8x8 Led Matrix

ROJECT REPORT ON DOT MATRIX DISPLAY

BY AUTI DINESH YADAV ANIL

UNDER THE GUIDANCE OF PROF.SACHIN CHARBE

DEPARTMENT OF ELECTRONICS RIZVI COLLEGE OF ENGINEERING, RIZVI COMPLEX, OFF CARTER ROAD BANDRA(W), MUMBAI-400050. YEAR: 2010-2011

RIZVI COLLEGE OF ENGINEERING, RIZVI COMPLEX, OFF CARTER ROAD BANDRA(W), MUMBAI-400050. DEPARTMENT OF ELECTRONICS

CERTIFICATE This is to certify that the following students Auti Dinesh (ETRX TE – 4) Yadav Anil (ETRX TE -62)

have successfully completed the synopsis work of project Titled “DOT MATRIX DISPLAY” ------------------------------INTERNAL EXAMINER

-----------------------------EXTERNAL EXAMINER

-----------------------------Prof. Sachin Charbe Internal Guide --------------------------Prof. Nargis Shaik Head of department ---------------------------Dr. Varsha Shah Principal

ABSTRACT The basic aim of our project is to present the led matrix in various form of its working, all of which find immense applications. The brain of the system lies well placed in the controller that co-ordinates the total working of the project and controls the minute aspects. It aptly demonstrates the multi faceted nature of the matrix, just by a mere click of the input switch, and the outputs thus obtained are very different from each other. A number of such applications can be in built into this device with no change in its efficiency. Along with , it provides adequate clarity and a fine tuning between brightness and contrast which proves pleasant for the eyes as well. Not to forget its energy efficient working that serves as an icing over the cake. Other possible enhancements would be using SMD led' s that are efficiently packed having adjustable contrast and more energy efficient nature than normal led' s, yet bright enough to capture your attention.

ACKNOWLEDGEMENT

It is With great pleasure that we are submitting this report on “Dot Matrix Display”. As in case project, we faced many problems while giving shape to our ideas and making the project mould into reality. We take this opportunity to express our sense of gratitude towards our internal guide Prof. Sachin Charbe for his valuable suggestions and guidance from time to time. We are also thankful to the head of department, Prof. Nargis Shaik and the remaining staff for making facilities available and giving their support and guidance. Although we have not mentioned each name, we would like to say that we appreciate every individual who was associated with our project and made experience satisfying and fulfilling one.

Auti Dinesh Yadav Anil

Table of contents Title...................................................................................................................1 Abstract …........................................................................................................3 Acknowledgement ….......................................................................................4 1. Introduction ….......................................................................................8 2. Schematic 2.1 Single Colour Matrix(Single Sided Board) …......................10 2.2 Dual Colour Matrix(Double Sided Board) ….......................11 3. Operation 3.1 Dev Board …........................................................................13 3.2 Matrix …................................................................................14 3.3 Final Board (©MATRIX V1.2) ….........................................16 4. Component List ….................................................................................20 5. Board Layout 5.1Single Colour Matrix(Single Sided Board) …..................................22 5.2Dual Colour Matrix(Double Sided Board – Top Layer) …..............22 5.3Dual Colour Matrix(Double Sided Board – Bottom Layer) ….......23 5.4Dual Colour Matrix(Double Sided Board – Top & Bottom Layer)..23 6. Programming 6.1 Program ….............................................................................25 6.2 Hex Code …............................................................................23 7. Easily Applicable Graphical Layout Editor 7.1 EAGLE Product Information …............................................37 7.2 Schematic Editor …...............................................................37 7.3 Auto-router …........................................................................38 7.4 CAM Processor ….................................................................38 7.5 EAGLE CAD Design Rules …..............................................39 8. Application and Future Scope …..............................................................43 9. Conclusion …...........................................................................................47 10. PCB Making Process 10.1 Artwork Generation …..........................................................49

10.2 10.3 10.4 10.5 10.6 10.7 10.8 10.9 10.10

Photoresist PCB Laminates …..............................................51 Exposure …...........................................................................51 Developing ….......................................................................53 Etching ….............................................................................54 Tin Plating …........................................................................55 Drilling ….............................................................................56 Cutting ….............................................................................58 Through – Plating …............................................................59 Through – Plating Using Rivets ….......................................61

11. References ….....................................................................................62

1.Introduction

1.Introduction Electronics is not just a field of study, it is a foundation pillar of the modern day technological advancements. After thinking a lot on above lines we finally decided to work on a device which is not just versatile in its functioning but also is the next step that the world is taking towards a highly energy efficient future. This project gives a detailed information on the basic structural anatomy of LED matrix and the wide interaction that is possible, owing to the ease with which it can be interfaced with a controller and can be used as a output device in embedded systems, in which power and space are areas of major concern especially when it comes to implementing them in consumer products Keeping a specific goal in mind, we travelled on the same lines , which is efficiently presented in the pages to be follow. Finally, having accomplished our aim, we concluded by throwing light on the modern day innovation of LED TV.

2. Schematic

2.1 Single Colour Matrix(Single Sided Board)

Matrix V1.1

2.2 Dual Colour Matrix(Double Sided Board)

Schematic: MATRIX V1.2

3. Operation

3.1 Dev Board The Dev Board or Development Board is very essential for experimenting with microcontrollers. Development is not easy if you use bread board or vero board. After some time wires will become loose and establishing a large circuit on vero board is too tedious. To solve this problem we decided to make our own low cost Dev Board which has following specifications • • • • •

Low cost. All basic connection for developing application with AVR MCU's. In circuit programmable with USB AVR Programmer. Supports 40 pin MCU's like Atmega16,ATmega32 and Atmega8535. Can be further extended for use with LCD,DOT MATRIX etc interfacing.

3.2 Matrix An LED Matrix is an array of LED's with the anode or positive terminal of each row connected together, and the cathode or negative terminal of each column connected together. Or the anode can be connected to a column, and cathode connected to a row.

Internal Structure of 8x8 Matrix

They come in various sizes, colors and formats. The most common sizes are 5x7, 5x8 and 8x8 displays. This means that, for example, a 5x8 display would have 5 columns with 8 rows of LED's.

5x7 Matrix

8x8 Matrix

The most common colors are red, green and yellow. There are also two and three colored versions, with the different colored LED's sharing a common pin in each row or column and a seperate pin for the corresponding column or row. This allows each color to be turned on or off individually. When there are two or more colors, the LED's will share a common anode or cathode (positive or negative respectively). Lets examine more closely the actual layout of a LED matrix Here we see that each row connects to that rows cathode or negative leg of the

LED's. Correspondingly, each column connects the anode or positive leg together. Please not that a LED matrix can also be the other way around.

Matrix Internal Structure

To control a LED matrix, we have two options: • Cycle through each row, turning on the LED's in that row as needed • Cycle through each column, turning on the LED's in that column as needed It is not possible to control the LED matrix all at once, as all the individual LED's share both their inputs. The way around this is to use Persistance of Vision. By cycling through each row or column quite fast (~50Hz and above) you should not see any flicker, and instead see the whole LED matrix display as if it was all working at once. If we were to choose the first of the two options, we would first ground the first row connection (connection ROW1) and leave the remaining ROWX connections floating or high.

Matrix Internal Structure - Row 1

Then, we would pull each column connection high if we wanted that LED to turn on, or leave it floating or low to keep it off. For example if we wanted to turn on LED3 and LED5, then with the ROW1 connection pulled low, we would leave COL1, COL2 and COL4 floating or low, and pull COL3 and COL5 high. Then after leaving ROW1's displayed LED's on for a set period of time, we would pull ROW1 high or floating and pull ROW2 low. At the same time, we would pull the corresponding column connections high to turn on the individual LED's in that row.

3.3 Final Board LEDs in the same column have the anodes on a common line, running top to bottom. Similarly for LEDs in a single row have cathodes on a common line, running left to right. This means that if on the wires that make up the column an 8 bit pattern say 10111110 is set and then the common line for some row is grounded, then the LEDs in that particular row will glow as dictated by this bit-pattern. With this bit-pattern, for example, if you ground the common line for the topmost row then the LED1 and LED7 will be OFF and rest in that row will be ON. You may ground the common line on any row and the bit-pattern set on the column wires will appear as glowing LEDs in that particular row. This design, however, is not the complete solution. The reason is that different rows cannot display different bit patterns. They will all display the same pattern that has been set on the column wires, once they are grounded. In order to overcome this problem, we shall use a clever trick - persistence of vision. The idea is that if changes are made in rapid succession, the human eye is unable to sense the small incrementals and perceives the event as smooth continuous motion. In practice we display one row at a time - we set the bit pattern on the column for the topmost row and ground that row keeping all other rows un-grounded. Next, we set the bit pattern for the second row on the column wires and then ground the second row, keeping all other rows ungrounded and so on till we have displayed all the rows, one at a time, in succession from top to bottom. We repeat the same process over and over again, just like scanlines in a TV. We make the switching between the rows so fast that it appears that you are viewing the entire LED matrix in one go.

Now we can attach the 8x8 LED module shown above to two different ports - one to set bit patterns for the column wires and other to ground different rows when desired. In the following figure PORTC is used to set patterns on column wires and PORTA is used to ground rows:

Interfacing

This type of connection has some drawbacks too. The thing is when a row is grounded then current from all the LEDs that are ON in that row sinks collectively at this pin and this may be dangerous for the microcontroller. That's where the driver IC shown in the figure on the top comes into picture. We use ULN2803 to sink the current safely from all 8 rows. The ULN2803 IC is shown below:

ULN 2803

Pin 9 is connected to ground. Pins 1-8 are connected to the PORTA[0:7] which we

use to control the selective sinking of the rows. The row [1:8] wires are connected to pins [18:11] so that when PORTA PIN0 is set ON, the row 1 is connected to the ground. So keeping these factors in mind, the block diagram can be modified as:

4. Component List

4. Component List Component name

Quantity

Price(Rs.)

Atmega16

1

130

ULN2803

1

15

AVR ISP Header

1

15

RF Cable

1

10

7805T

1

8

1N4007

1

2

DIP Switches

8

24

Led

1

2

Resistor - 330 ohm 1k ohm

1 1

2

Sliding Switch

1

3

Crystal

1

7

Capacitors- 22pF 100uF 0.1uF

2 2 2

6

Power Jack

1

5

Round Pin socket- 40pin 18pin

30 1 1

Double side copper clad epoxy

1

170

Screw and nuts

4

15

Total

444

5. Board

5.1 Single Layer Board Layout

5.2 Dual Colour Matrix (Top Layer)

5.3 Dual Colour Matrix (Bottom Layer)

5.4 Dual Colour Matrix(Top & Bottom Layer)

6. Programming

6.1 Program 1. #include 2. #include 3. int y; 4. unsigned char d[8]={1,2,4,8,16,32,64,128}; 5. unsigned char s2c[4]={0X3C,0X24,0X24,0X3C} ; 6. unsigned char s3c[6]={0X7E,0X42,0X42,0X42,0X42,0X7E}; 7. unsigned char s4c[8]={0XFF,0X81,0X81,0X81,0X81,0X81,0X81,0XFF}; 8. unsigned char s5c[8]={0XFF,0XC1,0XA1,0X91,0X89,0X85,0X83,0XFF}; 9. unsigned char s6c[8]={0XFF,0X83,0X85,0X89,0X91,0XA1,0XC1,0XFF}; 10.unsigned char s7c[8]={0XFF,0XC3,0XA5,0X99,0X99,0XA5,0XC3,0XFF}; 11.unsigned char w[8]={0x81,0x81,0x81,0x81,0x81,0x99,0XA5,0XC3}; 12.unsigned char lc[8]={0x80,0X80,0X80,0X80,0X80,0X80,0X80,0XFF}; 13.int move(int m,int n,int o,int p,int q,int r,int s,int t,int loop) 14.{ 15.int a=0; 16.int count; 17.if(loop==1) 18.{ 19.count=4000; 20.} 21.else 22.{ 23.count=10000; 24.} 25.label: 26.PORTC=m; 27.PORTD=1; 28.RESET(); 29.PORTC=n; 30.PORTD=2; 31.RESET(); 32.PORTC=o; 33.PORTD=4; 34.RESET(); 35.PORTC=p; 36.PORTD=8; 37.RESET(); 38.PORTC=q; 39.PORTD=16; 40.RESET(); 41.PORTC=r; 42.PORTD=32; 43.RESET();

44.PORTC=s; 45.PORTD=64; 46.RESET(); 47.PORTC=t; 48.PORTD=128; 49.RESET(); 50.a++; 51.if(a>=count) 52.{ 53.a=0; 54.if (loop==1) 55.{ 56.if((m