The document presents the design of a smart fuel theft detector system. It begins with an acknowledgment and dedication section. It then provides a table of contents and list of figures. The document discusses conducting a survey on fuel theft, presenting the problem and goals of the project. It describes the methodology and components of the solution, including using ultrasonic and slope sensors, a microcontroller, GPRS module for data transmission. It concludes with experimental results on the sensors and an overall conclusion.

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SMART Fuel Theft Detector

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An-Najah National University
Electrical Engineering Department
Graduation Project 2
SMART Fuel Theft Detector
Supervisor:
Dr. Samer Mayyalih
Prepared by:
Amjad Rabayaa
Adham Sawafta
December 2013

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‫اإلهــــــداء‬
‫هللا‬ ‫بسم‬‫الرحيم‬ ‫الرحمن‬
‫الحمد‬‫يعلمون‬ ‫ال‬ ‫والذين‬ ‫يعلمون‬ ‫الذين‬ ‫يستوي‬ ‫هل‬‫ل‬‫ق‬ .. " ‫التنزيل‬‫محكم‬ ‫في‬ ‫ائل‬‫الق‬ ‫العالمين‬‫رب‬‫هلل‬.. "‫والصالة‬‫األنام‬‫خير‬‫على‬ ‫والسالم‬
‫على‬ ‫العالم‬ُ‫ل‬ْ‫ض‬َ‫وف‬ .. ‫ة‬َّ‫ن‬‫الج‬‫إلى‬ً‫ا‬‫طريق‬ ‫به‬ ‫له‬ ‫هللا‬ ‫سهل‬ ،ً‫ا‬‫علم‬ ‫فيه‬ ‫يلتمس‬ً‫ا‬‫طريق‬ ‫سلك‬ ‫من‬ .."‫ائل‬‫الق‬‫هللا‬ ‫عبد‬ ‫بن‬ ‫محمد‬‫القمر‬‫كفضل‬ ‫العابد‬
‫و‬ ...‫الكواكب‬‫سائر‬ ‫على‬َّ‫أن‬‫منهاجا‬ ‫بذالك‬ ‫سطر‬ُّ‫ي‬‫ل‬ "‫األنبياء‬‫ورثة‬ ‫العلماء‬ً‫ا‬ّ‫رباني‬.‫والتعلم‬ ‫العلم‬‫حب‬‫على‬ً‫ا‬‫ائم‬‫ق‬
‫بعد‬‫التوكل‬‫الوقت‬‫كل‬ ‫منا‬ ‫استنفذ‬‫لطالما‬ ‫الذي‬ ‫المتواضع‬‫اإلنجاز‬ ‫هذا‬ ‫نهدي‬ ,‫هللا‬ ‫يشكر‬ ‫ال‬ ‫الناس‬ ‫اليشكر‬ ‫من‬ ‫باب‬ ‫ومن‬ ,‫هللا‬‫على‬
‫الكري‬‫هللا‬ ‫وجه‬ ‫نحو‬ ‫بذلك‬ ‫ماضين‬ ,‫والمثابرة‬ ‫الجد‬ ‫من‬ ‫طوال‬ ‫سنوات‬ ‫به‬ ‫تتوج‬ ‫إكليال‬ ‫بذلك‬ ‫ليكون‬ ‫والجهد‬‫م‬‫الجد‬‫على‬‫ائمة‬‫ق‬ ‫حياة‬‫نحو‬ ,
.‫والتضحية‬ ‫واإلجتهاد‬
‫إليك‬..‫إلهي‬‫وخالقي‬
‫الذي‬‫بطاعت‬ ‫إال‬ ‫النهار‬ ‫يطيب‬ ‫وال‬ ‫بشكره‬ ‫إال‬ ‫الليل‬‫يطيب‬ ‫ال‬‫ه‬‫إال‬ ‫ة‬ّ‫الجن‬‫تطيب‬ ‫وال‬ ‫بعفوه‬ ‫إال‬ ‫األخرة‬ ‫تطيب‬ ‫وال‬ ‫بذكره‬ ‫إال‬ ‫اللحظات‬ ‫تطيب‬ ‫وال‬
‫برؤيته‬
‫إلى‬..‫دي‬ّ‫سي‬‫وحبيبي‬
‫يامن‬‫اعته‬‫بشف‬ ‫نطمع‬ ‫من‬ ‫يا‬ ‫امه‬‫لمق‬ ‫العروق‬ ‫بين‬ ‫الدم‬‫ويقف‬ ‫لذكره‬ ‫العيون‬ ‫وسط‬ ‫من‬ ‫الدمع‬‫يسيل‬
‫محمد‬‫وسلم‬ ‫عليه‬ ‫هللا‬ ‫صلى‬
‫إلى‬..‫تعالى‬ ‫هللا‬ ‫بعد‬ ‫الوجود‬‫في‬ ‫من‬ ‫كل‬
‫سندي‬ّ‫ا‬‫من‬ ,‫هللا‬ ‫بعد‬ ‫ومالذي‬ ‫وقوتي‬‫ثروني‬‫واألمل‬ ‫اؤل‬‫والتف‬ ‫الصبر‬ ‫ومعنى‬ ‫الحياة‬ ‫معنى‬ ‫وعلموني‬ ‫أنفسهم‬‫على‬
‫والدي‬‫إنتظار‬ ‫بدون‬ ‫العطاء‬‫علمني‬ ‫من‬ .. ‫العزيز‬
‫أمي‬‫اء‬‫الشف‬‫وبلسم‬ ‫الحب‬‫رمز‬ .. ‫الحنون‬
‫إخواني‬‫..الذ‬ ‫وأخواتي‬‫المعين‬‫نعم‬ ‫فكانوا‬ ‫والمؤازرة‬ ‫المساندة‬‫اشكال‬‫بكل‬ ‫امدوني‬ ‫ين‬
‫أهلي‬... ‫بجانبي‬ ‫وقف‬ ‫من‬ ‫وكل‬ ‫بلدي‬ ‫وأهل‬ ‫وعشيرتي‬
‫إلى‬..‫خطوت‬‫نخطوا‬ ‫ونحن‬ ‫ووداعهم‬ ‫شكرهم‬ ‫علينا‬ ‫وجب‬ ‫الذين‬‫نا‬‫يبخل‬ ‫لم‬ ‫الذين‬ ,‫الحياة‬‫غمار‬ ‫في‬ ‫األولى‬‫وا‬‫ووقتهم‬ ‫بعلمهم‬ ‫علينا‬
‫الذين‬‫أينا‬‫ر‬‫األوفياء‬‫وسماحة‬ ‫العلماء‬‫وتواضع‬ ‫األباء‬‫محبة‬ ‫فيهم‬

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‫الدكتور‬‫الكهربائية‬ ‫الهندسة‬‫قسم‬ ‫رئيس‬ ‫خماش‬‫ماهر‬
‫الدكتور‬‫بريك‬ ‫عماد‬
‫الدكتور‬‫خير‬‫كل‬ ‫ا‬ّ‫عن‬ ‫هللا‬ ‫اه‬‫ز‬‫ج‬ .. ‫المشروع‬ ‫هذا‬ ‫على‬ ‫افه‬‫ر‬‫بإش‬ ‫تفضل‬ ‫الذي‬‫ميالة‬ ‫سامر‬
‫و‬‫الوطنية‬‫النجاح‬‫جامعة‬‫في‬ ‫الكهربائية‬ ‫الهندسة‬‫أسرة‬‫كل‬
‫إلى‬‫م‬ ‫الذين‬‫والقهر‬ ‫والظلم‬ ‫الغدر‬‫زنازين‬ ‫في‬ .. ‫هناك‬ ‫الوا‬‫ز‬‫ا‬
‫يامن‬‫الشهداء‬‫ألرض‬ ‫فداءا‬ ‫أعماركم‬‫دفع‬ ‫اليتم‬ ‫يامن‬ ‫بصبركم‬ ‫للنصر‬ ‫وحون‬ّ‫ل‬‫وت‬ ‫بصمودكم‬ ‫الحرية‬ ‫تكتبون‬
‫نعم‬‫سالم‬ ‫الف‬ ‫ا‬ّ‫من‬ ‫لكم‬ .. ‫األسرى‬ ‫..أيها‬
‫أما‬‫الوطن‬ ‫امتداد‬‫على‬ ‫النصر‬‫هة‬ّ‫فو‬ ‫ورسمتم‬ ‫اء‬‫البق‬‫حب‬‫فينا‬ ‫زرعتم‬ ‫من‬ ‫يا‬ ..‫أنتم‬
‫نسألكم‬‫منكم‬ ‫لنستلهم‬ ‫األيادي‬ ‫تمدوا‬ ‫أن‬‫ما‬‫جهادكم‬‫ومضات‬ ‫على‬ ‫يحيينا‬
‫سالم‬‫ريعا‬ ‫في‬ ‫األحياء‬‫أيها‬‫ن‬‫الشهادة‬

5. Page | 5
Contents
ACKNOWLEDGMENT...............................................................................Error! Bookmark not defined.
Table of Figures..................................................................................................................................6
CH 1 SURVEY...................................................................................................................................7
1.1 THE SURVEY ........................................................................................................................7
1.2 RESULTS AND ANALYISIS ......................................................................................................9
CH 2 Introduction..........................................................................................................................11
2.1 PROBLEMTO SOLVE...........................................................................................................11
2.2 ABSTRACT.........................................................................................................................12
2.3 METHODOLOGY.................................................................................................................13
2.4 ENVIRONMENT OF WORK ..................................................................................................14
CH 3 SOLUTION.............................................................................................................................15
3.1 FUEL MEASURMENT...........................................................................................................15
3.1.1 THE FIRST PROPER SENSOR (HC-SR04) .........................................................................15
3.1.2 THE SECONDPROPER SENSOR(LSM303DLH)…………………………………………………………………16
3.1.3 MICROCONTROLLER.................................................................................................187
3.1.3 FILTERING & PROCESSING......................................................................................... 219
3.2 TRANSMISSION OFDATA……………………………………………………………………………………………………….22
3.2.1 GPRS MODULE……………………………………………………………………………………………………………….22
3.2.2 INTERFACING BETWEEN THE GPRS AND THE CONTROLLER ...........................................25
3.2.3 TRANSMISSION USING GPRS MODULE.........................................................................25
3.3 The Whole system .............................................................................................................25
CH 4 CONCLUSION ANDOBSERVATIONS…………………………………………………………………………………………….25
4.1 Experiment on the Sensor..................................................................................................27
4.2 CONCLUSION.....................................................................................................................29
Bibliography.....................................................................................................................................31
APPENDEX A.1: The Code of the PIC16f877a.......................................................................................32

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Table of Figures
Figures1.2-1 The surveyresults………………………………………………………………………………………………………………7
Figure 3.1-1 Ultrasonic principle ........................................................................................................13
Figure 3.1-2 The HC-SR04 ultrasonic sensor........................................................................................14
Figure 3.1-3 The Principle of Work Ultrasonic Sensor...........................................................................17
Figure 3.1-4 Timing Diagram of the Ultrasonic Sensor.........................................................................17
Figure 3.1-5 The LSM303DLE slope sensor..........................................................................................20
Figure3.1-6 PIC16f877a…………………………...................................................................................................17
Figure 3.1-7 Flow Chartfor the Microcontroller .............................................................................. 2422
Figure 3.2-1 GPRS module.................................................................................................................25
Figure 4.1-1: 12cm distance from a rigid body ....................................................................................27
Figure 4.1-2: 16cm distance from a rigid body ....................................................................................27
Figure 4.1-3: 20cm distance from a rigid body ....................................................................................27
Figure 4.1-4: 24cm distance from a rigid body ....................................................................................27
Figure 4.1-5: Test of the Sensor on Fluids............................................................................................28

7. Page | 7
CH 1 SURVEY
1.1 THE SURVEY
Afterwe choose ourprojectidea we did a short survey about the projectto ensure thatthe system
isimportantfor the ownersof transport companies, aswell as find out if they have usedotherdevices
to solve the problem and how the success of these devices. In addition to that we want to identifythe
extent of the Palestinian marketneed forthe project and the possibility of marketingit effectively.
Our surveyis shownbelowinArabicaswe distributedit:
‫الى‬ ‫إرسالها‬ ‫و‬ ‫دقيق‬ ‫بشكل‬ ‫التنك‬ ‫داخل‬ ‫الوقود‬ ‫كمية‬ ‫حساب‬ ‫على‬ ‫يعمل‬ ‫جهاز‬ ‫بناء‬ ‫على‬ ‫المشروع‬ ‫فكرة‬ ‫تقوم‬
‫تج‬ ‫مناسبة‬ ‫بطريقة‬ ‫الجهاز‬ ‫وصمم‬ ‫دوري‬ ‫بشكل‬ ‫الشركة‬ ‫مقر‬‫عله‬‫ثم‬ ‫ومن‬ ‫الوقود‬ ‫إستهالك‬ ‫مقدار‬‫تتبع‬ ‫على‬ ‫قادرا‬
‫عن‬ ‫السرقة‬ ‫إكتشاف‬‫السرقة‬ ‫عن‬ ‫تبلغ‬ ‫فورية‬ ‫رسالة‬ ‫بإرسال‬ ‫يقوم‬ ‫حيث‬ ‫حدوثها‬ ‫د‬‫وكمية‬.‫المسروقة‬ ‫الوقود‬
‫ت‬ ‫على‬ ‫العمل‬ ‫فريق‬ ‫تساعد‬ ‫بطريقة‬ ‫وضع‬ ‫التالي‬ ‫اإلستبيان‬‫وقع‬‫وساعات‬ ‫يوميا‬ ‫المسروقة‬ ‫الوقود‬ ‫كميات‬
‫الوسائل‬ ‫جميع‬ ‫اإلعتبار‬ ‫بعين‬ ‫األخذ‬ ‫مع‬ ‫السرقة‬ ‫حالة‬ ‫مع‬ ‫التعامل‬ ‫طريقة‬ ‫من‬‫البيانات‬ ‫هذه‬ ‫تسهل‬ ‫حيث‬ ‫السرقة‬
.‫الوقود‬ ‫سرقة‬ ‫في‬ ‫المتبعة‬
‫ما‬‫دوري‬ ‫بشكل‬ ‫المستهلكة‬ ‫الوقود‬ ‫لكميات‬ ‫الدقيقة‬ ‫المعرفة‬ ‫أهمية‬ ‫هي‬
‫مهم‬‫جدا‬
‫مهم‬
‫محايد‬
‫غير‬‫مهم‬
‫الشعور‬‫ب‬‫الوقود‬ ‫سرقة‬
‫متأكد‬‫السرقة‬ ‫وجود‬ ‫من‬
‫شاك‬‫السرقة‬ ‫بوجود‬
‫ال‬‫لي‬ ‫علم‬
‫متأكد‬‫سرقة‬ ‫وجود‬ ‫عدم‬ ‫من‬
‫في‬‫الوقود‬ ‫سرقة‬ ‫تكون‬ ‫الغالب‬
‫أثناء‬‫المركبة‬ ‫عمل‬
‫خارج‬‫المركبة‬ ‫عمل‬ ‫ساعات‬
‫في‬‫السابقتين‬ ‫الحالتين‬ ‫كلتا‬
‫في‬‫قبل‬ ‫من‬ ‫الوقود‬ ‫سرقة‬ ‫تكون‬ ‫الغالب‬
‫سائق‬‫الشاحنة‬
‫ناس‬ُ‫أ‬‫(أثناء‬ ‫العمل‬ ‫خارج‬ ‫اخرون‬)‫العمل‬ ‫عن‬ ‫المركبة‬ ‫توقف‬
‫ال‬‫أعلم‬

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‫بكم‬‫شهريا‬ ‫المسروقة‬ ‫الوقود‬ ‫كمية‬ ‫تقدر‬.................................................................................................
‫هل‬‫الوقود‬ ‫سرقة‬ ‫من‬ ‫يمنع‬ ‫أو‬ ‫عن‬ ‫يكشف‬ ‫جهاز‬ ‫شراء‬ ‫حاولت‬
‫نعم‬
‫ال‬
‫إذا‬‫نعم‬ ‫اإلجابة‬ ‫كانت‬
‫ما‬‫عمل‬ ‫طبيعة‬ ‫هي‬
........................................................‫الجهاز؟‬.....................................
............................................................................................................................................
‫ما‬‫سعر‬ ‫هو‬
............................................................‫الجهاز؟‬.........................................
‫هل‬‫؟‬ ‫المشكلة‬ ‫حل‬ ‫على‬ ‫وقادرا‬ ‫اال‬ّ‫ع‬‫ف‬ ‫الجهاز‬ ‫كان‬
‫نعم‬
‫ال‬
‫إذا‬‫؟‬ ‫برأيك‬ ‫السبب‬ ‫هو‬ ‫فما‬ ‫ال‬ ‫اإلجابة‬ ‫كانت‬
.............................................................................................
............................................................................................................................................
‫هل‬‫؟‬ ‫المشكلة‬ ‫حل‬ ‫لك‬ ‫يكفل‬ ‫جهاز‬ ‫لشراء‬ ‫مستعد‬‫أنت‬
‫نعم‬
‫متردد‬
‫ال‬‫أرغب‬

9. Page | 9
1.2 RESULTS AND ANALYISIS
Evenour sample wasnotlarge enoughdue to the limitedcompaniesandfoundationswhichare
nearto us, we can say the following:
 The majorityof companiesstatedthatit isveryimportantforthemto identifyexactlytheir
expenses onthe fuel consumption.
 A significantnumberof the sample suffersfromuncertaintyinthe amountof itsfuel
consumption.
 Some of the companiesare sure thatthere issome kindof fuel theftfromtheirvehicles.
 Some of the companieshave alreadybought asystemtofindtrackthe fuel consumptionin
theirvehicles.
 Some of the companiesmentionedthatthe fuel theftisperformedbypersonsnotfromthe
drivers.
To understandthe surveyoutputsee the figuresbellow.
Figures1.2-1 the survey results

10. Page | 10
As we expected,thisphenomenaispresentandneedtoa reliable andcost-effective solutionwhich
can calculate the fuel consumptionanddetectthe fuel theftif happened.

11. Page | 11
CH 2 Introduction
2.1 PROBLEM TO SOLVE
Due to the high fuel price, fuel theft became worrying phenomenon and it is very
important for companies and foundations to monitor its fuel consumption rate in order to put
its best budget.
According to the Palestinian distributing fuel stations the cost of one litter of diesel in
excess of 5.7 NIS (as of 12:00 a.m. April 29, 2013), so any storage of fuel can be a target for
theft as well as transportation vans. In our project we provide a smart electrical system to help
our client to deal with this problem and we aim to protect our clients from the fuel theft
especially the transportation vans and vehicles.
Our duty to stop the fuel theft so, before we start the smart fuel level detector idea, we set
some advice for the fuel consumers which can help to a void the fuel theft.
 Consider installing a locking gas cap. Remember that many of the “fuel doors” that open
remotely or with a key are flimsy and easily compromised.
 Avoid parking in dark, isolated areas (especially for extended periods).
 At home, park in a locked garage where possible. If you don’t have a garage, park as
close as possible to the house and avoid parking on the street.
 If you must park on a street or in a parking lot, attempt to locate your vehicle so the fuel
door is visible to you or other residents in your area.
 If you have bulk fuel on your property, ensure you lock the tank and or dispenser to
prevent access.
Our fuel level detector continuously monitors your tank fuel with the ultrasonic fuel
detector, the easiest solution to prevent fuel theft and fraud.
Fuel theft: the moment our system tracks an unusual rate of decrease in the fuel-level (i.e.
in usual conditions, the vehicle consumes a certain amount of fuel; while in the theft case, the
rate of decrease of the fuel will be faster than the usual case) the fuel-tracker will send an
alarm via a GPRS module (may be a SMS) and can be automatically configured to ring an
audible alarm when the fuel theft occurs. The tracker is sensitive enough to detect when
someone tries to 'skim' excess fuel from a vehicles tank.

12. Page | 12
2.2 ABSTRACT
The level of the fuel, especially in cars and vehicles, is very important since it gives
indication about the remaining amount of fuel in the tank of the vehicle. However, particularly,
for the companies which have number of vehicles it is essential to monitor the fuel level at all
times in order to identify its budget and expenses also to capture the fuel theft.
The level measurement of fuel in the vehicle’s tank is a special case of general level
measuring applications because:
 The flammability of the fuel, so it is very dangerous to put any electrical devices or
wires inside the fuel tank.
 The very accurately closed tank, so it isn’t preferred to make holes other than the
main opening.
 The dynamic motion of the fuel, which means that the measuring process must take
into consideration the road condition such that if the road is flat or has some slope
(either positive or negative).
In our project, we aim to design a smart fuel level measuring system which:
 Measures the amount of fuel in the tank accurately and in real time.
 Has the ability to measure the amount of fuel even if the vehicle is moving on a flat
or has some slope roads.
 Can store the measurements in order to do some extra process such as consumption
rate per day or month … etc.
 Can be configured with a microcontroller to send the measurements via GPRS.
 Capture the fuel theft even if the vehicle is turned off!
Finally, our scope of work will be:
 Specify which kind of sensors will be suitable for our requirements.
 Make some data processing such as Filtering.
 Store the measurements.
 Capable to make data communication (GPRS).
 Display the measurements as graphical representation.
 Alarm in case of fuel theft.

13. Page | 13
2.3 METHODOLOGY
The methodology will be followed at this project is to:
 Identify the elements of the project and the functionality of each one.
 Identify the circumstances which presents in the environment surrounding the
project.
 Find the best arrangement of the elements of the system in order to achieve the
best performance.
 Find the best and safe way to take the measurements of the fuel.
 Write the best code of the microcontroller to filter and process the sensor’s
measurement.
 Connect the microcontroller to the GPRS module in order to send the measurements
to the site of the company.

14. Page | 14
2.4 ENVIRONMENT OF WORK
For the work environment there are many criteria that must be taken into consideration. If
we want to put the sensor on the surface of the tank we will be forced to make a suitable slot
to fix the sensor, for this reason it must be very careful because small arc will lead to huge
explosion. In addition of that, the large needed to speed and accurate transmission methods.
So in our project we have taken a lot of things in consideration, for example:
 Chemical properties of the diesel.
 Small dimensions of the sensor.
 The temperature effect on the sensor reading.
 A suitable sensor which works at low voltage.
 Good transmission methods like GPRS and GSM.
All these things and more will make from our system as safe as possible.

15. Page | 15
CH 3 SOLUTION
3.1 FUEL MEASURMENT
3.1.1 THE FIRST PROPERSENSOR (HC-SR04)
In a large number of ultrasonic distance measurements, the operating principle is
the estimation of time of flight (ToF) Tf. The sensor generates ultrasonic pulses and
these pulses will be reflected to the receiver when it reaches the fuel surface as shown
in figure 3.1-1. So that the distance can be estimated directly by the formula:
V: represents the propagation velocity of the ultrasonic wave in the medium (air).
Figure 3.1-1 Ultrasonic principle
According to the previous equation we see that the distance depends directly on
the propagation velocity of the ultrasonic wave and this quantity depends on the
relative humidity and the temperature, and also on some chemical and physical
parameters of the fluid. More over the time of flight will control the measured
distance.
In the ultrasonic system two kinds of sensing are possible (1) :
 The continuous wave method
 The pulse echo method
In our project there are many things must be considered when we select the
sensor kind, so we saw the advantages and the disadvantages for both kind.
Let us start with the first type which is the continuous wave method. In this
method two separate transmitting and receiving elements are used, so that the level is

16. Page | 16
evaluated through the estimation of a phase shift. In this case good performance can
be obtained, but a more complex hardware system is necessary.
The pulse echo method, on the other hand, requires only one transducer that
operates alternately in transmitting and receiving method. Also pulse echo method
offers a simple and low cost solution, even it yields poorer results due to uncertainty
in the time delay measurement .These results, in fact, can be improved by using a
cheap software signal processing.
However, our HC-SR04 ultrasonic sensor is included under the continuous wave
method but with some modification which is instead of the output in the form of
phase shift it is here a PWM (pulse width modulation) such that the time of flight is
represented by the width of the echo signal from the ultrasonic.
The HC-SR04 (2) ultrasonic sensor as shown in figure 2.3-1 is small and
meets our requirements so as not to take large space on the tank.
As shown, it has four legs:
 VCC: 5 volt
 GND: zero volt (ground).
 Trig: a 10us 5 volt pulse to start the sensor.
 Echo: the output signal of the sensor.
Figure 3.1-2 The HC-SR04 ultrasonic sensor
Ultrasonic ranging module HC - SR04 provides (2cm - 400cm) non-contact
measurement function, the ranging accuracy can reach to 3mm. The module includes
ultrasonic transmitter, receiver and control circuit.
The basic principle of work, figure 3.1-2 clarifies this principle:
1- Using IO trigger for at least 10us high level signal.
2- The Module automatically sends eight 40 kHz and detect whether there is a
pulse signal back.
3- IF the signal back, through high level , time of high output IO duration is the time
from sending ultrasonic to returning.
4- Test distance = (high level time X velocity of sound (340 m/sec) / 2

17. Page | 17
Figure 3.1-3 The Principle of Work Ultrasonic Sensor
Timing diagram
Figure 3.1-4 Timing Diagram of the Ultrasonic Sensor
The Timing diagram is shown in figure 2.3-2. We only need to supply a short 10uS
pulse to the trigger input to start the ranging, and then the module will send out an 8
cycle burst of ultrasound at 40 kHz and raise its echo. The Echo is a distance object
that is pulse width and the range in proportion .We can calculate the range through
the time interval between sending trigger signal and receiving echo signal.
The formula to calculate the distance is:
uSec / 58 = centimeters
or uSec / 148 =inch
or the range = high level time * velocity (340 m/sec) / 2
It is recommended to use over 60ms measurement cycle, in order to prevent trigger
signal to the echo signal.

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3.1.2 THE SECOND PROPERSENSOR(LSM303DLH)
Figure 3.1-5 The LSM303DLH slope sensor
Description:
The LSM303DLH is a system-in-package featuring a 3D digital linear acceleration sensor and a
3D digital magnetic sensor. The various sensing elements are manufactured using specialized
micromachining processes, while the IC interfaces are realized using a CMOS technology that
allows the design of a dedicated circuit which is trimmed to better match the sensing element
characteristics. The LSM303DLH includes an I2C serial bus interface that supports standard
mode (100 kHz) and fast mode (400 kHz).The system can be configured to generate an interrupt
signal by inertial wakeup/free-fall events, as well as by the position of the device itself.
Thresholds and timing of interrupt generators are programmable on the fly by the end user.
Magnetic and accelerometer parts can be enabled or put in power-down mode separately. The
LSM303DLH is available in a plastic land grid array (LGA) package, and is guaranteed to operate
over an extended temperature range from -30 to +85 °C. See the table below. (3)
Sensor Features
 Analog supply voltage: 2.5V to 3.3V.
 Digital supply voltage IOs:1.8V.
 Power-down mode.
 3 magnetic field channels and 3 acceleration channels.
 16 bit data out.
 I2C serial interface.
 2 independent programmable interrupt generators for free-fall and motion
detection.
 Embedded self-test.
Applications
 Compensated compassing.
 Map rotation.
 Position detection.

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 Motion-activated function.
 Free-fall detection.
 Display orientation.
 Vibration monitoring and compensation.
In our project, we used this sensor to determine the slope of the road so as to find the actual
fuel level even in the tilted roads this is due to the fact that most of our roads are tilted!
So we have derived an equation which relates the slope of the tank with the distance from the
Ultrasonic sensor to determine the fuel level as accurate as possible. However, the LSM303DLH
sensor communicates through the I2C protocol which is differ from the Ultrasonic which is
connected to the microcontroller directly, so we provide here some description of this protocol.
As for the coding of this sensor, it is attached in the appendix.
I2C serialinterface
I²C (Inter-Integrated Circuit, referred to as I-squared-C, I-two-C, or IIC) is a multimaster serial
single ended computer bus invented by Philips used for attaching low-speed peripherals to a
motherboard, embedded system, cell phone or other electronic device. At the low end of the
spectrum of communication options for "inside the box" communication is I2C .The name I2C is
shorthand for a standard Inter-IC (integrated circuit) bus.
I2C provides good support for communication with various slow, on-board peripheral devices
that are accessed intermittently, while being extremely modest in its hardware resource needs.
It is a simple, low-bandwidth, short-distance protocol. Most available I2C devices operate at
speeds up to 400Kbps, with some venturing up into the low megahertz range. I2C is easy to use
to link multiple devices together since it has a built-in addressing scheme. (4)
3.1.3 MICROCONTROLLER
All kinds of sensors need some device to process its readings and
measurements, so it’s common to find in such systems microcontrollers. The
common microcontrollers are PIC and ARDUINO. In our project we will use
the PIC microcontroller PIC16f877a which is shown in figure 3.1-5.

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Figure 3.1-6 PIC16f877a
These microcontrollers can be connected to more than one sensor and
devices such as small DC motors, LCD, computers and GPRS modules. Also
theses microcontrollers can be programmed using high level languages in
order to operate as the designer wants.
The PIC16f877a microcontroller is manufactured by MICROCHIP©
company. The oscillator which will be used is a crystal of 4 MHz frequency,
which allows us to take number of readings from the sensors per minute in
order to get the best and accurate reading in different conditions. The most
important feature of the PIC16f877a for this project is the capture property
which can trigger or start a timer when the rising edge of the echo signal
(from the ultrasonic) reach the microcontroller, then the value of that timer
can be directly treated as the time of flight Tf . However more details will be
mentioned in Appendix A.1.
However, the code of the microcontroller will convert measured distance
by the ultrasonic into a volume reading depending on the shape and
dimensions of the tank.
It is important to mention that each kind of vehicles has its own tank
shape and dimensions, so our system will be adaptive such that for each
vehicle the dimensions of the tank must be taken into consideration in the
programing process of the microcontroller which will be fitted on it.

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3.1.4 FILTERING & PROCESSING
After we did the survey we saw that there is a great importance to stop the fuel theft as
well as give accurate readings for the fuel level and in real time. As we said before, the
main function of our system to tracks an unusual rate of decrease in the fuel-level and we
said too the tracker is sensitive enough to detect when someone tries to 'skim' excess fuel
from a vehicles tank. After we stared the project we saw that there are two main
limitations to give an accurate reading in real time. Actually the two limitations are the
same but in different position and each one required special method to solve. The two
limitation leads to dynamic motion of the fuel. And because of the fuel inside the tank will
be dynamic, so it is important to take number of readings from the ultrasonic and then
make the filtering to it. We will perform the filtering process through the microcontroller
such that we will do averaging to these readings and take its average. Then we will
compare this reading of the fuel level with another reading after a specific time (this time
is determined from the vehicle itself according to its usual consumption rate of fuel) then
if the difference is greater than the usual consumption rate of fuel then a warning signal
will be sent to the GPRS module which in turn will send it to the appropriate address to
alarm for fuel theft. By the way, figure 2.1-4 shows a flow chart for our programed
microcontroller.
In this part we would like to explain the two limitations and what are the methods
which we used to solve these two limitations.
 The first problem occurs when the vehicle is moving on a flat road but this
road has large Protrusions. See the figures bellow

22. Page | 22
To solve this problem it is important to take number of readings from the ultrasonic sensor
and then make the filtering to it. We will perform the filtering process through the
microcontroller such that we will do averaging to these readings and take its average.
To solve this problem we did a simple averaging for the values because the normal
decreasing of the fuel level is small and so no needed to make a complicated filtering. See
the below equation
Simple filtration equation
 The second limitation occurs when the vehicle is moving on a road has some
slope (positive or negative) slope. See the figure bellow.
Actually we sit some alternatives to solve this problem for example
 The first method is to considerate the consumption rate only by reading the fuel level at
specific time and then we will compare this reading of the fuel level with another reading
after a specific time to calculate the consumption rate according the below equation. If the
consumption rate is greater than the usual consumption rate of the vehicle, the
microcontroller will send an alarm signal to the database on the company. In this way we
can detect the fuel theft which the main function of our project. But the same time we lose
an important thing which is know the fuel level in real time and so we will face some error
in the fuel consumption.
 The second method depends on both the fuel level and the consumption rate at the same
time, and here we ignore the first reading (the reading which make a large variation). In
this method we set a three probability.
1) Large change in both fuel level and consumption rate.
In this case we ensure that there is a fuel theft or some problem in the fuel tank, so the
microcontroller will send an alarm signal to the database on the company.
2) Large change in the fuel level and usual change in the consumption rate.
In this case we ensure that the vehicle is moving on a road has some slope (positive or
negative slope. And here the microcontroller will send an approximate fuel level
which equals the previous fuel level (from the microcontroller memory) minus the
consumption rate. In this method we give approximation readings, which is good

23. Page | 23
comparing with the other alternatives on the market. But at the same time we faced a
big problem in our country “Palestine” because a high percentage of the roads have a
large slope, and so this method become un valuable in some cases.
3) Small change on the fuel level and large change on the consumption rate.
In this case no probabilities and we ensure that there is a fuel theft from the fuel tank
and so, the microcontroller will send an alarm signal to the database on the company.
 The last method is depending on the same principle of the second method, but here with
more accurate approximation.
In this method we make an experiment to compare between the measured level and the
slope of the fuel level to calculate the accurate “actual” level depending on the bellow
equation.
Where:
D: the actual distance between the ultrasonic sensor and the fuel level
D`: the measured distance between the ultrasonic sensor and the fuel level
:the road slope (the measured angle by LSM303DLH sensor)
However, we can configure and program the microcontroller to periodically send its
reading to the GPRS module in order to allow the company to monitor and save the
consumption of the fuel by its vehicle.

24. Page | 24
Figure 3.1-7 Flow Chart for the Microcontroller
3.2 TRANSMISSION OF DATA
3.2.1 GPRS MODULE
It is a device used to send data through the wireless communication networks; it
needs a SIM card related to the cellular network which provides this service.
Fortunately, the local cellular network provides this service with cheap cost. All what we
need is to provide each module with a SIM card and connect it to the microcontroller to
enable the GPRS module to send the measurements. By the way, the size of GPRS
modules is small as shown in figure 3.2-1 which is very suitable for our project.
Doesthe falling
edge arrived
from the echo
Measure the echo time from
the interrupt (rising edge)
Increment counter
YESNO
Return from interrupt
Delay (1 mSec) to
allow the echo to
interrupt
Divide the echo time by 58
to get the distance in cm
Convert from binary to
decimal
Send the reading
to the GPRS
START
Enable Capture mode of the
microcontroller
Trigger The Sensor (Pulse
for 10uS)
Measure the echo time from
the interrupt (rising edge)

25. Page | 25
Figure 3.2-1 GPRS module
3.2.2 INTERFACING BETWEENTHE GPRS AND THE CONTROLLER
PIC-GSM is excellent board for adding remote monitoring and control in remote
places by GSM cellular network or Ethernet or internet network. (5)
The GSM antenna is built in the board so no need for external expensive GSM
antennas. PIC-GSM have two inputs which could be connected to alarm sensors or just
buttons for user actions (like call pre-loaded phone numbers), on-board temperature
sensor up to 30 meter distance from the module. So we can connect the microcontroller
easily to it in order to achieve the communication between them.
3.2.3 TRANSMISSIONUSING GPRS MODULE
The readings of the sensor will be sent through the GPRS module to a web server in
order to store, process and display the fuel rate consumption for each vehicle to allow
the company to benefit as best as possible to identify its budget.
3.3 The Whole system
As an overall sight on our system, based on the circumstances mentioned in section 1.4, we
have designed our system such that:
 The ultrasonic HC-SR04 will be fitted on the surface of the tank with small hole
(45X20 mm2) with insolating layer to isolate the connections from the fuel inside the
tank, this hole is required to let the ultrasonic waves propagates inside the tank to
measure the level of the fuel.
 The four pins of the Ultrasonic HC-SR04 will be connected to the microcontroller.
 The microcontroller and the GPRS module will be fitted inside the cabin of the
vehicle in order to facilitate the maintenance if required.

26. Page | 26
Finally, the needed power for the system will be fed from the battery of the vehicle and
since those component of the system is a very low power elements there will be no worry
about the consumed power from the battery of the vehicle.

27. Page | 27
CH 4 CONCLUSION ANDOBSERVATIONS
4.1 Experiment on the Sensor
At this part, we have tested the performance of the sensor in measuring the distances from
different objects.
As figures 4.1-1 to 4.1-4 show, the measured distance is displayed on an LCD with the object
is a rigid black body, from those pictures we can see that this sensor is very accurate with taking
into consideration that the object which we intend to measure its distance must be 2cm away
from the sensor as shown in the figures.
Figure 4.1-1: 12cm distance from a rigid body Figure 4.1-2: 16cm distance from a rigid body
Figure 4.1-3: 20cm distance from a rigid body Figure 4.1-4: 24cm distance from a rigid body
2cm
2cm12cm
20 cm 24 cm
16 cm

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Also to ensure that the ultrasonic waves of this sensor don’t penetrate the surface of the
fuel we have performed this part to measure the distance between the sensor and the surface
of the water inside a container of water as shown in figure 4.1-5.
Figure 4.1-5: Test of the Sensor on Fluids
As drawnon the picture,the distance measuredbythe sensorisexactlythe distancebetweenthe
surface of the waterand the sensoras provedfromthe rulerinthe picture.
AS a result,we are nowsure that thissensorwill be able tomeasure exactlythe level of the fuel
inside the tankandthe ultrasonicwaveswon’tpenetrate the fuel.Finally,the remainingthingistodo
the filteringandgetthe propermeasurementwhenthe vehicleisinmotionona tiltedroad.
2c
m
5
cm
Heightof water
inside the container
Ultrasonic
Sensor
12 cm
17 cm

29. Page | 29
4.2 CONCLUSION
As a result of the high cost of the fuel, it is very essential for the companies – which have its
own transportation vehicles and vans- to identify and calculate its consumption and expenses
on the fuel so as to put their efficient and reliable budget.
Also, as we found from the survey, most of the local companies mentioned that it’s very
important for them to know as exact as possible their fuel consumption and expenses.
Moreover, we found there is a critical need for those companies to protect their vehicles from
the fuel theft whoever the thief.
From the need of our market in Palestine, we took the first step in our project and then
started to combine the main features of our system in order to meet the needs of those
companies and foundations. Our duty is to design a ‘smart’ system to mainly detect the fuel
theft in various conditions and secondly allow those companies and foundations to know
exactly their expenses on the fuel.
In the first part of our graduation project, we have studied the circumstances surrounding
the environment of the system and then identified the best and reliable components which will
be assembled and built in the next part of the graduation project in the next semester. The
main part is the sensor responsible to take the level of the fuel inside the tank and we have
chosen the Ultrasonic HC-SR04 sensor for that role, then we have selected the PIC16f877a
microcontroller to filter and process the Ultrasonic readings, finally we have preferred the
GPRS module to transmit the readings to the server of the company in order to store and
handle those readings as they want.
In the second part of our graduation project, we have built the system, combined the
sensors, added new elements like the LSM303DLH, derived mathematical equation to relate the
slope of the road with the fuel level, sent the readings to the microcontroller then through the
serial port to the computer.
One of the problems we faced was the lack and the high cost of the GPRS modules in our
market, as a result, we couldn’t perform the transmission using it, instead we have sent the
data using the serial port of the computer to a database to simulate the real database of the
target company.
Finally, based on our study in the electrical engineering department at an-Najah University,
we hope to design a valuable and useful system so as to contribute to solving one of the

30. Page | 30
problems which our companies face regarding the fuel theft and consumption, which – to some
extent- will help them to do their best in achieving their jobs as better as possible.

31. Page | 31
Bibliography
1. Digital signalprocessing techniquesforaccurateultrasonic. GregorioAndria,FilippoAttivissimo,
NicolaGiaquinto.2001, www.elsevier.com.
2. Freaks, ELEC. UltrasonicRanging ModuleHC - SR04.
3. www.sparkfun.com
4. www.robot-electronics.co.uk
5.Ltd, OLIMEX. www.olimex.com. olimex. [Online] june 2008.
https://www.olimex.com/Products/PIC/Development/PIC-GSM/.
6. MICROCHIP. PIC16F87X Data Sheet.2001.
7. LSM303DLM Sensormodule:3-axisaccelerometerand 3-axismagnetomete.www.st.com
8. STAR. WH1602D LCD datasheet.

32. Page | 32
APPENDEX A.1: The Code of the PIC16f877a
We have written the code in the second part of the project using the PICC language as
follows:
The ultrasonic code:
#include <ultraTest.h>
#include <LCD.C>
#include <math.h>
#use fast_io(B)
int32 echo,timer1; // distancein binary
float height,area,volume;
#int_CCP1
void CCP1_isr(void)
{
set_timer1(0);
clear_interrupt(INT_CCP1);
}
#int_CCP2
void CCP2_isr(void)
{
echo =ccp_2;
clear_interrupt(INT_CCP2);
}
void trig() // triger thesensor by 10usec pulseon the triger pin RB#

33. Page | 33
{
output_low(PIN_C3);
delay_us(3);
output_high(PIN_C3);
delay_us(10);
output_low(PIN_C3);
}
display()
{
//printf(LCD_PUTC,"fD=%gcmnV=%gL",height,volume);
printf(LCD_PUTC,"f%gcm",height);
printf("%g",height);
//printf(LCD_PUTC,"fecho=%Luntimer1=%Lu",echo,timer1);
}
void divide() // convert timeto distanceaccording to thedata sheet oftheultrasonicsensor
{
if(echo) height =echo/58.0; // distanceis measuredin cmaccording to
// the ultrasonic sensor RS323
volume =area*height*0.001; // volume(liter) ofthe fuel provided thatthearea ofthetank is known;
}
void main()
{
setup_timer_1(T1_INTERNAL|T1_DIV_BY_1); //65.5 ms overflow
setup_ccp1(CCP_CAPTURE_RE);
setup_ccp2(CCP_CAPTURE_FE);
lcd_init();

34. Page | 34
enable_interrupts(INT_CCP1);
enable_interrupts(INT_CCP2);
enable_interrupts(GLOBAL);
//Example blinking LED program
while(true){
trig();
delay_ms(1);
divide();
display();
// delay_ms(1500);
}
}
The LSM303DLM code:
#include "D:adhami2c_testtest.h"
#include <LCD.C>
#include <LSM303DLH.h>
int data;
void main()
{
setup_adc_ports(NO_ANALOGS);
setup_adc(ADC_OFF);
setup_psp(PSP_DISABLED);
setup_timer_0(RTCC_INTERNAL|RTCC_DIV_1);
setup_timer_1(T1_DISABLED);

35. Page | 35
setup_timer_2(T2_DISABLED,0,1);
lcd_init();
// TODO: USER CODE!!
enableDefault();
while(1){
readAcc();
printf("n%X",X_H_A);
delay_ms(1000);
};
}
#ifndef LSM303DLH_h
#define LSM303DLH_h
float m_max_x, m_max_y, m_max_z;
float m_min_x, m_min_y, m_min_z;
int X_L_A, X_H_A, Y_L_A, Y_H_A, Z_L_A, Z_H_A;
int X_L_M, X_H_M, Y_L_M, Y_H_M, Z_L_M, Z_H_M;
// address ofacceleometerand magnetometer
#define sad_w_a 0x30 //b'00110000'
#define sad_r_a 0x31 //b'00110001'
#define sad_w_m 0x3C//b'00111100'
#define sad_r_m 0x3D//b'00111101'
#define ACC_ADDRESS (0x30 >>1)
#define MAG_ADDRESS (0x3C >>1)
// register addresses
#define LSM303DLH_CTRL_REG1_A 0x20

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#define LSM303DLH_CTRL_REG2_A 0x21
#define LSM303DLH_CTRL_REG3_A 0x22
#define LSM303DLH_CTRL_REG4_A 0x23
#define LSM303DLH_CTRL_REG5_A 0x24
#define LSM303DLH_HP_FILTER_RESET_A0x25
#define LSM303DLH_REFERENCE_A 0x26
#define LSM303DLH_STATUS_REG_A 0x27
#define LSM303DLH_OUT_X_L_A 0x28
#define LSM303DLH_OUT_X_H_A 0x29
#define LSM303DLH_OUT_Y_L_A 0x2A
#define LSM303DLH_OUT_Y_H_A 0x2B
#define LSM303DLH_OUT_Z_L_A 0x2C
#define LSM303DLH_OUT_Z_H_A 0x2D
#define LSM303DLH_INT1_CFG_A 0x30
#define LSM303DLH_INT1_SRC_A 0x31
#define LSM303DLH_INT1_THS_A 0x32
#define LSM303DLH_INT1_DURATION_A 0x33
#define LSM303DLH_INT2_CFG_A 0x34
#define LSM303DLH_INT2_SRC_A 0x35
#define LSM303DLH_INT2_THS_A 0x36
#define LSM303DLH_INT2_DURATION_A 0x37
#define LSM303DLH_CRA_REG_M 0x00
#define LSM303DLH_CRB_REG_M 0x01
#define LSM303DLH_MR_REG_M 0x02
#define LSM303DLH_OUT_X_H_M 0x03
#define LSM303DLH_OUT_X_L_M 0x04

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#define LSM303DLH_OUT_Y_H_M 0x05
#define LSM303DLH_OUT_Y_L_M 0x06
#define LSM303DLH_OUT_Z_H_M 0x07
#define LSM303DLH_OUT_Z_L_M 0x08
#define LSM303DLH_SR_REG_M 0x09
#define LSM303DLH_IRA_REG_M 0x0A
#define LSM303DLH_IRB_REG_M 0x0B
#define LSM303DLH_IRC_REG_M 0x0C
void LSM303DLH()
{
// These arejustsomevalues for a particular unit; it is recommendedthat
// a calibration bedone for your particular unit.
m_max_x =+540; m_max_y =+500; m_max_z =180;
m_min_x =-520; m_min_y = -570; m_min_z = -770;
}
// Writes an accelerometer register
void writeAccReg(bytesub, byte data){
i2c_start();
i2c_write(sad_w_a);
i2c_write(sub);
i2c_write(data);
i2c_stop();
}
// Reads accelerometer register
int readAccReg(byte sub){
byte data;

38. Page | 38
i2c_start();
i2c_write(sad_w_a);
i2c_write(sub);
i2c_start();
i2c_write(sad_r_a);
data =i2c_read();
i2c_stop();
return data;
}
// Writes a magnetometer register
void writeMagReg(byte sub, byte data)
{
i2c_start();
i2c_write(sad_w_m);
i2c_write(sub);
i2c_write(data);
i2c_stop();
}
// Reads a magnetometer register
byte readMagReg(bytesub)
{
byte data;
i2c_start();
i2c_write(sad_w_m);
i2c_write(sub);
i2c_start();
i2c_write(sad_r_m);

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data =i2c_read();
i2c_stop();
return data;
}
void enableDefault()
{
// Enable Accelerometer
// 0x27 =0b00100111
// Normal power mode, allaxes enabled
writeAccReg(LSM303DLH_CTRL_REG1_A, 0x27);
// Enable Magnetometer
// 0x00 =0b00000000
// Continuous conversionmode
writeMagReg(LSM303DLH_MR_REG_M, 0x00);
}
// Reads the 3accelerometer channels andstores them invector a
void readAcc()
{
X_L_A= readAccReg(LSM303DLH_OUT_X_L_A);
X_H_A =readAccReg(LSM303DLH_OUT_X_H_A);
Y_L_A = readAccReg(LSM303DLH_OUT_Y_L_A);
Y_H_A = readAccReg(LSM303DLH_OUT_Y_H_A);
Z_H_A = readAccReg(LSM303DLH_OUT_Z_L_A);
Z_H_A = readAccReg(LSM303DLH_OUT_Z_H_A);
/* i2c_start();
i2c_write(sad_w_a);

40. Page | 40
i2c_write(LSM303DLH_OUT_X_L_A);
i2c_start();
i2c_write(sad_r_a);
data =i2c_read();
i2c_stop();
Wire.beginTransmission(ACC_ADDRESS);
// assert theMSB oftheaddress to gettheaccelerometer
// to do slave-transmit subaddress updating.
Wire.send(LSM303DLH_OUT_X_L_A| (1 <<7));
Wire.endTransmission();
Wire.requestFrom(ACC_ADDRESS, 6);
while (Wire.available() <6);
uint8_t xla =Wire.receive();
uint8_t xha =Wire.receive();
uint8_t yla =Wire.receive();
uint8_t yha =Wire.receive();
uint8_t zla =Wire.receive();
uint8_t zha =Wire.receive();
a.x =(xha <<8 | xla) >>4;
a.y =(yha <<8 | yla) >>4;
a.z =(zha << 8 | zla) >> 4;
*/
}
// Reads the 3magnetometer channels and stores them invectorm
void readMag()
{

41. Page | 41
X_L_M= readAccReg(LSM303DLH_OUT_X_L_M);
X_H_M =readAccReg(LSM303DLH_OUT_X_H_M);
Y_L_M = readAccReg(LSM303DLH_OUT_Y_L_M);
Y_H_M = readAccReg(LSM303DLH_OUT_Y_H_M);
Z_H_M = readAccReg(LSM303DLH_OUT_Z_L_M);
Z_H_M = readAccReg(LSM303DLH_OUT_Z_H_M);
/*
Wire.beginTransmission(MAG_ADDRESS);
Wire.send(LSM303DLH_OUT_X_H_M);
Wire.endTransmission();
Wire.requestFrom(MAG_ADDRESS,6);
while (Wire.available() <6);
uint8_t xhm =Wire.receive();
uint8_t xlm =Wire.receive();
uint8_t yhm =Wire.receive();
uint8_t ylm =Wire.receive();
uint8_t zhm =Wire.receive();
uint8_t zlm =Wire.receive();
m.x =(xhm << 8 | xlm);
m.y =(yhm << 8 | ylm);
m.z = (zhm << 8 | zlm);
*/
}
// Reads all6 channels oftheLSM303DLH andstores them intheobject variables
void read()
{

42. Page | 42
readAcc();
readMag();
}
#endif

43. Page | 43
We have written the code using the Assembly language.
list p=16f877a ; list directiveto define processor
#include <p16f877a.inc> ; processor specificvariabledefinitions
__CONFIG _CP_OFF & _WDT_OFF & _BODEN_OFF & _PWRTE_ON & _XT_OSC & _WRT_OFF & _LVP_OFF & _CPD_OFF
; '__CONFIG' directive is used to embedconfiguration data within.asmfile.
; The labels following thedirectivearelocated intherespective.inc file.
; See respectivedata sheetfor additionalinformationon configurationword.
huns EQU 20h
tens EQU 21h
ones EQU 22h
bin_num1 EQU 23h ; variabletostorethedistanceinbinary form
bin_num2 EQU 24h
rising_tempL EQU 25h
rising_tempH EQU 26h
falling_tempL EQU 35h
falling_tempH EQU 36h
count EQU 27h ; counter for delay perposes
count_echoL EQU 28h ; LSByte for Echo duration
count_echoH EQU 29h ; MSByte for Echo duration
temp1 EQU 30h
temp2 EQU 31h
;**********************************************************************
ORG 0000H
GOTO start
ORG 0004H
goto isr
;---------------------------------------------------------------------
isr
btfsc PIR1,2 ; is the interruptfrom CCP1 (rising edge)?
GOTO rising ; yes, process rising
btfsc PIR2,0 ; no, check theiftheinterrupt is duetoCCP2?
GOTO falling ; yes, process falling
GOTO finished
rising
clrf TMR1H
clrf TMR1L
bcf PIR1,2
RETFIE
falling movf CCPR2H,w
movwf falling_tempH
movf CCPR2L,w
movwf falling_tempL
bcf PIR2,0
finished RETFIE
; _________________________________________________________________________
start
movlw b'11000000' ; enable GIEandPeripheral interrupts
movwf INTCON
banksel CCP1CON
movlw b'00000101'
movwf CCP1CON ; capture modeCPP1,every rising edge
movlw b'00000100'
movwf CCP2CON ; capture modeCCP2, every falling edge
MOVLW 01H
MOVWF T1CON
banksel PIE1

44. Page | 44
movlw b'00000100'
movwf PIE1 ; enable CCP1interrupt
movlw b'00000001'
movwf PIE2 ; enable CCP1interrupt
movlw b'00000110'
movwf TRISC ; To configure the Capture Mode ofCCP1 and CCP2
clrf TRISB ; RB3 Triger for the ultrasonic
banksel PORTB
clrf PORTB
;------------------------------------------------------------------------------------
; main code....................................
new_reading
CALL trig ; triger the ultrasonicsensor
CALL onems
CALL Divide ; divide thetime over 58 toget the distancein binary
CALL bintodec ; convert from binary todecimal
goto new_reading
;________________________________________________________________________________
; Subroutines ..................................
; Triger the sensor by10usecpulseon thetriger pin RB3
trig bcf PORTB,3
nob
nob
nob
bsf PORTB,3 ; triger is connectedto POTR B,3
movlw 05h
movwf count ; delay for morethan 10us
wait_de decfsz count
GOTO wait_de
bcf PORTB,3
RETURN
;..................................................................
; divide echo width(i.e. in terms oftime in1usec) over 58to get thedistance in(cm).
Divide movf falling_tempL,w ; save the timecounters in orderto redisplay it untilthenext trig
movwf temp1
movf falling_tempH,w
movwf temp2
movf falling_tempL,w ; check ifthe echo signal dosentreturn
btfss STATUS,Z
GOTO nonzero
movf falling_tempH,w
btfss STATUS,Z
GOTO nonzero
return
nonzero
movlw d'58' ; put the divisorin W
subwf falling_tempL ; count_echo1=count_echo1 -d'58'
btfss STATUS,C
GOTO Borrow
GOTO Div_2
Borrow
movlw 01h
subwf falling_tempH ; use subtract insteadofdecf
btfss STATUS,C ; ... because itsets the carry
GOTO Done ; generateda borrow sofinish
Div_2
incfsz bin_num1 ; LSByte is saved in bin_num1
GOTO nonzero
incf bin_num2 ; MSByte is saved inbin_num2
GOTO nonzero
Done

45. Page | 45
movf temp1,w ; return thetimecounters inorder toredisplay it until the next trig
movwf falling_tempL
movf temp2,w
movwf falling_tempH
RETURN
;.................................................................
; Convert from binary to decimal ..........................
bintodec clrf huns
clrf tens
clrf ones
movf bin_num2,w
btfsc STATUS,Z ; is the MSByte oftheechosignal zero?
GOTO low_byte ; yes, then go tothelowbytewhichis bin_num1
movlw b'11111110' ; no, then check ifitis morethand'256'=b'00000001'
andwf bin_num2
btfss STATUS,Z
GOTO outside ; yes, it is morethan d'256'then
;the distanceis more than 400cm i.e.over thesensor's range
movlw d'2' ; no, then it equals d'256'so thehundreds is two
movwf huns
movlw d'50' ; the tens is d'50'
addwf bin_num1
movlw d'6' ; the ones is d'6'
addwf bin_num1
;,,,, calculate thehundreds for theLSByteofthe echo signal
low_byte bsf STATUS,C ; set carry bit toperformsubtract operations
movlw d'100'
wait_hunssubwf bin_num1
incf huns
btfsc STATUS,C ; does the subtraction becomezero?
goto wait_huns ; No, calculatehundreds again
addwf bin_num1 ; Yes, add 100to binarynumber to becorrect
decf huns ; decrement huns counter tobecorrect
;,,,, calculate thetens
bsf STATUS,C
movlw d'10'
wait_tens subwf bin_num1
incf tens
btfsc STATUS,C
goto wait_tens
addwf bin_num1
decf tens
;,,,, calculate theones
movf bin_num1,w ; the ones aretheremaining in bin_num
movwf ones
outside clrf bin_num1
clrf bin_num2
RETURN ; return to theCALL Binary todecimal bintodec
;........................................................................
END