Ultrasonic Navigation For Blind With Audio Interface Documentation tw5x

ULTRASONIC NAVIGATION FOR BLIND WITH AUDIO INTERFACE

CHAPTER 1 OVERVIEW OF THE PROJECT 1.1

INTRODUCTION Since sometimes blind people collide against high and moving obstacles, we need

obstacle-sensing function in front of the blind people. This paper proposes a method of point-to-point distance measurement using ultrasonic for cap in order to detect moving and high obstacles. In this method, we apply ultrasonic wave technique to measure distance to obstacles, since it does not disturb other people. By setting two ultrasonic sensors on the cap, one for transmission and the other for reception, the moving and high obstacles are detected before colliding. Moreover, embedded systems are employed in the system in order to reduce system size and cost, as well as saving energy. In experiments (with wood, concrete, plastic, etc. as obstacles), the results reveal distance measurement accuracy 95 % approximately. In this project we are using an IR transmitter and Receiver circuit based path clearing assist stick. Path clearing assist stick is used to detect any obstacles. If any obstacle is found, the IR light will be reflected back and sensed by IR receiver and sends a signal to the buzzer driver circuit, which produces buzzer sound near hand. The project works very well even in night and day timings, irrespective of the lighting intensity. The project is reliable and effective. This project uses regulated 5V, 750mA power supply. Unregulated 12V DC is used for relay. 7805 three terminal voltage regulator is used for voltage regulation. Bridge type full wave rectifier is used to rectify the ac output of secondary of 230/12V step down transformer. This project can be powered by a simple 9V battery also for portability.

1.2 OBJECTIVE The objective of this project is to help Blind people in their daily commute. As Blind people are given less importance in the society, we took the initiate to help them in their day to day life with this project.

Department of ECE, MRITS

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1.3 TOOLS REQUIRED 1.3.1 HARDWARE REQUIREMENTS: 1. 2. 3. 4. 5. 6.

AT89S52 Micro Controller Power Supply 16 X 2 LCD Ultrasonic Sensor APR33A3 Speaker

1.3.2 SOFTWARE REQUIREMENTS: 1. Programming in embedded C 2. Keil Micro vision 3. Flash Magic

1.4 THESIS ORGANIZATION The rest of the thesis is organized as follows: Chapter 2 Micro-Controller Introduction. Chapter 3 Block diagram of the project is explained and mode of operation and also their function in detail. Chapter 4 Discuss about Circuit Diagram, Operation and also the code. Chapter 5 Checking the Result and also analyzing it. Chapter 6 Conclusion of the project and Future Scope.

CHAPTER 2 Department of ECE, MRITS

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MICROCONTROLLER 2.1 INTRODUCTION An Embedded System is a combination of computer hardware and software, and perhaps additional mechanical or other parts, designed to perform a specific function. A good example is the microwave oven. Almost every household has one, and tens of millions of them are used every day, but very few people realize that a processor and software are involved in the preparation of their lunch or dinner. This is in direct contrast to the personal computer in the family room. It too is comprised of computer hardware and software and mechanical components (disk drives, for example). However, a personal computer is not designed to perform a specific function rather; it is able to do many different things. Many people use the term generalpurpose computer to make this distinction clear. As shipped, a general-purpose computer is a blank slate; the manufacturer does not know what the customer will do wish it. One customer may use it for a network file server another may use it exclusively for playing games, and a third may use it to write the next great American novel. Frequently, an embedded system is a component within some larger system. For example, modern cars and trucks contain many embedded systems. One embedded system controls the anti-lock brakes, other monitors and controls the vehicle's emissions, and a third displays information on the dashboard. In some cases, these embedded systems are connected by some sort of a communication network, but that is certainly not a requirement. At the possible risk of confusing you, it is important to point out that a generalpurpose computer is itself made up of numerous embedded systems. For example, my computer consists of a keyboard, mouse, video card, modem, hard drive, floppy drive, and sound card-each of which is an embedded system. Each of these devices contains a processor and software and is designed to perform a specific function. For example, the modem is designed to send and receive digital data over analog telephone line. That's it and all of the other devices can be summarized in a single sentence as well.


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If an embedded system is designed well, the existence of the processor and software could be completely unnoticed by the of the device. Such is the case for a microwave oven, VCR, or alarm clock. In some cases, it would even be possible to build an equivalent device that does not contain the processor and software. This could be done by replacing the combination with a custom integrated circuit that performs the same functions in hardware. However, a lot of flexibility is lost when a design is hard-cooled in this way. It is much easier, and cheaper, to change a few lines of software than to redesign a piece of custom hardware.

2.2 Real Time Systems One subclass of embedded is worthy of an introduction at this point. As commonly defined, a real-time system is a computer system that has timing constraints. In other words, a real-time system is partly specified in of its ability to make certain calculations or decisions in a timely manner. These important calculations are said to have deadlines for completion. And, for all practical purposes, a missed deadline is just as bad as a wrong answer. The issue of what if a deadline is missed is a crucial one. For example, if the realtime system is part of an airplane's flight control system, it is possible for the lives of the engers and crew to be endangered by a single missed deadline. However, if instead the system is involved in satellite communication, the damage could be limited to a single corrupt data packet. The more severe the consequences, the more likely it will be said that the deadline is "hard" and thus, the system is a hard real-time system. Real-time systems at the other end of this discussion are said to have "soft" deadlines. All of the topics and examples presented in this book are applicable to the designers of real-time system who is more delight in his work. He must guarantee reliable operation of the software and hardware under all the possible conditions and to the degree that human lives depend upon three system's proper execution, engineering calculations and descriptive paperwork.

2.3 Application Areas


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Nearly 99 per cent of the processors manufactured end up in embedded systems. The embedded system market is one of the highest growth areas as these systems are used in very market segment- consumer electronics, office automation, industrial automation, biomedical engineering, wireless communication, data communication, telecommunications, transportation, military and so on. 2.3.1 Consumer Appliances At home we use a number of embedded systems which include digital camera, digital diary, DVD player, electronic toys, microwave oven, remote controls for TV and air-conditioner, VCO player, video game consoles, video recorders etc. Today’s high-tech car has about 20 embedded systems for transmission control, engine spark control, airconditioning, navigation etc. Even wristwatches are now becoming embedded systems. The palmtops are powerful embedded systems using which we can carry out many general-purpose tasks such as playing games and word processing. 2.3.2 Office Automation The office automation products using embedded systems are copying machine, fax machine, key telephone, modem, printer, scanner etc. 2.3.3 Industrial Automation Today a lot of industries use embedded systems for process control. These include pharmaceutical, cement, sugar, oil exploration, nuclear energy, electricity generation and transmission. The embedded systems for industrial use are designed to carry out specific tasks such as monitoring the temperature, pressure, humidity, voltage, current etc., and then take appropriate action based on the monitored levels to control other devices or to send information to a centralized monitoring station. In hazardous industrial environment, where human presence has to be avoided, robots are used, which are programmed to do specific jobs. The robots are now becoming very powerful and carry out many interesting and complicated tasks such as hardware assembly. 2.3.4 Medical Electronics


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Almost every medical equipment in the hospital is an embedded system. These equipment’s include diagnostic aids such as ECG, EEG, blood pressure measuring devices, X-ray scanners; equipment used in blood analysis, radiation, colonoscopy, endoscopy etc. Developments in medical electronics have paved way for more accurate diagnosis of diseases. 2.3.5 Computer Networking Computer networking products such as bridges, routers, Integrated Services Digital Networks (ISDN), Asynchronous Transfer Mode (ATM), X.25 and frame relay switches are embedded systems which implement the necessary data communication protocols. For example, a router interconnects two networks. The two networks may be running different protocol stacks. The router’s function is to obtain the data packets from incoming pores, analyse the packets and send them towards the destination after doing necessary protocol conversion. Most networking equipment’s, other than the end systems (desktop computers) we use to access the networks, are embedded systems 2.3.6 Tele-communications In the field of telecommunications, the embedded systems can be categorized as subscriber terminals and network equipment. The subscriber terminals such as key telephones, ISDN phones, terminal adapters, web cameras are embedded systems. The network equipment includes multiplexers, multiple access systems, Packet Assemblers Dissemblers (PADs), sate11ite modems etc. IP phone, IP gateway, IP gatekeeper etc. are the latest embedded systems that provide very low-cost voice communication over the Internet. 2.3.7 Wireless Technologies Advances in mobile communications are paving way for many interesting applications using embedded systems. The mobile phone is one of the marvels of the last decade of the 20’h century. It is a very powerful embedded system that provides voice communication while we are on the move. The Personal Digital Assistants and the palmtops can now be used to access multimedia services over the Internet. Mobile


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communication infrastructure such as base station controllers, mobile switching centres are also powerful embedded systems. 2.3.8 Security Security of persons and information has always been a major issue. We need to protect our homes and offices; and also the information we transmit and store. Developing embedded systems for security applications is one of the most lucrative businesses nowadays. Security devices at homes, offices, airports etc. for authentication and verification are embedded systems. Encryption devices are nearly 99 per cent of the processors that are manufactured end up in~ embedded systems. Embedded systems find applications in. every industrial segment- consumer electronics, transportation, avionics, biomedical engineering, manufacturing, process control and industrial automation, data communication, telecommunication, defence, security etc. Used to encrypt the data/voice being transmitted on communication links such as telephone lines. Biometric systems using fingerprint and face recognition are now being extensively used for authentication in banking applications as well as for access control in high security buildings. 2.3.9 Finance Financial dealing through cash and cheques are now slowly paving way for transactions using smart cards and ATM (Automatic Teller Machine, also expanded as Any Time Money) machines. Smart card, of the size of a credit card, has a small microcontroller and memory; and it interacts with the smart card reader! ATM machine and acts as an electronic wallet. Smart card technology has the capability of ushering in a cashless society. Well, the list goes on. It is no exaggeration to say that eyes wherever you go, you can see, or at least feel, the work of an embedded system.

2.4 Microcontroller 2.4.1 Definition Like all good things, this powerful component is basically very simple. It is made by mixing tested and high- quality "ingredients" (components) as per following receipt:


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1. The simplest computer processor is used as the "brain" of the future system. 2. Depending on the taste of the manufacturer, a bit of memory, a few A/D converters, timers, input/output lines etc. are added 3. All that is placed in some of the standard packages. 4. A simple software able to control it all and which everyone can easily learn about has been developed. On the basis of these rules, numerous types of microcontrollers were designed and they quickly became man's invisible companion. Their incredible simplicity and flexibility conquered us a long time ago and if you try to invent something about them, you should know that you are probably late, someone before you has either done it or at least has tried to do it. The following things have had a crucial influence on development and success of the microcontrollers: 1.

Powerful and carefully chosen electronics embedded in the microcontrollers can independently or via input/output devices (switches, push buttons, sensors, LCD displays, relays etc.), control various processes and devices such as industrial

automation, electric current, temperature, engine performance etc. 2. Very low prices enable them to be embedded in such devices in which, until recent time it was not worthwhile to embed anything. Thanks to that, the world is 3.

overwhelmed today with cheap automatic devices and various “smart” appliances. Prior knowledge is hardly needed for programming. It is sufficient to have a PC (software in use is not demanding at all and is easy to learn) and a simple device (called the programmer) used for “loading” ready-to-use programs into the microcontroller. So, if you are infected with a virus called electronics, there is nothing left for you

to do but to learn how to use and control its power.


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2.4.2 Operation Even though there is a large number of different types of microcontrollers and even more programs created for their use only, all of them have many things in common. Thus, if you learn to handle one of them you will be able to handle them all. A typical scenario on the basis of which it all functions is as follows: 1.

Power supply is turned off and everything is still…the program is loaded into the microcontroller, nothing indicates what is about to come…

2.

Power supply is turned on and everything starts to happen at high speed! The control logic unit keeps everything under control. It disables all other circuits except quartz crystal to operate. While the preparations are in progress, the first milliseconds go by.

3.

Power supply voltage reaches its maximum and oscillator frequency becomes stable. SFRs are being filled with bits reflecting the state of all circuits within the microcontroller. All pins are configured as inputs. The overall electronics starts operation in rhythm with pulse sequence. From now on the time is measured in micro and nanoseconds.

4.

Program Counter is set to zero. Instruction from that address is sent to instruction decoder which recognizes it, after which it is executed with immediate effect.

5.

The value of the Program Counter is incremented by 1 and the whole process is repeated...several million times per second.


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Fig 2.1: Microcontroller Architecture

2.5 Inside Microcontroller As you can see, all the operations within the microcontroller are performed at high speed and quite simply, but the microcontroller itself would not be so useful if there are not special circuits which make it complete. In continuation, we are going to call your attention to them.


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2.5.1 Read Only Memory (ROM) Read Only Memory (ROM) is a type of memory used to permanently save the program being executed. The size of the program that can be written depends on the size of this memory. ROM can be built in the microcontroller or added as an external chip, which depends on the type of the microcontroller. Both options have some disadvantages. If ROM is added as an external chip, the microcontroller is cheaper and the program can be considerably longer. At the same time, a number of available pins is reduced as the microcontroller uses its own input/output ports for connection to the chip. The internal ROM is usually smaller and more expensive, but leaves more pins available for connecting to peripheral environment. The size of ROM ranges from 512B to 64KB. 2.5.2 Random Access Memory (RAM) Random Access Memory (RAM) is a type of memory used for temporary storing data and intermediate results created and used during the operation of the microcontrollers. The content of this memory is cleared once the power supply is off. For example, if the program performs an addition, it is necessary to have a standing for what in everyday life is called the “sum”. For that purpose, one of the s in RAM is called the "sum" and used for storing results of addition. The size of RAM goes up to a few KBs. 2.5.3 Electrically Erasable Programmable ROM (EEPROM) The EEPROM is a special type of memory not contained in all microcontrollers. Its contents may be changed during program execution (similar to RAM), but remains permanently saved even after the loss of power (similar to ROM). It is often used to store values, created and used during operation (such as calibration values, codes, values to count up to etc.), which must be saved after turning the power supply off. A disadvantage of this memory is that the process of programming is relatively slow. It is measured in milliseconds.


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2.5.4 Special Function s (SFR) Special function s are part of RAM memory. Their purpose is predefined by the manufacturer and cannot be changed therefore. Since their bits are physically connected to particular circuits within the microcontroller, such as A/D converter, serial communication module etc., any change of their state directly affects the operation of the microcontroller or some of the circuits. For example, writing zero or one to the SFR controlling an input/output port causes the appropriate port pin to be configured as input or output. In other words, each bit of this controls the function of one single pin. 2.5.5 Program Counter Program Counter is an engine running the program and points to the memory address containing the next instruction to execute. After each instruction execution, the value of the counter is incremented by 1. For this reason, the program executes only one instruction at a time just as it is written. However…the value of the program counter can be changed at any moment, which causes a “jump” to a new memory location. This is how subroutines and branch instructions are executed. After jumping, the counter resumes even and monotonous automatic counting +1, +1, +1…

2.6 Block Diagram of project Block diagram consists of a micro-controller (AT89S52), Power Supply, LCD Display (16X2 Display), APR33A3 (Voice module), Ultrasonic Sensor, Speaker. The Block Diagram is shown below to get a better understanding of the project


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Fig 2.2: Block Diagram of Project


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CHAPTER 3 HARDWARE DESCRIPTION 3.1 AT89S52 3.1.1 Introduction to AT89S52 The system requirements and control specifications clearly rule out the use of 16, 32 or 64 bit micro controllers or microprocessors. Systems using these may be earlier to implement due to large number of internal features. They are also faster and more reliable but, the above application is satisfactorily served by 8-bit micro controller. Using an inexpensive 8-bit Microcontroller will doom the 32-bit product failure in any competitive market place. Coming to the question of why to use 89S52 of all the 8-bit Microcontroller available in the market the main answer would be because it has 8kB Flash and 256 bytes of data RAM32 I/O lines, three 16-bit timer/counters, a Eight-vector two-level interrupt architecture, a full duplex serial port, on-chip oscillator, and clock circuitry. In addition, the AT89S52 is designed with static logic for operation down to zero frequency and s two software selectable power saving modes. The Idle Mode stops the U 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. The Flash program memory s both parallel programming and in Serial In-System Programming (ISP). The 89S52 is also In-Application Programmable (IAP), allowing the Flash program memory to be reconfigured even while the application is running. By combining a versatile 8-bit U 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


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3.1.2 PIN DIAGRAM

Fig 3.1: Pin Diagram of AT89S52

3.1.3 PIN DESCRIPTION Pins 1-8: Port 1 Each of these pins can be configured as an input or an output. Department of ECE, MRITS

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Pin 9: RS A logic one on this pin disables the microcontroller and clears the contents of most s. In other words, the positive voltage on this pin resets the microcontroller. By applying logic zero to this pin, the program starts execution from the beginning. Pins10-17: Port 3 Similar to port 1, each of these pins can serve as general input or output. Besides, all of them have alternative functions: Pin 10: RXD Serial asynchronous communication input or Serial synchronous communication output. Pin 11: TXD Serial asynchronous communication output or Serial synchronous communication clock output. Pin 12: INT0 Interrupt 0 input. Pin 13: INT1 Interrupt 1 input. Pin 14: T0 Counter 0 clock input. Pin 15: T1 Counter 1 clock input. Pin 16: WR Write to external (additional) RAM. Pin 17: RD Read from external RAM. Pin 18, 19: X2, X1 Internal oscillator input and output. A quartz crystal which specifies operating frequency is usually connected to these pins. Instead of it, miniature ceramics resonators can also be used for frequency stability. Later versions of microcontrollers operate at a frequency of 0 Hz up to over 50 Hz. Pin 20: GND Ground. Pin 21-28: Port 2 If there is no intention to use external memory then these port pins are configured as general inputs/outputs. In case external memory is used, the higher address byte, i.e. addresses A8-A15 will appear on this port. Even though memory with capacity of 64Kb is not used, which means that not all eight port bits are used for its addressing, the rest of them are not available as inputs/outputs. Pin 29: PSEN If external ROM is used for storing program then a logic zero (0) appears on it every time the microcontroller reads a byte from memory.


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Pin 30: ALE Prior to reading from external memory, the microcontroller puts the lower address byte (A0-A7) on P0 and activates the ALE output. After receiving signal from the ALE pin, the external (usually 74HCT373 or 74HCT375 add-on chip) memorizes the state of P0 and uses it as a memory chip address. Immediately after that, the ALU pin is returned its previous logic state and P0 is now used as a Data Bus. As seen, port data multiplexing is performed by means of only one additional (and cheap) integrated circuit. In other words, this port is used for both data and address transmission. Pin 31: EA By applying logic zero to this pin, P2 and P3 are used for data and address transmission with no regard to whether there is internal memory or not. It means that even there is a program written to the microcontroller, it will not be executed. Instead, the program written to external ROM will be executed. By applying logic one to the EA pin, the microcontroller will use both memories, first internal then external (if exists). Pin 32-39: Port 0 Similar to P2, if external memory is not used, these pins can be used as general inputs/outputs. Otherwise, P0 is configured as address output (A0-A7) when the ALE pin is driven high (1) or as data output (Data Bus) when the ALE pin is driven low (0). Pin 40: VCC +5V power supply.


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3.1.4 RAM MEMORY

Fig 3.2: RAM Memory of AT89S52

3.1.5 Special Function s (SFRs) Special Function s (SFRs) are a sort of control table used for running and monitoring the operation of the microcontroller. Each of these s as well as each bit they include, has its name, address in the scope of RAM and precisely defined purpose such as timer control, interrupt control, serial communication control etc. Even though there are 128 memory locations intended to be occupied by them, the basic core, shared by all types of 8051 microcontrollers, has only 21 such s. Rest of locations are intentionally left unoccupied in order to enable the manufacturers to further develop microcontrollers keeping them compatible with the previous versions. It also enables programs written a long time ago for microcontrollers which are out of production now to be used today.


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(i) A (Accumulator)

Fig 3.3: Accumulator of AT89S52 A is a general-purpose used for storing intermediate results obtained during operation. Prior to executing an instruction upon any number or operand it is necessary to store it in the accumulator first. All results obtained from arithmetical operations performed by the ALU are stored in the accumulator. Data to be moved from one to another must go through the accumulator. In other words, the A is the most commonly used and it is impossible to imagine a microcontroller without it. More than half instructions used by the 8051 microcontroller use somehow the accumulator. (ii) B Multiplication and division can be performed only upon numbers stored in the A and B s. All other instructions in the program can use this as a spare accumulator (A).

Fig 3.4: B of AT89S52


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(iii) R s (R0-R7)

Fig 3.5: Set (R0-R7) This is a common name for 8 general-purpose s (R0, R1, R2 ...R7). Even though they are not true SFRs, they deserve to be discussed here because of their purpose. They occupy 4 banks within RAM. Similar to the accumulator, they are used for temporary storing variables and intermediate results during operation. Which one of these banks is to be active depends on two bits of the PSW . Active bank is a bank the s of which are currently used. (iv) Program Status Word (PSW)

Fig 3.6: Program Status Word (PSW) PSW is one of the most important SFRs. It contains several status bits that reflect the current state of the U. Besides, this contains Carry bit, Auxiliary Carry, two bank select bits, Overflow flag, parity bit and -definable status flag. 1.

P - Parity bit. If a number stored in the accumulator is even then this bit will be automatically set (1), otherwise it will be cleared (0). It is mainly used during data transmit and receive via serial communication.


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2.

Bit 1. This bit is intended to be used in the future versions of microcontrollers.

3.

OV - Overflow occurs when the result of an arithmetical operation is larger than 255 and cannot be stored in one . Overflow condition causes the OV bit to be set (1). Otherwise, it will be cleared (0).

4.

RS0, RS1 - bank select bits. These two bits are used to select one of four banks of RAM. By setting and clearing these bits, s R0-R7 are stored in one of four banks of RAM. Table 3.1: Bank Select Bits RS1

RS2

S PAC E I N R A M

0

0

Bank0 00h-07h

0

1

Bank1 08h-0Fh

1

0

Bank2 10h-17h

1

1

Bank3 18h-1Fh

1.

F0 - Flag 0. This is a general-purpose bit available for use.

2.

AC - Auxiliary Carry Flag is used for BCD operations only.

3.

CY - Carry Flag is the (ninth) auxiliary bit used for all arithmetical operations and shift instructions.

(v) Data Pointer (DPTR) DPTR is not a true one because it doesn't physically exist. It consists of two separate s: DPH (Data Pointer High) and (Data Pointer Low). For this reason it may be treated as a 16-bit or as two independent 8-bit s. Their 16 bits are primarily used for external memory addressing. Besides, the DPTR is usually used for storing data and intermediate results.


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Fig 3.7: Data Pointer (DPTR) (vi) Stack Pointer (SP)

Fig 3.8: Stack Pointer (SP) A value stored in the Stack Pointer points to the first free stack address and permits stack availability. Stack pushes increment the value in the Stack Pointer by 1. Likewise, stack pops decrement its value by 1. Upon any reset and power-on, the value 7 is stored in the Stack Pointer, which means that the space of RAM reserved for the stack starts at this location. If another value is written to this , the entire Stack is moved to the new memory location.


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(vii) P0, P1, P2, P3 - Input/output s

Fig 3.9: Input/output s If neither external memory nor serial communication system are used then 4 ports within total of 32 input/output pins are available for connection to peripheral environment. Each bit within these ports affects the state and performance of appropriate pin of the microcontroller. Thus, bit logic state is reflected on appropriate pin as a voltage (0 or 5 V) and vice versa, voltage on a pin reflects the state of appropriate port bit. As mentioned, port bit state affects performance of port pins, i.e. whether they will be configured as inputs or outputs. If a bit is cleared (0), the appropriate pin will be configured as an output, while if it is set (1), the appropriate pin will be configured as an input. Upon reset and power-on, all port bits are set (1), which means that all appropriate pins will be configured as inputs. 3.1.6 Counters and Timers As you already know, the microcontroller oscillator uses quartz crystal for its operation. As the frequency of this oscillator is precisely defined and very stable, pulses it generates are always of the same width, which makes them ideal for time measurement. Such crystals are also used in quartz watches. In order to measure time between two events it is sufficient to count up pulses coming from this oscillator. That is exactly what the timer does. If the timer is properly programmed, the value stored in its will be incremented (or decremented) with each coming pulse, i.e. once per each machine cycle. A single machine-cycle instruction lasts for 12 quartz oscillator periods, which means that by embedding quartz with oscillator frequency of 12MHz, a number stored in the timer will be changed million times per second, i.e. each microsecond. The 8051 microcontroller has 2 timers/counters called T0 and T1. As their names suggest, their main purpose is to measure time and count external events. Besides, they can be used for generating clock pulses to be used in serial communication, so called Baud Rate.


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3.1.7 Timer T0 As seen in figure below, the timer T0 consists of two s – TH0 and TL0 representing a low and a high byte of one 16-digit binary number.

Fig 3.10: Timer T0 Accordingly, if the content of the timer T0 is equal to 0 (T0=0) then both s it consists of will contain 0. If the timer contains for example number 1000 (decimal), then the TH0 (high byte) will contain the number 3, while the TL0 (low byte) will contain decimal number 232.

Fig 3.11: TH0 and TL0 Formula used to calculate values in these two s is very simple: TH0 × 256 + TL0 = T Matching the previous example it would be as follows: 3 × 256 + 232 = 1000


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Fig 3.12:TH0 and TL0 Since the timer T0 is virtually 16-bit , the largest value it can store is 65 535. In case of exceeding this value, the timer will be automatically cleared and counting starts from 0. This condition is called an overflow. Two s TMOD and TCON are closely connected to this timer and control its operation. 3.1.8 TMOD (Timer Mode) The TMOD selects the operational mode of the timers T0 and T1. As seen in figure below, the low 4 bits (bit0 - bit3) refer to the timer 0, while the high 4 bits (bit4 bit7) refer to the timer 1. There are 4 operational modes and each of them is described here.

Fig 3.13: TMOD (Timer Mode) Bits of this have the following function: 1) GATE1 enables and disables Timer 1 by means of a signal brought to the INT1 pin (P3.3): i) 1 - Timer 1 operates only if the INT1 bit is set. ii) 0 - Timer 1 operates regardless of the logic state of the INT1 bit.

2) C/T1 selects pulses to be counted up by the timer/counter 1: i) 1 - Timer counts pulses brought to the T1 pin (P3.5). ii) 0 - Timer counts pulses from internal oscillator.

3) T1M1, T1M0 these two bits select the operational mode of the Timer 1. Department of ECE, MRITS

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Table 3.2: TIM1 and TIM0 Modes T1M1

T1M0

MODE

DESCRIPTION

0

0

0

13-bit timer

0

1

1

16-bit timer

1

0

2

8-bit auto-reload

1

1

3

Split mode

1) GATE0 enables and disables Timer 1 using a signal brought to the INT0 pin

(P3.2): a) 1 - Timer 0 operates only if the INT0 bit is set. b) 0 - Timer 0 operates regardless of the logic state of the INT0 bit. 2) C/T0 selects pulses to be counted up by the timer/counter 0: a) 1 - Timer counts pulses brought to the T0 pin (P3.4). b) 0 - Timer counts pulses from internal oscillator. 3) T0M1, T0M0 these two bits select the operational mode of the Timer 0.

3.1.9 Timer Control (TCON) TCON is also one of the s whose bits are directly in control of timer operation. Only 4 bits of this are used for this purpose, while rest of them is used for interrupt control to be discussed later.

Fig 3.14: Timer Control (TCON)

1)

TF1 bit is automatically set on the Timer 1 overflow.

2)

TR1 bit enables the Timer 1. a)

1 - Timer 1 is enabled.


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b)

0 - Timer 1 is disabled.

3)

TF0 bit is automatically set on the Timer 0 overflow.

4)

TR0 bit enables the timer 0. a)

1 - Timer 0 is enabled.

b)

0 - Timer 0 is disabled.

3.1.10 TIMER T1 Timer 1 is identical to timer 0, except for mode 3 which is a hold-count mode. It means that they have the same function, their operation is controlled by the same s TMOD and TCON and both of them can operate in one out of 4 different modes.

Fig 3.15: TIMER 1

Fig 3.16: TIMER 1 Format 3.1.11 Serial communication UART (Universal Asynchronous Receiver and Transmitter) One of the microcontroller features making it so powerful is an integrated UART, better known as a serial port. It is a full-duplex port, thus being able to transmit and receive data simultaneously and at different baud rates. Without it, serial data send and receive would be an enormously complicated part of the program in which the pin state is constantly changed and checked at regular intervals. When using UART, all the programmer has to do is to simply select serial port mode and baud rate. When it's done, Department of ECE, MRITS

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serial data transmit is nothing but writing to the SBUF , while data receive represents reading the same . The microcontroller takes care of not making any error during data transmission.

Fig 3.17: SBUF Serial port must be configured prior to being used. In other words, it is necessary to determine how many bits is contained in one serial “word”, baud rate and synchronization clock source. The whole process is in control of the bits of the SCON (Serial Control). (viii) Serial Port Control (SCON)

Fig 3.18: Serial Port Control (SCON) 1.

SM0 - Serial port mode bit 0 is used for serial port mode selection.

2.

SM1 - Serial port mode bit 1.

3.

SM2 - Serial port mode 2 bit, also known as multiprocessor communication enable bit. When set, it enables multiprocessor communication in mode 2 and 3, and eventually mode 1. It should be cleared in mode 0.

4.

REN - Reception Enable bit enables serial reception when set. When cleared, serial reception is disabled.

5.

TB8 - Transmitter bit 8. Since all s are 8-bit wide, this bit solves the problem of transmitting the 9th bit in modes 2 and 3. It is set to transmit a logic 1 in the 9th bit.

6.

RB8 - Receiver bit 8 or the 9th bit received in modes 2 and 3. Cleared by hardware if 9th bit received is a logic 0. Set by hardware if 9th bit received is a logic 1.


28


7.

TI - Transmit Interrupt flag is automatically set at the moment the last bit of one byte is sent. It's a signal to the processor that the line is available for a new byte transmit. It must be cleared from within the software.

8.

RI - Receive Interrupt flag is automatically set upon one byte receive. It signals that byte is received and should be read quickly prior to being replaced by a new data. This bit is also cleared from within the software.

As seen, serial port mode is selected by combining the SM0 and SM2 bits: SM0

SM1

MODE

DESCRIPTION

B A U D R ATE

0

0

0

8-bit Shift

1/12 the quartz frequency

0

1

1

8-bit UART

Determined by the timer 1

1

0

2

9-bit UART

1

1

3

9-bit UART

1/32 the quartz frequency (1/64 the quartz frequency) Determined by the timer 1

Table 3.3: SM0 and SM1 Mode selection In mode 0, serial data are transmitted and received through the RXD pin, while the TXD pin output clocks. The bout rate is fixed at 1/12 the oscillator frequency. On transmit, the least significant bit (LSB bit) is sent/received first. 3.2 POWER SUPPLY All digital circuits require regulated power supply. In this article we are going to learn how to get a regulated positive supply from the mains supply.

Fig 3.19: Power Supply Block Diagram Figure 3.19 shows the basic block diagram of a fixed regulated power supply. Let us go through each block.


29


Fig 3.24 Circuit Diagram of power supply 3.2.1 TRANSFORMER

Fig 3.20: Transformer Types A transformer consists of two coils also called as “WINDINGS” namely PRIMARY & SECONDARY. They are linked together through inductively coupled electrical conductors also called as CORE. A changing current in the primary causes a change in the Magnetic Field in the core & this in turn induces an alternating voltage in the secondary coil. If load is applied to the secondary then an alternating current will flow through the load. If we consider an ideal condition then all the energy from the primary circuit will be transferred to the secondary circuit through the magnetic field.


30


So

The secondary voltage of the transformer depends on the number of turns in the Primary as well as in the secondary.

3.2.2 Rectifier A rectifier is a device that converts an AC signal into DC signal. For rectification purpose we use a diode, a diode is a device that allows current to only in one direction i.e. when the anode of the diode is positive with respect to the cathode also called as forward biased condition & blocks current in the reversed biased condition. Bridge Rectifier

Fig 3.21: Bridge Rectifier As the name suggests it converts the full wave i.e. both the positive & the negative half cycle into DC thus it is much more efficient than Half Wave Rectifier & that


31


too without using a center tapped transformer thus much more cost effective than Full Wave Rectifier. Full Bridge Wave Rectifier consists of four diodes namely D1, D2, D3 and D4. During the positive half cycle diodes D1 & D4 conduct whereas in the negative half cycle diodes D2 & D3 conduct thus the diodes keep switching the transformer connections so we get positive half cycles in the output. 3.2.3 FILTER CAPACITOR Even though half wave & full wave rectifier give DC output, none of them provides a constant output voltage. For this we require to smoothen the waveform received from the rectifier. This can be done by using a capacitor at the output of the rectifier this capacitor is also called as “FILTER CAPACITOR” or “SMOOTHING CAPACITOR” or “RESERVOIR CAPACITOR”. Even after using this capacitor a small amount of ripple will remain. We place the Filter Capacitor at the output of the rectifier the capacitor will charge to the peak voltage during each half cycle then will discharge its stored energy slowly through the load while the rectified voltage drops to zero, thus trying to keep the voltage as constant as possible.

Fig 3.22: Filter Capacitor Input/output


32


If we go on increasing the value of the filter capacitor then the Ripple will decrease. But then the costing will increase. The value of the Filter capacitor depends on the current consumed by the circuit, the frequency of the waveform & the accepted ripple.

Where, Vr= accepted ripple voltage. (Should not be more than 10% of the voltage) I= current consumed by the circuit in Amperes. F= frequency of the waveform. A half wave rectifier has only one peak in one cycle so F=25Hz 3.2.4 VOLTAGE REGULATOR A Voltage regulator is a device which converts varying input voltage into a constant regulated output voltage. Voltage regulator can be of two types 1)

Linear Voltage Regulator Also called as Resistive Voltage regulator because they dissipate the excessive

voltage resistively as heat. 2)

Switching Regulators

They regulate the output voltage by switching the Current ON/OFF very rapidly. Since their output is either ON or OFF it dissipates very low power thus achieving higher efficiency as compared to linear voltage regulators. But they are more complex & generate high noise due to their switching action. For low level of output power switching regulators tend to be costly but for higher output wattage they are much cheaper than linear regulators.


33


The most commonly available Linear Positive Voltage Regulators are the 78XX series where the XX indicates the output voltage. And 79XX series is for Negative Voltage Regulators.

Fig 3.23: Switching Regulators After filtering the rectifier output the signal is given to a voltage regulator. The maximum input voltage that can be applied at the input is 35V.Normally there is a 2-3 Volts drop across the regulator so the input voltage should be at least 2-3 Volts higher than the output voltage. If the input voltage gets below the Vmin of the regulator due to the ripple voltage or due to any other reason the voltage regulator will not be able to produce the correct regulated voltage. 3.2.5 IC 7805 7805 is an integrated three-terminal positive fixed linear voltage regulator. It s an input voltage of 10 volts to 35 volts and output voltage of 5 volts. It has a current rating of 1 amp although lower current models are available. Its output voltage is fixed at 5.0V. The 7805 also has a built-in current limiter as a safety feature. 7805 is manufactured by many companies, including National Semiconductors and Fairchild Semiconductors. The 7805 will automatically reduce output current if it gets too hot. The last two digits represent the voltage; for instance, the 7812 is a 12-volt regulator. The 78xx series of regulators is designed to work in complement with the 79xx series of negative voltage regulators in systems that provide both positive and negative regulated voltages, since the 78xx series can't regulate negative voltages in such a system.


34


The 7805 & 78 is one of the most common and well-known of the 78xx series regulators, as it's small component count and medium-power regulated 5V make it useful for powering TTL devices. Table 3.4: Specifications of IC7805 SPECIFICATIONS

IC 7805

Vout

5V

Vein - Vout Difference

5V - 20V

Operation Ambient Temp

0 - 125°C

Output Imax

1A

3.3 LCD MODULE 3.3.1 DESCRIPTION To display interactive messages we are using LCD Module. We examine an intelligent LCD display of two lines, 16 characters per line that is interfaced to the controllers. The protocol (handshaking) for the display is as shown. Whereas D0 to D7th bit is the Data lines, RS, RW and EN pins are the control pins and remaining pins are +5V, -5V and GND to provide supply. Where RS is the Select, RW is the Read Write and EN is the Enable pin. The display contains two internal byte-wide s, one for commands (RS=0) and the second for characters to be displayed (RS=1). It also contains a -programmed RAM area (the character RAM) that can be programmed to generate any desired character that can be formed using a dot matrix. To distinguish between these two data areas, the hex command byte 80 will be used to signify that the display RAM address 00h will be chosen.Port1 is used to furnish the command or data type, and ports 3.2 to3.4 furnish select and read/write levels.


35


The display takes varying amounts of time to accomplish the functions as listed. LCD bit 7 is monitored for logic high (busy) to ensure the display is overwritten. Liquid Crystal Display also called as LCD is very helpful in providing interface as well as for debugging purpose. The most common type of LCD controller is HITACHI 44780 which provides a simple interface between the controller & an LCD. These LCD's are very simple to interface with the controller as well as are cost effective.

2x16 Line Alphanumeric LCD Display Fig 3.25: LCD Display The most commonly used ALPHANUMERIC displays are 1x16 (Single Line & 16 characters), 2x16 (Double Line & 16 character per line) & 4x20 (four lines & Twenty characters per line). The LCD requires 3 control lines (RS, R/W & EN) & 8 (or 4) data lines. The number on data lines depends on the mode of operation. If operated in 8-bit mode then 8 data lines + 3 control lines i.e. total 11 lines are required. And if operated in 4-bit mode then 4 data lines + 3 control lines i.e. 7 lines are required. How do we decide which mode to use? It’s simple if you have sufficient data lines you can go for 8 bit mode & if there is a time constrain i.e. display should be faster than we have to use 8-bit mode because basically 4-bit mode takes twice as more time as compared to 8-bit mode.


36


Table 3.4: PINS of LCD Pin

Symbol

Function

1

Vss

Ground

2

Vdd

Supply Voltage

3

Vo

Contrast Setting

4

RS

Select

5

R/W

Read/Write Select

6

En

Chip Enable Signal

7-14

DB0-DB7

Data Lines

15

A/Vee

Gnd for the backlight

16

K

Vcc for backlight

When RS is low (0), the data is to be treated as a command. When RS is high (1), the data being sent is considered as text data which should be displayed on the screen. When R/W is low (0), the information on the data bus is being written to the LCD. When RW is high (1), the program is effectively reading from the LCD. Most of the times there is no need to read from the LCD so this line can directly be connected to Gnd thus saving one controller line. The ENABLE pin is used to latch the data present on the data pins. A HIGH LOW signal is required to latch the data. The LCD interprets and executes our command at the instant the EN line is brought low. If you never bring EN low, your instruction will never be executed.


37


Fig 3.26: Controller to LCD Interface

3.3.2 COMMANDS USED IN LCD

Fig 3.27: Commands Used In LCD

3.4 ULTRASONIC RANGE FINDER Department of ECE, MRITS

38


3.4.1 DESCRIPTION

Fig 3.28: Ultrasonic Sensor A guide to using the Arduino Ultrasonic Range Detection Sensor with Arduino in order to calculate distances from objects. In this case I'm also altering the output of an LED with PWM according to how close an object is to the sensor. So the nearer you are the brighter the LED. So if we start with the Arduino Ultrasonic Range Detection Sensor, it's an IC that works by sending an ultrasound pulse at around 40 KHz. It then waits and listens for the pulse to echo back, calculating the time taken in microseconds (1 microsecond = 1.0 x 10-6 seconds). You can trigger a pulse as fast as 20 times a second and it can determine objects up to 3 meters away and as near as 3cm. It needs a 5V power supply to run. Adding the Arduino Ultrasonic Range Detection Sensor to the Arduino is very easy, only 4 pins to worry about. Power, Ground, Trigger and Echo. Since it needs 5V and Arduino provides 5V I'm obviously going to use this to power it. Below is a diagram of my Arduino Ultrasonic Range Detection Sensor, showing the pins. There are 2 sets of 5 pins, 1 set you can use, the other is for programming the PIC chip so don't touch them! 3.4.2 Specification: 1.

Working Voltage : 5V(DC) Working

2.

Current: max 15 ma


39


3.

Working frequency : 40HZ

4.

Output Signal: 0-5V (Output high when obstacle in range)

5.

Sentry Angle : max 15 degree

6.

Sentry Distance: 2cm - 500cm

7.

High-accuracy: 0.3cm

8.

Input trigger signal: l0us

9.

TTL impulse Echo signal: output TTL PWL signal

10.

Size: 45*20* 15mm

Fig 3.29: Trigger and Echo Radius


40


Note: This module is not suitable to connect with electric power, if you need to connect this module with electronic power, then let the GND terminal of this module to be connected first, otherwise, it will affect the normal work of the module 3.4.3 Interface:

1: VCC; 2: trig (T); 3: echo (R); 4: GND Fig 3.30: Ultrasonic Sensor Pins


41


3.4.4 Usage Supply module with 5 V, the output will be 5 V while obstacle in range, or OV if not. The out pin of this module is used as a switching output when anti-theft module, and without the feet when ranging modules, Note: the module should be inserted in the circuit before been power, which avoid producing high level of miss operation; if not, then power again. 3.4.5 Module Working Principle 1.

Adopt 10 trigger through supplying at least l0us sequence of high level signal,

2.

The module automatically send eight 40khz square wave and automatically detect whether receive the returning pulse signal,

3.

If there is signals returning, through outputting high level

Test distance = (high level time * sound velocity (340M/S) / 2, 3.4.6 The circuit

Very, very simple circuit, I've used the breadboard to share the GND connection and to add the LED which I could probably have done without the breadboard. You'll see the most complex thing is the code later on.

3.5 APR33A3 3.5.1 DESCRIPTION Today’s consumers demand the best in audio/voice. They want crystal-clear sound wherever they are in whatever format they want to use. APLUS delivers the technology to enhance a listener’s audio/voice experience. The APR33A3 series are powerful audio processor along with high performance audio analog-to-digital converters (ADCs) and digital-to-analog converters (DACs). The aPR33A series are a fully integrated solution offering high performance and unparalleled integration with anaput, digital processing and analog output functionality. The APR33A3 series incorporates all the functionality Department of ECE, MRITS

42


required to perform demanding audio/voice applications. High quality audio/voice systems with lower bill-of-material costs can be implemented with the APR33A3 series because of its integrated analog data converters and full suite of qualityenhancing features such as sample-rate convertor. The aPR33A series C2.0 is specially designed for simple key trigger, can record and playback the message averagely for 1, 2, 4 or 8 voice message(s) by switch, It is suitable in simple interface or need to limit the length of single message, e.g. toys, leave messages system, answering machine etc. Meanwhile, this mode provides the power-management system. s can let the chip enter power-down mode when unused. It can effectively reduce electric current consuming to 15uA and increase the using time in any projects powered by batteries. 3.5.2 FEATURES 1.

Operating Voltage Range: 3V ~ 6.5V

2.

Single Chip, High Quality Audio/Voice Recording & Playback Solution

3.

No External ICs Required

4.

Minimum External Components

5.

Friendly, Easy to Use Operation

6.

Powerful 16-Bits Digital Audio Processor.

7.

Non-volatile Flash Memory Technology

8.

No Battery Backup Required

9.

Very Low Standby Current: 1uA

10.

Low Power-Down Current: 15uA

11.

s Power-Down Mode for Power Saving

12.

Built-in Audio-Recording Microphone Amplifier

13.

Resolution up to 16-bits

14.

Simple And Direct Interface

15.

Averagely 1,2,4 or 8 voice messages record & playback


43


3.5.3 PIN CONFIGURATION

Fig 3.31: PIN CONFIGURATION of APR33A3


44


3.5.4 PIN DESCRIPTION

Fig 3.32: PIN Description of APR33A3


45


CHAPTER 4 CIRCUIT DIAGRAM AND OPERATION 4.1 CIRCUIT DIAGRAM

Fig 4.1: Circuit Diagram of Project


46


4.2 OPERATION The existing range finders measure the distance to the object using ultrasound beam and represent it via variable tone sound signals. This approach has limitations because the individual must the lookup table between sound tone and the distance. In addition, these range finders are incapable of detecting moving objects such as cars or people which reduce safety. This contest entry describes the vision system which helps the blind orienting in the surround space. As contrasted to existing systems, the proposed device combines the usefulness, simplicity to use together with low cost. Device measures the distance to the object and “visualizes” the measurement results as special slider position which can be easily touched by blind people. Moreover, the device estimates the neighboured objects speed using Doppler and generates the proportional to the objects speed number of sound signals. As result, the blind individual with the proposed system can travel efficiently and safely. The system consist of the ultrasound transmitter TX and receiver RX, the U-controlled carrier generator to form the ultrasound carrier signal, the transmitter driver to amplify the carrier signal to the piezoelectric transmitter acceptable levels, the signal mixer to select the Doppler frequency shift during speed measurements, synchronous rectifier to rectify the incoming signal during distance measurements, multiplexer, low- filter to suppress the high frequency mixer/rectifier products, U for system control, an buzzer.

4.3 OBSTACLE DETECTION AND DISTANCE CALCULATION 4.3.1 Obstacle detection Ultrasonic sensors are used for obstacle detection and calculation of its adaptive distance from the visually impaired person. Ultrasonic sensors are used in pair as transceivers. One device which emits sound waves is called as transmitter and other who receives echo is known as receiver. These sensors work on a principle similar to radar or sonar which detects the object with the help of echoes from sound waves. An algorithm is implemented in C-language on AT89S52 microcontroller. The time interval between sending the signal and receiving the echo is calculated to Department of ECE, MRITS

47


determine the distance to an object. As these sensors use sound waves rather than light for object detection, so can be comfortably used in ambient outdoor application. Five ultrasonic sensor pairs are used in this system. Input Requirement: A Working Voltage: 5V (DC) A Working Current: 15mA .A Input trigger signal: 10us impulse TTL Output Signals: An Echo signal: PWM signal. Time required for sound signal to travel twice between source and obstacle. A Range: 5 meters. 4.3.2 Distance calculation For distance calculation following equation is used: D= [(EPWHT) * (SV)/2]

… (1)

Where, D = Distance in cm EPWHT = Echo pulse width high time SV = Sound velocity in cm/s Before concluding the obstacle distance from the subject, repeated information sampling and averaging is performed. As ambient light conditions do not affect ultrasonic sensors, object detection and distance calculation can be performed accurately.

4.4 COMMUNICATION BETWEEN SYSTEM AND SUBJECT This system can understand 500 meters distant object / obstacle in any direction. This system announces calculated real time distance as it is in meters or centimetres using speech messages. To make distance understanding more appealing to the subject, speech messages can be stored in a universal language. 4.4.1 Speech warning messages for conveying detected conditions to subject Many researchers [10, 11, 12] used vibration array, buzzer based audio frequency clips or text to speech conversion for announcing any detected condition to the subject. This system uses pre-recorded speech messages for conveying any Department of ECE, MRITS

48


detected condition to the subject. It uses APR33A3 audio recording and playback flash memory. It can store variable duration speech messages up to 60 sec. duration. Number of messages can be increased by reducing the duration of each message. AT89S52 microcontroller processes real-time data collected by ultrasonic sensor array and takes the correct decision. Based on processed data, correct decision is taken and relevant message is invoked from the flash memory and conveyed to the subject through earphone. Sample speech messages stored in flash memory are shown in table 1. Table 4.1: Sample obstacle distance speech messages SR.NO

AUDIO OUPUT

1

D I S TAN C E IN METERS Less than 50cm

2

50cm to 100cm

Object is less than 100cm

3

100cm to 150cm


4

150cm to 200cm


5

200cm to 250cm


6

250cm to 300m



Formal distance scaling (with speech message) 1 Less than 70 cm Object is very close 2 70 cm to 99 cm Object is at 1 meter distance 3 100 cm to 199 cm Object is at 2 meter distance 4 200 cm to 299 cm Object is at 3 meter distance 5 300 cm to 399 cm Object is at 4 meter distance 6 400 cm to 499 cm Object is at 5 meter distance. 4.4.2 Flexibility to use any language for speech warning messages For speech assisted navigation, many researchers are using text to speech conversion. In such cases researchers are converting text into English language only. As this system uses APR33A3 flash memory to store the pre-recorded speech messages, there is no barrier for usage of any language. Any appealing universal language can be used for recording speech warning messages. This system offers a simple mechanism for recording and storing such speech warning messages. Department of ECE, MRITS

49


CHAPTER 5 RESULT AND ANALYSIS 5.1 Test Methodology Ultrasonic sensors, AT89S52 and APR9600 are tested individually as well as an integrated system. As ultrasonic sensors work on principle of echo, study of its reflection properties on different object surfaces is very important. Four such tests are carried on concrete wall, static human body, wood and metal. Surface smoothness plays key role in obstacle detection. Smooth surface object can be detected from maximum detection range of ultrasonic sensors. Metal surface gives highest reflections and then concrete wall, wood and human body. These four surfaces are considered for testing as subject can come across any of them during navigation. All these tests are carried out in laboratory environment and their readings are recorded. Details of test carried and their distance range outcomes are given in table 5.1.

Table 5.1: Response of ultrasonic sensor to different object surface O B S TA C L E S U R FAC E

DETECTION RANGE IN CM Test 1

Test 2

Test 3

Test 4

Metal

490

485

476

480

Concrete wall

412

446

437

450

Wood

400

402

412

406

Human Body

392

380

401

394


50


5.2 RESULT

Figure 5.1 Final output snap shot


51


A wearable system prototype is developed by integration five ultrasonic sensor pairs on customized spectacles & waist belt, APR33A3 flash memory, earphone with AT89S52 microcontroller. After blindfolding the person, he was asked to walk through the corridor where different type of obstacles has been placed within 10 meter range. During the experiment, ’s walking motion is recorded. Time taken by the s (trained and novice) for successfully walking through the obstacles is measured and travel speed for each test has been calculated. It is that average speed of a trained and novice s are 0.76 and 0.38 m/s respectively. In comparison with the traveling speed of the sighted people (1.4 m/s), this result is acceptable. The accuracy of the device in finding out obstacles is also very good. This result shows that training of the is one of the important factors for gaining high traveling speed and also to increase the confidence to choose obstacle free path.


52


CHAPTER 6 CONCLUSION AND FUTURE SCOPE 6.1 CONCLUSION This wearable electronic navigation system is successfully tested on blind folded subjects in indoor environment. Less training time is required to use this system. With rigorous training, system can be used for outdoor navigation also. Considering the expectations and requirements of the visually impaired and blind people, this system offers a low cost, reliable, portable, low power and robust solution for smooth navigation. Though the system is light weight, but hard wired with sensors and other components. Further wearable aspect of this system can be improved using wireless connectivity between the system components. This system is developed considering visually impaired and blind people in developing countries.

6.2 FUTURE SCOPE In future we would see more compact and more friendly devices which can be operated with ease and comfort. We are presently using this application in various projects like Automated parking systems, Velocity meter, Automatic door systems and other applications. By adding more sensors and appropriate technology we can make it more compatible and mobile. We would see the future tech more friendly in of size and material.


53


REFFERENCES [1] Margrain, TH. Helping blind and partially sighted people to read: the effectiveness of low vision aids. British Journal of Ophthalmology. Pp.919-922, 2000. [2] Blindness and Visual Impairment: Global Facts.http://www.vision202 -0.org. [3] A. Dodds, D. Clark-Carter, and C. Howarth, “The sonic Pathfinder: an evaluation,” Journal of Visual Impairment and Blindness, vol. 78, no. 5, pp. 206–207, 1984. [4] A. Heyes, “A polaroid ultrasonic travel aid for the blind,” Journal of Visual Impairment and Blindness, vol. 76, pp. 199– 201, 1982. [5] I. Ulrich, and J. Borenstein, “The guide cane-Applying mobile robot technologies to assist the visually impaired,” IEEE Transaction on Systems, Man, and Cybernetics-Part A: Systems and Humans, vol. 31, no.2, pp. 131-136, 2001. [6] J. Barth, and E. Foulhe, “Preview: A neglected variable in orientation and mobility,” Journal of Visual Impairment and Blindness, vol. 73, no.2, pp. 41–48, 1979. [7] S. Shoval, J. Borenstein, and Y. Koren, “The NavBelt- A computerized travel aid for the blind based on mobile robotics technology,” IEEE Transactions on Biomedical Engineering, vol. 45, no 11, pp. 1376-1386,1998. [8] P. Meijer, “An Experimental System for Auditory Image Representations,” IEEE Transactions on Biomedical Engineering, vol.39, no 2, pp. 112-121, Feb 1991. [9] G. Sainarayanan, “On Intelligent Image Processing Methodologies Applied to Navigation Assistance for Visually Impaired”, Ph. D. Thesis,University Malaysia Sabah, 2002. [10] G. Balakrishnan, G. Sainarayanan, R. Nagarajan and S. Yaacob,“Wearable RealTime Stereo Vision for the Visually Impaired,” Engineering Letters, vol. 14, no. 2, 2007. [11] G. P. Fajarnes, L. Dunai, V. S. Praderas and I. Dunai, “CASBLiP- a new cognitive

object

detection

and

orientation

system

for

impaired

people,”

Proceedings of the 4th International Conference on Cognitive Systems,ETH Zurich, Switzerland, 2010. Department of ECE, MRITS

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[12] Amit kumar, M. Manjunatha and J. Mukhopadhyay, “An Electronic Travel Aid for Navigation of Visually Impaired Person,” Proceeding of the 3rd International Conference on Communication Systems and Networks, pp.1-5, 2011.


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