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Abstract
This project report gives us an idea about displaying messages and animated images on the Display Board; First of all we design a circuit that works as a driver between the computer and the Display Board, that takes input from computer in the form of binary numbers and using these binary numbers, it light the led’s of the Display Board that are necessary for our desired message or desired images. All these circuits take inputs from input/output card using Turboo C++ compiler. Compiler work on arrange data and give result on Board
Table of Contents
Chapter1.Introduction
Figure 1 ( Bird eye view of whole project )
Electronic Banner is a hardware system that displays our information instantly from a computer. It can be programmed by using input/output interfacing card through ISA slot, and we can mount it on a wall. Using microcontroller it can be programmed through the programming software using language C and then we can interface it through any port of computer. The basic unit is the Dot matrix, with the help of other component such as de-multiplexers, Latches, transistors, we can light the led’s in a specific manner. Dot Matrix display board is simply a grid of LEDs. The combination of led’s can be used to perform some specific task or some displaying functionalities. By arranging these 8*8 Dot-matrixes in a square shape or rectangle shape we define the numbers of rows and columns of Board. Combining the Dot-matrixes in square shape dimensions of the Board will be 64x64 pixels. 64 rows It means and 64 columns and combining them in a rectangular shape the size of the Display Board will be 32x128 pixels. It means 32 rows and 128 columns. Characters size of message will be 5x7 =35 pixels; it means that 7 rows and 5 columns. Small characters messages can be displayed on it. Small characters size will be 5x4 =20 pixels, 5 rows and 4 columns. The image and message appears on the Display Board by lighting the Led’s in a very few interval of time (one mille-second/less). The image appears on display Board 1/ 25 seconds; its
copy is made on the retina. This process continues and these dots make image on the retina. In this way our eyes feel continues image rather than dots.
1.1 Display Features:
- Static characters, static images and static symbols can be displayed on it.
- Moving text message can be displayed on it.
- Numeric symbols and animated images can be displayed on it.
- Text message can be displayed in reversed order
- The movement of messages should be column wise, not row wise
- Computer link through input/output interfacing card.
- Maximum character size is 5x7 pixels and maximum 12 characters are visible in one row.
It is extendable up to four times according to its hard ware drivers
- Total number of display Board rows are eight
- Total size is 64x64=4096 Pixels and also extendable.
- Automatic text source selection
- Character width 0-5 pixels (+optional blank column between the characters)
- No scrolls, scrolls left, scroll right, controlling scroll speed, and all features are possible.
1.2. Comparison with others:
My project is large in size from [3], [4] and [5]. The projects from these links are single line display but my display board is multiple lines display and has extra display features. It is GUI based as others. Its GUI interface is made in Turboo C++. All features of all other project that are available on these links [3], [4], and [5] are added with it. Its size is further extendable and we can extend its size four times and complete project size will become 32x8=256 Dot-matixes.it means that its complete size will become 256x64=16384 Pixels. Due to large size it is more costly.
Figure 2.1.1 (Block Diagram of Input/output Card Interfacing with sign board)
From Block diagram it shown that Mux is connected with one port of I/O card and the other one is used to control the Latch inputs and 4 bits of third port are used to control the CP pins of four Latches and other 4 bits are used to control OE pins of four Latches. Each Latch has one CP pin and one OE pin. All four Latches are connected parallel and their input is common. 8 to 256 lines De-multiplexer is used to controlled the columns of Display Board. These outputs are used to move column of Dot – matrix (Bloch of characters).By controlling Cp and OE pins of the Latches, the input data appears on each Latch output. ISA slot is earlier technology, in new system it is not available and this device is not sported by new windows. Only we can operate it on window 98. In window XP and other latest windows, its driver is not installed automatically and their drivers for window XP are not available. To remove this difficulty we use parallel port to interface any external device.
2.1.2. Serial Port Interfacing:
P
RxD P
Using serial port of PC the Display Board can be controlled through Microcontroller 89S52. The serial data come from PC through TxD pin of serial port to RxD pin of Microcontroller and the data will be save in the Microcontroller Memory and then the Microcontroller convert the serial data to parallel. In this way the drivers of Display Board can be controlled.
2.3: Data Flow Diagrams:
Each time every block is shifted one column on Display Board
And then moves forward up-to display length Moves on ward ----------
Moves on ward ----------
Moves on ward ----------
A
A B
A B C
Serial Port 89C
Mux
Display Board
Array of Latches
P
P
Figure 3 (Serial Port Interfacing):
2.5. Reverse display:
2.6. Flow of Characters on Display Board (By shifting 1-col)
Step 1:
Step2:
Step3:
Step4:
Step5:
Step6:
Step7:
Step8:
2 3 ....................................................................................^ 63 64 65
Mux read data from Data-Array, starting from index [0]--index [63] of Data-Array, each time it reads 64 columns from data array, Mux take 64 columns as a frame, each time start index[] and ending index[] changed by increment of one. In this way the Mux read next frame of Data-Array that is incremented by one column, starting index of next frame is index [1] and ending index is index [64] and further next frame is index [2]--index [65]. This process continues up to the length of Data-Array. When Mux reached last frame and further next frame is the first frame. This process continues in circular way by changing the frames in few mile-second.in this way we can see a message on the Sign Board.
2.8: Left to Right Scrolling Procedure (Using Frames):
Mux-input:
Data-Array:
Length(Data-array) …………………………………………………..
Length-Frame-Size (length-64)
Length=Length- 1 ……………………………………………………
Length-Frame-Size (length- 64 )
Length=Length- 2 ................................................................................
Length-Frame-Size (length- 64 )
Length=Length- 63 ……………………………………………………
Length-Frame-Size (length- 64 )
In left to right scrolling, Mux read data from Data-Array in reverse order. In reverse scrolling the start index of first frame is index [length] and last index of the first frame is index [length-frame- size]. It means that first frame is index [length]--index [length-frame-size] and the second frame is frame that Mux read, is index [length-1] ---index [length-Frame-size] and the further next frame is index [length-2] ---index [length-Frame-size]. In this way this process continues until the index [0] of Data-Array is reached. It means that the end point of last frame is index [0]. When Mux reach at last frame then the next frame is the first frame, this process continue in circular way, then scrolling is visible from left to right.
2.9: Static Display Procedure (using Frame)
Mux-input:
Data-Array:
0 1 ....................................................................................^ 61 62 63
0 1 ....................................................................................^ 61 62 63
From right to left scrolling, each time compiler took a new frame one index shifted from left towards right and displays it on the Display Board. Each time a new data appears on the Display Board and the characters seem to scrolling from right to left.
2.11: Left to Right Scrolling Frames:
From right to left scrolling, each time compiler reads a frame from last index of data array up to length-frame size and each time one index shifted frame towards left from right is display on the Display Board. In this way characters are seem to scrolling from right towards left.
Chapter3. Hard ware
3.1: Hardware Components:
The main hardware components that are used in my project are
- De-multiplexer (MUX)
- Dot-matrix
- Latches
- Transistors
- Programmable peripheral interface (PPI)
