Twitter Arduino Display Project

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ABSTRACT The main goal of this project is to design system that can display a twitter in real time. Rather than connecting the display to the computer, this project comes out with a more interesting method, which is to connect the display directly to the twitter server without the need of a computer. This concept require a display and Ethernet Shield – each one of them has their own functions, which consist of Local Area Network (LAN) connection to the internet. Both item are connected together and are connected by the RJ45 Cable to a modem. The display used are LED matrix type and it works as an output of the system which is to display any data received from the twitter server. This project is divided into two parts. The design and construction of a hardware part of this project is carried out by this author, while coding and programming implementation is done by a project partner. In this part, the hardware system is design from the scratch. From the basic of how the single color single LED matrix work principal until the design of a working 64x32 multicolor LED matrix has been carried out. Furthermore, the hardware construction and programming coding of a Clock Shield also has been done. The project for me is a success since the display is fully functional and the clock shield is already up and running. I also successfully connect the Ethernet Shield to the modem and it can now post a message to twitter. However, there are slight problem to display the twitter message since twitter change its API’s a few months ago and most developer is struggling to find a way to connect to the server and grab the data from it. i

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ACKNOWLEDGEMENT

First praise is to Allah, the Almighty, on whom ultimately we depend for substance and guidance. Second, my appreciation goes to my supervisors Mr Mahazani bin Mohamad, whose guidance careful reading and constructive comments were valueable. His timely and efficient contribution helped me a lot to shape this into current form and I’m expressing my sincerest appreciation for his assistance in any way that I may have asked. In particular, I would like to thank my working partner, Mohd Ifwat for his contribution and invaluable support throughout this project. Last but not least, I would like to thank my parents and family for their unconditional loves, constantly supporting and encouraging me to work hard on this project. That my inner strength and their support and encouragement are much valued.

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Contents Declaration by the candidate Abstract Acknowledgement List of tables List of figures Abbreviation

Chapter 1

Background of the research

1.1

Introduction ………………………………………………………

1

1.2

Project overview ………………………………………………….

3

1.3

Objectives ………………………………………………………...

5

1.4

Problem statement ………………………………………………..

6

1.5

Report structure …………………………………………………..

7

Chapter 2

Introduction to main concept of the project

2.1

Hardware 2.1.1

The Arduino UNO …………………………………

2.1.2

The Ethernet Shield ……………………………....

13

2.1.3

The Clock Shield …………………………………

16

2.1.4

The LED Matrix Display …………………………

18

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2.2

Software 2.2.1

Arduino Programming Language …………….….…

20

2.1.2

Visual Studio 2010 ……………………..……..…....

21

Chapter 3

Hardware implementation

3.1

Design Introduction ……………………….………………….…….

23

3.2

System Overview ………………………………………………....…

23

3.3

System Flowchart ……………………………………………….…..

24

3.4

Hardware Building 3.4.1

LED Matrix ……………………………...…………

25

3.4.2

Clock Shield ……………………………………….

35

Chapter 4

Result and analysis

4.1

Simulation of Operation ……………………………………………

Chapter 5

Conclusion and recommendation

5.1

Conclusion ……………………………………………………….…

46

5.2

Recommendation for future work ………………………………….

46

References

……………………………………………………………………….

48

44

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List of Figures Figure No.

Title

Page

1.1

Windows Twitter Layout

2

1.2

Overview of the project

4

2.1

Arduino UNO

9

2.2

Arduino UNO Connection

12

2.3

Ethernet Shield

14

2.4

Ethernet Shield Reset Button

15

2.5

Clock Shield

17

2.6

LED Matrix Display

18

2.7

Arduino Programming Language

21

2.8

Microsoft Visual Studios 2010

22

3.1

Overview of the project

23

3.2

Project Flowchart

24

3.3

LED Matrix

25

3.4

7x5 LED Matrix Schematic

26

3.5

Multiple LED Matrix Schematic

27

3.6

Multiple LED Matrix on Breadboard

28

3.7a

Multiple LED Matrix Circuit

29

3.7b

Completed Multiple LED Matrix

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3.8

Multiple tricolor LED Matrix Schematic

31

3.9

LED Matrix Pin Connection

33

3.10

Acrylic Design

33

3.11a

Top plate Measurement

34

3.11b

Bottom plate Measurement

34

3.12

DS1307 RTC Chip

35

3.13

Clock Shield Schematic

39

3.14a

Completed Clock Shield - Back

40

3.14b

Completed Clock Shield - Front

40

4.1

Completed System

41

4.2a

Prototype Display - Top View

42

4.2b

Prototype Display - Side View

42

4.2c

Prototype Display - Perspective View

42

4.3

Initialization of The System

43

4.4

Date and Time Mode

43

4.5a

Attempting Connection

44

4.5b

Connection Failed

44

4.6a

Display Time Mode

45

4.6b

Display Date Mode

45

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List of Tables Table No.

Title

Page

2.1

LED Matrix Pin Function Description

20

3.1

LED Matrix Pin Function Description

32

3.2

DS1307 Pin Function Description

36

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Abbreviations

PCB

Printed Circuit Board

WLAN

Wireless Local Area Network

LCD

Liquid Crystal Display

DC

Direct Current

AC

Alternating Current

WI-FI

Wireless Fidelity

LAN

Local Area Network

USB

Universal Serial Bus

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CHAPTER 1 Background of Research 1.1 INTRODUCTION Twitter is a social networking and microblogging service that allow users to answer question by sending short text messages 140 characters in length, called “tweets”, to your friends, or “followers”. There are many methods to send and view the tweets nowadays. The most common method is using windows apps via computer or using mobile apps through mobile phone. [1] Micro-blogging can be defined as simple and quick update. It usually contains a very limited number of characters, 140 to be exact for twitter. It is a very important feature of social network nowadays like Facebook where anyone can update their status, but it has become best known because of twitter. Twitter is more like a miniature blog or online diaries. It is perfect for people who don’t want a blog but want to share their thought online. A personal blog let people around you keep informed on what happen in your life, but not everyone willing to spend a hefty hours to create a beautiful post about something simple. Sometimes, I just want to say “She sure look good in that dress. I want to find something similar later”.[2]

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So what is twitter? It is easy to explain twitter as a great place for letting your friends and family keep updated about what you are up to without the need to spend long time on creating the entire post of what is happening. You can say anything and leave it at that. It is a social messaging, event coordinator, business tool, news reporting service and marketing utility. It is many different things to different people to different usage.

User

Timeline

No of Tweets

Tweets

Figure 1.1 Windows Twitter Layout

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1.2 PROJECT OVERVIEW The most important component of the project is the display. Since twitter works by sending short text messages, the display doesn’t need to be too high in resolution. So, even a simple LED matrix can be used to display the message. To make the project more intuitive, arrays of LED matrix are used. Which means, the LED matrix are combined to make it able to display several characters at the same time. A microcontroller is needed to control the output of the displays. This microcontroller will work as a “brain” of the array displays. The microcontroller doesn’t need to be very fast and powerful since it only needs several bytes of data to be sent to the array of display. The microcontroller will connect with the router through Ethernet connection. It will feed the data directly from twitter without any computer. To do this, we have to get an Ethernet shield since this hardware enable us to directly connect to the internet via RJ45 cable. By using Ethernet shield, it writes sketches which connect to the internet using the shield. The Ethernet shield connects to an Arduino board using long wire-wrap headers which extend through the shield. This keeps the pin layout intact and allows another shield to be stacked on top. This thesis project concentrates on designing a display hardware. The wide uses of twitter nowadays make this project very useful especially to display important tweets.

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Figure 1.2 shows the operation of this project.

Ethernet Shield

LED Matrix Display

Twitter Server

Arduino Uno

Clock Shield Figure 1.2 Overview of the project

This project is divided into two parts, in which the title of the author’s part is “Hardware Development of Twitter Display”. The other part of this project entitled “Software Development of Twitter Display”, which was done by the author’s partner. The concept that the author has applied in this project is quite simple. In this part, LED matrix act as display, the Ethernet Shield, Arduino UNO and Clock Shield act as the brain of the system and twitter server is the input of the system. This project requires the author to create a system, in which the LED matrix should be able to retrieve data from the combination of Arduino and the Ethernet shields. The LED matrix must display the feed in real time whenever there are input coming from the twitter server. If there is no input from Ethernet shield, the UNO will just take the input from clock shield. 4

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1.3 OBJECTIVE The aim of this project is to get a fully functional display with custom circuit design that can communicate with twitter server to display twitter status in real time. It should be capable of receiving necessary data from the twitter server in order to view it on display panel. Communicating to and from the server will be done using this Ethernet Shield standard. In theory, by using this hardware, the microcontroller should be able to load the status from within the twitter server. The program that will be loaded to the microcontroller will have to be able to work with the Ethernet shield and retrieve the data in real time. All the hardware should work together without the need of any human operating the device. The main objective of this project is to design a display module for a twitter message. A few secondary objectives are as follow: i)

Connect to the twitter without the need of any computer

ii)

Use a Arduino UNO to program the task of a controller

iii)

Setting clock and date using Clock Shield

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1.4 PROBLEM STATEMENT The increasing numbers of people who use twitter as their social network service keep increasing from day to day. This make twitter as one of the most popular social network platform as of today. The popularity of twitter is achievable because more and more peoples are become aware of their services. One of the reasons why twitter is so popular compared to other social network service is its simplicity. Twitter doesn’t have crowded and complicated interface. Twitter also doesn’t need lots of personal information to get started. One email account is all its need before we can start tweeting. The simple user interface make people tend to choose it and the ability to update status in almost an instance become the added bonus for this great software. Because of this, we planned to make a display panel that can display specific twitter to a specific group of people. By doing that, important information can be spread in a mere seconds especially in a closed environment community. Instead of using the application in windows or mac desktop/pc, we choose a different approach for this project which is to display the status directly from twitter server to the microcontroller and to the display panel. This concept saves a lot of cost since the most basic PC will cost at least Rm1000 and also the power consumption for the PC is enormous, let alone a very effective cooling system is needed to power up a PC around a clock.

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1.5 REPORT STRUCTURE There are 5 chapters in this report, with respective subtopics. Each chapter is described as follows: Chapter 1 provides the introduction of Twitter, project overview, problem statement and report structure. The objectives of this project are also stated in this chapter. Several steps have been done in order to meet the objective of this project Chapter 2 provides a review about the important concept used in this project. The topic covers the study on the details of one of the core concepts used in this project which is the display. Furthermore, other studies that are related to this project are also described including the time shield, C# Programming Language and also Arduino Programming Language. Chapter 3 represents the methodology of project conducted. The methodology written in this report described five stages, on how this project is conducted. An overview of hardware and software implementation also explained in this chapter. The design and making of the project is explained in details. In addition, deep explanation on constructing the clock shield with LCD display are done, including how to construct the circuit board and the programming. Chapter 4 elaborates the results and analysis obtained from the project. Chapter 5 will conclude the whole project and thus provide the problems encountered by the devices, the solutions and also the conclusion of this project 7

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CHAPTER 2 Introduction to Main Concepts of Projects Wide coverage of internet connection today lead humans to a new way of interacting with peoples using a social media. The number of people using this application keeps growing as the time goes by. Majority of people prefer to use this method compared to conventional method of socializing is mainly because they can still interact and socialize with other people from the comfort seat of their couch at home without the need to go out at all. Design a twitter based application is a unique and difficult challenge. In the old days, people just use a computer to connect to the internet. This is because computer is the most user friendly interface that can help user to interact with any kind of program easily. However, this project is about displaying a twitter status update without any means of connecting it to a computer. The only thing controlling the whole circuits is the Arduino UNO

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2.1 Hardware 2.1.1 The Arduino UNO The Arduino UNO is a microcontroller board based on the ATmega328. It has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz crystal oscillator, a USB connection, a power jack, an ICSP header, and a reset button. It contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started.

The UNO differs from all preceding boards in that it does not use the FTDI USBto-serial driver chip. Instead, it features the Atmega16U2 (Atmega8U2 up to version R2) programmed as a USB-to-serial converter.

Figure 2.1 Arduino Uno

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"UNO" means one in Italian and is named to mark the upcoming release of Arduino 1.0. The UNO and version 1.0 will be the reference versions of Arduino, moving forward. The UNO is the latest in a series of USB Arduino boards, and the reference model for the Arduino platform. [3]

Summary Microcontroller Operating Voltage Input Voltage (recommended) Input Voltage (limits) Digital I/O Pins Analog Input Pins DC Current per I/O Pin DC Current for 3.3V Pin Flash Memory SRAM EEPROM Clock Speed

ATmega328 5V 7-12V 6-20V 14 (of which 6 provide PWM output) 6 40 mA 50 mA 32 KB (ATmega328) of which 0.5 KB used by bootloader 2 KB (ATmega328) 1 KB (ATmega328) 16 MHz

As our project require us to communicate and handle data transfer between the Ethernet Shield, Clock Shield and LED matrix display, we have decided to use Arduino UNO as the brain for the system. This Arduino make the programming command for hardware to be systematic and easier because this Arduino basically control everything that are connected to its pin.

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The Arduino UNO is used for connecting the Ethernet Shield, Clock Shield and LED matrix display together and since the data coming from the Ethernet shield is not in a language that the display can understand, Arduino will acts as translator which will translate the data into something the display can understand. This will enable the display to convert the digital data into the pattern of display that can easily be seen by human. Each of the 14 digital pins on the UNO can be used as an input or output, using pinMode(), digitalWrite(), and digitalRead() functions. They operate at 5 volts. Each pin can provide or receive a maximum of 40 mA and has an internal pull-up resistor (disconnected by default) of 20-50 kOhms. In addition, some pins have specialized functions: 

Serial: 0 (RX) and 1 (TX). Used to receive (RX) and transmit (TX) TTL serial data. These pins are connected to the corresponding pins of the ATmega8U2 USB-to-TTL Serial chip.



External Interrupts: 2 and 3. These pins can be configured to trigger an interrupt on a low value, a rising or falling edge, or a change in value. See the attachInterrupt() function for details.



PWM: 3, 5, 6, 9, 10, and 11. Provide 8-bit PWM output with the analogWrite() function.



SPI: 10 (SS), 11 (MOSI), 12 (MISO), 13 (SCK). These pins support SPI communication using the SPI library.



LED: 13. There is a built-in LED connected to digital pin 13. When the pin is HIGH value, the LED is on, when the pin is LOW, it's off.

The UNO has 6 analog inputs, labeled A0 through A5, each of which provide 10 bits of resolution (i.e. 1024 different values). By default they measure from ground to 5 11

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volts, though is it possible to change the upper end of their range using the AREF pin and the analogReference() function. This project doesn’t use all the pins on the Arduino board. Only certain pin are used. For LED matrix, only pin Digital 1,2,5,7 are connected to it and for Clock Shield, only pin Analog 4 and 5 are used. This is shown clearly in the Figure 2.2 below.

Figure 2.2 Arduino Uno Connection

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2.1.2 The Ethernet Shield The Arduino Ethernet Shield connects the Arduino UNO to the internet in mere seconds. Just plug this module onto Arduino board, connect it to the network with an RJ45 cable (not included) and follow a few simple instructions to start controlling the world through the internet. As always with Arduino, every element of the platform – hardware, software and documentation – is freely available and open-source. This means we can learn exactly how it's made and use its design as the starting point for the circuits. [4] Hundreds of thousands of Arduino boards are already fueling people’s creativity all over the world, everyday. 

Requires and Arduino board



Operating voltage 5V (supplied from the Arduino Board)



Ethernet Controller: W5100 with internal 16K buffer



Connection speed: 10/100Mb



Connection with Arduino on SPI port

Description

The Arduino Ethernet Shield allows an Arduino board to connect to the internet. It is based on the Wiznet W5100 Ethernet chip providing a network (IP) stack capable of both TCP and UDP. The Arduino Ethernet Shield supports up to four simultaneous

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socket connections. Use the Ethernet library to write sketches which connect to the internet using the shield.

The Ethernet shield connects to an Arduino board using long wire-wrap headers which extend through the shield. This keeps the pin layout intact and allows another shield to be stacked on top..

Figure 2.3 Ethernet Shield

The latest revision of the shield also includes a reset controller, to ensure that the W5100 Ethernet module is properly reset on power-up. Previous revisions of the shield were not compatible with the Mega and need to be manually reset after power-up. The original revision of the shield contained a full-size SD card slot; this is not supported.

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Arduino communicates with both the W5100 and SD card using the SPI bus (through the ICSP header). This is on digital pins 11, 12, and 13 on the UNO and pins 50, 51, and 52 on the Mega. On both boards, pin 10 is used to select the W5100 and pin 4 for the SD card. These pins cannot be used for general i/o. On the Mega, the hardware SS pin, 53, is not used to select either the W5100 or the SD card, but it must be kept as an output or the SPI interface won't work.

The shield provides a standard RJ45 Ethernet jack.

The reset button on the shield resets both the W5100 and the Arduino board.

Reset Button

Figure 2.4 Reset Button on Ethernet Shield

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2.1.3 CLOCK SHIELD This clock shield is designed to deliver the accurate time for the display. The Maxim DS1307 RTC IC(Integrated Circuit) is a fairly accurate clock that can keep time when not powered if been connected to 3V battery. The address and data are send through pins 4 and 5 which attached to the UNO.

Most of the components of the typical applications are incorporated on the circuit board. The board is ready to be plugged and play by stacking the board on top of the Arduino. Its power also supplied by the UNO directly through the 5v pins in the clock shield.

The component needed are: 

One Arduino protoshield pack.



32.768 kHz crystal



IC1 – Maxim DS1307 real time clock IC



8-pin IC socket



CR2032 3v battery



CR2032 PCB mount socket



R1~R3 – 10k ohm metal film resistors



C1 – 0.1 uF ceramic capacitor

The first thing to do is create the circuit on a solderless breadboard. It is much easier to troubleshoot possible issues before soldering the circuit together. The next step is to consider the component placement and wiring for the protoshield.

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The completed and labeled Clock Shield is shown in Figure 3.4 and description label is below: A – Connector for SCL-Analog 5 B – Connector for SDA-Analog 4 C – Fairly accurate clock that can keep time when not powered D – Power Supply E – LED to indicate power supply. It is green coloured. This LED wil turned ON only when power is supplied into the circuit. F - Uses the mechanical resonance of a vibrating crystal to create an electrical signal with a very precise frequency. This frequency is commonly used to keep track of time

C D F

B A

E Figure 2.5 Clock Shield

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2.1.4 The LED Matrix Display A dot matrix display is a display device used to display information on machines, clocks, railway departure indicators and many other devices requiring a simple display device of limited resolution. The display consists of a matrix of lights or mechanical indicators arranged in a rectangular configuration (other shapes are also possible, although not common) such that by switching on or off selected lights, text or graphics can be displayed. A dot matrix controller converts instructions from a processor into signals which turns on or off lights in the matrix so that the required display is produced. Common sizes of dot matrix displays: 128×16 (Two lined) 128×32 (Four lined) 128×64 (Eight lined)

Figure 2.6 LED Matrix Display

A common size for a character is 5×7 pixels, either separated with blank lines with no dots (in most text-only displays), or with lines of blank pixels (making the real size 6x8). [5] In this project, the dot matrix used are of 8x8 type. The combination of 16 dot matrix produced the display with a pixel density of 64x16. To control the dot matrix, HT1632C are used for each of the 4 dot matrix.

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This LED matrix is designed to be able to not only display a words, but also a picture. This display consist of 8x2 LED matrix. Each of the LED Matrix is 8x8 pixels, so the total pixel available to the display is 64x16 which make it ideal to display not only a words, but also a picture. The display have 3 mode of color which is red, yellow and orange. We can set the color according to our preferences in the coding and let the display and Arduino do the rest of the operation. Most of the component are incorporated on the circuit board. It is just simply add in power and connect the display to the Arduino UNO. The LED display has been designed as in the Figure 3.3 with capability and features of: 

Each component is soldered properly and tested



Support up to 10A maximum



5V logic level compatible inputs



12V as Vcc



8 LED Matrix with tri-colour function

The pin function description is presented in the Table 2.1

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Table 2.1 LED Matrix Pin Function Description Pin Number

Pin Name

Function Description

8, 11, 13, 15

GND

GND

12, 14, 16

VCC

Power Supply

3, 4, 6, 9, 10

NC

No Connection

1

CS

Chip Select signal input

2

CLK

Chip Select clock signal input

5

WR

WRITE data clock input

7

DATA

Data Input

2.2 SOFTWARE 2.2.1 Arduino Programming Language Arduino Programming language is used to create a program on the Arduino Bootloader component. The program created in this programming language will enable the LED Matrix display to be connected with the internet by the combination of Arduino UNO and the Ethernet Shield. The coding is made to enable the Arduino UNO to act as the brain for the whole system while Ethernet Shield work as an input whereas LED matrix display works as the output. Without the proper coding, all the hardware cannot work together to perform the required task. [6]

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Figure 2.7 Arduino Programming Language

2.2.2 Visual Studio 2010 In order to make this system fully integrated and functional automatically, we have decided to use C# as our programming language. C# intended to be a simple, modern, general purpose, object oriented programming language. Anders Hejlsberg led the development team. The screenshot of this software is shown in Figure 3.6 [7]

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Figure 2.8 Microsoft Visual Studio 2010

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CHAPTER 3 Hardware and Software Implimentation 3.1 Design Introduction The main objective of this project is to design a Twitter Based display system that can display tweets in real time. Therefore, the main part of the system are the display since it’s work as an output of the project and also the Arduino along with Ethernet Shield and Clock Shield because it is the brain of the system.

3.2 System Overview

LED Matrix Display

Ethernet Shield

Twitter Server

Arduino Uno

Clock Shield Figure 3.1 Overview of the project

Figure 3.1 serves as the general block diagram of the project. The Ethernet Shield will always be connected to the internet. Once it detects any data coming from the internet, it will send the data to the Arduino UNO and it will convert the data before it is sent to the LED matrix display. At the same time, the Arduino UNO is also connected to clock shield which will always update the current time to be displayed. 23

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In the case no data coming from twitter server, the display will always display the time and acts as a clock.

3.3 System Flowchart

Figure 3.2 Project Flowchart

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3.4 Hardware Building 3.4.1 LED MATRIX As stated earlier, this project is divided into several parts. The first part consists of the LED Matrix display. For this part, the design of LED matrix display is done in several stage and starting with only one LED matrix. The goal of this display is to be able to display any character coming from Arduino and also display the time from clock shield. The data obtained will be displayed on the LED matrix display. The main component of this display is few LED matrix, power supply and microcontroller. This is how the device work: When there are any input coming from Ethernet shield, the Arduino will process the data and send it to the LED displays. The display will continuously display the status for a certain period of time. If there is no input from Ethernet shield, the input from clock shield is used as an output for the display. Constructing of the LED display The real purpose of this project is to light up a display. We choose LED Matrix 7x5 like in Figure 3.3 to start the project. Using the circuit from the project before, we modify it a bit to used it with the display.

Figure 3.3 7x5 LED Matrix

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The main difference to use LED matrix compared to LED is that we have to use transistor to control the circuit. First we hooked up the LED matrix with some resistor and mapped out the pins. We noticed the ROW and COLUMN pin are not in the sane order. Next, we added transistor into the fray. Next we turned on all the rows with jumpers to Vcc via 220 ohms and get the port to light each column in turn. Lastly, we wired up the rows to the micro and started to watch the show. After that, we added scrolling. The complete circuit schematic is shown in Figure 3.4. [8]

7x5 LED Matrix

Transistor

ATMEGA8-PU

Figure 3.4 7x5 LED Matrix Schematic

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After successfully light up a single LED matrix, we move on to the next phase which is to light up multiple LED display together. To do this, we realize that we will need a lot more component and also a bigger board to cater our need. First thing we do is we read a lot of article and tutorial regarding on how to combine multiple LED matrix and connected it together in a simplest way because we don’t want my circuit to be too complicated. The simpler the circuit, the better because not only it can reduce cost by reducing the needed component, it is also easier to troubleshoot a much simpler circuit. The final design is as Figure 3.5 below. [9] Not only it require minimal amount of component, the component needed also available locally which make it easier to get.

Figure 3.5 Multiple LED Matrix Schematic

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After lots of hassle trying to connect the circuit to follow the above schematic, we finally manage to make it work. The hardest thing about this circuit is that it is very hard to solder it properly since most of its legs are positioned very near to each other. There are some problems with the solder too since its look as if it was soldered correctly but actually the solder is not properly connected. The figure below shows the initial orientation of the circuit using breadboard. The only problem doing the project of this scale using a breadboard is about the wire because it is easily disconnected. Also the amount of jumper wire needed is enormous. 74HC595

LED Matrix

TPIC6C595

Jumper Wire

Figure 3.6 Multiple LED Matrix on Breadboard

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The after soldered product is more simpler and looks neater. Figure 3.7a and 3.7b below shows the completed product at this point. 74HC595

TPIC6C595

Female Header Figure 3.7a Multiple LED Matrix Circuit

8x8 LED Matrix

Figure 3.7b Completed Multiple LED Matrix

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The next step is to make this project more intuitive and more interesting. After successfully do the display using single colour LED matrix, we are planning of using multiple colours LED matrix. This is a huge upgrade from the previous step and at this point we just realized that we couldn’t do this using the normal board. A normal led matrix have 16 pins connected together and this multicolour have 16 pins more than that-32 pins to be exact. Imagine how hard it is to connect 16 of those LED matrix together to make the complete project. This is when we started to think of something else. We guess we need to design a complete PCB for this project. Figure below shows the completed circuit design of the PCB. Guys in Sure Electronic sure knows how to help us design the circuit and what component we need to use and need to left out in the first place. This design consist of using 8 ht1632c [10] chip as each of the chip will be used to control 2 set of LED matrix. the total LED matrix uses are 8 which is in the configuration of 8x2 Below are the details of the hardware: 1. 8 pieces of 8*8 bicolor LED dot matrix. Light-emitting diameter of DE-DP14112 is 3mm. Light-emitting diameter of DE-DP14211 is 5mm. 2. LED drive chip (U2, U3, U5, and U6): four HT1632C chips, QFP packaging. 3. 16-pin male sockets (BR1 and BR2): used for data, clock, control signal and +5V supply input. 4. Auxiliary power supply terminal (+5V) (J1and J2): for external power input when more info boards are connected in series. 30

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LED Matrix

HT1632 Chip

Figure 3.8 Multiple tricolor LED Matrix Schematic

The pin configuration of this hardware is listed in the table 3.1 below. For this project, only few pins are involve which is the VCC and ground pin, data, clock, select and data. If we look at the communication pins in the back of the matrix we can read some interesting names: cs, clk, data, wr. All the others are power signals (+5 V and GROUND) or useless (NC).

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cs

CHIP SELECT - select the microchip at which Arduino send the data to; by

changing the chip we can control all the LEDs of the matrix with the method explained before.

clk

CLOCK - the clock signal helps the microchip to sync with data sent from the

Arduino,

data

this

clock

is

needed

to

sync

the

chip

selection

information

DATA - the series of 0 and 1 that forms the information explained before

wr WRITE - sync the data information, it’s the clock for the data transmission Table 3.1 LED Matrix Pin Function Description

Pin Number

Pin Name Function

Description

8, 11, 13, 15

GND

GND

12, 14, 16

VCC

Power Supply

3, 4, 6, 9, 10

NC

No Connection

1

CS Chip Select

Signal input

2

CLK Chip

Select clock signal input

5

WR

WRITE data clock input

7

DATA

Data Input

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Figure 3.9 Led Matrix Pin Connection

After making sure the display working fine as it should, we started to design the case which will hold all the component together using Autocad 2012.[11] The case we are using is completely homemade as we are using acrylic as the base model. The acrylic is easy to cut and therefore, we don’t need a very complicated tools to make it.

2 layer of acrylic Display panel

Plate for shield

Figure 3.10 Acrylic Design

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Figure 3.10 shows the design of the acrylic casing that we planned to make. It has 2 layer of acrylic-top and bottom, with about 10 holes to hold the casing together with the display and all the shields. This casing is design such that is because to make it less complicated and less messy since all the wired and connection will be hide under the display. Figure 3.11a and 3.11b shows the 2d plan for all the plate along with the measurement.

Figure 3.11a Top plate Measurement

Figure 3.11b Bottom plate Measurement

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3.4.2 CLOCK SHIELD The clock shield is the second part of the project. This part is intended to make a working clock shield as it is needed to provide real time to the Arduino. The first thing to do to make the clock is to learn about how to use the RTC chip. The chip we used are DS1307 serial real-time clock (RTC).

Figure 3.12 DS1307 RTC Chip

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The DS1307 serial real-time clock (RTC) is a low power, full binary-coded decimal (BCD) clock/calendar plus 56 bytes of NV SRAM. Address and data are transferred serially through an I2C, bidirectional bus. The clock/calendar provides seconds, minutes, hours, day, date, month, and year information. The end of the month date is automatically adjusted for months with fewer than 31 days, including corrections for leap year. The clock operates in either the 24-hour or 12- hour format with AM/PM indicator. The DS1307 has a built-in power-sense circuit that detects power failures and automatically switches to the backup supply. Timekeeping operation continues while the part operates from the backup supply. [12] The reason we choose DS1307 is because it have several features that really suits this project. Among all the feature are: 

Real-Time Clock (RTC) Counts Seconds, Minutes, Hours, Date of the Month, Month, Day of the week, and Year with Leap-Year



Compensation Valid Up to 2100



56-Byte, Battery-Backed, General-Purpose RAM with Unlimited Writes



I2C Serial Interface



Programmable Square-Wave Output Signal



Automatic Power-Fail Detect and Switch Circuitry



Consumes Less than 500nA in Battery-Backup Mode with Oscillator Running



Optional Industrial Temperature Range: -40°C to +85°C



Available in 8-Pin Plastic DIP or SO



Underwriters Laboratories (UL) Recognized 36

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The DS1307 serial real-time clock (RTC) has 8 pin in total and each pins have their own function. Table 3.3below will explain about the pin Table 3.2 DS1307 Pin Function Description

PIN

NAME

1

X1

FUNCTION Connections for Standard 32.768kHz Quartz Crystal. The internal oscillator circuitry is designed for operation with a crystal having a specified load capacitance (CL) of 12.5pF. X1 is the input to the oscillator and can optionally be connected to an external 32.768kHz oscillator. The output of

2

X2

the internal oscillator, X2, is floated if an external oscillator is connected to X1. Backup Supply Input for Any Standard 3V Lithium Cell or Other Energy Source. Battery voltage must be held between the minimum and maximum limits for proper operation. Diodes in series between the battery and the VBAT pin may prevent proper operation. If a backup supply is not required, VBAT must be grounded. The nominal power-fail trip point

3

VBAT

(VPF) voltage at which access to the RTC and user RAM is denied is set by the internal circuitry as 1.25 x VBAT nominal. A lithium battery with 48mAh or greater will back up the DS1307 for more than 10 years in the absence of power at +25°C. UL recognized to ensure against reverse charging current when used with a lithium battery.

4

GND

Ground Serial Data Input/Output. SDA is the data input/output for the

5

SDA

I2C serial interface. The SDA pin is open drain and requires an external pullup resistor. The pullup voltage can be up to 5.5V regardless of the voltage on VCC. 37

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Serial Clock Input. SCL is the clock input for the I2C 6

SCL

interface and is used to synchronize data movement on the serial interface. The pull up voltage can be up to 5.5V regardless of the voltage on VCC. Square Wave/Output Driver. When enabled, the SQWE bit set to 1, the SQW/OUT pin outputs one of four square-wave frequencies (1Hz, 4kHz, 8kHz, 32kHz). The SQW/OUT pin is

7

SQW/OUT open drain and requires an external pull up resistor. SQW/OUT operates with either VCC or VBAT applied. The pull up voltage can be up to 5.5V regardless of the voltage on VCC. If not used, this pin can be left floating. Primary Power Supply. When voltage is applied within normal limits, the device is fully accessible and data can be

8

VCC

written and read. When a backup supply is connected to the device and VCC is below VTP, read and writes are inhibited. However, the timekeeping function continues unaffected by the lower input voltage.

To design the Clock shield, we need few other component to make the RTC work properly. Here is the list of component that will be used to make this clock [13]        

One Arduino protoshield pack X1 – 32.768 kHz crystal IC1 – Maxim DS1307 real time clock IC 8-pin IC socket CR2032 3v battery CR2032 PCB mount socket R1~R3 – 10k ohm metal film resistors C1 – 0.1 uF ceramic capacitor

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The next step is to consider the component placement and wiring for the protoshield. [14] The schematic is shown in figure below. This is a very simple circuit and therefore we only use protoshield and design the circuit on it. The PCB is neater but there is no need for that to make this clock.

32.768 kHz crystal

Resistor 10kΩ

Capacitor 0.1uF

Battery 3v

Figure 3.13 Clock Shield Schematic

Now we just have to follow the schematic and designing the board positioning. We triple-check the layout against the schematic. As my protoshield has a yellow LED, we have wired the square-wave output to make it as an indicator if the shield is working perfectly.

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Picture below shows the completed clock shield

Figure 3.14a Completed Clock Shield - Back

Figure 3.14b Completed Clock Shield - Front

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CHAPTER 4 Result And Discussion 4.1 SIMULATION OF OPERATION

Display Panel

Arduino Uno

RJ45 Cable

Laptop

Ethernet Shield

Clock Shield

Figure 4.1 Completed Figure 4.2 System System Flowchart

Figure 4.1 shows the completed product of the Twitter display system, consisting of the display, the Arduino UNO, the clock shield, the Ethernet shield and modem. The laptop is there to upload the program to the Arduino UNO. The program is done by the author’s project partner. 41

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The completed prototype is shown below. We try our best to cramp everything inside the acrylic casing so that it will look neater and more portable.

Figure Figure 4.4a 4.2a Prototype Prototype Display Display - Top - Top View View

Figure Figure 4.4b 4.2b Prototype Prototype Display Display - Side - Side View View

Figure 4.2c Prototype Display - Perspective View

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To start the Display, just plug in the USB cable to the Arduino UNO. At the beginning, the Arduino UNO will wait for the signal from the Ethernet shield. If there is no signal coming from it, it will take the signal from clock shield and display it until there is any signal coming from the Ethernet shield.

Figure Figure Figure 4.5 4.4 4.3 Initialization Initialization Initialization of ofof The theThe system System System

The clock shield will provide information for the LED matrix to display time and date as in Figure 4.4

Date

Time

Figure 4.4 Date and Time Mode

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Next, if there are any signal coming from Ethernet shield, the UNO will process the data and send it to be displayed by the LED matrix for about 1 minutes. If no other signal coming from the Ethernet shield, the led matrix will revert back to display time and date. Since we still could not figure out how to get the data from the twitter server, the connection is definitely unsuccessful.

Figure 4.7a Attempting Connection Figure 4.5a Attempting Connection Figure 4.6a Attempting Connection

Figure 4.5b Connection Failed

The process keep on repeating until we took the supply off the hardware.

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If there are any problem with the twitter server or internet connection, the LED matrix will continue to display time and clock and it will never rendered useless even without internet connection as the clock shield can provide time offline.

Figure Figure 4.8a Display Display Time Time Mode Mode 4.7a4.6a

Figure 4.6b Display Date Mode Figure 4.7a Display Time Mode

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CHAPTER 5 Conclusion and Recommendation 5.1 CONCLUSION It can be concluded that this project is a success in meeting the objectives of the project which is to create a system that can display a message and can connect to the internet. However, the system still cannot display the twitter message because we still couldn’t figure out a way to go into the twitter server and grab the data from there. The system only manage to show time and date for the moment.

5.2 RECOMMANDATION FOR FUTURE WORK 5.2.1 Wireless Twitter display Even though the display does not require wireless connection as the Ethernet shield already provides internet connection through LAN cable to the modem, it will be much more convenient if the connection is by wireless connectivity. First, it will make the display more portable and second, it will make the display easier to read as we can place it somewhere high.

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5.2.2 Constructing Low Power Consumption WI-FI Device By using current WI-FI system, the power consumption is not so efficient as the device to detect, transmit and receive the data requires high power to work. The wifi access point itself needs a power supply to be switched on. Hence, further upgrade on these devices should be made in order to improve the implementation of WI-FI as the wireless data transfer for the receiver and transmitter device.

5.3.3 Constructing battery powered device By using WI-FI system, the device will be very portable. So, it can be placed anywhere we want. However, the device will still rely heavily on power supply and that means, the device itself needs to be placed near power socket. If the device can be powered by battery, it will be ultimately portable and more practical to be used as information display.

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REFERENCE [1] (URL-http://en.wikipedia.org/wiki/Twitter), November 2011 [2] (URL-http://tweeternet.com/), November 2011 [3] (URL-http://Arduino.cc/en/Main/arduinoBoardUno), January 2012 [4] (URL-http://Arduino.cc/en/Main/ArduinoEthernetShield), March 2012 [5] (URL-http://en.wikipedia.org/wiki/Dot-matrix_display), November 2011 [6] (URL-http://www.Arduino.cc/),January 2012 [7] (URL-http://en.wikipedia.org/wiki/Microsoft_Visual_Studio), December 2011 [8] (URL-http://www.avrfreaks.net/index.php?module=Freaks%), January 2012 [9] (URL-http://g33k.blogspot.com/2010/02/Arduino-56x8-scrolling-led-matrix.html) December 2011 [10] (URL-http://www.holtek.com/english/docum/consumer/1632c.htm) ,February 2012 [11] (URL-http://cad-notes.com/2011/04/autocad-2012-creating-drawing-views-from3d-model/), April 2012 [12] (URL-http://www.maxim-ic.com/datasheet/index.mvp/id/2688) February 2012 [13] (URL-http://tronixstuff.wordpress.com/2010/05/28/lets-make-an-Arduino-realtime-clock-shield/) February 2012 [14] (URLhttp://www.cytron.com.my/viewProduct.php?pid=IhgMNTU8NzgbLi43BDkWA0WVh Do99TrhxkKylH8ZYzM=), February 20120

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Additional References [15] (URL-http://arduino.cc/en/Tutorial/RowColumnScanning),November 2011 [16] (URL-http://forums.parallax.com/showthread.php?128037-Sure-Electronics-new32x16-bi-color-display-3216-RG), February 2012 [17] (URL-http://www.instructables.com/id/Twitter-controlled-Arduino-Outputs-noPCLCD-Disp/),January 2011 [18] (URL-http://arduino.cc/forum/index.php/topic,92858.15.html),February 2012 [19] (URL-http://www.kicadlib.org/), December 2011 [20] (URL-http://www.anzel360.com/arduino/socialbot9000-arduino-based-twitterdisplay/),Mac 2012 [21] (URL-http://arduino.cc/forum/index.php/topic,8031.0.html), February 2012

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