current electrical power into mechanical power. The most common types rely on the forces produced by magnetic fields. Nearly all types of DC motors have some internal mechanism, either electromechanical or electronic, to periodically change the direction of current flow in part of the motor. Most types produce rotary motion; a linear motor directly produces force and motion in a straight line. In this Project, two motors of 10 rpm (revolutions per minute) and 500 rpm motor is used.

CHAPTER 3

Component Listing and Pricing

Table 3.1: Components list and Costing

Sr. No. Item description Estimate INR

1 Microcontroller AT89S51(*1) 60

2 Motor Driver IC (*2) 80

3 12 V DC Motor (*3) 375

4 IC 7805 (*5) 25

5 IC 7812 (*5) 25

6 Crystal Oscillator (*2) 30

7 Chassis 120

8 Switches & Diodes (1N4007) 30

9 Resistors, Capacitors & LED’s 50

10 Jumper Wire 200

11 Solar Panel 650

TOTAL Estimated Cost of the Project 1845

CHAPTER 4

CIRCUIT DIAGRAM AND EXPLANATION

1. Solar panel

Figure 4.1: Circuit Diagram or Schematic

4.1 Microcontroller (AT89S51):

4.1.1 Description: The AT89S51 is a low-power, 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 pin out. 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 in-system programmable Flash on a monolithic chip, the Atmel AT89S51 is a powerful microcontroller which provides a highly-flexible and cost-effective solution to many embedded control applications. The AT89S51 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 AT89S51 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 con-tents but freezes the oscillator, disabling all other chip functions until the next interrupt or hardware reset.

Fig 4.2: Microcontroller AT89S51

Fig 4.3: Microcontroller Mounted on PCB

4.1.2 FEATURES:  Compatible with MCS-51™ Products  4K Bytes of In-System Reprogrammable Flash Memory Endurance: 1,000 Write/Erase Cycles.  Fully Static Operation: 0 Hz to 24 MHz  Three-level Program Memory Lock  128 x 8-bit Internal RAM  32 Programmable I/O Lines  Two 16-bit Timer/Counters  Six Interrupt Sources  Programmable Serial Channel

4.1.3 PIN DESCRIPTION:

Fig 4.4: Pin Diagram of AT89S51

VCC: Supply voltage

GND: Ground.

Port 0: Port 0 is an 8-bit open drain bidirectional 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 low-order address/data bus during accesses to external program and data memory. In this mode, P0 has internal pull-ups. Port 0 also receives the code bytes during Flash programming and outputs the code bytes during program verification. External pull-ups are required during program verification.

Port 1: Port 1 is an 8-bit bidirectional 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 trigger input (P1.1/T2EX), respectively, as shown in the following table. Port 1 also receives the low-order address bytes during Flash programming and verification.

Port 2: Port 2 is an 8-bit bidirectional I/O port with internal pull-ups. The Port 2 output buffers can sink/source four TTL inputs. When 1s are written to Port 2 pins, they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 2 pins that are externally being pulled low will source current (IIL) because of the internal pull-ups. Port 2 emits the high-order address byte during fetches from external program memory and during accesses to external data memory that use 16-bit addresses (MOVX @ DPTR). In this application, Port 2 uses strong internal pull-ups when emitting 1s. During accesses to external data memory that use 8- bit addresses (MOVX @ RI), Port 2 emits the contents of the P2 Special Function Register. Port 2 also receives the high-order address bits and some control signals during Flash programming and verification.

Port 3: Port 3 is an 8-bit bidirectional I/O port with internal pull-ups. The Port 3 output buffers can sink/source four TTL inputs. When 1s are written to Port 3 pins, they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 3 pins that are externally being pulled low will source current (IIL) because of the pull-ups. Port 3 receives some control signals for Flash programming and verification. Port 3 also serves the functions of various special features of the AT89S51, as shown in the following table.

Table 4.1: Alternate Functions of Port 3

RST (Reset input): A high on this pin for two machine cycles while the oscillator is running resets the device. This pin drives high for 98 oscillator periods after the Watchdog times out. The DISRTO bit in SFR AUXR (address 8EH) can be used to disable this feature. In the default state of bit DISRTO, the RESET HIGH out feature is enabled.

ALE/PROG Address Latch Enable: ALE is an output pulse for latching the low byte of the address during accesses to external memory. This pin is also the program pulse input (PROG) during Flash programming. In normal operation, ALE is emitted at a constant rate of 1/6 the oscillator frequency and may be used for external timing or clocking purposes. Note, however, that one ALE pulse is skipped during each access to external data memory. If desired, ALE operation can be disabled by setting bit 0 of SFR location 8EH. With the bit set, ALE is active only during a MOVX or MOVC instruction. Otherwise, the pin is weakly pulled high. Setting

the ALE-disable bit has no effect if the microcontroller is in external execution mode.

PSEN (Program Store Enable): PSEN is the read strobe to external program memory. When the AT89S51 is executing code from external program memory, PSEN is activated twice each machine cycle, except that two PSEN activations are skipped during each access to external

data memory.

EA/VPP External Access Enable: EA must be strapped to GND in order to enable the device to fetch code from external program memory locations starting at 0000H up to FFFFH. Note, however, that if lock bit 1 is programmed, EA will be internally latched on reset. EA should be strapped to VCC for internal program executions. This pin also receives the 12-volt programming enable voltage (VPP) during Flash programming.

XTAL1: Input to the inverting oscillator amplifier and input to the internal clock operating circuit.

XTAL2: Output from the inverting oscillator amplifier.

Oscillator Characteristics: The XTAL1 and XTAL2 are the input and output, respectively, of an inverting amplifier which can be configured for use as an on-chip oscillator, as shown in Figure below. Either a quartz crystal or ceramic resonator may be used. To drive the device from an external clock source, XTAL2 should be left unconnected while XTAL1 is driven as shown in Figure. There are no requirements on the duty cycle of the external clock signal, since the input

to the internal clocking circuitry is through a divide-by-two flip-flop, but minimum and maximum voltage high and low time specifications must be observed.

Fig 4.5: Microcontroller oscillator section

4.2 SOLAR PANEL:

Solar panel refers to a panel designed to absorb the sun's rays as a source of energy for generating electricity or heating. A photovoltaic (in short PV) module is a packaged, connected assembly of typically 6×10 solar cells. Solar Photovoltaic panels constitute the solar array of a photovoltaic system that generates and supplies solar electricity in commercial and residential applications. Each module is rated by its DC output power under standard test conditions, and typically ranges from 100 to 365 watts. The efficiency of a module determines the area of a module given the same rated output – an 8% efficient 230 watt module will have twice the area of a 16% efficient 230 watt module. There are a few solar panels available that are exceeding 19% efficiency. A single solar module can produce only a limited amount of power; most installations contain multiple modules. A photovoltaic system typically includes a panel or an array of solar modules, a solar inverter, and sometimes a battery and/or solar tracker and interconnection wiring.

Solar modules use light energy (photons) from the sun to generate electricity through the photovoltaic effect. The majority of modules use wafer-based crystalline silicon cells or thin- film cells based on cadmium telluride or silicon. The structural (load carrying) member of a module can either be the top layer or the back layer. Cells must also be protected from mechanical damage and moisture. Most solar modules are rigid, but semi-flexible ones are available, based on thin-film cells. These early solar modules were first used in space in 1958.

Electrical connections are made in series to achieve a desired output voltage and/or in parallel to provide a desired current capability. The conducting wires that take the current off the

modules may contain silver, copper or other non-magnetic conductive [transition metals]. The cells must be connected electrically to one another and to the rest of the system. Externally, popular terrestrial usage photovoltaic modules use MC3 (older) or MC4 connectors to facilitate easy weatherproof connections to the rest of the system.

Bypass diodes may be incorporated or used externally, in case of partial module shading, to maximize the output of module sections still illuminated.

Figure 4.6: Solar Panel

4.3 BATTERY: The rechargeable batteries are lead-lead dioxide systems. The dilute sulphuric acid electrolyte is absorbed by separators and plates and thus immobilized. Should the battery be accidentally overcharged producing hydrogen and oxygen, special one way valves allow the gases to escape thus avoiding excessive pressure build-up, otherwise, the battery is completely sealed and is, therefore, maintenance-free, leak proof and can be useful in any condition.

Figure 4.7: Battery

4.4 12V DC Motor:

A DC motor in simple words is a device that converts direct current (electrical energy) into mechanical energy. It’s of vital importance for the industry today, and is equally important for engineers to look into the working principle of DC motor in details that has been discussed in this article. In order to understand the operating principle of dc motor we need to first look into its constructional feature.

Fig 4.8: Basic Working Principle of DC Motor

The very basic construction of a dc motor contains a current carrying armature which is connected to the supply end through commutator segments and brushes and placed within the north south poles of a permanent or an electro-magnet as shown in the diagram below. Now to go into the details of the operating principle of DC motor it’s important that we have a clear understanding of Fleming’s left hand rule to determine the direction of force acting on the armature conductors of dc motor. Fleming’s left hand rule says that if we extend the index finger, middle finger and thumb of our left hand in such a way that the current carrying conductor is placed in a magnetic field (represented by the index finger) is perpendicular to the direction of current (represented by the middle finger), then the conductor experiences a force in the direction (represented by the thumb) mutually perpendicular to both the direction of field and the current in the conductor.

Fig 4.9: Fleming’s Left Rule

Fig 4.10: 12V DC motor

4.5 Motor Driver IC (L293D):

L293D is a typical Motor driver or Motor Driver IC which allows DC motor to drive on either direction. L293D is a 16-pin IC which can control a set of two DC motors simultaneously in any direction. It means that you can control two DC motor with a single L293D IC. Dual H- bridge Motor Driver integrated circuit (IC). The l293d can drive small and quiet big motors as well.

It works on the concept of H-bridge. H-bridge is a circuit which allows the voltage to be flown in either direction. As you know voltage need to change its direction for being able to rotate the motor in clockwise or anticlockwise direction, hence H-bridge IC are ideal for driving a DC motor.

In a single l293d chip there two h-Bridge circuit inside the IC which can rotate two dc motor independently. Due its size it is very much used in robotic application for controlling DC motors. Given below is the pin diagram of a L293D motor controller.

There are two Enable pins on l293d. Pin 1 and pin 9, for being able to drive the motor, the pin 1 and 9 need to be high. For driving the motor with left H-bridge you need to enable pin 1 to high. And for right H-Bridge you need to make the pin 9 to high. If anyone of the either pin1 or pin9 goes low then the motor in the corresponding section will suspend working. It’s like a switch

4.6 Pin Diagram:

Fig 4.11: Pin Diagram of L293D

Pin no 1, 9: This pins are given 5V DC voltage for enabling the pins 2, 7, 10, 15. Pin no 2, 7: This is the input pins of L293D. This will be driven by the input coming from microcontroller. Pin no 3, 6: Between this two pins motor will get connected. According to the input coming from microcontroller the output will vary. Pin no 4, 5, 13, and 12: This pins will be connected to ground. Pin no 8 and 16: Pin no 8 will be provided by motor voltage that is 12V and Pin no 16 will be provided by logic voltage that is 5V.

Pin no 10, 15: This is the input pins of L293D. This will be driven by the input coming from microcontroller. Pin no 11, 14: Between this two pins motor will get connected. According to the input coming from microcontroller the output will vary.

4.7 Pin Description:

Table 4.2: Pin description of L293D Pin Function Name No 1 Enable pin for Motor 1; active high Enable 1,2 2 Input 1 for Motor 1 Input 1 3 Output 1 for Motor 1 Output 1 4 Ground (0V) Ground 5 Ground (0V) Ground 6 Output 2 for Motor 1 Output 2 7 Input 2 for Motor 1 Input 2

8 Supply voltage for Motors; 9-12V (up to 36V) Vcc 2 9 Enable pin for Motor 2; active high Enable 3,4 10 Input 1 for Motor 1 Input 3 11 Output 1 for Motor 1 Output 3 12 Ground (0V) Ground 13 Ground (0V) Ground 14 Output 2 for Motor 1 Output 4 15 Input2 for Motor 1 Input 4

16 Supply voltage; 5V (up to 36V) Vcc 1

4.8 RESISTOR:

Fig 4.12 Resistor

A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. The current through a resistor is in direct proportion to the voltage across the resistors terminals. The relationship is represented by Ohm’s law: I=V/R. Where I is the current through the conductor in units of amperes, V is the potential difference measured across the conductor in units of volts, and R is the resistance of the conductor in units of ohms (symbol: Ω). They are used to limit current in the circuit and are connected to led to prevent excess current flowing through them and preventing them from getting damaged.

4.9 Capacitor:

Fig 4.13: Capacitor

A capacitor (originally known as a condenser) is a passive two-terminal electrical component used to store energy electrostatically in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors (plates) separated by a dielectric (i.e., insulator). The conductors can be thin films of metal, aluminium foil or disks, etc. The 'non- conducting' dielectric acts to increase the capacitor's charge capacity. A dielectric can be glass, ceramic, plastic film, air, paper, mica, etc. Capacitors are widely used as parts of electrical circuits in many common electrical devices. When there is a potential difference across the conductors, a static electric field develops across the dielectric, causing positive charge to collect on one plate and negative charge to collect on the other plate. Energy is stored in the electrostatic field. An ideal capacitor is characterized by a single constant value for its capacitance. Capacitance is expressed as the ratio of the electric charge on each conductor to the potential difference between them. Capacitors are widely used in electronic circuits for blocking direct current while allowing alternating current to pass.

In analogue filter networks, they smooth the output of power supplies. In resonant circuits they tune radios to particular frequencies. In electric power transmission systems they stabilize voltage and power flow, and for many other purposes. An electrolytic capacitor of 1000uf is used as filter where as 33pf and 104 are used to avoid external interferences in the circuit. An electrolytic capacitor of 1000uf is used as filter where as 33pf and 104 are used to avoid external interferences in the circuit.

4.10 LED:

Fig 4.14 LED

Light emitting diodes (LEDs) are semiconductor light sources. They operate on low power and voltages. LEDs are one of the most common electronic components and are mostly used as indicators in circuits. LEDs emit photons when electrons recombine with holes on forward biasing. The two terminals of LEDs are anode (+) and cathode (-) and can be identified by their size. The longer leg is the positive terminal or anode and shorter one is negative terminal. The forward voltage of LED (1.7V-2.2V) is lower than the voltage supplied (5V) to drive it in a circuit. Using an LED as such would burn it because a high current would destroy its p-n gate. Led is used as an indication in the circuit. One of them is used as power indicator, one is used to indicate synchronization between gsm and microcontroller and another led is used to indicate that gps is receiving the location coordinates from the satellite. Specification:  Forward voltage = 0.1 to 1.2 volt  Reverse current = 10 UA

CHAPTER 5

ALGORITHIM, FLOW CHART AND PROGRAM

5.1 ALGORITHIM

● Start ● Go straight ● Pause for 5 sec ● Take right turn ● Pause for 5 sec ● Go straight for 18 sec ● Pause for 5 sec ● Take right turn ● Pause for 5 sec ● Go straight for 18 sec ● Pause for 5 sec ● Take right turn ● Go straight for 18 sec ● Stop

5.2 FLOW CHART

Start

Go straight for 18 sec

Pause for 5 sec

Take right turn

Pause for 5 sec

Go straight for 18 sec

Pause for 5 sec

Take right turn

Pause for 5 sec

Go straight for 18 sec

Pause for 5 sec

Take right turn

Go straight for 18 sec

END

5.3 PROGRAM

#include sbit motora= P0^0; sbit motorb= P0^1; sbit motorc= P2^7; sbit motord= P2^6; sbit motore= P2^5; sbit motorf= P2^4; void delay(unsigned int); void main(void)

{ motora=0; motorb=1; while(1)

{ motorc=0; motord=0; motore=0; motorf=0; delay(5000); motorc=1; motord=0;

motore=1; motorf=0; delay(25000); motorc=0; motord=0; motore=0; motorf=0; delay(5000); motorc=1; motord=0; motore=0; motorf=0; delay(12500); motorc=0; motord=0; motore=0; motorf=0; delay(5000); motorc=1; motord=0; motore=1; motorf=0; delay(25000);

motorc=0; motord=0; motore=0; motorf=0; delay(5000); motorc=1; motord=0; motore=0; motorf=0; delay(12500); motorc=0; motord=0; motore=0; motorf=0; delay(5000); motorc=1; motord=0; motore=1; motorf=0; delay(25000); motorc=0; motord=0; motore=0;

motorf=0; delay(5000); motorc=1; motord=0; motore=0; motorf=0; delay(12500); motorc=0; motord=0; motore=0; motorf=0; delay(5000); motorc=1; motord=0; motore=1; motorf=0; delay(25000); motorc=0; motord=0; motore=0; motorf=0; delay(5000); motorc=1;

motord=0; motore=0; motorf=0; delay(12500);

}

} void delay(unsigned int time)

{ unsigned int i,j; for(i=0;i<=time;i++) for(j=0;j<1275;j++);

}

CHAPTER 6

PCB FABRICATION AND SOLDERING

6.1 Description:

A printed circuit board is used to mechanically & electrically connect electrical components using conductive pathways, tracks traces etched from copper sheets laminated on to conductive substrate.

As such, most of today’s PCB is not pushing, if nor exceeding, the limits of classic board design. In mobile telecom, for example, interconnect and board dimension are shrinking rapidly, while designs are utilizing fewer, but more complex (and higher pin-count) components. At the same time, boards for networking and computer applications are getting larger, with more interconnect and plane layers.

In order to produce higher quality, more complex products, quicker and more cost effectively than their competition, companies are taking inventory of their PCB design tools. Understanding which tools best support the needs of design teams is key to determining the proper infrastructure investment, required services, support structure and intellectual skill set of the company. Advanced functionality already exists in today’s leading design tools to solve current and future design challenges. Therefore, companies effectively utilizing the proper design tools have an advantage over those companies using dated technology to design their boards-the inherent ability to automatically solve design challenges without workarounds or short-term, inefficient solutions.

6.2 PCB Materials:

1. Laminate materials: a. FR-4, the most common PCB material. b. FR-2 c. Composite epoxy material, CEM-1,5 d. Polyimide. e. BT-Epoxy. f. Cyan ate Ester. g. PTFE, Polytetrafluoroethylene(Teflon) 2. Conductive ink 3. Heavy copper

6.3 PCB layout designing software’s :

1. Altium Designer by Altium Limited 2. Autotrax 3. EAGLE by Cad soft 4. Dip Trace by Novarm 5. Edwinxp 6. Free PCB by Allan Wright(open-source Ein2k/XP) 7. Free routing by alfonswirtz 8. Cadstar by zuken 9. CR5000 by zuken 10. Multisim 11. gEDA, open source PCB software project 12. OrCAD by cadence 13. Allegro by cadence 14. TARGET 3001! 15. Ki cad, open source suite 16. PADS by mentor graphics 17. PCB123 design by sunstone circuits 18. Proteus 19. Board station by mentor graphics

6.4 Software used for PCB Designing:

EASILY APPLICABLE GRAPHICAL LAYOUT EDITOR (EAGLE)

1. Installation:

For installing EAGLE you need to have an EAGLE installation file, your personal installation code, and the appropriate license file. If you have asked for an upgrade for an existing current installation or for an extension of your license, you don't have to install EAGLE anew. Your new installation code and its appropriate license file will update your existing license. If you intend to install the EAGLE Freeware, the EAGLE installation file is all you need.

2. New Installations:

On the CadSoft website you will always find the newest installation files. Keep ready your personal license data, consisting of your license file "serial number”. Key and the installation code. The installation routine determines depending on the operating systems' language used whether EAGLE will be installed in English or in German language. Any recent information about installation may be found in the README files.

3. Windows:

EAGLE for Windows is available as a self-extracting archive, which is named, for example, eagle-win 5.0.0.exe. Double-click this file and the WinZip Self-Extractor window will appear. The installation routine starts with extracting the files from the archive. Click the Setup button to begin. The version number in the file name may, depending on the current version, differ. Now the actual installation starts. Follow the instructions step by step.

4. Installation:

At the end of this process you will be asked how you want to license EAGLE:

5. Use License file:

This implies that you have already bought an EAGLE license. In this case the following dialog asks you for the path to your license file "serial number”. Key and for your personal installation code which you have got from CadSoft.

6. Use Freemium Code:

If you registered at http://www.element-14.com/eagle-freemium and got a Freemium code, use this option.

6.5 Making an Eagle Schematic:

1. Start the EAGLE Control Panel application. Create a new project: File->New->Project.

2. Rename the project if you wish as follows: the control panel window indicates whether a project is open with a green circle next to the project name. Click this if necessary to close the project.

3. Right-click->Rename on the project's name. After having renamed the project you can reopen it. Right-click on the Project name ->New->Schematic. The schematic window will open. Inside the schematic window:

File->Save as (choose a suitable name for your schematic sheet. NB - the freeware version of

EAGLE allows only one sheet per design). For the first half of this tutorial you will be working with the schematic window, and can minimize the control panel window. Open component libraries

4. By default all the standard EAGLE libraries are open which makes it inconvenient to select your components from the EEE library. Download the design project library from the web and save it somewhere. In the schematic command window (long thin box at top) type the following commands to change the open libraries.

Add components to your schematic:

Edit->Add-> Select component.

Each open library in the ADD window contains a list of components (click + if not visible).

Some components have multiple packages (click on + to select the correct package). The component schematic symbol and package layout appear in the two windows to the right of the library window. Each component has a description you can check to see what it is. When you have identified the correct component and package (component & package will be visible in the two windows) click OK to start the ADD procedure.

Fig 6.1: Control Panel of EAGLE

Fig 6.2: Schematic Editor of EAGLE

Fig 6.3: Board Editor of EAGLE

6.6 Making layout using EAGLE:

Here is the procedure of designing the layout using eagle software:

1. Setting up initial settings: this stage of PCB designing involves setting up snaps and visible grid. At this stage the default track and pad size should be set.

2. Set the mechanical elements of the PCB design: it is necessary to import the details for the printed circuit board outline into the PCB layout software programme as soon as possible. It is also necessary to set up any reference marks and holes. These may be required for pick and place machines, of test fixtures during the production process.

3. Putting all components on the board: at this stage of the PCB layout, the components need to be placed onto the printed circuit board so that they are available to be moved and set in place later.

4. Creating functional buildings blocks: at this stage of PCB layout, the components should be moved into their functional blocks so that associated components are close to each other and the circuit can be routed easily later.

5. Identifying and routing layout critical tracks: any tracks that are layout critical should be identified and then routed as they are required. By routing these tracks at this stage, then the remained of the design can implemented around these tracks rather than trying to resolve problems later in the PCB layout.

6. Routing power and earth rails: often the earth and power rails may be included as planes, occupying a complete layer of the printed circuit board. This has significant advantage not only in terms of enabling the higher levels of current to be routed easily, but it also significantly reduces any problem with interference on the printed circuit board.

7. Routing the remaining lines: usually it is necessary to use the auto-route function on the PCB layout software. Although there are manual routing options on PCB layout

software, it is normal to use the auto-route function s this may save many days trying to rout the PCB layout manually.

8. Manually routing any final line on the PCB layout: after the PCB layout software has complemented the auto-routing, there may be routed manually. Alternatively if the design has become too complicated for the space and available numbers of layers, it may be necessary to make some fundamental changes to the board.

9. Undertaking final tidy up: once all the design rules should have been followed during the design, it is necessary to do a final check. It is better to catch any problems at this stage rather than once a prototype PCB has been made. Thus we completed the PCB layout designing process.

10. PCB designing rules:

1. While designing a layout, it must be noted that the size of the board should be as small as possible.

2. Before starting, all components should be placed properly so that an accurate measurement of space can be made.

3. The component should not be mounted very close to each other or far away from one another and neither one should ignore the fact that some component reed ventilation, which considerably the dimension of the relay and transformer in view of arrangement, the bolting arrangement is also considered.

4. The layout is first drawn on paper then traced on copper plate which finalized with the pen or permanent marker which is efficient and clean with etching.

5. The resistivity also depends on the purity of copper, which is highest for low purity of copper. The high resistance paths are always undesired for soldered connections.

6. The most difficult part of making an operation, it provides greater amount of satisfaction because it is carried out with more care and skill.

7. The board used for project has copper-foil thickness in the range of 25 40 75 microns.

8. The soldering quality requires 99.99% efficiency.

9. It is necessary to design copper path extra-large. There are two main reasons for this.

10. The copper may be required to carry an extra-large overall current.

11. It acts like a kind of a screen or ground plane to minimize the effect of interaction.

12. The first function is to connect the components together in there right sequence with minimum need for interlinking i.e. the jumpers with wire connections.

13. It must be noted, that when layout is done, on the next day it should be dripped in the solution and board is moved continuously right and left after etching perfectly the board is cleaned with water and is drilled.

14. After those holes are drilled with 1mm or 0.8mm drilled. Now the marker on the PCB is removed.

15. The printed circuit board is now ready for mounting the components on i

6.7 PCB Layout:

Fig 5.5: Layout of Rectifier and Filter Section

Fig 6.4: Layout of microcontroller section

Fig 6.5: Layout of motor part

6.8 PCB etching:

STEP-1:-After cutting the copper clad sheet to size, the PCB is cleaned with thinner, so that the dust on the PCB is removed and we get a shiny surface. Then we insert the PCB in Dip coat, that is, negative photo resistive material.

Fig 6.6: PCB Cutter

Fig 6.7: Cleaning of PCB

Fig 6.8: Dip Coat

STEP-2:-the photo resistive material should be made hard on the PCB for which the PCB is kept in the oven for four minutes.

Fig 6.9: PCB Oven

STEP-3:-after the liquid is made hard, it is kept in the UV exposure for two minutes. In the UV exposure, the circuit is kept with its layout. The ultraviolet rays are passed through the PCB.

Fig 6.10: UV Exposure

STEP-4:-then we have to expose out PCB to nail polish remover solution which is also called as developer liquid. As a result of this an impression of tracks is formed on the PCB. Repeat the STEP-2, in which the PCB is kept in the oven for four minutes.

Fig 6.11: Agitating PCB

STEP-5:-after removing the PCB from the oven, the tracks on the PCB will be developed. After this the PCB is dipped into the PRITO-ETCH for five minutes. The solution used in the PEORO-ETCH is ferric chloride. Due to this tracks are fully developed on the PCB.

Fig 6.12: Easy etcher

6.9 PCB drilling:

 Description:

Holes through a PCB are typically drilled with tiny drill bits made of solid tungsten carbide. The drilling is performed by automated drilling machines with placement controlled drill (NCD) files or “Excellon”. The drill file describes the location and size of each drilled hole. These holes are often filled with annular rings (hollow rivets) to create vias. Vias allow the electrical and thermal connection of conductors on opposite sides of the PCB.

Most common laminate is epoxy filled fiberglass. Drill bit wear is in part due to the fact that glass, being harder than steel on the Mohs scale, can scratch steel. High drill speed necessary for cost effective drilling of hundreds of holes per board causes very high temperatures at the laminate filler. Copper is softer than epoxy and interior conductors may suffer damage during drilling.

When very small vias are required, drilling with mechanical bits is costly because of high rates of wear and breakage. In this case, the vias may be evaporated by lasers. Laser-drilled vias typically have an inferior surface finish inside the holes. These holes are called micro vias.

It is also possible with controlled-depth drilling, laser drilling, or by pre-drilling the individual sheets of the PCB before lamination, to produce holes that connect only some of the copper layers, rather than passing through the entire board. These holes are called blind vias when they connect an internal copper layer to an outer layer, or buried via when they connect two or more internal copper layers and no outer layers.

The walls of the holes, for boards with 2 or more layers, are made conductive then plated with copper to form plated-through holes that electrically connect the conducting layers of the PCB. For multilayer boards, those with 4 layers or more, drilling typically produces a smear of the high temperature decomposition products of bonding agent in the laminate system. Before the holes can be plated through, this smear must be removed by a chemical de-smear process, or by plasma-etch. Removing (etching back) the smear also reveals the interior conductors as well.

 Drilling process:

1. First the PCB is placed on the drilling machine and drill bit is inserted. We used the drill bit of 0.8mm.

2. The PCB is placed in such a way that the drill bit is exactly on the top of the place where we need to drill.

3. Then, the machine is turned on and the handle is to pressed down to drill on the PCB.

4. Care should be taken while drilling that PCB is firmly held or else it will come up into the drill bit.

5. After drilling first hole we checked whether the component is getting inserted in the hole or not. Some components like diodes and TSOP had thick leads which were not able to get into the hole.

6. For this we changed the drill bit to 1mm and drilled those holes again so that components were properly inserted.

Fig 6.13: Drill machines

6.10 PCB soldering:

 Steps:

1. For soldering of any joints first the terminal to be soldered are cleaned to remove oxide film or dirt on it. If required flux is applied on the points to be soldered.

2. Now the joint to be soldered is heated with the help of soldering iron. Heat applied should be such that when soldered wire is touched to joint, it must melt quickly.

3. The joint and the soldering iron are held such that molten solder should flow smoothly over the joint

4. When joint is completely covered with molten solder the soldering iron is removed.

5. The joint is allowed to cool, without any movement.

6. The bright shining solder indicates good soldering.

7. In case of dry solder join, and air gap remains in between the solder material and joint. It means that soldering is improper. This is removed and again soldering is done.

8. In this way all the components are soldered on PCB.

Fig 6.14: Soldering of PCB

 Cold solder joints:

1. A "cold solder joint" can occur when not enough heat is applied to the component, board, or both. Another common cause is a component moving before the solder has completely cooled and solidified. A cold joint is brittle and prone to physical failure. It is also generally a very high resistance connection which can affect the operation of the circuit or cause it to fail completely.

2. Cold joints can often be recognized by a characteristic grainy, dull gray color, but this is not always the case. A cold joint can often appear as a ball of solder sitting on the pad and surrounding the component lead. Additionally you may notice cracks in the solder and the joint may even move. Below is the shocking image of every example of a bad solder joint you will ever see. It appears that this FM transmitter kit was assembled using the technique of "apply solder to iron then drip onto joint". If your joints are looking like this, then stop and practice after rereading this page. Note that not a single of these joints is acceptable, but amazingly the circuit worked.

Fig 6.15: Dry Soldering

3. Most cold solder joints can be easily fixed. Generally all that is required is to

4. Reheat the joint and apply a little more solder. If there is already too much solder on the joint, then the joint will have to be de-soldered and then soldered again. This is done by first removing the old solder with a de-soldering tool or simply by heating it up and flicking it off with the iron. Once the old solder is off, you can re-solder the joint, making sure to heat it thoroughly and keep it still as it cools.

Chapter 7

Troubleshooting and testing

7.1 Troubleshooting:-

7.1.1 Description:

Troubleshooting is a form of problem solving, often applied to repair failed circuits. It is a logical, schematic search for the source of a problem so that it can be solved, and circuit can be made operational again. Troubleshooting is needed to develop and maintain complex systems where the symptoms of a can have many possible causes. Troubleshooting requires identification of the malfunction(s) or symptoms within the system and confirms the solution so that it can work again.

7.1.2 Need of Troubleshooting:-

1. Every product, circuit and instruments are designed to give desired output, but there are many problems associated with the design which tend to produce unexpected output. Therefore, for satisfactory performance, it needs to be troubleshooted so that the circuit can be made operational again.

2. Troubleshooting is needed to develop and maintain complex systems where the symptoms of problem can have many possible causes.

3. It is needed for identifying the symptoms and rectifying the problem so that it gives the desired output.

4. Troubleshooting is used in many fields such as engineering, system administration, electronics, automotive repair and diagnostic medicine.

7.1.3 Steps prior to troubleshooting:

1. Before applying power, read the instructions carefully to check we haven’t missed anything, and whether there are any specific instructions for switching on and testing. Check again that we have all polarity sensitive components the right way around, and that all components are in the correct places .then check whether off board components are connected correctly.

2. Check the underside of board for short circuit between tracks which is command reason for circuit failing to work.

3. When we are sure that everything is correct, apply power and see if the circuit behaves as expected.

7.1.4 Troubleshooting steps:-

1. Identify the system:

Determine what the voltage level in circuit should be so that you know what to look for. 2. Power check:

The first thing to do while checking a defective circuit is to make sure the power cord is plugged in and the fuse is not burnt. In case of battery powered systems, make sure the battery is good. 3. Perform sensory check:

After power check, observe for the obvious defects. E.g. Poor solder connections, broken tracks, broken component and burnt out fuses. Also when certain type of components fails, may be able to detect a smell of smoke.

Since some failures are detected by their temperature, unplug the circuit and immediately use your sense of touch to detect an overheated component.

Always perform sensory check before proceeding with more sophisticated troubleshooting methods. Never touch operating circuit because there may be risk of burn or electric shock.

4. Signal tracing:

In this we look for a point in a circuit or a system where we first lose signal or an incorrect signal first occurs. There are 3 ways of signal tracing as given below: a. Method 1: It starts at the input of a circuit where there is the known input signal and work towards the output. Check the signal at successive test points until you get incorrect measurement, when it is found, the problem is isolated from the last test point to the present test points. b. Method 2: It starts at the output of the circuit and work towards the input. Check for the voltage at each test point until you get correct measurement. At this point you have isolated the problem between the last point and the current test point.

c. Method 3: This method is called half splitting. It starts at the middle of the test circuit. If a beginning test point has a correct signal you know that the circuit is working properly from input to that test point. This means that the fault is some ware between test point and the output. Therefore begin signal tracing from test point towards output and get the point at fault.

5. Fault analysis:

 Voltages analysis: After performing the visible testing if the problem still persists, then go for voltage analysis. In this method the voltage at different test points is checked.

 Resistance analysis: In this analysis, power supply connected to the circuit must be switched when resistance is measured. Resistance analysis is generally used for

continuity testing. E.g., check the continuity of PCB track from one test point to other or in case of double sided PCB it helps in checking the connectivity between the holes from both the sides. Similarly this can be used for testing the component such as diode, capacitor and transistor (e.g.: open or short). This method requires the instrument such as DMM.

 Signal analysis: Sometimes it is important to observe the nature of the signal at the test point (e.g. in case of rectifier). Whereas it is not possible in voltage analysis. By observing the waveform at test point we can estimate the waveform distortion. For testing the circuit such as rectifier, multivibrator, amplifier it is important to know the nature. Therefore signal analysis is done. For carrying signal analysis we require a CRO.

6. Replace or repair : With the power turned off, replace the defective component or repair defective connection. Turn on the power; check the proper operation of the circuit.

7.2 Practical troubleshooting:

When we were actually implanting hardware of our project, we came to know the different types of problem which arises while implantation of any project. Here are those experiences.

1. Dry soldering: While troubleshooting the circuit we found that some solder points had become dry as they were soldered a long time before. So, we heated the points where solder had dried and even added some solder.

2. Shorted paths: During soldering IC555 we shorted the adjacent tracks by mistake and this shorted track were creating problems in the operation of the circuit and so we removed the shorts by de-soldering them.

3. Over heating: When there was an obstacle between the entry sensors, the IC555 was getting extremely heated. Then we removed it from the circuit and tested it on the IC tester. The result was bad. So we replaced it with new IC555.

4. Discontinuity: While troubleshooting we found that there was lack of continuity between some of the tracks. We overcome this problem by soldering the dry solder points again. For checking the continuity we use digital multi-meter.

5. Grounding: While troubleshooting we found that some of the components were not connected to ground through tracks. We found that while making schematic those components had not been connected to ground. We overcome this problem by connecting those components to ground by making use of wires.

6. Faulty layout: While troubleshooting we found that some of the tracks were connected to the wrong point. We overcome this problem by scratching those tracks. The pitch of the relay was not matching with the relay. So we overcome this problem by mounting it on the general purpose PCB and connecting the points of the relay to the PCB via wires.

7.3 Testing the Board with various tools:

There are some basic procedures for finding faults with PCBs and fixing those faults. Though there are many in circuit testing programs and probes available in the market for skilled technicians and test engineers there are no general guidelines given for novice users.

If you face some problems like when you end up removing an entire track (connection from one component to another) on the PCB you can use a simple piece of wire to imitate the connection. Solder the two ends of the wire where you think the connection should be present on the PCB.

Transistors can be damaged by heat when soldering or by misuse in a circuit. If you suspect that a transistor may be damaged there is an easy way to test it. Use a multi meter to check each pair of leads for conduction. Set a digital multi meter to diode test and an analog multi meter to a low resistance range. Test each pair of leads both ways:

The base-emitter (BE) junction should behave like a diode and conduct one way only. The base-collector (BC) junction should behave like a diode and conduct one way only. The collector-emitter (CE) should not conduct either way.

To test a capacitor, first short the capacitor leads for discharging it completely. Set the multi-meter to high resistance mode. Connect the multi-meter terminals to the capacitor leads. For electrolytic capacitors the positive terminal of multi-meter must be connected to the positive lead of the capacitor and negative terminal of multi-meter to the negative lead of capacitor. At the moment you connect the multi-meter terminals to the capacitor leads, the multi-meter needle will move to zero and then slowly move towards infinity and settle there. This will happen only if the capacitor under test is healthy.

To check an ordinary silicon diode using a digital multi-meter, put the multi-meter selector switch in the diode check mode. Connect the positive lead of multi-meter to the anode and negative lead to cathode of the diode. If multi-meter displays a voltage between 0.6V to 0.7V, we can assume that the diode is healthy. This is the test for checking the forward conduction mode of diode.

 Tools

Fig 7.1: Multi-Meter

Most basic PCB troubleshooting can be done with just a few tools. The most versatile tool is a multimeter, but depending on the complexity of the PCBs and the problem, an LCR meter, oscilloscope, power supply and logic analyser may also be needed to dig deep in to the operational behaviour of the circuit.

 Discrete Component Testing

Fig 7.2: Cathode Ray Oscilloscope

Often the most effective techniques for PCB troubleshooting are to test each individual component. Testing each resistor, capacitor, diode, transistor, inductor, MOSFET, LED, and discrete active components can be done with a multimeter or LCR meter. Components that have less than or equal to the stated component value, the component is typically good, but if the component value is higher it is an indication that either the component is bad or that the solder joint is bad. Diodes and transistors can be checked using the diode testing mode on a multimeter. The base-emitter (BE) and base-collector (BC) junctions of a transistor should behave like discrete diodes and conduct in one direction only with the same voltage drop. Nodal analysis is another option that allows unpowered testing of components by applying power just to a single component and measuring its voltage vs. current (V/I) response.

 ICs Testing

Fig 7.3: IC Tester

The most challenging components to check are ICs. Most ICs can be easily identified by their markings and many can be operationally tested using oscilloscopes and logic analysers, but the number of specialty ICs in various configurations and PCB designs can make testing ICs very challenging. Often a useful technique is to compare the behaviour of a circuit to a known good circuit, which should help anomalous behaviour to stand out.

CHAPTER 8 DATASHEET

8.1 Microcontroller

Features:

• Compatible with MCS-51® Products • 4K Bytes of In-System Programmable (ISP) Flash Memory • 4.0V to 5.5V Operating Range • Fully Static Operation: 0 Hz to 33 MHz • Three-level Program Memory Lock • 128 x 8-bit Internal RAM • 32 Programmable I/O Lines • Two 16-bit Timer/Counters • Six Interrupt Sources • Full Duplex UART Serial Channel • Low-power Idle and Power-down Modes • Interrupt Recovery from Power-down Mode • Watchdog Timer • Dual Data Pointer • Power-off Flag • Fast Programming Time • Flexible ISP Programming (Byte and Page Mode)

8.2 L293D Features:

• Featuring Unitrode L293 and L293D Products Now From Texas Instruments • Wide Supply-Voltage Range: 4.5 V to 36 V • Separate Input-Logic Supply • Internal ESD Protection • Thermal Shutdown • High-Noise-Immunity Inputs

• Functionally Similar to SGS L293 and SGS L293D • Output Current 1 A Per Channel (600 mA for L293D) • Peak Output Current 2 A Per Channel (1.2 A for L293D) • Output Clamp Diodes for Inductive Transient Suppression (L293D)

Pinout:

Fig 8.1: Pinout of L293D

Block Diagram:

Fig 8.2: Internal block diagram of L293D

8.3 Solar panel Features: • Supply power to monitor remote assets and their locations to improve emergency response time and eliminate time-consuming, on-site inspection • Solar power is a mature technology which has been used for over 30 years in many applications requiring safe/reliable power sources • Eliminate the need for conduit, cables, cable tray, and the necessary infrastructure involved in developing grid power in remote applications • Pre-wired kits allow for quick installation by any qualified electrician • Long, maintenance-free battery life (4-6 years) eliminates the need for frequent battery replacement • Recommended temperature range: • -30ºC to 50ºC (consult factory for more extreme temperatures) • Class I, Division 2 assemblies available Standard Materials

• PV module (solar panel) – clear anodized • aluminum frame, potted or terminal-type • junction box, high transmission 1/8" thick • tempered glass front with white • polyester back and EVA (ethylene vinyl • acetate) encapsulant • • Enclosure - aluminum NEMA 3R standard • - painted sheet steel NEMA 4 (optional) • - 316 stainless steel NEMA 4X (optional) Electrical Ratings: • 0-20A, 12VDC (consult factory for • applications above 20A) • Regulator prevents the battery from • deep discharging by disconnecting the • battery at 11.5V and re-connecting the • battery at 12.5V

8.4 Rechargeable Battery Features: • Superb recovery from deep discharge. • Electrolyte suspension system. • Gas Recombination. • Multipurpose: Float or Cyclic use. • Usable in any orientation • Superior energy density. • Lead calcium grids for extended life. • Manufactured Worldwide. • Application specific designs. Operating Temperature Range

• The batteries can be used over a broad temperature range • Permitting considerable flexibility in system design and location. • Charge – 15°C to 50°C • Discharge – 20°C to 60°C • Storage – 20°C to 50°C (fully charged battery)

CHAPTER 9

ADVANTAGES, LIMITATIONS, FUTURE SCOPE, APPLICATIONS AND CONCLUSION

8.1 ADVANTAGES

1. It reduces human efforts.

2. Not bulky as commercial grass cutter.

3. Power consumption of this device is very less.

4. Cost efficient.

5. It is more reliable than grass cutter available in the market.

8.2 LIMITATIONS

1. It will not be suitable in cloudy and rainy season as solar panel is used.

2. It cannot provide the storage facility as commercial grass cutter since cylindrical blades are not used. They require high voltage which will increase the power consumption.

3. As the 12V DC rechargeable lithium battery is used which makes the system quite heavy.

8.3 FUTURE SCOPE

1. It will be very much cost efficient if this will get implemented on a large scale that is mass production.

2. By using cylindrical blades storage facility can be provided

8.4 APPLICATIONS

1. It will be very much useful in big playgrounds.

2. It will be useful in industry.

3. It will be also used for general purpose in home.

8.5 CONCLUSION

In this project we have designed a robot which is going to be used for grass cutting and this is powered by solar panel. The system basically is design to remove flaws in commercial grass cutters. The system main objective is to convert sun’s energy into electrical energy and then give it battery and then to rest of the circuit. After testing the robot the objective is completely achieved. We have developed a hardware solution for grass cutting.

CHAPTER 10 BIBLIOGRAPHY

1. www.google.com 2. www.wikipedia.org 3. www.electronicsforu.com 4. www.engineersgarage.com 5. www.instructibles.com 6. www.nevonprojects.com 7. PCB designing steps PDF using eagle software 8. Electronics for you- volume- JAN 2016, FEB 2016. 9. Applied electronics- R.S. SEDHA 10. Electronic devices and circuits- Floyd Boysteald 11. Embedded systems- Mohammed Mazidi