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1. 12 5 us has past Set transmit bit to O state 12 5 us has past no 0 6ms has Return to main past program The receive program flowchart Enable INT for detect start the time counting lt Time counter 1836us Feet counter 1 Reset time counter Return to main program Feet counter gt 10 The tone generate and vibration trigger flowchart Pick up the feet counter set off the vibrator INT flag has set Feet counter gt 2 Set the vibrator on No Beep 1 times Return to the main program Feet counter 1 Feet a counter 0 l User manual Plug in the power 2 When the system normal a beep sound will be generate in very 3 single second Apply the ultrasound sensor to the obstacle you will hear a burst beep sound the burst will indicate your location to the obstacle the sound will be beep more frequently for example the obstacle will beep 2 times when the obstacle at 10 feet 4 times when the obstacle at 8feet etc When the obstacle is close to 2 feet the vibrator will be vibrating Test procedure Test instrument 10MHz or above oscillopscope 4069 406 fi 3 2 13 30khz signal in iranducer T 7 4064 N p LN 2 Tpl i EE 4069 4065 ELI z Ld M Fig 1 1 Apply test probe to figl Tpl and tp2 the normal situation w
2. 1 iranducer p 4069 LP La 3 4065 3 En 7 4063 LE i k At Tpl 50us per each vertical block 5v per each horizontal block 24 El ite FI 1 el A Faan E ED T4 TS e L aa To NTI DIN Sa ddl a Ae a ponsu 77 An6551 3 ox P La At Tp3 This record at the 5 inch that 4mv for each horizontal block 2us per each vertical block 25 At Tp4 This record at 3m 10mv for each vertical block 2ms per each horizontal block At Tp4 This record at 3m 0 5v for each vertical block 2ms per each horizontal block 26 Comments and discussions Our project is fail to the receiver circuit output signal was so low to detected by the microproccer 1 V peak to peak There 1s more than 3 2V that can be detected by the microproccer with the buffer IC As long as our observe the receiver circuit 18 running properly Because the receiver circuit has a large amplify about 30db amplify this is hard to amplify the signal to more large level Because the slew rate is limit to the amplify action for example the slew rate 1v us it means that if the amplifier circuit is the voltage follow bandwidth 1MHz if 10 time amplify the bandwidth will decrease to 100kHz 1 the 30db amplify the bandwidth will decrease to very low level we have use the two level amplifier to due the 30db amplify result but more large level will
3. Transmission part M edium air The signal detector amp distance counter a j Jl A A a a a a a ea R efect signal W hen hit the object The warning sound generater Signalamplifer The vibrator for the vibration warning l Receiver part signal Circuit diagram The hardware part will be break down to three parts to discuss The first part is transmission part the 40khz ultrasound that generate by the microproccer that though the 4069 and the sin wave that will transmit the ultrasonic though by the transducer 4069 that is a hex inverter buffer to use to buffering and shaping the pulse more like than the sin wave The circuit will be show as follow 4069 1 7 bo 13 40khz signal in tranducer 4069 ue E 4063 As follow 18 the receiver part circuit C1 u L T The first stage of the amplifier gain 10 and the second stage amplifier gain 13 times total gain 1s gain 10 13 130 about 40db gain and output to the microproccer The first stage of the amplifier 1s the high pass filter the 100p cap Is use to filtering the noise under the 40khz signal the resistor of the cap 1s xc 2nf c For example at 37khz or below xc 1 2Tt 37k 100p 43k or bigger the resistor 1s good enough to limit the current to flow to amplifier The second stage amplifier will call by VCVS voltage controlled voltage source amplifier This 1s one of the types of the butterworth filter
4. 15 81 ON R 28 2702 1 251u5 82 DNZ RI SLOCP1 2U5 251 4 2 2ns 83 RET 84 END 1 12 are the initial part of the program 5 the external int pointer has been set 6 the main program set to 100H prevent the data area in microproccer 7 the stick point set to safety data area 8 disable all the int 9 11 are use to initial the meter counter feet R5 and the receive signal flag R6 is use to like a flag If receive a signal R6 1 R1 is use to determine the pulse width of the 40khz pulse that transmit for detector 12 reset the buzzer sound to off 14 27 are the second part of the program produce a 0 3ms width 40khz pulse 14 16 are the program produce high state of the 40khz 14 set to high state and then 15 16 is provide looping for a suitable waiting timing from the way of the machine cycle 14 1 machine cycle 15 1 16 2 machine cycle 5 12us 17 20 are the program produce low state of the 40khz the method as use as 14 16 two of them will add to the full cycle 12us 12us 24us nearly to the 40khz 1 25us 40khz 1 24us 38khz because that the 40khz 1 25us 2 12 5us half on off cycle in 12Mhz clock the machine cycle lus the IC can t provide less than lus clock So 38khz 1s the best resolution to this situation 21 1s use the looping provide 0 3ms timing 24us 6 times 2machine cycle 2us 0 3ms 22 27 is use to do the looping to prevent the cross talk of the two sensor because the
5. 7 lus R2 795 lus R2 Aus on 5 2 1 11us P1 7 lus R2 75 lus Aus of f 5 2 1 11us R1 LOQ 25us lperoid 5 9 3ns R1 2 TI ME CELAY FCR TH DETECT SI NAL PERI CD R2 206 lus Aus on 5 2 1 11us R2 76 lus Aus of f 5 2 1 11us R1 26us 1peroi d 5 9 6ns E 81H SETUP TO DETECT THE SI TO 32 EEK My 3 Mi D 34 JM 3 ADL ACAL 36 JM 37 38 BAK MY TFE INT 39 ACALL 40 AM 41 42 DASR MV THE SI GAL 43 MOV 44 JZ 45 Ed ON 0 1 FEETS 46 AM 47 ERE dR 48 ACALL 49 SETB 50 ACALL 51 AM 52 RN REN 53 54 DELAYO1 G NE 55 A M 56 X MY 57 LOPL MY 58 D NZ 59 D NZ 60 NC 61 RET 62 63 SON GR SOUND 64 MV LIMT 10 FEET 1 FEET CALL DELAY FCR THE 1 FEET TI ME R7 11 R7 ALO1 DELAYO1 E 00H AFTER THE CHECK NG RESET FCR SOUND CEN PROGRAM ext tO program TO USE TORECEI VE AC ERL1 SAND CEN PROGRAM EACH TIM pl 5 SLELAY pl 5 SLELAY ECHL Ro 1 CHECK BACK R1 4 lus R2 227 lus R2 2us 229 2 1 459us R1 LOCP1 2us 459 2 2 1836us R5 DELAY 1 FEET PROGRAM P1 5 SAND PROGRAM FOR N THE SYSTEM NORMAL A R5 65 JZ SSA 66 SS ON AGS 67 JP Sg 68 SH ANL SEELAY 69 AM SSI 70 SS SEB PL5 71 MY ARS 7 SS ON a ccsar 73 JP ss4 7 SGD AAL SOW 75 AM 653 7 S SEB PLS 77 RET 78 7 SDELAY MV RL3200 1U5 0 1S DELAY PROGRAM 80 SLOPl MY R2 250
6. And RC factor can defined by follow equation c 1 V 27 fo R as r 560k freq fo 40khz c 11 v 2m 40khz 560k 100p As upper result second stage 1s a bandpass filter that selected 40khz signal 11 Here are third parts of the hardware the CPU part 402 signal out el ADA u WV H E 4 s s s s The CPU P1 7 generate a 3ms width 40khz pulse signal to the transmission part after that the INTO wait to receive a signal from the receiver part Whatever the receiver part have a signal or not that the CPU will generate a sound about every signal second to indicate the CPU is running properly If a reflect signal was pick up at the receiver part the burst sound will be generate If the reflect signal 1s very close a signal will send to P1 4 to control the vibrator to vibrate 12 Part list 560k 4 l Capacitor 7k Ok luf V 1 Ouf LM po Lo 00 _ Lo 789 _ Lo 8902051 _ Lo 4069 Lo A551 Ultrasound transducer 400ST160 400RI60 i NN LT o duf 1 a M MA LE ae Li ME l l l l l l l l l Software Program listing O O uN HGH UJ N N N N N N N N N N PP PPP PrP ere HP O O ON ADU BWNeF O UO O DD BWN PP O DO CCP CRG AM SETB D NZ CLR D NZ D NZ MOV D NZ D NZ D NZ SETB 00H START 03H EXOI SR 100H SP 60H E 00H R5 0 Ro 0 R1 6 P1 5 P1
7. transmits will need two time so the looping will use 0 6ms 29 38 42 61 is the receiver program 29 30 is use to setup the IntO and enable the trigger 32 R7 is use to limit the detect range 1Ofeet 1 feet 33 amp 34 is use observe that the detect range has been out now 35 1s use to call 1 feet time counter delay to counter feet 38 1s use to disable the input signal after the counting feet 42 521s a IntO service routine 42 1s use to set the flag R6 to Ack the main program that 1s the signal 1s receive 45 52 1s use to feet counter to generate the sound when the less feet has been count the sound will be generate more frequently There 1s about 0 1 second generate in every period 54 61 1s a delay program to counter the 1 feet ultrasound transmits in the air the ultrasound transmits has been cal to 1836us 39 40 63 84 1s the sound generate program 39 40 1s use to call the sound program to generate system normal beep sound no detect 63 84 1s the procedure that generate single beep sound 63 is use to enable the sound 64 84 1s the procedure that make a 0 5s delay Flowchart The flowchart of the main program Generate the 40kHz for 0 3ms 4 Detect range Time out Reflect signal Counter timing converter to desistance Generate sound Wave Object too Near Trigger to Vibrator The flowchart of the transit a 0 3ms 40khz ultrasound pulse Set transmit bit to 1 state
8. Abstract There is so many blind persons that use a blind stick to help their dally walking or life But the blind stick will be hit some person when the blind stick waggling So there 1s need to develop new walking stick that the stick can be detected the obstacle stealthy So the bat are the very best object to learn at to stealthy detected the obstacle From observe the bat we have a conclusion that use a ultrasound for the detected the obstacle 1s a good way to do and the new walking stick is use ultrasound theory of the bat perform by the microproccer and the electronic component This walking stick can be help the blind persons or the person hit by the old waggling blind stick Aims This Electronic Walking Stick for the Blind 1s use to help the blind person to detect obstacle and depressions in front of him After detect an object in front of the blind person the Electronic Walking Stick will be sound a the tone of warning signal and warning signal will change gradually when the blind person get closer to the obstacle Also 11 too close to the object it will generate a vibration signal with the vibrator 4 Scope In our project we will focus on the ultrasound propagation technique sound speed And follow are the basic theory the ultrasound propagation technique sound speed in the free air Pulse echo technique This technique 1s a means of underwater Echolocation developed by the military for locating submarines Brief pulses of ul
9. ill like this You will observe a 5V Tp1 or 9V Tp2 X 6 pulse and every single pulse period is 2508 ronca Tp4 os cs Se eee aF u tie al B a DH sa 1 QU c An6551 Ea in JE d Fig2 2 Apply test probe to fig2 Tp3 at he normal situation will like this The pulse will more than 4mV and not more than 2us second pulse width 21 21 2 Apply test probe to fig2 Tp4 at he normal situation will like this 1f the obstacle 1s hit The pulse width will not less than 2ms and the level will not less than 40mv 3 apply test probe to fig2 Tp5 at he normal situation will like this 1f the obstacle is hit The pulse width will not less than 2ms and the level will not less than 1V peak to peak c fkhesigmdleut PEZ E ore ee ee DO i et as ls Tp7 o a p Liz 11 wibrator d Tvibrator A o E E 4 3 3 Se 3 Apply the test probe to Tp6 amp Tp7 and the result when obstacle hit tp6 will appear a burst pulse the single pulse width will not less then 0 1s all of the pulse not more than 1s when the obstacle at 10 feet tp6 will generate 2 pulse 1 feet will generate 10 pulse etc when the obstacle at 2 feet or below Tp7 will have a turn to Ov in normal there is a 5v in Tp7 Result Here are the result of our observe aA eed 4065 P17 z 12 113 40Khz signal in i E
10. made signal distort the signal itself because of the signal to noise ratio 18 not very good about 1 2 2 noise 4 signal So there 1s not to do with the receiver part at now we think that the transmit part should use follow method to improve the signal that picked up at receiver 1 Parallel connection resistor to the transducer at the transmit part to matching the transducer to cause full power transfer 2 Connect a amplifier between the microproccer 40kHz pulse clock output and the transducer to increase transducer voltage 27 Conclusion The electronic walking stick is a portable electronic product the power consummation is mainly target to due with But the transmit and receive circuit will have a great power lost it will power down when the blind person that on the street so the walking stick may need to design less power lost and indicate the blind person to change their battery when it was too late 28
11. trasound ranging from 21kHz to 50 kHz are emitted in narrow intense beams The pulses hit to hard surface 11 makes the echoes of these pulses returning at different time intervals depending on the Speed of Sound in the medium Form the timing from travel time between measurements to surface can be converted the distance between each other Here are the times schedule of the pulse echo technique detect method T Emit detect pulse Os o V R2 2 o V RL 2 The speed of the ultrasound in the air In 1816 the mathematician Laplace proposed that the speed of a longitudinal wave in a gas 1s given by Ve e Where p 18 the pressure of the gas p the density and Y isa dimensionless constant the ratio of the specific heats of the gas this is covered in the unit Thermal properties In the Atmospheric pressure Y 1 4 P 0 76x13600x9 8 Pa p y 14x076x13600 98 1 24 so that v is 1 29 v 332 ms it means that the ultrasonic will traffic in the air is 332m per second Specification Supply voltage 12v supply by high voltage battery VA23GA Transmit amp receiver frequency 40kHz Detect method pulse echo technique Sampling rate 1 time second Detect range 10 feet Accuracy 1 feet Detect angle 45 Design Block system level diagram for hardware Pizeoelectric Transducer transfer pulse Signal Ultra sound pulse generate unit Produce by 89c51 to ultra sound

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