1

CHAPTER 1

INTRODUCTION

People with visual disabilities are often challenged by the places that

are not designed for their special condition. Examples of such places are bus,

train terminals, offices, hospitals, educational buildings, and shopping malls.

Everyday objects that are present in the environments become real obstacles

for blind people and even putting them at risk. Simple objects such as chair,

table and stairs hinder their movements and can often cause serious

accidents.

This problem involves many issues like accuracy, coverage, usability

and interoperability that are not easy to address with the current technology.

Therefore, this can be considered as an open problem. This project presents

a prototype of a navigation system that helps the visually impaired to move

within indoor environments. The system designed has been focused on

usability of the solution for the problem and also on its suitability for

deployment in several built areas.

The main objective of the system is to provide an real-time,

navigation information that enables the user to make appropriate and timely

decisions on which route to follow in an indoor space. In order to provide

such information, the system must take into the account of all the objects in

the immediate physical environment which may become potential obstacles

for blind people. This kind of solution is known as a micro-navigation

system. In order to deal with these issues the system uses the interaction

among several components which process the user and environment

information, to generate and deliver navigation messages to users while they

are moving in an indoor area. The system’s main components are infrared

LED and speaker.

2

When the user gives input by pressing the button in the keypad, the

Radio frequency receiver couples with the transmitter and APR33A3 which

is sound recording device guides the user with the direction. On reaching the

destination IR transmitter and receiver attains the line of sight path. This

indicates that the destination is reached through the speaker.

3

CHAPTER 2

BLIND PEOPLE NAVIGATION SYSTEM

2.1 TRANSMITTER BLOCK

INTRODUCTION

IR TRANSMITTER:

IR transmitter continuously transmits the IR signal to the receiver.

RF TRANSMITTER:

Waiting for the blind person to press any key be a pair with radio

frequency of the receiver.

MICROCONTROLLER:

Faster speed of execution and inexpensive.

Fig no.:2.1 Transmitter

4

2.2 RECEIVER BLOCK

INTRODUCTION

IR RECEIVER:

It receives the IR signal from the transmitter to detect any obstacle

crossing the way.

RF RECEIVER:

By using the radio frequen

cy (434 MHz) to be paired with the desired location.

KEYPAD:

Select to reach the target position.

Fig.:2.2Receiver

5

2.3 TRANSMITTER BLOCK CIRCUIT DIAGRAM

Fig no.:2.3 Blind people navigation system for indoor

environment(Transmitter)

6

2.4 RECEIVER BLOCK CIRCUIT DIAGRAM

Fig.:2.4 Blind people navigation system forindoor

environment(Receiver)

7

CHAPTER 3

HARDWARE DESCRIPTION

3.1 POWER SUPPLY

3.1.1 BATTERY

The battery has both terminals in a snap connector on one end. The

smaller circular terminal is positive, and the larger hexagonal or octagonal

terminal is the negative contact. The connectors on the battery are the same

as on the connector itself; the smaller one connects to the larger one and vice

versa. The same snap style connector is used on other battery types in

the power pack (PP) series. Battery polarization is normally obvious since

mechanical connection is usually only possible in one configuration. A

problem with this style of connector is that it is very easy to connect two

batteries together in a short circuit, which quickly discharges both batteries,

generating heat and possibly a fire. Because of this hazard, 9-volt batteries

should be kept in the original packaging until it is going to be used. An

advantage is that several nine-volt batteries can be connected to each other

in series in order to provide higher voltages.

3.1.2 TECHNICAL SPECIFICATIONS

The most common type of 9V battery is referred as 9V, although

there are less common 9V batteries of different sizes. Codes for the usual

size include PP3 (for size and voltage, any technology), 6LR61 (IEC code

for alkaline batteries).

The PP3 size battery has height 48.5 mm, length 26.5 mm, width

17.5 mm (or 1.9"x1.0"x0.68"). Both terminals are at one end and their

centers are 1/2 inch (12.7 mm) apart.

8

Inside an alkaline or carbon-zinc 9-volt battery there are six cylindrical

or flat cells connected in series. Some brands use welded tabsinternally to

attach to the cells, others press foil strips against the ends of the cells.

Rechargeable Nickel-Cadmium (Ni CD) and Nickel-Metal Hydride

(Ni MH) batteries of nominal 9V rating have between six and eight 1.2V

cells. Lithium ion versions typically use two cells (3.7V nominal each).

There are also lithium polymer and low self-discharge Ni MH versions.

Mercury batteries were formerly made in this size. They had higher

capacity than the standard carbon-zinc types, a nominal voltage of 8.4 V and

very stable voltage.

Fig no. 3.1.:Battery

9

3.1.3 REGULATOR

Voltage regulator ICs are available with fixed or variable output voltages.

Regulator IC unit contain the circuitry for reference source, comparator

amplifier, control device, and overload protection all in a single IC.

IC units provide regulation of either a fixed positive voltage, a fixed

negative voltage, or an adjustable set voltage. The regulators can be selected

for operation with load currents from hundreds of mA to tens of amperes,

corresponding to power ratings from mW to tens of watts.

A fixed three-terminal voltage regulator has an unregulated dc input

voltage, applied to one input terminal, a regulated dc output voltage obtained

from a second terminal, with the third terminal connected to ground. The

series 78 regulators provide fixed positive regulated voltages from 5 to 24 V.

7805 voltage regulator provides positive 5 V.

3.1.4 INTRODUCTION OF MICROCONTROLLER

Microcontroller is a general purpose device, which integrates a

number of the components of a microprocessor system on to single chip. It

has inbuilt CPU, memory and peripherals to make it as a mini computer.

Micro controller is a stand-alone unit, which can perform functions on

its own without any requirement for additional hardware like I/O ports and

external memory. The heart of the microcontroller is the CPU core. In the

past, this has traditionally been based on a 8-bit microprocessor unit. For

example Motorola uses a basic 6800 microprocessor core in their 6805/6808

microcontroller devices.

In the recent years, microcontrollers have been developed around

specifically designed CPU cores, for example the microchip PIC range of

microcontrollers.

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3.1.5 INTRODUCTION TO PIC (PERIPHERAL

INTERFACE CONTROLLER)

The microcontroller that has been used for this project is from PIC

series. PIC microcontroller is the first RISC(Reduced Instruction Set

Computer) based microcontroller fabricated in CMOS (complementary

metal oxide semiconductor) that uses separate bus for instruction and data

allowing simultaneous access of program and data memory.

The main advantage of CMOS and RISC combination is low power

consumption resulting in a very small chip size with a small pin count. The

main advantage of CMOS is that it has immunity to noise than other

fabrication techniques.

3.1.6 PIC 16F877A

Various microcontrollers offer different kinds of memories.

EEPROM, EPROM, FLASH etc. are some of the memories in which

FLASH is the most recently developed. Technology that used in PIC

16F877A is flash technology, so that data is retained even when the power is

switched off. Easy Programming and Erasing are other features of PIC

16F877A.

3.1.7 SPECIAL FEATURES OF PIC MICROCONTROLLER

(i) CORE FEATURES

High-performance RISC CPU

Only 35 single word instructions to learn

All single cycle instructions except for program branches which are two

cycle

Operating speed: DC - 20 MHz clock input.

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DC - 200 ns instruction cycle

Up to 8K x 14 words of Flash Program Memory,

Up to 368 x 8 bytes of Data Memory (RAM) Up to 256 x 8 bytes of

EEPROM data memory

Interrupt capability (up to 14 internal/external)

Eight level deep hardware stack

Direct, indirect, and relative addressing modes

Power-on Reset (POR)

Power-up Timer (PWRT) and Oscillator Start-up Timer (OST)

Watchdog Timer (WDT) with its own on-chip RC Oscillator for reliable

operation

Programmable code-protection

Low-power, high-speed CMOS EPROM/EEPROM technology

In-Circuit Serial Programming (ICSP) via two pins

In-Circuit Debugging via two pins

Processor read/write access to program memory

Wide operating voltage range: 2.5V to 5.5V

Low-power consumption: 2mA typical @ 5V, 4 MHz

20mA typical @ 3V, 32 kHz

1mA typical standby current

(ii) PERIPHERAL FEATURES

Timer0: 8-bit timer/counter with 8-bit prescaler.

Timer1:16-bit timer/counter with prescaler, can be incremented during sleep

via external crystal/clock.

Timer2: 8-bit timer/counter with 8-bit register, prescaler and postscaler.

12

Two Capture, Compare, PWM modules, Capture is 16-bit, max resolution is

12.5 ns, Compare is 16-bit, max resolution is 200 ns, PWM max. Resolution

is 10-bit.

10-bit multi-channel Analog-to-Digital converter.

Synchronous Serial Port (SSP) with SPI. (Master Mode) and I2C.

(Master/Slave).

Universal Synchronous Asynchronous Receiver Transmitter (USART/SCI)

with 9- bit address detection.

3.1.8 PIN DIAGRAM OF PIC 16F877A

Fig.3.2 Pin Configuration of PIC 16F877A

13

3.1.9 ARCHITECTURE

Fig 3.3 Architecture of 16F877A

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3.1.10 I/O PORTS

Some pins for these I/O ports are multiplexed with an alternate

function for the peripheral features on the device. In general, when a

peripheral is enabled, that pin may not be used as a general purpose I/O pin.

(i)PORT A AND THE TRISA REGISTER

PORT A is a 6-bit wide bi-directional port. The corresponding data

direction register is TRISA. Setting a TRISA (bit=1) will make the

corresponding PORT A pin an input, i.e., put the corresponding output

driver in a High-impedance mode. Clearing a TRISA (bit=0) will make the

corresponding PORT A pin an output, i.e., put the contents of the output

latch on the selected pin. Reading the PORT A register reads the status of

the pins whereas writing to it will write to the port latch. All write operations

are read-modify-write operations. Therefore a write to a port implies that the

port pins are read; this value is modified, and then written to the port data

latch. Pin RA4 is multiplexed with the Timer0 module clock input to

become the RA4/T0CKI pin. The RA4/T0CKI pin is a Schmitt Trigger input

and an open drain output. All other RA port pins have TTL input levels and

full CMOS output drivers. Other PORT A pins are multiplexed with analog

inputs and analog VREF input. The operation of each pin is selected by

clearing/setting the control bits in the ADCON1 register (A/D Control

Register1).

15

(ii) PORT B AND TRISB REGISTER

PORT B is an 8-bit wide bi-directional port. The corresponding data

direction register is TRISB. Setting a TRISB (bit=1) will make the

corresponding PORT B pin an input, i.e., put the corresponding output driver in

a high-impedance mode. Clearing a TRISB (bit=0) will make the corresponding

PORT B pin an output, i.e., put the contents of the output latch on the selected

pin. Three pins of PORT B are multiplexed with the Low Voltage Programming

function; RB3/PGM, RB6/PGC and RB7/PGD. Each of the PORT B pins has a

weak internal pull-up.

Four of PORT B’s pins, RB7:RB4, have an interrupt on change feature.

Only pins configured as inputs can cause this interrupt to occur (i.e. any

RB7:RB4 pin configured as an output is excluded from the interrupt on change

comparison).

(iii) PORT C AND THE TRISC REGISTER:

PORT C is an 8-bit wide bi-directional port. The corresponding data

direction register is TRISC. Setting a TRISC (bit=1) will make the

corresponding PORT C pin an input, i.e., put the corresponding output driver in

a high-impedance mode. Clearing a TRISC (bit=0) will make the corresponding

PORT C pin an output, i.e., put the contents of the output latch on the selected

pin. PORT C is multiplexed with several peripheral functions. PORTC pins

have Schmitt Trigger input buffers. When the Inter Integrated Circuits module

is enabled, the PORT C (3:4) pins can be configured with normal Inter

Integrated Circuits levels or with SMBUS levels by using the CKE bit

(SSPSTAT <6>). When enabling peripheral functions, care should be taken in

defining TRIS bits for each PORT C pin. Some peripherals override the TRIS

bit to make a pin an output, while other peripherals override the TRIS bit to

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make a pin an input. Since the TRIS bit override is in effect while the peripheral

is enabled, read-modify write instructions (BSF, BCF, XORWF) with TRISC as

destination should be avoided. The user should refer to the corresponding

peripheral section for the correct TRIS bit settings.

(iv) PORT D AND TRISD REGISTERS

PORT D is an 8-bit port with Schmitt Trigger input buffers. Each pin is

individually configurable as an input or output. PORT D can be configured as

an 8-bit wide microprocessor Port (parallel slave port) by setting control bit

PSPMODE (TRISE<4>). In this mode, the input buffers are TTL.

(v) PORT E AND TRISE REGISTER

PORT E has three pins RE0/RD/AN5, RE1/WR/AN6 and RE2/CS/AN7,

which are individually configurable as inputs or outputs. These pins have

Schmitt Trigger input buffers. The PORT E pins become control inputs for the

microprocessor port when bit PSPMODE (TRISE<4>) is set. In this mode, the

user must make sure that the TRISE<2:0> bits are set (pins are configured as

digital inputs). Ensure ADCON1 is configured for digital I/O. In this mode the

input buffers are TTL.

PORT E pins are multiplexed with analog inputs. When selected as an

analog input, these pins will read as '0's. TRISE controls the direction of the RE

pins, even when they are being used as analog inputs. The user must make sure

to keep the pins configured as inputs when using them as analog inputs.

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3.1.11 MEMORY ORGANIZATION:

The memory module of the PIC controller has three memory blocks.

Program memory

Data memory

Stack

(i) Program Memory:

The PIC 16F8XX has 4k x14 program memory space (0000H-0FFFH).It

has a 13 bit Program counter(PC) to access any address (213

=4k).

(ii) Data memory:

The data memory of PIC 16F8XX is partitioned into multiple banks

which contain the general purpose registers and the Special function

Registers(SFRs).The bits RP1 and RP0 bits of the status register are used to

select these banks. Each bank extends upto 7FH (128 Bytes).The lower bytes of

the each bank are reserved for the Special Function Registers. Above the SFRs

are general purpose registers implemented as static RAM.

(iii) Stack:

PICs have a hardware call stack, which is used to save return addresses.

The hardware stack is not software accessible on earlier devices, but this

changed with the 18 series devices. Hardware support for a general purpose

parameter stack was lacking in early series, but this greatly improved in the 18

series, making the 18 series architecture supports to high level language

compilers.

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3.1.12 CPU REGISTERS

The CPU registers are used in the execution of the instruction of the PIC

microcontroller. The PIC16F877AMicrocontroller has the following registers.

Working Register-W (Similar to Accumulator)

Status Register

FSR – File Select Register (Indirect Data memory address pointer)

INDF

Program Counter

(i) Working Register:

Working Register is used by many instructions as the source of an

operand. It also serves as the destination for the result of instruction execution

and it is similar to accumulator in other cs and ps.

(ii) Status Register:

This is an 8-bit register which denotes the status of ALU after any

arithmetic operation and also RESET status and the bank select bits for the data

memory.

7th

bit 0th

bit

Fig no.:3.4 Status Register

C: Carry/borrow bit

DC: Digit carry/borrow bit

Z: Zero bit

19

NOT_PD: Reset Status bit (Power-down mode bit)

NOT_TO: Reset Status bit (time- out bit)

RPO: Register bank Select

(iii) FSR – (File Select Register):

It is the pointer used for indirect addressing. In the indirect addressing

mode the 8-bit register file address is first written into FSR. It is a special

purpose register that serves as an address pointer to any address throughout the

entire register file.

(iv) INDF – (Indirect File):

It is not a physical register addressing but this INDF will cause indirect

addressing. Any instructions using the INDF register actually access the register

pointed to by the FSR.

(v) Program counter:

PIC16F877A has a 13 bit program counter in which PCL is the lower 8-

bits of the PC and PCLATH is the write buffer for the upper 5 bits of the PC.

12th

bit 0th

bit

Fig no.:3.5 Program counter

3.1.13 A/D CONVERTER:

The A/D converter carries out the process of analog to digital conversion.

A/D convertor is a single chip integrated circuit having a single input

connection for the analog signal and multiple pins for digital output. It may

have 8, 12, 16 or even more output pins, each representing an output bits.

20

Higher the numbers of bits will higher the precision of conversion. Each step

represents a change in the analog signal: 8-bits gives 256 steps, 12- bits

provides 4096 steps and we get 32768 steps with 16 output bits. Speed of an

A/D converter is generally expressed as its conversion time, i.e. the time

elapsed between application of a convert command and the availability of data

at its output. The speed of A/D Converter is measured by its settling time for a

full scale digital input change. The PIC 16F877A has an on-chip eight channel

10-bit Analog-to-Digital Converter (ADC) which enables the PIC

microcontroller to communicate with the peripherals which produce its output

asphysical quantity. So the physical quantities can be converted into digital

signals which are suitable for PIC operations by means of ADCs.

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CHAPTER 4

4.1 ATMEL AT89C51 MICROCONTROLLER

4.1.1 INTRODUCTION

The AT89C51 is a low-power, high –performance CMOS 8-bit

microcomputer with 8Kbytes of Flash Erasable andProgrammable ReadOnly

Memory (EPROM). The device is manufactured using Atmel’s high-density

nonvolatilememory technology and is compatible with the industry-standard

80C51 instruction set and pin out .The on-chip flash allows the program

memory to be reprogrammed in-system or by a conventional

nonvolatilememory programmer. By combining a versatile8-bit CPU with Flash

on a monolithic chip, theAtmel AT89C51is a powerful microcomputer which

provides a highly-flexible and cost- effective solution to many embedded

control applications.

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4.1.2 PIN CONFIGURATION OF MICROCONTROLLER

(Atmel AT89C51)

Fig no.4.1:-Pin configuration

23

4.1.3ARCHITECTURE OF MICROCONTROLLER

(Atmel AT89C51)

Fig no. 4.2:-BlockDiagramof Microcontroller.

24

The AT89C51 provides the following standard features:

1.8KbytesofFlash

2.256 bytes of RAM

3.32 I/O lines

4. Three16-bit timer/counters

5. six-vectortwo-level interrupt architecture

6. Afull-duplex serial port

7. On-chip oscillator, and clock circuitry.

In addition, the AT89C51 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.

4.1.4PIN DESCRIPTION

Vcc-Supply voltage (+5V).

Gnd-Ground (0V).

(i) I/O PORTS

Port 0

Port0 is an 8-bit open drain bi-directional I/O port.When 1 iswritten to

port0 pins, the pins can be used as high- impedance inputs. Port 0 can also be

25

configured to be the multiplexed low-order address/ data bus during accesses

to external programdata memory .In this mode, P0 has internal pull-ups.

Port0 also receivesthe code bytesduring Flash programming and outputs the

code bytes during program verification. External pull-ups are required during

program verification.

Port 1

Port1 is an 8-bit bi-directional I/O port with internal pull-ups. The Port1

output buffers can sink/source four TTL inputs. When 1 iswritten to Port1 pins,

they are pulled high by the internal pull-ups and can be used as inputs. As

inputs, Port1 pins that are externally beingpulled low will source

currentbecause of the internal pull-ups. In addition, P1.0 and P1.1 can be

configured to be the timer/counter 2 external countinput(P1.0/T2)and the

timer/counter 2 trigger input (P1.1/T2EX), respectively, as shown in the

following Table-4.1. Port1 also receives the low-order address bytes during

flash programming and verification.

Ports Alternate Functions

P1.0 T2 (external count input to

Timer/Counter2),

P1.1 T2 EX(Timer/Counter2

capture/reload trigger

Table no.:4.1: Port-1 Pins

26

Port2

Port2 is an 8-bit bi-directional I/O port with internal pull-ups. The Port2

output buffers can sink/source four TTL inputs. When 1s are written to Port2

pins, they are pulled high by the internal pull-ups and can be used as inputs .As

inputs, Port2 pins that are externally being pulled low will source current (IIL)

because of the internal pull-ups.

Port2 emits the high-order address byte during fetches from external

program memory and during accesses to external data memory that use16-bit

addresses (MOVX @DPTR). In this application, Port2 uses strong internal

pull-ups when emitting 1s. During accesses to external data memory that use

8-bit addresses (MOVX@RI), Port2 emits the contents of the P2 Special

Function Register. Port2 also receives the high-order address bits and some

control signals during Flash programming and verification.

Port 3

Port3 is an 8-bit bi-directional I/O port with internal pull-ups. The Port3

output buffers can sink/source four TTL inputs. When 1s are written to Port3

pins, they are pulled high by the internal pull-ups and can be used as inputs .As

inputs, Port3 pins that are externally being pulled low will source current

becauseof the pull-ups.

Port3 also serves the functions of various special features of

theAT89C51, as shown in the following Table no-4.2. Port3 also receives

some control signals for Flash programming and verification.

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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(timer0 external input)

P3.5 T1(timer1 external input)

P3.6 WR (external data memory write

P3.7 RD(external data memory read

Table no.:4.2 Port3 pins

(ii) RST

Reset input. A high on this pin for two machine cycles while the

oscillator is running resets the device.

(iii) ALE

Address Latch Enable (ALE)is an output pulse for latching the low

byte of the address during accesses to external memory. This pin is also the

program pulse input duringFlash programming. In normal operation, ALE is

emitted data constant rate of 1/6th

oscillator frequency and may be used for

external timing or clockingpurposes. Note, however, that one ALE pulse is

skipped during each access to external data memory. If desired, ALE

operation can be disabled by setting bit0 of SFR location 8EH. With the bit

set, ALE is active only during a MOVX or MOVC

instructionOtherwise;thepin is weakly pulled high.

28

(iv) PSEN

Program Store Enable (PSEN)is the read strobe to external program

memory.Whenthe AT89C51 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.

(v) EA/VPP

External Access Enable.Amust be strapped to GND in order to enable the

device to fetch code from external pro-gram memory locations starting at

0000H up to FFFFH. Note, however, that if lock bit1is programmed, EA will be

internally latched on reset. EA should be strapped to VCC for internal program

executions. This pin also receives the12-volt programming enable voltage

(VPP) during FlashProgramming when12- volt programming is selected.

(vi) XTAL1

Input to the inverting oscillator amplifier and input to the internal

clock operating circuit.

(vii)XTAL2

Output fromthe inverting oscillator amplifier.

4.1.5 SPECIAL FUNCTION REGISTER

(i) Timer 2 Registers

Control and status bits are contained in registers T2CON and

T2MODfor Timer 2.The register pair (RCAP2H,RCAP2L) are the

Capture/Reload registers for Timer2 in 16-bitcapture mode or 16-bit

Auto-reload mode.

29

(ii)Interrupt Registers

The individual interrupt enable bits are in the IE register. Two

priorities can be set for each of the six interrupt sources in the IP register.

Symbol Function

TF2 Timer 2overflow flag set by a Timer2 overflow and must be cleared by

software. EXF2 Timer2 external flag set when either a capture or reload is caused by a

negative transition on T2EX andEXEN2= 1. WhenTimer2 interrupt is

enabled, EXF2= 1will cause the CPU to vector to theTimer2 interrupt

routine.EXF2 must be cleared bysoftware.EXF2 does not cause an interrupt

in up/down counter.

RCLK Receive clock enable.

When set, causes the serial port to use Timer2 overflow pulses for its

receiveclock in serial port Modes1and 3.RCLK= 0causesTimer1

overflow to be used for the receive clock.

Table no.:4.3T2CON-Timer/Counter2ControlRegister

TCLK Transmit clock enable. When set, causes the serial port to useTimer2

overflow pulses for its transmit clock input.

Serial port Modes 1 and 3. TCLK= 0 causes Timer1 overflows to be used for

the transmit clock.

EXEN2 Timer2 external enable. When set, allows a capture or reload to occurs a

result of a negative transition on T2EX.

If Timer2 is not being used to clock the serial port.EXEN2= 0 causes

Timer2 to ignore events atT2EX.

TR2 Start/Stop control for Timer2. TR2= 1starts the timer.

C/T2 Timer or counter select for Timer2. C/T2= 0for timer function .C/T2=

1for external event counter (falling edge triggered).

Table no.:4.4 Timer2 Operating Modes

30

(iii) Data Memory

The AT89C51 implements 256 bytes of on-chip RAM. The upper

128 bytes occupy a parallel address space to the Special Function

Registers. That means the upper 128 bytes have the same addresses as

the SFR space but are physically separate from SFR space. When an

instruction accesses an internal location above address 7FH, the address

mode used in the instruction specifies whether the CPU accesses the

upper 128 bytes of RAM or the SFR space. Instructions that use

directaddressing access SFR space.

For example, the following direct addressing instruction

accessesthe SFR at location0A0H(which is P2).

MOV0A0H, #data

Instructions that use indirect addressing access the upper 128 bytes

of RAM. For example, the following indirect addressing instruction,

where R0 contains0A0H, accesses the data byte at address

0A0H,ratherthan P2 (whose address is 0A0H).

MOV@R0, #data

Note that stackoperations are examples of Indirect addressing,so the

upper128 bytes of data RAM are available as stack space.

(iv) Timer 0 and1

31

Timer 0 functions as either a Timer or event Counter in four modes of

operation. Timer 0 is controlled by the four lower bits of TMOD register and

bits 0,1, 4 and 5 of TCON register .

1. TMOD register selects the method of Timer gating (GATE0),

Timer or Counter operation (T/C0#) and mode of operation (M10

and M00). TCON register provides Timer 0 control functions:

overflow flag (TF0), run control bit (TR0), interrupt flag (IE0)

and interrupt type control bit (IT0).

2. Timer 1 can serve as the Baud Rate Generator for the Serial Port.

Mode 2 is best suited for this purpose.

3. For normal Timer operation (GATE1 = 0), setting TR1 allows

TL1 to be incremented by the selected input. Setting GATE1 and

TR1 allows external pin INT1# to control Timer operation.

4. Timer 1 overflows (count rolls over from all 1s to all 0s) sets the

TF1 flag generating an interrupt request.

5. When Timer 0 is in mode 3, it uses Timer 1’s overflow flag (TF1)

and run control bit (TR1). For this situation, use Timer 1 only for

applications that do not require an interrupt (such as a Baud Rate

Generator for the Serial Port) and switch Timer 1 in and out of

mode 3 to turn it off and on.

6. It is important to stop Timer/Counter before changing mode

(v) Timer 2

Timer2 is a 16-bit Timer/Counter that can operate as either a timer or

an event counter. The type of operation is selected by bit C/T2 in the

SFRT2CON.Timer2 has three operating modes: capture, auto-reload (up or

down counting),andbaud rate generator.

32

Timer2 consists of two8-bit registers, TH2 and TL2.In the Timer

function, the TL2register is incremented every machine cycle. Since a

machine cycle consists of 12 oscillator periods, thecountrate is 1/12 of the

oscillator frequency.

In the Counter function, the register is incremented in response to

a1-to-0 transition at its corresponding external input pin, T2. In this

function, the external input is sampled during S5P2 of every machine cycle.

When the samples show a high in one cycle and a low in the next cycle, the

count is incremented. The new count value appears in the register during

S3P1 of the cycle following the one in which the transition was detected.

Since two machine cycles (24 oscillator periods) are required to recognize a

1-to-0 transition, the maximum count rate is 1/24 of the oscillator

frequency. To ensure that a given level is sampled at least once before it

changes, the level should be held for at least one full machine cycle.

(vi)Capture mode

In the capture mode, twooptions are selected by bit EXEN2 in

T2CON. If EXEN2=0, Timer2 is a 16-bit timer or counter which up on

overflow sets bit TF2 in T2CON. This bit can then be used to generate an

interrupt. IfEXEN2=1,Timer2 performs the same operation, but a 1-to-0

transition at external input T2EX also causes the current value in TH2 and

TL2 to be captured into RCAP2H and RCAP2L , respectively. In addition,

the transition at T2EX causes bit EXF2 in T2CON to be set. The EXF2 bit,

like TF2, can generate an interrupt.

(vii) Autoreload (Up or down mode)

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Timer2 can be programmed to count up or down when configured

in its 16-bit auto-reload mode. This feature is invoked by the DCEN (Down

Counter Enable) bit located in the SFRT2MOD.Upon reset, the DCEN bit is

set to 0 so that timer2 will default to count up. When DCEN is set, Timer 2

can count up or down, depending on the value of the T2EX pin.

4.2 RF TRANSMITTER / RECEIVER:

The frequency range of RF Transmitter and Receiver varies between

30 KHz & 300 GHz. In this RF system, the digital data is represented as

variations in the amplitude of carrier wave. This type of modulation is

known as Amplitude Shift Keying (ASK).

Transmission through RF is better than IR (Infrared) because of many

reasons. Firstly, the signals through RF can travel through larger distances

making it suitable for long range applications. Also, IR mostly operates in

line-of-sight mode; RF signals can travel even when there is an obstruction

between transmitter & receiver.

Next, RF transmission is more strong and reliable than IR

transmission. RF communication uses a specific frequency unlike IR signals

which are affected by other IR emitting sources.

This RF module comprises of an RF Transmitter and an RF Receiver.

The Transmitter/Receiver pair operates at a frequency of 434 MHz. An RF

transmitter receives serial data and transmits it wirelessly through RF

through its antenna connected at Pin4.

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The transmission occurs at the rate of 1Kbps - 10Kbps.The

transmitted data is received by an RF receiver operating at the same

frequency as that of the transmitter.

4.2.1 RADIO FREQUENCY OF TRANSMITTER AND

RECEIVER

Fig no.:4.3 RF Transmitter and Receiver Pins

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4.2.2 RF TRANSMITTER PIN DETAILS:

in No Function Name

1 Ground (0V) Ground

2 Serial data input pin Data

3 Supply voltage; 5V Vcc

4 Antenna output pin ANT

Table no.: 4.5 RF Transmitter Pin Details

The RF module is often used along with a pair of encoder/decoder. The

encoder is used for encoding parallel data for transmission feed while reception

is decoded by a decoder. HT12E-HT12D, HT640-HT648, etc. are some

commonly used encoder/decoder pair ICs.

4.2.3 RF RECEIVER PIN DETAILS:

Pin

No Function Name

1 Ground (0V) Ground

2 Serial data output pin Data

3 Linear output pin; not connected NC

4 Supply voltage; 5V Vcc

5 Supply voltage; 5V Vcc

6 Ground (0V) Ground

7 Ground (0V) Ground

8 Antenna input pin ANT

Table no.: 4.6 RF Receiver Pin Details

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4.3 IR SENSOR

4.3.1 INTRODUCTION

Infrared (IR) technology is used in variety of wireless applications,

especially in the areas of sensing and remote control. Today’s newest products

such as cell phones, digital cameras, and DVD players as well as remote

controls for every market segment rely on IR sensing and control devices.

4.3.2 OPTICAL SENSORS

To understand infrared technology, the best starting point is the

electromagnetic spectrum. The IR portion of the electromagnetic spectrum is

usually divided into three regions: the near-mid- and far- infrared. Infrared

wavelengths range formed to violet. The frequencies are higher than microwave

but shorter than visible light.

Focusing on near infrared devices and applications, Photo-Optic

technologies are used for optical sensing and optical communications with

numerous general market applications, since light is less complex than RF when

implemented as the signal source. Optical sensors are used in industrial,

consumer and other applications for sensing movement, position, proximity,

ambient light, speed, and direction.

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4.3.3IR RANGE

Fig no.: 4.7Wavelength Range of IR

Optical wireless communication uses IR data transmission for short range

applications such as computer peripherals and PDAs (personal digital

assistants). For optical communication, a modulated IR light beam transmitted

by an emitter LED is received by a silicon photodiode. Since IR does not

penetrate walls, it does not interfere with other signals in indoor environments.

IR technology is the most commonly used technique for remotely controlling

appliances.

4.3.4 SPECIAL FEATURES OF IR SENSOR:

• High reliability

• High radiant intensity

• Peak wavelength λp=940nm

• Low forward voltage

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4.3.5 GENERAL APPLICATIONS FOR IR COMPONENT

• Office Automation (OA) equipment such as copiers, fax machines and

printers.

• Vending machines

• Gaming products

• Home entertainment products

• Medical / health care equipment

• Banking terminals such as ATMs

• Testing equipment such as IC/LSI testers, encoders and more.

4.3.6 TYPES OF IR DEVICES

To address the variety of sensing applications, products take advantage of

several IR technologies.

These include:

• IR Emitters

• IR Receivers (sensors)

• Photo interrupters & Photo Reflectors

• Tilt Sensors and

• Remote Control Module Receivers

An IR Emitter is a light emitting diode (LED). Different types of IR

LEDs are specified based on their packaging and special features, such as

39

output optical power, wavelength, and response time.IR Receivers are also

called sensors since they detect the wavelength and spectral radiation of the

light from the IR emitter. IR receivers are specified by optic features,

packaging, special circuitry such as an ambient light filter, wide viewing angle,

and more.

A photo interrupter is a photo sensor that integrates an optical receiver

and emitter in a single U-shaped package. In a transmission type photo

interrupter, the light emitting and detecting elements are placed facing each

other. Shape and size are two of the main differentiating features of a photo

interrupter.

Photo reflectors or reflective type sensors are side by-side emitter-sensor

(photo interrupter) devices that detect reflected beams from a surface. Key

electrical characteristics are transfer gain rate, sensor collector current, IR LED

current, wavelength, and response switching time. Reflective type sensors can

be used in proximity sensing applications.

Fig no.:4.8 Reflective type photo sensors detect light reflected by a target

object.

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4.4APR33A3 (VOICE RECORDING DEVICE)

The APR33A series are powerful audio processor along with high

performance audio Analog to Digital Converters (ADCs) and Digital to Analog

Converters (DACs). The APR33A series incorporates all the functionality

required to perform demanding audio/voice applications. High quality

audio/voice systems with lower bill-of-material costs can be implemented with

the aPR33A series because of its integrated analog data converters and full suite

of quality-enhancing features such as sample-rate convertor.

The APR33A series C3.1 is Tape mode manages messages sequentially

much like traditional cassette tape recorders. Within tape mode two options

exist such as auto rewind and non-auto rewind. Auto rewind mode configures

the device to automatically rewind to the beginning of the message immediately

following recording or playback of the message. In tape mode, using either

option, messages must be recorded or played back sequentially, like a

traditional cassette tape recorder specially designed for simple key trigger, user

can record and playback the message. This mode provides the power-

management system. Users can let the chip enter power-down mode when it is

unused. It can effectively reduce electric current consuming to 15uA and

increase the using time in any projects powered by batteries.

41

Fi

Fig 4.9:- Diagram of APR33A3 (Voice recording IC)

4.5SPEAKER

Speakers are one of the most common output devices for the audio

outputs. Some speakers are designed to work specifically with computers, while

others can be hooked up to any type of sound system. The purpose of speakers

is to produce audio output that can be heard by the listener.

Speakers are transducers that convert electromagnetic waves into sound

waves. The speakers receive audio input from a device such as a computer or an

audio receiver. This input may be either in analog or digital form. Analog

speakers simply amplify the analog electromagnetic waves into sound waves.

42

Since sound waves are produced in analog form, digital speakers must first

convert the digital input to an analog signal, and then generate the sound waves.

The sound produced by speakers is defined by frequency and amplitude.

The frequency determines the pitch of the sound. A speaker system's ability to

accurately reproduce sound frequencies is a good indicator of how clear the

audio will be. Many speakers include multiple speaker cones for different

frequency ranges, which helps toproduce more accurate sounds for each range.

Two-way speakers typically have a tweeter and a mid-range speaker, while

three-way speakers have a tweeter, mid-range speaker, and subwoofer.

Amplitude, or loudness, is determined by the change in air pressure

created by the speaker sound waves. But the signal produced by some audio

sources is not very high (like a computer sound cards), it may need to be

amplified by the speakers. Therefore, most external computer speakers are

amplified, meaning they use electricity to amplify the signal. Speakers that can

amplify the sound input are often called active speakers. A speaker is active if it

has a volume control or can be plugged into an electrical outlet. Speakers that

don't have any internal amplification are called passive speakers. Since these

speakers don't amplify the audio signal, they require a high level of audio input,

which may be produced by an audio amplifier.

Speakers typically come in pairs, which allow them to produce stereo

sound. This means the left and right speakers transmit audio on two completely

separate channels. By using two speakers, music sounds are more natural since

our ears are used to hearing sounds from the left and right at the same time.

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4.6 KEYPAD

A keypad is a set of buttons arranged in a block or pad which usually bear

digits, symbols and usually a complete set of alphabetical letters. If it contains

numbers then it can also be called a numeric keypad. Keypads are found on

many alphanumeric keyboards and on other devices such as calculators, push-

button telephones, combination locks, and digital door locks, which require

mainly numeric input.

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CHAPTER 5

SOFTWARE TOOLS

There are various kinds of software tools are available to program the PIC

microcontroller. The software tools used in this project are:

Embedded C language

MP lab

PIC Kit2 boot loader

5.1 EMBEDDED C LANGUAGE:

The C for microcontrollers and the standard C syntax and semantics are

slightly different from each other. The former is aimed at the general purpose

programming paradigm whereas the latter is for a specific target microcontroller

such as 8051 or PIC. The underlying fact is that everything will be ultimately

mapped into the microcontroller machine code. If a certain feature such as

indirect access to I/O registers is inhibited in the target microcontroller, the

compiler will also restrict the same at higher level. Similarly some C operators

which are meant for general purpose computing are also not available with the

C for microcontrollers. Even theoperators and constructs which may lead to

memory inefficiency are not available in C programming meant for

microcontrollers.

Be aware that the target code should fit in the limited on-chip memory of

the processor. Even the I/O functions available in standard C such as printf() or

scanf() are either not made available in C compilers for microcontrollers or

advised not to use them. These functions eat up lot of memory space and are not

time-efficient owing to the dragging of supporting functions like floating point

routines and lot of delimiters. Another striking difference in case of embedded

systems programs is that they do nothave the umbrella or support of the

45

operating system. The programmer has to be accustomed with the absence of

system calls which makes life easy in traditional C.

5.2 MPLAB

MPLAB is a free integrated development environment for the

development of embedded applications on PIC and dspmicrocontrollers, and is

developed by Microchip Technology. MPLAB X is the latest edition of

MPLAB, and is developed on the net beans platform. MPLAB and MPLAB X

support project management, code editing, debugging and programming of

Microchip 8-bit, 16-bit and 32-bit PIC microcontrollers. MPLAB is designed to

work with MPLAB-certified devices such as the MPLAB ICD 3 and MPLAB

REAL ICE, for programming and debugging PIC microcontrollers using

a personal computer. PIC Kit programmers are also supported by MPLAB .

5.2.1 MPLAB IDE

MPLAB IDE is a software program that runs on a PC to develop

applications for Microchip microcontrollers. It is called an Integrated

Development Environment, or IDE, because it provides a single integrated

environment to develop code for embedded microcontrollers. Experienced

embedded systems designers may want to skip ahead.

MPLAB Integrated Development Environment (IDE) is a comprehensive

editor, project manager and design desktop for application development of

embedded designs using Microchip PICmicro MCUs and dspPIC DSCsof

MPLAB IDE. The basic steps involved are:

MPLAB IDE Features and Installation

Tutorial Overview

Selecting the Device

46

Creating the Project

Setting Up Language Tools

Naming the Project

Adding Files to the Project

Building the Project

Creating Code

Building the Project Again

Testing Code with the Simulator

Tutorial Summary MPLAB IDE Users Guide

5.2.2 MPLAB IDE FEATURES AND INSTALLATION

MPLAB IDE is a Windows Operating System (OS) based Integrated

Development Environment for the PICmicro MCU families and the dsPIC

Digital Signal Controllers. The MPLAB IDE provides the ability to:

Create and edit source code using the built-in editor.

Assemble, compile and link source code.

Debug the executable logic by watching program flow with the built-in

simulator or in real time with in-circuit emulators or in-circuit debuggers.

Make timing measurements with the simulator or emulator.

View variables in Watch windows.

Program firmware into devices with device programmers (for details,

consult the user’s guide for the specific device programmer).

5.2.3 SOFTWARE DEVELOPMENT

In order to create code that is executable by the target PICmicro MCU,

source files are needed to be put into a project. The code can then be built into

47

executable code using selected language tools (assemblers, compilers, linkers,

etc. . All projects will have these basic steps:

1. Select Device

The capabilities of MPLAB IDE vary according to which device is

selected. Device selection should be completed before starting a project.

2. Create Project

MPLAB IDE Project Wizard will be used to create a Project.

3. Select Language Tools

In the Project Wizard the language tools will be selected. For this tutorial,

the Built-in assembler and linker will be used. For other projects, one of the

Microchip compilers or other third party tools might be selected.

4. Put Files in Project

Two files will be put into the project, a template file and a linker script.

Both of these exist in sub-folders within the MPLAB IDE folder. It is easy to

get started using these two files.

5. Create Code

Some code will be added to the template file to send an incrementing

value out an I/O port.

6. Build Project

The project will be built ñ causing the source files to be assembled and

linked into machine code that can run on the selected PICmicro MCU.

7. Test Code with Simulator

Finally, the code will be tested with the simulator

5.3 PIC Kit BOOT LOADER

PIC kit boot loader is a family of programmers for PIC

microcontrollers made by Microchip Technology. They are used to program

and debug microcontrollers, as well as program EEPROM. They provide inter

48

communication between the software tool and the PIC microcontroller. It is

used to burn the program from MPLAB to PIC.

The most notable difference between the two is that the PICkit 2 has a

separate programmer/debugger unit which plugs into the board carrying

the chip to be programmed, whereas the PICkit 1 was a single unit. This

makes it possible to use the programmer with a custom circuit board via

an In Circuit Serial Programming (ICSP) header. This feature is not

intended for so-called "production" programming, however.

The PICkit 2 uses an internal PIC18F2550 with FullSpeed USB. The

latest PIC kit2 firmware allows the user to program and debug most of

the 8 and 16 bit PICmicro and dsPIC members of the Microchip product

line.

The PICkit 2 is open to the public, including its hardware schematic,

firmware source code (in C language) and application programs (in C#

language). End users and third parties can easily modify both the

hardware and software for enhanced features. E.g. GNU/Linux version of

PIC kit2 application software, DOS style CMD support, etc.

The PICkit 2 has a programmer-to-go (PTG) feature, which can

download the hex file and programming instructions into on-board

memory (128K byte I2C EEPROM or 256K byte I2C EEPROM), so that

no PC is required at the end application.

The Microchip version of PICkit 2 has a standard 128K byte memory.

256K byte memory can be achieved by modifying the hardware or from

third party.

Additionally, a 500 kHz three-channel logic analyzer and a UART tool

are built into the PICkit 2.

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CHAPTER 6

WORKING MODULE

When the user gives input by pressing the button in the keypad, the Radio

frequency receiver couples with the transmitter and APR33A3 which is sound

recording device guides the user with the direction. On reaching the destination

IR transmitter and receiver attains the line of sight path. This indicates that the

destination is reached through the speaker.

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51

CHAPTER 7

CONCLUSION AND FUTURE WORK

Thus the blind navigation using RFID for indoor environment helps the

blind people for direction guidance. Using this destination can be reached safely

by the blind people. Andthis system must be a worthwhile investment for blind

users in terms of cost of equipment and time invested in learning to use

it.Depending on the wide deployment of Radio Frequency for the system, or at

least consistent deployment within a particular area.

The future scope to implement this system as easily portable with the

hand stick. Then the direction commands are guided through Bluetooth device,

earphone, this portability helps the blind person to feel at ease and easy to

handle.IR sensor is used in the hand-stick for the obstacle detection. And also

by using GPRS, this system can be implemented in outdoor environment.

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CHAPTER 8

REFERENCE

[1] KushagraTandon and TanujaPande, “A Blind Navigation System Using

RFID for Indoor Environment:” International Journal of Computer Systems,

Volume 2– Issue 4, April, 2015

[2] S. Willis and S. Helal, “RFID information grid for blind navigation and

way finding,” in Proceedings of the 2005 Ninth IEEE International Symposium

on Wearable Computers, 2005

[3] Arjun Sharma, Rahul Patidar, ShubhamMandovara, “Blind Audio

Guidance System”(Blind Navigation) International Journal of Emerging

Technology and Advanced Engineering, Volume 3, Special Issue 2, January

2013)

[4] F. Gaunet and X. Briffault, “Exploring the functional specifications of a

localized wayfinding verbal aid for blind pedestrians: simple and structured

urban areas,” Human Computer Interaction, vol. 20, no. 3, pp. 267–314, 2005.

[5] Programming and customizing with PIC microcontrollers-by, MykePredko,

3rd

edition, publisher: Tata McGraw Hil.

[6] PIC microcontrollers-by, Milan Verle, publisher: micro electronika

[7] Basic programming in PIC microcontrollers-by, Milan Verle, publisher:

micro electronika.

[8] http:\\www.microchip.com

[9] www.mdpi.com

[10]www.sciencedirect.com