CONTENTSPAGE NO. 1. ABSTRACT 2 2. INTRODUCTION 3 3. BACKGROUND 4 4. LITERATURE SURVEY 5 5. DESCRIPTION 6 5.1. BLOCK DIAGRAM 6 5.2. EXPLANATION 6 6. HARDWARE REQUIREMENTS 7 6.1. MICROCONTROLLER (AT89c2051) 8 6.2. Ultrasonic Modules HC-SR04 11 6.3. 74ls153(4:1) Multiplexer 13 6.4. RF TX Rx 434 Mhz 17 6.5. Flame and Fire Detection Sensor Module 21 6.6. Water sensor module 22 7. SCHEMATIC DIAGRAM 23 7.1 DESCRIPTION 23 7.2 OPERATION EXPLANATION 25 8. SOFTWARE IMPLEMENTATION 27 8.1 SOURCE CODE 27 9. HARDWARE TESTING 35 9.1 CONTINUITY TEST 35 9.2 POWER ON TEST 36 10. RESULTS AND DISCUSSIONS 37 11. CONCLUSION AND FUTURE SCOPE 38 10. BIBLIOGRAPHY 39 1 ABSTRACT God gifted sense of vision to the human being is an important aspect of our life. But there are some unfortunate people who lack the ability of visualizing things. The visually impaired have to face many challenges in their daily life. The problem gets worse when there is an obstacle in front of them. Blind stick is an innovative stick designed for visually disabled people for improved navigation. The paper presents a theoretical system concept to provide a smart ultrasonic aid for blind people. The system is intended to provide overall measures – Artificial vision and object detection. The aim of the overall system is to provide a low cost and efficient navigation aid for a visually impaired person who gets a sense of artificial vision by providing information about the environmental scenario of static and dynamic objects around them. Ultrasonic sensors are used to calculate distance of the obstacles around the blind person to guide the user towards the available path. Output is in the form of sequence of beep sound which the blind person can hear. 2 INTRODUCTION There are approximately 37 million people across the globe who are blind, over 15 million are from India. Even for the non-visually impaired the congestion of obstacles is sometimes problematic, it’s even worse for the visually impaired. People with visual disabilities are often dependent on external assistance which can be provided by humans, trained dogs, or special electronic devices as support systems for decision making. Existing devices are able to detect and recognize objects that emerge on the floor, but a considerable risk is also includes the objects that are at a sudden depth, or obstacles above waist level or stairs. Thus we were motivated to develop a smart white cane to overcome these limitations. The most common tool that the blind currently use to navigate is the standard white cane. We decided to modify and enhance the walking cane, since blind are only able to detect objects by touch or by cane. The user sweeps the cane back and forth in front of them. When the cane hits an object or falls off of the edge of a stair, the user then becomes aware of the obstacle –sometimes too late. We accomplished this goal by adding ultrasonic sensors at specific positions to the cane that provided information about the environment to the user through audio feedback. The main component of this system is the Radio-Frequency module which is used to find the stick if it is misplaced around. 3 With the rapid advances of modern technology. Many blind guidance systems use ultrasound because of its immunity to the environmental noise. Another reason why ultrasonic is popular is that the technology is relatively inexpensive. and also ultrasound emitters and detectors are small enough to be carried without the need for complex circuit. range of motion and very little information conveyed. The traditional and oldest mobility aids for persons with visual impairments are the walking cane (also called white cane or stick) and guide dogs. Also high-end technological solutions have been introduced recently to help blind persons to navigate independently. 4 .BACKGROUND Vision is the most important part of human physiology as 83% of information human being gets from the environment is via sight. but it was not until after World War I that the white cane was introduced. Blind people have used canes as mobility tools for centuries. The most important drawbacks of these aids are necessary skills and training phase. The 2011 statistics by the World Health Organization (WHO) estimates that there are 285 million people in world with visual impairment. both in hardware and software front have brought potential to provide intelligent navigation capabilities. 39 billion of which are blind and 246 with low vision [2]. Recently there has been a lot of Electronic Travel Aids (ETA) designed and devised to help the blind navigate independently and safely. The feedback given is through the vibration as well as the speaker/headphones. Even this is a PIC based system. 5 . It also has a wet detector to detect the water. The only feedback given to the user is through the vibration motor [4]. “Project Prakash” is a humanitarian mission to help the blind children especially by training them to utilize their brains to learn a set of objects around them [3]. The microcontroller circuit is on the outside of the stick but is protected with a code so its security cannot be breached. pit sensor and the water sensor. The micro-controller used is PIC microcontroller. Three sensors are used viz. No information on how a blind man would do that. The stick has a ping sonar sensor to sense the distant objects. ultrasonic. There is a GPS system where-in the user has to feed his location. Also they haven’t mentioned anything about the size and shape of their cane and neither.LITERATURE SURVEY Numerous attempts have been made in the society to help the blind. 6 . Buzzer will sound differently for different conditions. We have used three ultrasonic sensors at different height to detect the height of the object. There is one more advantage of this system. Additional features are also added in the blind stick for safety purposes like. they can find it by using the wireless remote. Sometimes when the blind loose there sticks or forgot where have they put it. fire detector and water detector.DESCRIPTION Explanation: In this system the ultrasonic sensor are used to sense the obstacle (if there is any). The signal is then send to microcontroller to operate a buzzer. The output of the blind stick will be in the form of sound produced by a buzzer. Ultrasonic Modules HC-SR04 3. 74ls153(4:1) Multiplexer 4. Flame and Fire Detection Sensor Module 6. MICROCONTROLLER (AT89c2051) 2. Water sensor module 7 .HARDWARE REQUIREMENTS MAJOR HARDWARE COMPONENTS USED 1. RF TX Rx 434 Mhz 5. 000 Write/Erase Cycles • 2.7V to 6V Operating Range • Fully Static Operation: 0 Hz to 24 MHz • Two-level Program Memory Lock • 128 x 8-bit Internal RAM • 15 Programmable I/O Lines • Two 16-bit Timer/Counters 8 . Features • Compatible with MCS®-51Products • 2K Bytes of Reprogrammable Flash Memory – Endurance: 10. As the circuit space requirements of intelligent blind stick is very less. The purpose of using this is that it have only 20 pins and it is very compact and use less space.AT89C2051 At89c2051 is 8051 family microcontroller having only 20 pins. high-performance CMOS 8-bit microcomputer with 2K bytes of Flash programmable and erasable read-only memory (PEROM). PIN diagram And basic circuitry: 9 . The Idle Mode stops the CPU while allowing the RAM. on-chip oscillator and clock circuitry. In addition. 15 I/O lines. By combining a versatile 8-bit CPU with Flash on a monolithic chip. The AT89C2051 provides the following standard features: 2K bytes of Flash. a five vector two-level interrupt architecture. timer/counters. 128 bytes of RAM. a precision analog comparator. The device is manufactured using Atmel’s high-density nonvolatile memory technology and is compatible with the industry-standard MCS-51 instruction set. the Atmel AT89C2051 is a powerful microcomputer which provides a highly-flexible and cost-effective solution to many embedded control applications. The power-down mode saves the RAM contents but freezes the oscillator disabling all other chip functions until the next hardware reset. the AT89C2051 is designed with static logic for operation down to zero frequency and supports two software selectable power saving modes. serial port and interrupt system to continue functioning. a full duplex serial port.Description: The AT89C2051 is a low-voltage. two 16-bit timer/counters. 0592MHZ frequency is connected at X1 and X2 to provide clock pulses. It is also called power on reset. Other connections depends on the pin requirements of the application to be designed. AN RC circuit is connected at RST pin to reset the microcontroller whenever the power is turned on. A crystal of 11. 10 .Above Is the basic circuitry for the 89c51 microcontroller. To measure the amount of liquid in a tank. Ultrasonic sensors generate high frequency sound waves and evaluate the echo which is received back by the sensor. For measuring speed or direction a device uses multiple detectors and calculates the speed from the relative distances to particulates in the air or water. Sensors calculate the time interval between sending the signal and receiving the echo to determine the distance to an object.000 hertz. by turning electrical energy into sound. Systems typically use a transducer which generates sound waves in the ultrasonic range. The technology is limited by the shapes of surfaces and the density or consistency of the material. 11 .ULTRASONIC SENSOR Ultrasonic sensors (also known as transceivers when they both send and receive) work on a principle similar to radar or sonar which evaluate attributes of a target by interpreting the echoes from radio or sound waves respectively. For example foam on the surface of a fluid in a tank could distort a reading. medical ultra sonography. above 18. This technology can be used for measuring: wind speed and direction (anemometer). sonar. then upon receiving the echo turn the sound waves into electrical energy which can be measured and displayed. fullness of a tank and speed through air or water. Further applications include: humidifiers. burglar alarms and non-destructive testing. the sensor measures the distance to the surface of the fluid. 12 . It Came back to the Ultrasonic receiver and ultrasonic coverts it to a digital pulse and interrupt the controller. 4. And calculate the overall distance in cms. 2. The MCU calculate the time taken by the Pulse to strike back. 3.INTERFACING Working: 1. When the pulse strikes an object. In our Blind stick project we use three Ultrasonic receivers. Therefor we have to use a 3:1 multiplexer to multiplex the echo pins of the ultrasonic sensors with the MCU INT pin. 3:1 mux is not commercially available so we used 4:1 Mux IC(74LS153). After receiving the pulse the ultrasonic transmitter sends 40 kHz ultrasound pulse train. The MCU sends 10us pulse to the ultrasonic sensor module. It can select two bits of data from four sources. The two buffered outputs present data in the true (non-inverted) form. In addition to multiplexer operation. the LS153 can generate any two functions of three variables.74LS153 DUAL 4-INPUT MULTIPLEXER The LSTTL/MSI SN54/74LS153 is a very high speed Dual 4-Input Multiplexer with common select inputs and individual enable inputs for each section. The LS153 is fabricated with the Schottky barrier diode process for high speed and is completely compatible with all Motorola TTL families. • Multifunction Capability • Non-Inverting Outputs • Separate Enable for Each Multiplexer • Input Clamp Diodes Limit High Speed Termination Effects 13 . 14 . Schottky barrier diode process for high speed. Eb) which can be used to strobe the outputs independently. S1). When the Enables (Ea. 4-position switch. This is useful for implementing highly irregular random logic. The LS153 can generate two functions of three variables. Za = Ea V (I0a V S1 V S0 + I1a V S1 V S0 + I2a V S1 V S0 +I3a V S1 V S0) Zb = Eb V (I0b V S1 V S0 + I1b V S1 V S0 + I2b V S1 V S0 +I3b V S1 V S0) The LS153 can be used to move data from a group of registers to a common output bus. The LS153 is the logic implementation of a 2-pole. 15 . The two 4-input multiplexer circuits have individual active LOW Enables (Ea. The particular register from which the data came would be determined by the state of the Select Inputs. where the position of the switch is determined by the logic levels supplied to the two Select Inputs. A less obvious application is a function generator. the corresponding outputs (Za. Eb) are HIGH.FUNCTIONAL DESCRIPTION The LS153 is a Dual 4-input Multiplexer fabricated with Low Power. It can select two bits of data from up to four sources under the control of the common Select Inputs (S0. The logic equations for the outputs are shown below. Zb) are forced LOW. A=1. The echo pulse is read by MCU at 1Y pin of the mux. MCU sends trigger pulse at TRIG 1 pin. 4. And for sensor 3. A=0. 5. 1. B=1. A and B input of mux ic are also connected to the MCU. Similarly for sensor 2. WORKING: Here the Trigger pins of the sensors are directly connected to the MCU. B=0 2. 3.INTERFACE The mux is used to multiplex three ultrasonic sensors with the MCU. So that MCU can select different inputs. MCU selects sensor 1 by A =0. B=0. 1X1 and 1X2. 16 . But the ECHO pins are connected to 1X0. Pin Assignment of the 434MHz Transmitter module Note that. Apart from “Data” and the “Vcc” pin. consisting of a 434MHz license-exempt Transmitter module and an encoder IC . was designed to remotely switch simple appliances on and off. there is a common ground (GND) for data and supply. The current consumption with a supply voltage of near 5. I have used the renowned encoder IC HT12E from Holtek. for the transmission of a unique signal. HT12E is capable of encoding information which consists of N address bits and 12N data bits.92 MHz.RF Tx-Rx 434 MHz RF Transmitter This simple RF transmitter. Recommended antenna length is 17 cm for 433. Remember to mount the antenna (aerial) as close as possible to pin 4 (ANT) of the transmitter module 17 . Since the current consumption is very little. Last is the RF output (ANT) pin. an encoder is crucial. Each address/ data input can be set to one of the two logic states. The programmed addresses/data are transmitted together with the header bits via an RF transmission medium upon receipt of a trigger signal. which works at a frequency of 433. and a stiff wire can be used as the antenna. The transmitter module has four pins.the power can also be provided by standard button cells. For this. The RF part consists of a standard 434MHz transmitter module. Solder bridges TJ1 and TJ2 are used to set the address and data bits.92 MHz and has a range of about 400m according to the manufacture.4V is about 10 mA. exactly same as for the RF transmitter. this is an Amplitude Shift Keying (ASK) receiver module based on a single-conversion.92MHz. Local oscillator is made of Phase Locked Loop (PLL) structure.RF Transmitter – Schematic Diagram RF Receiver This circuit complements the RF transmitter built aorund the small 434MHz transmitter module. Technically. This integrated RF receiver module has been tuned to a frequency of 433. super-heterodyne receiver architecture and incorporates an entire 18 . 434MHz receiver module The miniature 434MHz RF receiver module receives On-Off Keyed (OOK) modulation signal and demodulates it to digital signal for the next decoder stage. The receiver picks up the transmitted signals using the 434Mhz receiver module. HT12D compare the serial input data three times continuously with the local addresses. HT12F is capable of decoding informations that consist of N bits of address and 12N bits of data. The receiver module has eight (4+4) pins. It can use in OOK / HCS / PWM modulation signal and demodulate to digital signal. 19 . there are two pins (one for Digital Data & other for Linear Data) for data output. Last is the RF input (ANT) pin. HT12F decoder IC receives serial addresses and data from the HT12E encoder that are transmitted by the RF transmitter module. Apart from three “ground (GND) ” and two “Vcc” pins. Pin Assignment of the 434MHz Receiver module Pin Connections 1 Antenna 2 Ground 3 Ground 4 Vcc 5 Vcc 6 Linear Data (Normally NOT used) 7 Digital Data (Normally Used) 8 Ground The “coded” signal transmitted by the transmitter is processed at the receiver side by the decoder IC HT12F from Holtek.Phase-Locked Loop (PLL) for precise local oscillator (LO) generation. Any possible variations due to component tolerences and/or a different supply voltage can be compensated by this arrangement. VR1 and R1 are used to tweak the oscillator frequency of the decoder to that of the transmitter. 92 MHz) has to be mounted as close as possible to the RF IN (ANT) pin of the 434MHz RF receiver module. This output is also fed to the relay driver transitor T1. making the logical signal available to circuits that need it. Output of the decoder is brought out on a pinheader K1 . The data bits are set up using solder bridges RJ1 and RJ2. The “Valid Transmission” (VT) pin also goes high to indicate a valid transmission. Just as for the RF Transmiitter. the input data codes are decoded and then transferred to the output pins. For proper operation.If no error or unmatched codes are found. a pair of HT12E/HT12F ICs with the same number of addresses and data format should be chosen. The RF Receiver circuit can be powered from a standard 5VDC supply. the aerial (17 cm for 433. RF Receiver – Schematic Diagram 20 . 4cm Using a wide voltage LM393 comparator 21 . than 15mA With adjustable precision potentiometer for sensitivity adjustment With LED indication Operating Voltage: 3. The larger the flame.Flame and Fire Detection Sensor Module Description The Fire sensor is used to detect fire flames .3V-5V Output in the form: DO digital switching outputs (0 and 1) and AO analog voltage output Fixed bolt holes for easy installation Small PCB size: 3. the greater the distance test The detection angle of approx 60 degrees. sensitive to the flame spectrum Sensitivity adjustable (Refer picture for blue digital potentiometer) The comparator output signal clean waveform is good. The test flame lighters distance of 80cm. driving ability.3V to 5V Features: Can detect the flame or the wavelength at 760nm to 1100nm range of the light source. The module makes use of Fire sensor and comparator to detect fire up to a range of 1 meters.2cmx1. Allows your robot to detect flames from up to 1M Typical Maximum Range: 1 meter Calibration preset for range adjustment Indicator LED with easy interface connector Input Voltage: 3. the output analog signal can be read directly on the arduino board to achieve the effect of water level alarm . Easy to complete water to analog signal conversion and output analog values can be directly read Arduino development board to achieve the level alarm effect. cost-effective high level/drop recognition sensor. which is obtained by having a series of parallel wires exposed traces measured droplets/water volume in order to determine the water level. Water Sensor water level sensor is an easy-to-use.This sensor module can estimate the water level through a series of exposed parallel conductor line marks measuring the water droplets and capacity . It is low power consumption and high sensitivity. It can make better performance with Arduino 328 controller and sensor relay shield.The surface have gone through plating processing to enhance the electrical conductivity and corrosion resistance .Brand new Water Level Alarm Sensor Module Liquid Level Sensor Circuit Board .Sensor relay shield 22 . Complete water yield and analog conversion.Easily convert water to analog signal. the output value apply to your custom function. detection sensor water that have high cost performance. Key Features .Water Sensor Module Description This is simple and small portable water level/water droplet identification.Arduino 328 controller.Simple circuit and easy to use and high cost performance Specifications Working Voltage: DC 3-5V Working Current: <20mA Detection Area: 40 mm x 16 mm Optional Accessories: 3 pin sensor connecting line. “89S52”.SCHEMATIC DIAGRAM SCHEMATIC EXPLANATION STANDARD CONNECTIONS TO 8051 SERIES MICRO CONTROLLER ATMEL series of 8051 family of micro controllers need certain standard connections. 23 . Every microcontroller requires a timing reference for its internal program execution therefore an oscillator needs to be functional with a desired frequency to obtain the timing reference as t =1/f. The actual number of the Microcontroller could be “89C51” . The 4 set of I/O ports are used based on the project requirement. and as regards to 20 pin configuration a number of “89C2051”. “89S51”. “89C52”. to enable the program execution from the beginning. This operation of high to low of the reset pin takes place in fraction of a second as decided by the time constant R and C.A crystal ranging from 2 to 20 MHz is required to be used at its pin number 18 and 19 for the internal oscillator.e. Typically 11. At the time of switch on. A pushbutton switch is connected across the capacitor so that at any given time as desired it can be pressed such that it discharges the capacitor and while released the capacitor starts charging again and then pin number 1 goes to high and then back to low. It may be noted here the crystal is not to be understood as crystal oscillator It is just a crystal. RESET Pin no 1 is provided with an resset arrangement by a combination of an electrolytic capacitor and a register forming RC time constant. After the capacitor gets fully charged the current stops flowing and pin number 1 goes low which is pulled down by a 10k resistor to the ground. For example: A 10µF capacitor and a 10kΩ resistor would render a 100ms time to pin number 1 from logic high to low. Two small value ceramic capacitors of 33pF each is used as a standard connection for the crystal as shown in the circuit diagram. This arrangement of reset at pin 1 going high initially and then to logic 0 i.0592 MHz crystal is used in general for most of the circuits using 8051 series microcontroller. 24 . the capacitor gets charged. low helps the program execution to start from the beginning. while connected to the appropriate pin of the microcontroller it results in oscillator function inside the microcontroller. and it behaves as a full short circuit from the positive to the pin number 1. there after the pin number 1 remains low. In absence of this the program execution could have taken place arbitrarily anywhere from the program cycle.. 7 and 6 respectively. Pin 1 of the IC is the reset pin which is connected to a mechanical switch. Water sensor and the buzzer connected to P1. The arrow in the NPN transistor symbol is on the emitter leg and points in the direction of the conventional current flow when the device is in forward active mode. The multiplexed echo pin of the sensors is connected to P3. The 20th pin of the IC is given a 5v power supply. then current starts flowing through base and emitter and after that only current will pass from collector to emitter. The trigger pins of the ultrasonic sensors are connected to P3.4 and 3. 25 .2 which is INT pin of MCU.5. Pins 4 & 5 of the IC are used to connect crystal to the microcontroller. Whenever base is high. OPERATION EXPLANATION Microcontroller and connections: The microcontroller used is AT89C2051.BRIEF DESCRIPTION OF TRANSISOR ACTING AS SWITCH An NPN transistor is "on" when its base is pulled high relative to the emitter. It compares that distance with the already stored value which is 60cm. The buzzer in this case continuously beeps. 26 . If the distance calculated by the topmost sensor is less than 60cm. The buzzer gets turned on and it will help the blind to find his stick. If the water sensor detects water at the bottom of the stick. Whenever the blind person have to finds his stick. The circuit gets the power supply and the MCU activates sensors by giving appropriate signals to the select pins of the multiplexer IC and triggering the sensors. After it gets all the distance of the sensors. The signal gets received by the rf receiver and decoded by the decoder and its output triggers the buzzer. Whenever Fire is detected it triggers the buzzer. He will simply have to press a micro switch on his remote. Buzzer is also directly connected to RF receiver circuit. In the circuit diagram of our purposed design when the blind person presses the switch on the stick. After that MCU selects the second sensors and calculate its distance also. This variation can be used by the blind person to approximate the height of the object. It will give high signal to the controller. Fire sensor is directly connected to buzzer. which gives input the RF encoder and transmitted by the transmitter.CIRCUIT WORKING As it is an embedded project. The buzzer will beep very fast after 200ms. Otherwise if the middle sensors distance is less than 60 cm then buzzer beep will be slow at 400ms interval. And controller is programmed to beeps the sound 3 times faster and give it a delay. Same will be done for sensor 3. The MCU calculates the time and distance and stores it. For lowest sensor the buzzer beep will be 1sec. the circuit compilations are reduced with an efficient program. After getting trigger pulse the selected ultrasonic sensor transmits a ultrasound of 40k and its gets back after striking the object. h> #define delay_10us() _nop_()._nop_().h> #include<intrins. Distance Value in Centimeter unsigned long distance_cm2._nop_(). unsigned long high_time_us. sbit buzzer = P1^7. // 32 bit variable. sbit TRIG1 = P3^5. _nop_(). sbit TRIG2 = P3^4. stores pulse time in uS unsigned long distance_cm1._nop_()._nop_(). sbit SEL0 = P1^0. Distance Value in Centimeter 27 .h> #include <stdio. // 32 bit variable._nop_() sbit wat = P1^2. unsigned int T0_ISR_count = 0. sbit TRIG3 = P3^3. // 32 bit variable. Distance Value in Centimeter unsigned long distance_cm3. sbit SEL1 = P3^7._nop_(). // 32 bit variable.SOFTWARE IMPLEMENTATION SOURCE CODE #include <reg51. void serial_init() { /*-------------------------------------Set serial port for 9600 baud at 11. TMOD |= 0x20. // 32 bit variable.unsigned long distance_in. PCON |= 0x80. --------------------------------------*/ SCON = 0x50. TR1 = 1. Distance Value in Inches void calculate(). void delay_ms(int). unsigned int i. } void T0_ISR (void) interrupt 1 { 28 . Note that we use Timer 1 for the baud rate generator. TH1 = 0xFA.0592 MHz. TI = 1. while (1) { SEL1=0. TRIG1 = TRIG2 = TRIG3 = 0. TRIG1 = 1. ET0 = 1. calculate(). TRIG1 = 0. delay_10us().T0_ISR_count++. TMOD = (TMOD & 0xF0) | 0x09.SEL0=0. TF0 = 0. 29 . //serial_init(). // Init serial port at 9600 // printf ("\nUltrasonic Distance Sensor\n"). } void main (void) { buzzer = 0. EA = 1. delay_ms(50). distance_cm2=high_time_us/58. delay_ms(50). SEL1=1. delay_ms(50). calculate(). TRIG2 = 0. delay_10us(). TRIG3 = 1. TRIG3 = 0. distance_c0m3=high_time_us/58.SEL0=1.distance_cm1=high_time_us/58. 30 . SEL1=0. distance_cm1). TRIG2 = 1. calculate(). delay_10us(). /*if(distance_cm1 > 0 && distance_cm1 < 500) // check valid range then only print printf("Distance1: %6lu cm\n".SEL0=0. buzzer=0. delay_ms(50). delay_ms(50). buzzer=1. buzzer=0.*/ if(wat == 0) { buzzer=1. if(distance_cm3 > 0 && distance_cm3 < 500) // check valid range then only print 0 printf("Distance3: %6lu cm\n". buzzer=1. delay_ms(50).if(distance_cm2 > 0 && distance_cm2 < 500) // check valid range then only print printf("Distance2: %6lu cm\n". } else if(distance_cm3 <60) 31 . delay_ms(50). distance_cm2). distance_cm3). delay_ms(50). delay_ms(50). buzzer=0. } else 32 . } else if(distance_cm1 < 60) { buzzer=1. delay_ms(200). delay_ms(850). delay_ms(1000). delay_ms(250). buzzer=0. buzzer=0. } else if(distance_cm2 < 60) { buzzer=1. delay_ms(400). buzzer=0. delay_ms(50).{ buzzer=1. i=0. } i=0. } } void calculate() { T0_ISR_count = 0. while (!INT0) { i++. if(i>20000) break. TR0 = 1. TL0 = 0. 33 . while (INT0) { i++.buzzer=0. TH0 = 0. while(x>=0) { for (y=0. y<100. } } 34 . // return high_time_us.if(i>20000) break.085. } high_time_us = (unsigned long)((TH0 << 8) | TL0 | ((unsigned long)T0_ISR_count << 16))*1. y++). } void delay_ms(int x) { int y=0. x--. damaged components. component failures and presence of bugs in the circuit diagram. improper usage of the soldering iron. a continuity test is the checking of an electric circuit to see if current flows (that it is in fact a complete circuit). If there is continuation then you will hear the beep sound. We use a multi meter to perform this test. wrong and rough handling of the PCB. more basic devices. there will be a negligible resistance between the "right" ends. If electron flow is inhibited by broken conductors. An important application is the continuity test of a bundle of wires so as to find the two ends belonging to a particular one of these wires. We connect both the terminals across the path that needs to be checked. generally with a simple light bulb that lights up when current flows. Many a times. the electrical continuity in the circuit is lost due to improper soldering. and only between the "right" ends. or excessive resistance. Devices that can be used to perform continuity tests include multi meters which measure current and specialized continuity testers which are cheaper. This test is the performed just after the hardware soldering and configuration has been completed. We keep the multi meter in buzzer mode and connect the ground terminal of the multi meter to the ground. 35 . the circuit is "open".HARDWARE TESTING CONTINUITY TEST: In electronics. A continuity test is performed by placing a small voltage (wired in series with an LED or noise-producing component such as a piezoelectric speaker) across the chosen path. This test aims at finding any electrical open paths in the circuit after the soldering. Note that we do this test without microcontroller because if there is any excessive voltage.e. We take a multi meter and put it in voltage mode. 36 ..POWER ON TEST: This test is performed to check whether the voltage at different terminals is according to the requirement or not. Then we apply this voltage to the power supply circuit. We check for the input to the voltage regulator i. whether we get the required 12 v AC voltage. we check for the other terminals for the required voltage. This 5v output is given to the microcontrollers’ 40th pin. In this way we can assure that the voltage at all the terminals is as per the requirement. Similarly. Hence we check for the voltage level at 40th pin. are we getting an input of 12v and an output of 5v. Remember that this test is performed without microcontroller. Firstly. this may lead to damaging the controller. we check the output of the transformer. 37 . The prototype suffers from some limitations as well. It is built using 8051 FAMILY MCU which has limited memory. and therefore. there is a limitation on maximum number of SENSORS that it can use. The prototype was well designed to implement all the software modules and tested with all possible cases.RESULTS AND DISCUSSIONS We validated the effectiveness and advantages of our proposed methodology by doing software testing. The device was programmed in such a way that it uses the available memory of AT89C2051 efficiently. Each module of the program was verified with various test cases. The idea can be further modified by using a voice playback module which alerts the blind person by giving speech notifications. 38 . Also the purposed design provides safety to the blind person by alerting the fire and water. The blind stick can also be equipped with GPS module for partially deaf people.CONCLUSION AND FUTURE SCOPE The proposed project undertakes a viable solution to the blind persons by providing artificial vision on objects and to determine their way. com/elechouse/index.visually-disabled-persons.com/images/doc0368. 39 .elechouse. 2.mit.com/8712/rf-based-wireless-remote-control-system https://electrosome.BIBLIOGRAPHY TEXT BOOKS REFERED: 1.ijser.php?main_page=product_info&cPath=&products_id=2233 http://www.an electronic approach to assist visually disabled persons” “http://www. THE INTERNET SOURCES http://www.org/researchpaper%5CSmart-walking-stick-an-electronicapproach-to-assist.jpg REFERENCES [1] Rohit Sheth “Smart White Cane. “The 8051 Microcontroller and Embedded systems” by Muhammad Ali Mazidi and Janice Gillispie Mazidi .atmel. ATMEL 89C2051 Data Sheets.an Elegant and Economic Walking Aid” [2] www.who.int/mediacentre/factsheets/fs282/en/ [3] “Project Prakash” http://web.com/wp-content/uploads/2014/08/Working-of-HC-SR04-Ultrasonic-Sensor.pdf”.electroschematics.pdf http://www.html [4] Mohammad Hazzaz Mahmud. “Smart walking stick . Pearson Education.edu/bcs/sinha/prakash.