ABSTRACT
The microcontroller based display board is an advert system that displays information based on a specific purpose. The system is designed to enable the viewer know the designers aim.
The system comprises of different blocks of functional circuit that are put together to achieve the desired aim. These blocks include; the power supply section, the control section, the demultiplexer section and the display unit. The power supply unit is the section of the system that ensures that the system is turned ON and this section comprises of a 12- volt step-down transformer, a bridge rectifier circuit, a smoothening capacitor and a voltage regulator IC.
The control section is in charge of interpreting the changes that occur in the environment. The section controls the function of all other parts of the circuit. The function of the control unit is carried out using a micro-controller (AT89S52). It is programmed to carry out the desired function.
The demultiplexer section distributes signal to the display unit and allows them to light at appropriate time. This unit is achieved using a demultiplexer (74LS138). The display unit comprises of light emitting diode which are in dot matrix form. The light emitting diode is arranged in 64 columns and 14 rows.
TABLE OF CONTENTS
Title Page ................................................................................... i
Approval page ……………………………………………………. ii
Dedication ................................................................................. iii
Acknowledgement ...................................................................... iv
Abstract .................................................................................. v
Table of Content ....................................................................... vi
List of figures ……………………………………………………… x
List of tables ……………………………………………………….. xi
INTRODUCTION
1.0 Background ....................................................................... 1
1.1 Objective of the project ..................................................... 3
1.2 Scope of the project ……………………………………….. 4
1.3 Uses of the project ............................................................ 6
1.4 Project report organization ……………………………….. 7
1.4.1 Block diagram overview …………………………………… 8
2.0 Literature review ............................................................... 9
3.0 Description of the system components ........................... 13
3.1 The mains unit ………………………………………….. 13
3.2 The power supply unit ………………………………….. 13
3.2.1 Transformer ……………………………………………... 15
3.2.2 Rectifiers ………………………………………………… 15
3.2.3 Filters …………………………………………………….. 16
3.2.4 Regulators ………………………………………………. 16
3.3 The address generator unit ……………………………… 18
3.4 The memory/microcontroller unit ……………………….. 19
3.4.1 Description of the micro-controller ……………………. 19
3.5 The drivers unit …………………………………………… 20
3.5.1 Transistor ………………………………………………… 20
3.5.2 Light Emitting Diodes (LEDs) ………………………….. 21
3.5.3 Sizes, shapes and viewing angles of LEDs ………… 22
3.5.4 Diodes ……………………………………………………. 22
3.6 Implementation process ………………………………….. 23
3.7 Making the LED blink with the micro-controller ………. . 25
3.8 Implementation details ……………………………………. 27
3.8.1 Micro-controller pin descriptions ………………………. 28
3.8.2 System reset ……………………………………………. 34
3.8.3 Oscillator characteristics ……………………………….. 34
3.9 Software ………..………………………………………….. 35
3.9.1 Software development ………………………………….. 36
3.10 Development process …………………………………… 38
3.11 Program entry and editing ……………………………….. 39
3.12 Assembling and linking ………………………………….. 39
3.13 System control program steps …………………………... 40
3.14 Software for the programmers ………………………….. 41
4.0 Implementation, construction step and packaging …….. 45
4.1 Programming the micro-controller (AT89S52) ………….. 45
4.1.1 Flash or EPROM programmer …………………………... 45
4.2 Using a personal computer to program the micro-controller… 47
4.3 System flow chart ……………………………………………. 49
4.4 Information gathering ……………………………………….. 51
4.5 Data analysis ………………………………………………….. 53
4.6 Implementation approach …………………………………. 56
4.7 Choices of implementation approach ……………………. 56
4.8 packaging ……………………………………………………. 57
5.0 Test results, summary and conclusion …………………… 58
5.1 System testing and integration …………………………….. 58
5.2 Test plan and test data ……………………………………… 58
5.2.1 Component test …………………………………………… 59
5.2.2 System test ………………………………………………... 60
5.2.3 Transformer test ………………………………………….. 60
5.2.4 Other tests …………………………………………………. 61
5.3 Summary……………………………………………………….. 61
5.4 Summary of achievement …………………………………. 62
5.5 Conclusion ……………………………………………………. 62
BIBLIOGRAPHY …............................................................... 64
APPENDIX ……………………………………………………. 65
