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CHAPTER NO.1 INTRODUCTION The objective type examinations are now conducted for entrance into many professional courses and jobs. Candidates sit through these examinations in large numbers. Manual checking of these papers is not only time consuming but can also lead to erroneous marking. To overcome this problem, we are developing an answer paper evaluator. Students record their answers to MCQ on a machine readable answer sheet. These sheets are fed through an Optical Mark Reading Scanner. The OMR allows automated data entry that turns pencil marks into useable computer information. If two or more circles are filled in on the answers sheet, or the correct answer is carelessly marked, the question will be marked `wrong’. Specially written software controls the test scoring and analysis. The software analyses the students’ answers to product the Test Scoring and Analysis output. OMR is the scanning of media to detect the presence or absence of a mark in a specific position. It is widely used in surveys, assessments and evaluations. The multiple choice answer sheet and course evaluation forms are daily examples utilizing OMR technology. OMR is used for recognizing optical marks (checkmarks). Typical applications of OMR technology include the processing of questionnaires, ballots, educational tests and reporting, and ordering sheets, where the documents to be processed are form-like and filled in by hand by respondents. Programmers who need to add OMR technology into their software applications can purchase components to make the task easy. 1|Page One of the most familiar applications of optical mark recognition is the use of HB pencil bubble optical answer sheets in multiple choice question examinations. Students mark their answers, or other information, by darkening circles marked on a pre-printed sheet. Afterwards the sheet is automatically graded by a scanning machine. Students likewise mark answers of other information via darkening circles marked on a pre-printed sheet. Then the sheet is automatically graded by a scanning machine. This apparatus scans the answer sheets. The answers are in the form of opaque dots blackened by either pen or pencil. The correct answers are fed into the system prior to the scanning. The answer sheet is then scanned and the marking is done on the basis of comparison with the correct ones. The result is stored in the PC and displayed in UID. The scanning process involves the use of IR sensors. The number of IR sensors depends on the number of option in the question paper. The general trend has been the use of four options for each question which demands the use of four IR sensors. Whenever a dark spot appears between the transmitter and the receiver of IR sensor, then it considers it as an input for comparison with the correct answers stored and it increments the score of the particular person. This is how the evaluation is done in our system. 2|Page 1.1 NECESSITY The present day OMR scanning machines are very expensive and require a high initial investment. This makes it unsuitable for smaller applications like placement exams, objective entrance exams etc. This problems gives rise to the need of our project which is low cost and high accuracy. This system will be used in our TRAINING AND PLACEMENT cell for placement exam evaluation. This system is designed to be convenient and simple in use for a broad class of people. Thus this system can be operated by students also and requires no prior training. 1.2 OBJECTIVE This project is aimed to reduce the price of the conventional OMR based exam paper evaluator. The price of this project is low as compared to the market price of prefabricated OMR system which cost up to Rs.70000/-. This reduced price enhances its application to collage level tasks like objective exams, placement exams etc. Moreover the simplicity and convenience to use this project makes it extremely user friendly. This project requires high accuracy and average execution time. Hence, this project suffices the basic need for average processing time and high reliability. 3|Page 1.3 THEME The project consists of IR sensors which are moved on the answer sheet to detect the answers provided by the candidate. The IR sensors provide a cheap but effective way to replace the conventional high priced optical sensors used in branded OMR machines. The use of Micro Controllers simplifies the cumbersome task of data transfer via Rs.232 serial port communication. The Microcontroller used is 89C51. The stepper motor is used to drive the IR sensor assembly on the answer sheet. An additional accessory of LCD display is provided to make the project more users friendly. 1.4 ORGANIZATION The basic need of our Training and Placement cell was accurate and time saving solution for checking the large quantity of MCQ answer sheets. This application required a low costing highly accurate and reliable solution. By replacing the conventional optical scanners by IR sensors the use of `trans optic’ paper can be avoided. Hence our project is aimed to counter this problem and come up with a solution compatible to the need of our college’s need for the Training and Placement cell. Thus we have organizes our projects in the following steps: 1) Deciding the basic concept of the project. 2) Conducting an overall survey of the required idea, i.e. the current system being used. 3) Developing a Block Diagram of our system. 4|Page 4) Working on the selection of components and their interfaces. 5) Working on VB for creating a GUI. 6) Developing the microcontroller coding to control the stepper motor. 7) PCB designing and testing. 8) Hardware implementation and troubleshooting 5|Page CHAPTER NO.2 LITERATURE SURVEY 2.1 BACKGROUND Many traditional OMR devices work with a dedicated scanner device that shines a beam of light onto the form paper. The contrasting reflectivity at predetermined positions on a page is then utilized to detect the marked areas because they reflect less light than the blank areas of the paper. Some OMR device use forms which are preprinted onto `trans optic’ paper and measure the amount of light which passes through the paper, thus a mark on either side of the paper will reduce the amount of light passing through the paper. In contrast to the dedicated OMR device, desktop OMR software allows a user to create their own forms in a word processor and print them on a laser printer. The OMR software then works with a common desktop image scanner with a document feeder to process the forms once filled out. OMR is generally distinguished from optical character recognition by the fact that a complicated pattern recognition engine is not required. That is, the marks are constructed in such a way that there is little chance of not reading the marks correctly. This does require the image to have high contrast and an easily- recognizable or irrelevant shape. A related field to OMR and OCR is the recognition of barcodes such as the UPC bar code found on product packaging. One of the most familiar applications of optical mark recognition is the use of #2 (HB in Europe) pencil buble optical answer sheets in multiple choice question 6|Page examinations. Students mark their answers, or other personal information, by darkening circles marked on a pre-printed sheet. automatically graded by a scanning machine. Afterwards the sheet is In most European countries, a horizontal or vertical `tick’ in rectangular `lozenge` is the most commonly used type of OMR form, the most familiar application being the UK National lottery form. Lozenge marks are a later technology and have the advantage of being easier to mark and easier to eras. The large ‘bubble’ marks are legacy technology from the very early OMR machines that were so insensitive a large mark was required for reliability. In most Asian countries, a special marker is used to fill in an optical answer sheet. Students likewise mark answers or other information via darkening circles marked on a pre-printed sheet. Then the sheet is automatically graded by a scanning machine. Many of today’s OMR applications involve people filling in specialized forms. These forms are optimized for computer scanning, with careful registration in the printing, and careful design so that ambiguity is reduced to the minimum possible. Due to its extremely low cost and ease-of-use, OMR is a popular method of tallying votes. 7|Page 2.2 HISTORY Optical mark recognition (OMR) is the scanning of paper to detect the presence or absence of a mark in a predetermined position. Optical mark recognition has evolved from several other technologies. In the early 1800’s and 1900’s patents were given for machines that would aid the blind. OMR is now used as an input device for data entry. Two early forms of OMR are paper tape and punch card which are actual holes punched into the medium instead of pencil filled circles on the medium. Paper tape was used as early as 1857 as an input device for telegraph. Punch cards were created in 1890 and were used as input devices for computers. The use of punch cards declined greatly in the early 1970’s with the introduction of personal computers. With modern OMR, where the presence of a pencil filled in bubble is recognized, the recognition is done via an optical scanner. The first mark sense scanner was the IBM 805 Test Scoring Machine; this read marks by sensing the electrical conductivity of graphite pencil lead using pairs of wire brushes that scanned the page. In the 1930s, Richard Warren at IBM experimented with optical mark sense systems for test scoring, as documented in US Patents 2,150,256 (filed in 1932, granted in 1939) and 2,010,653 (filed in 1933, granted in 1935). The first successful optical mark-sense scanner was developed by Everett Franklin Lindquist as documented in US Patent 3,050,248 (filed in 1955, granted in 1962). Lindquist had developed numerous standardized educational tests, and needed a better test scoring machine than the then-standard 8|Page IBM 805. The rights to Lindquist’s patents were held by the Measurement Research Center until 1968, when the University of lowa sold the operation to Westinghouse Corporation. Westinghouse Learning Corporation was acquired by National Computer Systems in 1983; in 2000, Pearson Education acquired NCS. IN 2008, NCS Person was acquired by Scranton. During the same period, IBM also developed a successful optical mark-sense testscoring machine, as documented in US Patent 2,944,734 (filed in 1957, granted in 1960). IBM commercialized this as the IBM 1230 Optical mark scoring reader in 1962. This and a variety of related machines allowed IBM to migrate a wide variety of applications developed for its mark sense machines to the new optical technology. These applications included a variety of inventory management and trouble reporting forms, most of which had the dimensions of a standard punch card. While the other players in the educational testing arena focused in selling scanning services, Scranton Corporation, founded in 1972, had a different model, distribute inexpensive scanners to schools and make profits from selling the test forms. As a result, many people came to think of all mark-sense forms (whether optically sensed or not) as Scranton forms. Scranton operates as a subsidiary of M&F Worldwide (MFW) and provides testing and assessment systems and services and data collection and analysis services to educational institutions, businesses and government. Like Scranton, Chatsworth Data Corporation is a seller of OMR scanners. Founded in 1971, Chatsworth has always focused on selling the scanners themselves, mostly as OEM products incorporated into systems developed by others. 9|Page sCHAPTER NO. 3 SYSYEM DEVELOPMENT 3.1 BLOCK DIAGRAM Scanner Personal (mechanical computer system) μcontroller Stepper 89s51 Software motor console Stepper Motor drive LCD 10 | P a g e Fig 3.1:Block Diagram of Exam Paper Evaluator 3.2 BLOCK DIAGRAM DESCRIPTION 3.2.1 SCANNER The filled answer sheet provided by the student after an objective exam is fed the scanner assembly of the project. The scanner block consists of a series of ten LEDs which are placed in such a way that they check the required number of answers. The Scanner head which moves vertically along the axis of the paper is driven by the stepper motor. The answers detected by the receivers (Rx) are fed to the comparators. The output of the this block is then is provided to the microcontroller (89s52). The spacing between the paper and the sensors is about 5mm. This small distance is required for the high sensitivity of the optical reader. 3.2.2 STEPPER MOTOR The mail function of this block is to drive the scanner head. The step angles are thus decided in accordance to our spacing in the answer sheet. The movement of the scanner head is in the vertical direction and its mail function is to place the sensors directly on top of the answer bubbles. The answers provided by the students is then detected by the sensors and the stepper motor places the sensor head again to the initial position for the next paper to be checked. 11 | P a g e 3.2.3 STEPPER MOTOR DRIVER The digital system and the microcontroller lack the sufficient current to drive the relay. While the relays coil need around 10mA to be energized, the microcontroller pin can provide a maximum of 1-2mA current. For this reason, we place a driver such as the L298 between the microcontroller and the relay. Thus we can say that this block is used as an device that is used for providing sufficient amount of current shich will drive the stepper motor. 3.2.4 MICROCONTROLLER The microcontroller block is the heart of our project. It accepts the voltage level from the scanner block and compares it with the option provided by the examiner. The correct series of option provided via the software console. The bubble which is darkened generates a certain through the comparators is provided to the microcontroller. Another major task of the microcontroller is to drive the stepper motor. But since the voltage level at the microcontroller’s output is very less we use a driver. The series of correct answers is stored in the memory of the microcontroller block. The result of the comparison is given to the next block i.e. computer. This input is then computed upon and the result is generated. The generated result i.e. number of correct and incorrect answers is displayed on the LCD. 3.2.5 LIQUID CRYSTAL DISPLAY We are using a 16*2 matrix LCD. The primary use of this block is to display the answers which have been detected by the sensor block. Moreover, 12 | P a g e when the answers are fed to the microcontroller via the software, the total score of the students as well his name is displayed. We are using this block to improve the ergonomics of the project. This makes the handling of the system easy and convenient. 3.2.6 COMPUTER The mail use of the computer is that it act as an interface between the project blocks(hardware) and the program module (software). We can conveniently store the result of each student as an excel sheet file, thus making our project easily manageable and easy to handle. We are using RS 232 cable to connect the hardware with our computer via serial port. 3.2.7 SOFTWARE CONSOLE This block is used to determine the number of questions the student is going to face in the examination. The software also gives us the provision of storing the exam result according to roll number and the name. The correct answers are fed by the examiner into the memory of the microcontroller block according to which the answers will be evaluated. The compared correct and incorrect answers are then properly arranged and displayed along with the score of the respective student. The software console consists of a database where the result of every student appearing for the exam is stored. This information can be used in the future for analysis and grading. 13 | P a g e 3.3 PCB DESIGN 3.3.1 PCB LAYOUT AND ARTWORK DESIGN A PRINTED CIRCUIT BOARD is popularly known as the first thing we would require when we decide to build an electronic circuit. A roper PCB ensures that various components are interconnected as per the circuit diagram, once they have been placed on the PCB and subsequently soldered. PCB design and fabrication techniques have undergone so much of development that it has become a subject itself. Double sided PCB, multilayer PCB with PTH (plated through holes), using CAD software design for PCB layout design, flexible PCB’s etc are only some of the developments. An average experimenter however needs to go into the details of these technologies or is supposed to learn the intricacies of the art of PCB layout designing. What he needs familiarization with different steps involved in PCB fabrication particularly the etching process so that he can make his own PCB economically from an available PCB layout design. 14 | P a g e 3.3.2 PCB FABRICATION Different steps involved in the fabrication of a PCB are as follows. 1. Component layout design. 2. PCB layout design. 3. Transferring the PCB layout design onto the PCB board Laminate 4. Developing or etching the PCB 5. Other operation like drilling, cutting, tinning etc. 3.3.2.1 Components Layout Designing Component layout designing’s the exercise of placement of different consisting the circuits & then showing their interconnection as per the circuit diagram. This exercise usually begins with an estimate of size of the PCB needed to accommodate various circuit components. The estimated dimensions are marked on a graph paper & an attempt is made to optimally place the components. It may be mentioned here that the relative position of different components will largely depend upon the nature of interconnections & the circuit input, output & ground points. Knowledge of dimensions of different components , making up to the circuit is another perquisite in designing the components layout. Having placed all the components the interconnections can be made by drawing lines (Known as tracks) the lines should be optimum length & should not be unnecessarily long. In fact the components layouts can be best drawn by carrying out twin job of placement of the components and making the interconnections side by side. 15 | P a g e 3.3.2.2 PCB LAYOUT DESIGN The PCB layout design is nothing but the mirror image of component layout is drawn by looking from the component side, wherases the PCB layout is drawn by looking from the copper side. It can best be obtained by taking a carbon copy of component layout already drawn by pacing a reserved carbon underneath the paper. The hobbyist can take a photo copy of the layout on to the copper side of the PCB laminate. 3.3.2.3 Transferring PCB Layout onto Laminate The first thing to be done here is to the type of PCB laminate. There are two types of PCB laminate available for the purpose. 1. Phenolic Boards 2. 2. Fibre Glass epoxy boards. Phenolic boards are much cheaper and good enough for most of the commercial applications but it is not very suitable. When there is heating of components, the most ideal material for power supplies is fire resistant material. The commercial grade of the same is known as FR2/FR3/FR4.The normal single sided boards are manufactured by using FR2 material. However when PCB is length more, then there can be changes of getting the PCB warpage which would cause track breaking or bending of the components in loose connections. 16 | P a g e For the purpose of power control application it is advisable to use the FR4 grade which is popularly known as glass epoxy material.It has very good strength against warpage.It has property to with stand almost any climayic conditions.It has also the property of flame resistant.Hence we have chosen the material (FR4) for our project. The next step is to thouroughly clean the copper side of the laminate with petrol to make it completely free from any contaminates. The PCB layout can be transferred on to copper side of the laminate by using a pointed tool to mark the position of holes so that you did not miss any. After carbon copying the PCB layout pattern,the sane can be redrawn by giving proper width to different tracks and leaving space for the components.all this can be simply done with the help of enamel paint and a fine brush. The most popular and accurate method is silk-screen painting the track side layout for copper clad by using PCB grade ink.silk screen printing process is widely used by the PCB manufacturers as it is easy,accurate and same reproduction can easily be obtained.for silk screen painting a film positive is required .when the layot is printed onto the copper clad laminate the next processs comes is etching. 3.3.2.3 ETCHING In the etching process,all excess copper is removed leaving behind only the painted pattern. To do etching, the painted PCB board laminate is placed in a flat tray with the copper side facing upwards.an aqueous solution of ferric chloride with the quantity depend on the size of PCB. The PCB to the etched is then pourd in the tray.The PCB should be fully immersed in the ferric chloride sol. The sol is prepared by adding abt.40-50 grams of 17 | P a g e ferricchloride of 100ml of warmwater. The sol. Should be nicely stirred and a few drops of HCL are added to speed up the etching process.The tray can be moved up and down. The etching process may take abt. Half an hour to one hour. The etching tjme again depends on the size of PCB and area to be etched.it must the PCb is neither under etched nor over etched.If the PCB is kept immersed in the sol. After etching is completed, the sol.is likely to be penetrating the copper portion that is require to be preserved and cause more etching. The ferric chloride should be preserved in the bottle for future use and should not be wasted.sol.once made can be used for 3-4 etchings. The laminate is thoroughly wasted in water etching is completed.the paint is removed with alcohol or thinner. 3.3.2.4 DRILLING – TINNING The next major operation after etching is drilling and tinning,the diameter of hole varies from component to component.it is 0.8mm for IC pins,1mm to 1.25mm for resistors and capacitors,1.5mm for diodes and presets. The size of holes for the resistors would also depend on wattage of resistor. The oxidation of copper portions can be prevented by either tinning that can be done by using soldering iron or by giving a coat of some insulating varnish. 3.3.2.5 SOLDERING THE COMPONENTS ON THE PCB Mounting of the components is done on the PCB in its exact place on the non-conducting materials or surface. If the component is not placed on the exact place then, there is no change for the project to give a result. So proper mounting of the component is more essential. 18 | P a g e Before mounting any component we check the PCB carefully to prevent the occurance of the non-conducting path. The lead of the component like register & capacitor should be inserted into the mounting hopefully. After inserting the co9mpone3nt carefully cut the lead of the component so that the lead remains about 3mm above the soldering side of PCB to make the firm contact these lead are bend are at angle need the component can solder easily. In this case of the semiconductor devices such as transistor & diodes the length of the lead extended above the component side of the PCB should remain above 5mm. This prevent not only heat sink applied to the each lead while soldering but it is useful for the measuring the voltage across these lead. Certain component like a transformer, potentiometer & variable capacitor are simply inserted in the holes PCB and soldered. Soldered is the process for the joining of metal .soft soldering generally implies that the joining process occurs at temperature below 45 degree Celsius. It should be noted that that while soldering . so air gap should be remained, because due to it there will be no proper contact of the range of 10-25 watts.This prevents the damage to PCB by excessive heating .To avoid the short circuit with the adjacent conducting path one should not used the excessive solder .For this purpose of solder wire 60/60 ratios should be used. For this purpose soldering IC one should have to use a solder iron of the thin or pointed tip .so while soldering the semiconductor device great care should be taken .The alloy used for soldering is tin-lead . The percentage of tin content is of 3050%. The fluxes are applied while soldering for proper fixing of the molten solder with the PCB. 19 | P a g e 3.4 PCB LAYOUT 3.4.1 COMPONENT VIEW 20 | P a g e 3.4.2 BOTTOM VIEW 21 | P a g e CHAPTER NO.4 CIRCUIT DIAGRAM 22 | P a g e 4.1 HARDWARE DESCRIPTION 4.1.1 Transformer A transformer is a device that transfers electrical energy from one to other through inductively coupled conductors –the transformer’s coils or “windings”. Except for air-core transformer, the conductors are wound around a single iron-rich core, or around separate but magnetically-coupled cores. A varying current in the first or “primary” winding creates a varying magnetic field in the core (or cores) of the transformer. This varying magnetic field induces a varying electromotive force (EMF) or “voltage” in the “secondary” winding. This effect is called as mutual induction. If a load is connected to a secondary, an electric current will flow in the secondary winding the electrical energy will flow from the primary circuit through the transformer to the load. In an ideal transformer, the induced voltage in the secondary winding (Vs) is in proportion to the primary voltage (Vp), and is given by the ratio of the number of turns in the secondary to the number of turns in the primary as follows By appropriate selection of the ratio of turns, a transformer thus allows an alternating current (AC) voltage to be "stepped up" by making Ns greater than Np, or "stepped down" by making Ns less than Np. Transformers range in size from a thumbnail-sized coupling transformer hidden inside a stage microphone to huge units weighing hundreds of tons used to 23 | P a g e interconnect portions of power grids. All operate with the same basic principles, although the range of designs is wide. While new technologies have eliminated the need for transformers in some electronic circuits, transformers are still found in nearly all electronic devices designed for household ("mains") voltage. Transformers are essential for high-voltage electric power transmission, which makes long-distance transmission economically practical. Here, we have used a 230V/12V transformer. It is basically a step-down transformer. It is used to get the 12V AC from 230V AC supply, the frequency being unchanged. This output is then given to the power supply. 4.1.2 POWER SUPPLY What is AC and DC? A representation of an Alternating Current (AC) supply is shown in figure 1. The voltage (and current) alternates between positive and negative over time and the resulting waveform shape is a sine wave. In the case of the UK mains supply, the frequency of this sine wave is 50Hz, or 50 cycles per second. A Direct Current (DC) supply, shown in figure 2, stays at a fixed, regular, voltage all of the time, like the voltage from a battery. A DC supply is needed 24 | P a g e by most circuits as a constant reference voltage. Also, some components would be damaged by the negative half-cycles of an AC supply. The Parts of a Power Supply Figure 3 shows a block diagram of a power supply system which converts a 230V AC mains supply (230V is the UK mains voltage) into a regulated 5V DC supply. A simple power supply circuit that includes each of these blocks in given in figure 4. The following articles in this series look at each block of the power supply in 25 | P a g e detail, but if you just want to build a 5V regulated power supply without understanding how it works, you can follow the instructions later in this article The Power supply consists of the transformer, bridge rectifier, regulator IC. The transformer is a step down one having 12V rating. The bridge rectifier is used to convert the ac supply into a dc. There are two regulators used one is a 9V and a 5V. The 78XX series is used to regulate power. During the positive half cycle of secondary voltage diodes D13 and D16 are forward biased while diodes D15 and D14 are reverse biased. Therefore, only diodes D13 and D16 conduct. These two diodes will be in series through the load. Hence the positive half cycle is rectified to the load. During the negative half cycle of secondary voltage diodes D15 and D14 are forward biased while diodes D13 and D16 are reverse biased. Therefore, only diodes D15 and D14 conduct. These two diodes will be in series through the load. Hence the negative half cycle is rectified to the load. These output is of pulsating character, hence the ac is filtered out by capacitor C1. Further regulation in output voltage is obtained by IC 7805 and IC 7809. The output is shown by the LED. 26 | P a g e 4.1.3 STEPPER MOTOR A stepper motor (or step motor) is a brushless, synchronous electric motor that can divide a full rotation into a large number of steps. The motor's position can be controlled precisely, without any feedback mechanism (see Open-loop controller). Stepper motors are similar to switched reluctance motors (which are very large stepping motors with a reduced pole count, and generally are closed-loop commutated.) Fundamentals of Operation Stepper motors operate differently from DC brush motors, which rotate when voltage is applied to their terminals. Stepper motors, on the other hand, effectively have multiple "toothed" electromagnets arranged around a central gear-shaped piece of iron. An external control circuit, such as a microcontroller, energizes the electromagnets. To make the motor shaft turn, first one electromagnet is given power, which makes the gear's teeth magnetically attracted to the electromagnet's teeth. When the gear's teeth are thus aligned to the first electromagnet, they are slightly offset from the next electromagnet. So when the next electromagnet is turned on and the first is turned off, the gear rotates slightly to align with the next one, and from there the process is repeated. Each of those slight rotations is called 27 | P a g e a "step," with an integer number of steps making a full rotation. In that way, the motor can be turned by a precise angle. Stepper motor characteristics 1. Stepper motors are constant power devices. 2. As motor speed increases, torque decreases. 3. The torque curve may be extended by using current limiting drivers and increasing the driving voltage. 4. Steppers exhibit more vibration than other motor types, as the discrete step tends to snap the rotor from one position to another. 5. This vibration can become very bad at some speeds and can cause the motor to lose torque. 6. The effect can be mitigated by accelerating quickly through the problem speeds range, physically damping the system, or using a micro-stepping driver. 7. Motors with a greater number of phases also exhibit smoother operation than those with fewer phases. 28 | P a g e There are three main types of stepper motors: Permanent Magnet Stepper Hybrid Synchronous Stepper Variable Reluctance Stepper Permanent magnet motors use a permanent magnet (PM) in the rotor and operate on the attraction or repulsion between the rotor PM and the stator electromagnets. Variable reluctance (VR) motors have a plain iron rotor and operate based on the principle of that minimum reluctance occurs with minimum gap, hence the rotor points are attracted toward the stator magnet poles. Hybrid stepper motors are named because they use use a combination of PM and VR techniques to achieve maximum power in a small package size. Two-phase stepper motors There are two basic winding arrangements for the electromagnetic coils in a two phase stepper motor: bipolar and unipolar. Unipolar motors A unipolar stepper motor has two windings per phase, one for each direction of magnetic field. Since in this arrangement a magnetic pole can be reversed without switching the direction of current, the commutation circuit can be made very simple (eg. a single transistor) for each winding. Typically, given a phase, one end of each winding is made common: giving three leads per phase and six leads for a typical two phase motor. Often, these two phase commons are internally joined, so the motor has only five leads. A microcontroller or stepper motor controller can be used to activate the drive transistors in the right order, and this ease of operation makes unipolar motors popular with hobbyists; they are probably the cheapest way to get precise angular movements. Unipolar stepper motor coils 29 | P a g e Bipolar motor Bipolar motors have a single winding per phase. The current in a winding needs to be reversed in order to reverse a magnetic pole, so the driving circuit must be more complicated, typically with an H-bridge arrangement. There are two leads per phase, none are common. Static friction effects using an H-bridge have been observed with certain drive topologies Because windings are better utilised, they are more powerful than a unipolar motor of the same weight. 8-lead stepper An 8 lead stepper is wound like a Unipolar stepper, but the leads are not joined to common internally to the motor. This kind of motor can be wired in several configurations: Unipolar. Bipolar with series windings. This gives higher inductance but lower current per winding. Bipolar with parallel windings. This requires higher current but can perform better as the winding inductance is reduced. Bipolar with a single winding per phase. This method will run the motor on only half the available windings, which will reduce the available low speed torque but require less current. Higher-phase count stepper motors Multi-phase stepper motors with many phases tend to have much lower levels of vibration, although the cost of manufacture is higher. Stepper motor drive circuits Stepper motor performance is strongly dependent on the drive circuit. Torque curves may be extended to greater speeds if the stator poles can be reversed more quickly, the limiting factor being the winding inductance. To overcome the inductance and switch the windings quickly, one must increase the drive voltage. This leads further to the necessity of limiting the current that these high voltages may otherwise induce. L/R drive circuits L/R drive circuits are also referred to as constant voltage drives because a constant positive or negative voltage is applied to each winding to set the step positions. However, it is winding current, not voltage that applies torque to the stepper motor shaft. The current I in each winding is related to the applied voltage V by the winding inductance L and the winding resistance R. The resistance R determines the maximum current according to Ohm's law I=V/R. The inductance L determines the maximum rate of change of the current in the winding according to the formula 30 | P a g e for an Inductor dI/dt = V/L. Thus when controlled by an L/R drive, the maximum speed of a stepper motor is limited by its inductance since at some speed, the voltage V will be changing faster than the current I can keep up. With an L/R drive it is possible to control a low voltage resistive motor with a higher voltage drive simply by adding an external resistor in series with each winding. This will waste power in the resistors, and generate heat. It is therefore considered a low performing option, albeit simple and cheap. Chopper drive circuits Chopper drive circuits are also referred to as constant current drives because they generate a somewhat constant current in each winding rather than applying a constant voltage. On each new step, a very high voltage is applied to the winding initially. This causes the current in the winding to rise quickly since dI/dt = V/L where V is very large. The current in each winding is monitored by the controller, usually by measuring the voltage across a small sense resistor in series with each winding. When the current exceeds a specified current limit, the voltage is turned off or "chopped", typically using power transistors. When the winding current drops below the specified limit, the voltage is turned on again. In this way, the current is held relatively constant for a particular step position. This requires additional electronics to sense winding currents, and control the switching, but it allows stepper motors to be driven with higher torque at higher speeds than L/R drives. Integrated electronics for this purpose are widely available. Phase current waveforms A stepper motor is a polyphase AC synchronous motor (see Theory below), and it is ideally driven by sinusoidal current. A full step waveform is a gross approximation of a sinusoid, and is the reason why the motor exhibits so much vibration. Various drive techniques have been developed to better approximate a sinusoidal drive waveform: these are half stepping and microstepping. Full step drive (two phases on) This is the usual method for full step driving the motor. Both phases are always on. The motor will have full rated torque. 31 | P a g e Stepper motor ratings and specifications Stepper motors nameplates typically give only the winding current and occasionally the voltage and winding resistance. The rated voltage will produce the rated winding current at DC: but this is mostly a meaningless rating, as all modern drivers are current limiting and the drive voltages greatly exceed the motor rated voltage. A stepper's low speed torque will vary directly with current. How quickly the torque falls off at faster speeds depends on the winding inductance and the drive circuitry it is attached to, especially the driving voltage. Steppers should be sized according to published torque curve, which is specified by the manufacturer at particular drive voltages and/or using their own drive circuitry. It is not guaranteed that you will achieve the same performance given different drive circuitry, so the pair should be chosen with great care. 32 | P a g e 4.1.4 SCANNER Fig 4.1.4.1 Receiver used in the sensor block This is the part of the system which deals with the scanning of the answers sheets. It consists of IR sensors(transceivers) placed such that the dark circles fall in line while the answers sheets are passed through it. It also consists of stepper motors which drive the belt mechanism for the movement of the IR sensors. When the answers is detected ,i.e. there is a change in voltage level of sensors output leakage current is 280µA under ideal condition, when no light is incident, leakage current flows through the receiver, the current increases . 33 | P a g e CHAPTER NO. 5 MICROCONTROLLER 89S51 MICROCONTROLLER The AT89S52 is a low-power, high-performance 8-bit microcomputer with 4K 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 industrystandard MCS-51 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 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 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. FEATURES OF 89S52 Following is the features of 89S52 microcontroller as per the datasheet given by Atmel Compatible with MCS-52™ 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 34 | P a g e 128 x 8-bit Internal RAM 32 Programmable I/O Lines Two 16-bit Timer/Counters Six Interrupt Sources Programmable Serial Channel Low-power Idle and Power-down Modes PIN DIAGRAM OF 89S51: 35 | P a g e BRIEF DESCRIPTION The AT89S52 is a low-power, high-performance 8-bit microcomputer with 4K 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 MCS-52 instruction set and pinout. 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. 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 may 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. 36 | P a g e 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. Port 1 also receives the low-order address bytes during Flash programming and verification. Port 2: Port 2 is an 8-bit bi-directional 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 uses 16-bit addresses (MOVX @ DPTR). In this application, it uses strong internal pullups when emitting 1s. During accesses to external data memory that uses 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 bi-directional 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 37 | P a g e pull-ups. Port 3 also serves the functions of various special features of the AT89S52 as listed below: Port Pin Alternate Functions – P3.0 RXD (serial input port) P3.1 TXD (serial output port) P3.2 INT0 (external interrupt 0) P3.3 INT1 (external interrupt 1) P3.4 T0 (timer 0 external input) P3.5 T1 (timer 1 external input) P3.6 WR (external data memory write strobe) P3.7 RD (external data memory read strobe) Port 3 also receives some control signals for Flash programming and verification. RST Reset input. A high on this pin for two machine cycles while the oscillator is running resets the device. ALE/PROG Address Latch Enable 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 38 | P a g e 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 ALEdisable bit has no effect if the microcontroller is in external execution mode. PSEN Program Store Enable is the read strobe to external program memory. When the AT89S52 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, for parts that require 12-volt VPP. XTAL1 Input to the inverting oscillator amplifier and input to the internal clock operating circuit. XTAL2 Output from the inverting oscillator amplifier. 39 | P a g e CHAPTER NO .6 IR SENSOR OBJECT DETECTION USING IR LIGHT It is the same principle in ALL Infra-Red proximity sensors. The basic idea is to send infra red light through IR-LEDs, which is then reflected by any object in front of the sensor. Then all you have to do is to pick-up the reflected IR light. For detecting the reflected IR light, we are going to use a very original technique: we are going to use another IR-LED, to detect the IR light that was emitted from another led of the exact same type! This is an electrical property of Light Emitting Diodes (LEDs) which is the fact that a led Produce a voltage difference across its leads when it is subjected to light. As if it was a photocell, but with much lower output current. In other words, the voltage generated by the leds can't be - in any way - used to generate electrical power from light, It can barely be detected. that's why as you will notice in the schematic, we are going to use a Op-Amp (operational Amplifier) to accurately detect very small voltage changes. 40 | P a g e Design 1: Low range, Always ON As the name implies, the sensor is always ON, meaning that the IR led is constantly emitting light. this design of the circuit is suitable for counting objects, or counting revolutions of a rotating object, that may be of the order of 15,000 rpm or much more. However this design is more power consuming and is not optimized for high ranges. in this design, range can be from 1 to 10 cm, depending on the ambient light conditions. As you can see the schematic is divided into 2 parts the sender and the receiver. The sender is composed of an IR LED (D2) in series with a 470 Ohm resistor, yielding a forward current of 7.5 mA. The receiver part is more complicated, the 2 resistors R5 and R6 form a voltage divider which provides 2.5V at the anode of the IR LED (here, this led will be used as a sensor). When IR light falls on the LED (D1), the voltage drop increases, the cathode's voltage of D1 may go as low as 1.4V or more, depending on the light intensity. This voltage drop can be detected using an Op-Amp (operational Amplifier LM358). You will have to adjust the variable resistor (POT.) R8 so the the voltage at the positive input of the Op-Amp (pin No. 5) would be somewhere near 1.6 Volt. if you understand the functioning of Op-Amps, you will notice that the output will go High when the volt at the cathode of D1 drops under 1.6. So the output will be High when IR light is detected, which is the purpose of the receiver. 41 | P a g e CHAPTER NO .7 LCD LCD INTERFACING WITH MICROCONTROLLER 7.1 LCD Backgorund Frequently, an 8051 program must interact with the outside world using input and output devices that communicate directly with a human being. One of the most common devices attached to an 8051 is an LCD display. Some of the most common LCDs connected to the 8051 are 16x2 and 20x2 displays. This means 16 characters per line by 2 lines and 20 characters per line by 2 lines, respectively. Fortunately, a very popular standard exists which allows us to communicate with the vast majority of LCDs regardless of their manufacturer. The standard is referred to as HD44780U, which refers to the controller chip which receives data from an external source (in this case, the 8051) and communicates directly with the LCD. The 44780 standard requires 3 control lines as well as either 4 or 8 I/O lines for the data bus. The user may select whether the LCD is to operate with a 4-bit data bus or an 8-bit data bus. If a 4-bit data bus is used the LCD will require a total of 7 data lines (3 control lines plus the 4 lines for the data bus). If an 8-bit data bus is used the LCD will require a total of 11 data lines (3 control lines plus the 8 lines for the data bus). 42 | P a g e The three control lines are referred to as EN, RS, and RW. The EN line is called "Enable." This control line is used to tell the LCD that you are sending it data. To send data to the LCD, your program should make sure this line is low (0) and then set the other two control lines and/or put data on the data bus. When the other lines are completely ready, bring EN high (1) and wait for the minimum amount of time required by the LCD datasheet (this varies from LCD to LCD), and end by bringing it low (0) again. The RS line is the "Register Select" line. When RS is low (0), the data is to be treated as a ommand or special instruction (such as clear screen, position cursor, etc.). When RS is high (1), the data being sent is text data which sould be displayed on the screen. For example, to display the letter "T" on the screen you would set RS high. The RW line is the "Read/Write" control line. When RW is low (0), the information on the data bus is being written to the LCD. When RW is high (1), the program is effectively querying (or reading) the LCD. Only one instruction ("Get LCD status") is a read command. All others are write commands--so RW will almost always be low. Handling the en control line As we mentioned above, the EN line is used to tell the LCD that you are ready for it to execute an instruction that you've prepared on the data bus and on the other control lines. Note that the EN line must be raised/lowered before/after each instruction sent to the LCD regardless of whether that instruction is read or write, text or instruction. In short, you must always manipulate EN when communicating with the LCD. EN is the LCD's way of knowing that you are talking to it. If you don't raise/lower EN, the LCD doesn't know you're talking to it on the other lines. Thus, before we interact in any way with the LCD we will always bring the EN line low with the following instruction: CLR EN And once we've finished setting up our instruction with the other control lines and data bus lines,we'll always bring this line high. 43 | P a g e SETB EN The instruction is executed by the LCD at the moment the EN line is brought low with a final CLR EN instruction. Initializing the lcd Before you may really use the LCD, you must initialize and configure it. This is accomplished by sending a number of initialization instructions to the LCD. The first instruction we send must tell the LCD whether we'll be communicating with it with an 8-bit or 4-bit data bus. We also select a 5x8 dot character font. These two options are selected by sending the command 38h to the LCD as a command. As you will recall from the last section, we mentioned that the RS line must be low if we are sending a command to the LCD. Programming Tip: The LCD command 38h is really the sum of a number of option bits. The instruction itself is the instruction 20h ("Function set"). However, to this we add the values 10h to indicate an 8-bit data bus plus 08h to indicate that the display is a two-line display. We've now sent the first byte of the initialization sequence. The second byte of the initialization sequence is the instruction 0Eh. Programming Tip: The command 0Eh is really the instruction 08h plus 04h to turn the LCD on. To that an additional 02h is added in order to turn the cursor on. The last byte we need to send is used to configure additional operational parameters of the LCD. We must send the value 06h. Programming Tip: 44 | P a g e The command 06h is really the instruction 04h plus 02h to configure the LCD such that every time we send it a character, the cursor position automatically moves to the right. Clearing the display An LCD command exists to accomplish this function. Not suprisingly, it is the command 01h. Programming Tip: Executing the "Clear Screen" instruction on the LCD also positions the cursor in the upper left-hand corner as we would expect. 45 | P a g e CHAPTER NO .8 SAMPLE ANSWER SHEET 46 | P a g e CHAPTER NO .9 APPENDICES 9.1 ALGORITHM 1. Start 2. Initialize the LCD. 3. Wait for student’s name. 4. If the name is receive, the wait for the enter button to be pressed. 5. The ASCII character “Q” is sent to VB and wait for number of questions. 6. The questions receive is displayed on the LCD with the number of questions. 7. Start /initialize the stepper motor. Save the result in the scratch memory. 8. Increment the stepper motor position till number of questions check ’+1’. 9. Reverse the motor to original position. 10.Sent the result serially and save the result in data base. 47 | P a g e 9.2 FLOWCHART S ta rt B I n it ia l iz e t h e L C D N o W a it f o r n a m e Yes n am e N o W a it f o r e n t e r b u t t o n T o b e p re sse d Yes S e n d A S C II c h a ra c t e r D is p l a y t h e q u e s t io n o n L C D I n it ia l iz e s t e p p e r m o to r S a v e r e s u lt in sc ra tc h m e m o ry A 48 | P a g e A Increment the stepper motor position Move to original position Transmit result serially and save in database B 49 | P a g e CHAPTER NO .10 PROGRAMMING Opcode for microcontroller LCD_DATA EQU p2 RS EQU p0.5 RW EQU p0.6 EN EQU p0.7 PORT _KEY EQU p1 KEY_READ EQU 09H ORG 0000H JMP MAIN MAIN: LCALL DISPLAY_DATA ; LCALL STEPPER_TEST LCALL DELAY_1_SEC ; LCALL READ_KEY_PAD RET DISPLAY_DATA: 50 | P a g e MOV A, #38H LCALL COMMAND MOV A, #0EH LCALL COMMAND MOV A, #01H LCALL COMMAND MOV A, #06H LCALL COMMAND MOV A, #80H LCALL COMMAND MOV A, #’D’ LCALL DISPLAY MOV A, #’E’ LCALL DISPLAY MOV A, #’V’ LCALL DISPLAY MOV A, #’I’ LCALL DISPLAY MOV A, #’C’ LCALL DISPLAY MOV A, #’E’ LCALL DISPLAY MOV A, #’ ‘ 51 | P a g e LCALL DISPLAY MOV A, #’O’ LCALL DISPLAY MOV A, #’K’ LCALL DISPLAY MOV A, #’.’ LCALL DISPLAY MOV A, #’.’ LCALL DISPLAY MOV A, #’.’ LCALL DISPLAY RET STEPPER_TEST: MOV R0, #25H HERE: MOVA, #0CCCH MOV P0, A LCALL DELAY_STEPPER MOV A, #066H MOV P0, A LCALL DELAY_STEPPER MOV A, #033H 52 | P a g e MOV P0, A LCALL DELAY_STEPPER MOV A, #099H MOV P0, A LCALL DELAY_STEPPER DJNZ R0, HERE RET ; READ_KEY_PAD: ; MOV PORT_KEY, #00001111B ; AGAIN: ; MOV A, PORT_KEY ; CLR C ; SUBB A, #00001111B ; JZ AGAIN ; MOV PORT_KEY_, 01111111B ; MOV A, PORT_KEY ; CLR C ; SUBB A, #01111111B ; JZ C1 ; MOV A, PORT_KEY ; CJNE A, #01110111B, C1R1 ; MOV A, #00H ; MOV KEY_READ, A 53 | P a g e ; JMP C4 ; C1R1: ; CJNE A, #01111011B, C1R2 ; MOV A, #01H ; MOV KEY_READ, A ; JMP C4 ; C1R2: ; CJNE A, #01111101B, C1R3 ; MOV A, #02H ; MOV KEY_READ, A ; JMP C4 ; C1R3: ;CJNE A,#01111110B,CIR4 ;MOV A,#03H ;MOV KEY_READ,A ;JMP C4 ;C1R4: ;C1: ;MOV PORT_KEY,#10111111B ;MOV A,PORT_KEY ;CLR C ;SUBB A,#10111111B ;JZ C2 54 | P a g e ;MOV A,PORT_KEY ;CJNE A,#10110111B,C2R1 ;MOV A,#05H ;MOV KEY_READ,A ;JMP C4 ;C2R1: ;CJNE A,#10111011B,C2R2 ;MOV A,#05H ;MOV KEY_READ,A ;JMP C4 ;C2R2: ; CJNE A,#10111011B,C2R3 ;MOV A,#06H ;MOV KEY_READ,A ;JMP C4 ;C2R3: ; CJNE A,#10111110B,C2R4 ;MOV A,#07H ;MOV KEY_READ,A ;JMP C4 ;C2R4: ;C2: ;MOV PORT_KEY,#11011111B 55 | P a g e ; MOV A,PORT_KEY ;CLR C ;SUBB A,#11011111B ;JZ C3 ;MOV A,PORT_KEY ;CJNE A,#11010111B,C3R1 ;MOV A,#08H ;MOV KEY_READ,A ;JMP C4 ;C3R1: ;CJNE A,#11011011B,C3R2 ;MOV A,#09H ;MOV KEY_READ,A ;JMP C4 ;C3R2: ; CJNE A,#11011101B,C3R3 ;MOV A,#0AH ;MOV KEY_READ,A ;JMP C4 ;C3R3: ; CJNE A,#11011110B,C3R4 ;MOV A,#0BH ;MOV KEY_READ,A 56 | P a g e ;JMP C4 ;C3R4: ; C3: ;MOV PORT_KEY,#11101111B ; MOV A,PORT_KEY ;CLR C ;SUBB A,#11101111B ;JZ C4 ;MOV A,PORT_KEY ;CJNE A,#11100111B,C4R1 ;MOV A,#0CH ;MOV KEY_READ,A ;JMP C4 ;C4R1: ;CJNE A,#11101011B,C4R2 ;MOV A,#0DH ;MOV KEY_READ,A ;JMP C4 ;C4R2: ; CJNE A,#11101101B,C4R3 ;MOV A,#0EH ;MOV KEY_READ,A ;JMP C4 57 | P a g e ;C4R3: ; CJNE A,#11101110B,C4R4 ;MOV A,#0FH ;MOV KEY_READ,A ;JMP C4 ;C4R4: ;C4: ;LCALL DELAY_20_M_SEC: ;RET DELAY_20_M_SEC: MOVR2,#01H FRFRDR:MOV R2,#0FFH FRFR2S:MOV R4,#0FFFH FRFRS:DJNZ R4,FRFRS DJNZ R3,FRFR2S DJNZ R2,FRFRDR RET COMMAND: MOV LCD_DATA,A 58 | P a g e CLR RS CLR RW SETB EN CLR EN LCALL DELAY RET DISPLAY: MOV LCD_DATA,A SETB RS CLR RW SETB EN CLR EN LCALL DELAY RET DELAY: MOV R3,#03H FRFR2: MOPV R4,#09FH FRFR: DJNZ R4,FRFR DJNZ R3,FRFR2 RET DELAY_STEPPER: 59 | P a g e MOV R2,#01H FRFFR: MOV R3,#00F FRFFR2: MOV R4,#0FFH FRFFR: DJNZ R4,FRFFR DJNZ R3,FRFFR2 DJNZ R2,FRFFR3 RET DELAY_1_SEC: MOV R2,#0AH FFFR3: MOV R3,#0FFH FFFR2: MOV R4,#0FFH FFFR: DJNZ R4,FFFR DJNZ R3,FFFR2 DJNZ R2,FFFR3 RET END 60 | P a g e CHAPTER NO .11 CONCLUSION This project is extremely cost effective and easy to implement at college level.The systems high accuracy,reliability and convenience to use,makes it a good substitute for the conventional OMR based exam paper evaluator .The use of transcopic paper limits the application of conventional OMR machines to very expensive applications. This problem is negated in this project as it uses any kind of paper irrespective of its size ,grade, quality etc. The problem of counterfeiting the answer sheet is also tackled using the barcode scanner.Thus our project provides a comprehensive solution to the need of our college to establish a low cost,reliable and effective evaluation system for variousMCQ based examinations. 61 | P a g e CHAPTER NO.12 FUTURE SCOPE Our project manages the growing complexities faced by any organization in conducting examinations time and again to select the right candidates for various courses.In order to speed up this process and to ensure quick response and flexibility,our system has been offering OMR based examination services to various corporate bodies,institutes and recruitement organizations.our system can provide quality services to any organization or institute and establish along term satisfactory service.As a result of the wide spread adoption and ease of use of OMR ,standardized examinations consist primarily of multiple-choice questions,changing the nature of what is being tested. 62 | P a g e CHAPTER NO.13 APPLICATION There are many other applications for OMR ,for example: In the process of institutional research Community surveys Consumer surveys Geo coding Voting Time sheets Evaluations Data compilation Product evaluation Membership subscription forms 63 | P a g e CHAPTER NO.14 REFERENCES www.google.com www.datasheet.com www.omr.com www.wikipedia.com M.MAZIDI,”8051microcontroller & microprocessor” Steven holzner, ”visual basics black book” Greg Perry , “visual basics in 21 days “ 64 | P a g e Chapter no .15 DATA SHEETS 65 | P a g e 66 | P a g e 67 | P a g e 68 | P a g e 69 | P a g e 70 | P a g e 71 | P a g e 72 | P a g e 73 | P a g e 74 | P a g e 75 | P a g e 76 | P a g e 77 | P a g e S 78 | P a g e 79 | P a g e 80 | P a g e 81 | P a g e 82 | P a g e 83 | P a g e 84 | P a g e 85 | P a g e 86 | P a g e 87 | P a g e 88 | P a g e 89 | P a g e 90 | P a g e