THE DESIGN AND CONSTRUCTION OF A MICRO-CONTROLLER BASED LIQUID LEVEL DETECTING SYSTEM
The project is based on the design and construction of a micro-controller based liquid level detector. This is a system that will measure the level of liquid in a container and display the level on 3 seven segment display screen. The system will output an audio and visual alerting indicator when the tank is full and when the tank is empty. This alarm can be re-set using an override switch.This feat is achieved using a a programmable integrated circuit that is programmed using assembly language as well as other integrated circuits such as a seven-segment display driver, a multiplexer, and logic gates. Also, I used other discrete components such as resistors, transistors, capacitors, diodes etc.After the design, construction, and implementation, the system functioned satisfactorily as a microcontroller-based liquid level detector system with digital display readout.
TABLE OF CONTENTS
Title page - - - - - - - - - iCertification - - - - - - - - - iiDedication - - - - - - - - - iiiAcknowledgement - - - - - - - - ivTable of contents - - - - - - - - v Abstract - - - - - - - - - viii
CHAPTER ONE1.1 Introduction - - - - - - - - 11.2 Aim - - - - - - - - - 31.3 Objective of the study - - - - - - 31.4 Scope of the study - - - - - - - 41.5 Uniqueness of the project - - - - - - 41.6 Methodology - - - - - - - - 5
CHAPTER TWO2.1 Introduction - - - - - - - - 82.2 The Sub-circuits review - - - - - - 82.2.1 Power supply unit - - - - - - 92.2.2 Level detector circuit - - - - - 92.2.3 Block diagram - - - - - - 112.2.4 Signal translating section - - - - - 112.2.5 Micro controller unit- - - - - - 122.2.6 Display unit - - - - - - - 122.2.7 Alarm circuit - - - - - - - 132.2.8 Override reset- - - - - - - 13
CHAPTER THREE3.1 Introduction - - - - - - - - 153.2 Block diagram - - - - - - - 153.3 Power supply - - - - - - - 163.4 Level detector - - - - - - - 243.5 Signal processing unit - - - - - - 263.6 Display unit - - - - - - - - 283.7 Alarm circuit - - - - - - - - 293.8 Microcontroller unit - - - - - - - 333.9 The complete circuit diagram - - - - - 433.10 Mode of operation - - - - - - - 44
CHAPTER FOUR4.1 Introduction - - - - - - - - 474.2 The assemblage of the electronic components - - - 474.3 The construction of the electronic circuit enclose - - 494.4 The construction of the model container - - - - 504.5 The installation of the electronic signals - - - - 524.6 Installation of the complete system - - - - 524.7 Bill of engineering measurement and evaluation - - 53
CHAPTER FIVE5.0 Conclusion - - - - -- - - - 565.1 Recommendation - - - - - - - 57References - - - - - - - - 59
CHAPTER ONEINTRODUCTION1.1 INTRODUCTION
The liquid is one of the basic forms of matter and it is embedded into our everyday lives. Since the whole earth is made up of matter and we interact with it daily, it means that the application or usefulness of fluid is a very essential part of our daily activity. Various materials come in fluid form and in the process of the utilization of it for our daily activities, we may desire a need to store it in containers or tanks. Secondly, the need to accurately or approximately determine the volume or quantity of fluid contained in the storage container or tank is also important so that we can monitor its usage and track its movement.In the detection of the level of liquid in a tank, various methodologies could be applied in other to accurately or approximately obtain the quantity of liquid in a tank, without actually viewing inside the tank. The use of completely mechanical means such as analog calibrated meters which is vastly used in many commercial and industrial products such as the fuel gauge in a car and other similar products is widely deployed. Or the use of a purely physical phenomenon such as liquid pressure as seen in the operation of barometric-based meters in liquid detection as applied in most crude oil tanks in flow stations and other similar conditions. Or the use of a purely manual method as seen in the use of a dipstick, as applied in the majority of petrol filling stations in the country. These methodologies, although very effective and serves the purpose of which they are applied in the first place, lack sophistication and sometimes inaccurate reading of the actual quantity is impossible. To this effect, more accurate methods will be applied in this project, the use of electronics in the measurement and calibration of a liquid level in the tank.A microcontroller is an integrated circuit that carries out instructions under the guidance of a program. Microcontroller-based applications are embedded in every sphere of life that involves the use of electrical or electronic devices. The range of applications includes industrial, medicine, navigation, space exploration, measuring, and calibration, etc.For the measuring and calibration applications, the microcontroller is designed together with other discreet electronic components and implemented in such a way as to accurately collect datum of the measured material and using a suitable calibration protocol, present the quantity of the measured material into a suitable reading output in weight, volume, level or height. Other features will be added to the basic operational principle of this circuit, such as notification of tank empty and a tank full, also a fully digital display readout of the level of fluid in the container.
1.2 AIM OF THE STUDYThe aim of the project is to design and construct a microcontroller-based electrical electronic embedded system circuit or device that will accurately measure the level of liquid in a container and present the data into a readable digital format that could be easily read and completely understood by the user.
1.3 OBJECTIVE OF THE STUDYi. To actualize the above aims, the following objective has to be met.ii. To obtain a standard embedded systems schematic diagram to achieve the system that will enable one to measure accurately, the level of liquid in a containeriii. To choose a suitable programming language that will be used in the programming of an 8052 microcontroller that will be used in the circuitiv. To obtain a power supply unit that will suitably power such a systemv. To create a mechanical system that will allow the physical quantity (liquid level) to be translated into electrical quantity or signalsvi. To design a suitable electronic circuit that will enable the microcontroller to drive the display unit that will show the level of liquid in the containervii. To design an alerting system that will comprise of both audio and visual indicators that will be activated when the tank/container is full and when it is empty
1.4 SCOPE OF THE STUDYThe scope of the study will involve the presentation of the usual methodologies in determining the liquid level in a tank or container used worldwide by various spheres of professionals in existence today and to explain, using technical theories and accurate engineering principles how the use of a microcontroller and electronic implementation is more modern and user friendly.The scope also covers the careful presentation of the various stages of the system, ranging from the power supply, the level detectors, the modulator circuits, the microcontroller unit and flowcharts, the digital display, and the alerting system.
1.5 UNIQUENESS OF THE PROJECTThe liquid level detector circuit is a common technology and as stated earlier, various methods exist worldwide that measures the level of liquid in a container, however, the uniqueness of this circuit is the utilization of an embedded system as the heart of the system. An embedded system is simply an electronic circuit that has at least one programmable integrated circuit. The addition of the microcontroller makes the system to be intelligent and leaves room for upgrade. The circuit has an overfull and under full liquid detector, while the alerting signals are activated, the signal can only be deactivated either by the liquid level changing state from one level to the other. This means that the over full has to become normal while the under full will also be normal.Furthermore, another unique feature that the circuit has is that in most systems when over full is detected or under full is detected, it's only a change of state that can stop the notification, however, in this circuit, there is a notification override push button than can be pressed by the user to stop the notification alert even if the state of the fluid level has not changed.
1.6 METHODOLOGYThe methodology employed in the design and construction of an electronic circuit that will measure the liquid level in a tank and produce the value in a digital read-out format is one that involves also the creation of every masterpiece engineering technology.Textbooks and the internet were consulted as well as the use of standard electronic circuit network theorems and principles all with the aim of actualizing the most appropriate electronic circuit diagram to perform the expected functionIn the programming of an 8052 microcontroller, many programming languages can be utilized. Amongst the options are, EMBEDDED C, BASIC, MACHINE CODE, and ASSEMBLY LANGUAGE. of the available options, assembly language is chosen because of its ability to perfectly blend high-level syntax that enables humans to write a program code that will be easily compactable with everyday language, with a language that is closely related to machine codes which is the only language that electronic systems can understand.The whole system must be operated from a 5 volts dc power supply unit. The choice of battery-powered system and electrical public mains was considered but due to its ability not to need recharging, the public mains was chosen. An a.c to dc converter circuit was used to obtain 5 volts dc from the 220 volts ac public mains power source.The mechanical system that was used in the translation of the liquid level into electrical quantity is metallic screws that were screwed into the body of the container. Conductors were connected from these screws to the system and when a liquid rises above the screws, it will send electrical signals from the terminals to the electronic circuitThe level of liquid will be displayed using common cathode 7-segment displays. To adequately drive these display units, the common cathode 7-segment display driver CD4511 was used. To ensure that the display units don’t use up all the terminals from the microcontroller, the one-of-eight lines de-multiplexer integrated circuit, DM74138, was usedFinally, for the audio and visual alerting system, a light-emitting diode (LED) was used for the visual output while an electronic buzzer was used for the audio output. For effect, a pulse width modulator, 555 timers connected in the astable mode, was used to dive these indicators.