March 2014 - Islamic University of Gaza

March 2014

5

2 Embedded Systems Lab

Objectives

1. To be familiar with Graphical LCD displays.

2. To be familiar with LED Dot-Matrix display.

Graphical LCD

Graphical LCDs allows creating more elaborate visual messages than usual

alphanumerical (character) LCDs can provide, involving graphics (bitmaps

pictures, drawings and shapes) and characters.

Controllers

The most important consideration in choosing an LCD display is the

controller. An LCD display without a controller needs to be refreshed at a fast

enough rate to prevent flickering. The most popular, though slightly

outdated standard is the T6963C controller made by Toshiba.

GLCD & Led-Matrix


T6963C Graphic Lcd Library

Mikrobasic for PIC provides a library for working with Glcds based on

TOSHIBA T6963C controller. The Toshiba T6963C is a very popular Lcd

controller for the use in small graphics modules. It is capable of controlling

displays with a resolution up to 240x128. Because of its low power and small

outline it is most suitable for mobile applications such as MP3 players or

mobile measurement equipment. Although small, this controller has a

capability of displaying and merging text and graphics and it manages all the

interfacing signals to the displays Row and Column drivers.

For creating a custom set of Glcd images use Glcd Bitmap Editor Tool.

GLCD Modes

- Graphics mode (for pictures, drawings and shapes)

- Text mode (for characters)

Both modes have specific routines for activating mode and making a

command to draw, load image and write text.

At Proteus: PG128128A

LCD graphics displays come in a variety of sizes. In this lab we will work with

PG128128A LCD (128 * 128 _size) that have T6963C controller Use

mikrobasic T6963C Graphic LCD Library to program such LCDs.


Library Routines

Example: T6963C_init(128, 128, 8, PORTB, PORTD, 3, 2, 1, 5)

- init display for 128 pixel width and 128 pixel height

- 8 bits character width

- data bus on PORTB

- control bus on PORTD

- bit 3 is !WR (write- Look at GLCD pins: wr: active low)

- bit 2 is !RD (read)

- bit 1 is !CD (command/data)

- bit 5 is RST (reset)


For activating text mode

For writing texts


For activating graphics mode

For drawing rectangle


For viewing an image

In order to load an image into GLCD, this image must have many properties which

are generated by many steps as the following procedure shows:

Wanted specifications => 128 * 128 pixels monochrome (black & white)

bitmap image

1. Open the image using paint “open with paint” >> Get the wanted size

using Resize icon >> choose pixels <<un-tick ratio << enter 128*128 for the

size.


2. Save as >> Monochrome Bitmap (with Arabic versions: أحادية اللون )

3. Now your image is ready to be used with GLCD

4. Use Mikrobasic tool GLCD bitmap editor from tools menu.

5. From T6963c tab choose the appropriate value for GLCD size/controller

according to your LCD size: 128*128.

6. Load the bmp picture from load button << you can also invert colors >>

7. An automated code will be generated for this picture.

8. Choose mikrobasic code from the bottom right list.

9. Copy the generated mikrobasic code to clipboard and paste it into your

program << before the main >>.


Proteus

1. Write a basic program to display the following figure on

the GLCD: Draw triangle then view an image with a text

like following figure.

2. Simulate the circuit using Proteus ISIS program.

Lab Work 1


Mikrobasic

How to think …

In order to draw the rectangle then write a text with an image, we must

firstly think of the arrangement of the functions (in general):

- Initiate the GLCD

- Enable graphics mode

- Draw rectangle

- View image

- Enable text mode

- Write a text

You can use T6963C_init

instead of these


Some important notes (code will be your own task, do it by yourself )

Initiate the glcd << enable text mode << write a message <<write ‘*’ at each button

test << if password is correct: write the name, enable graphics mode and load image

<< else do the suitable actions << do suitable work for reset.

1. Improve your application by replacing the lcd with glcd

<< Enter your password message << numbers as ‘*’ <<

when button is checked, if password is correct, show

the user’s photo and his name, else show warning

message>>

2. - edit reset part using glcd

Application - Part 3


LED Dot Matrix Display

A dot matrix is a 2-dimensional array of dots used to represent characters, symbols

and images. Typically the dot matrix is used in many digital display devices. In

displays, the dots light up, as in an LED or CRT display. Led matrix display can show

pictures and words, and RGB led matrix even can show video.

LED matrix has the size from 0.7'' to 4.6''. According to its dot arrangements, LED

dot matrix display also can be divided into 5*7 dot matrix, 5*8 dot matrix and 8*8

dot matrix. Actually there are also led matrix consists of led lamps.

Internal connection of the Dot-matrix display illustrates its idea of work. Note that

every LED is simply a diode that lights when you put it in a circuit with a drop

voltage. So using MCU we are going to loop over every column and supply the right

voltage and ground values.

For every led to be shined:

VCC must be connected to

the column and GND to

the row


How it works

The LED matrix used in this lab is of size 5×7. We will learn how to display still

characters in a standard 5×7 pixel format. The figure below shows which LEDs are to

be turned on to display the English alphabet ‘A’. The 7 rows and 5 columns are

controlled through the microcontroller pins. Now, let’s see in detail how it works.

Suppose, we want to display the alphabet A. We will first select the column C1

(which means C1 is pulled low in this case), and deselect other columns by blocking

their ground paths (one way of doing that is by pulling C2 through C5 pins to logic

high). Now, the first column is active, and you need to turn on the LEDs in the rows

R2 through R7 of this column, which can be done by applying forward bias voltages

to these rows. Next, select the column C2 (and deselect all other columns), and

apply forward bias to R1 and R5, and so on. Therefore, by scanning across the

column quickly and turning on the respective LEDs in each row of that column, the

persistence of vision comes in to play, and we perceive the display image as still.


The table below gives the logic levels to be applied to R1 through R7 for each of the

columns in order to display the alphabet ‘A’.

At proteus : matrix-5x7 At hardware


For ‘A’ letter-the const is: 7E,11,11,11,7E

In order to load these values to the led**matrix using pic code, we can do the

following:

For all characters and numbers values use the following constant to display on

DotMatrix, every character has 5-values as a constant array.

- Columns are connected to portd << rows at portb

- Code will be:

For i = 0 to 50 ‘reload every character to be shown for the user

Portd= 0x01

Portb=Not 0x7E ‘in order to get the wanted char. As a shining

one on an un-shined background (led-matrix inverses 0/1)

Delay_ms(10)

Portd= 0x02

Portb= Not 0x11

‘repeat previous code for other columns and values

const font as byte[215] = (

$7E,$11,$11,$11,$7E, 'A

$7F,$49,$49,$49,$36, 'B

$3E,$41,$41,$41,$22, 'C

$7F,$41,$41,$22,$1C, 'D

$7F,$49,$49,$49,$41, 'E

$7F,$09,$09,$09,$01, 'F


$3E,$41,$49,$49,$7A, 'G

$7F,$08,$08,$08,$7F, 'H

$00,$41,$7F,$41,$00, 'I

$20,$40,$41,$3F,$01, 'J

$7F,$08,$14,$22,$41, 'K

$7F,$40,$40,$40,$40, 'L

$7F,$02,$0C,$02,$7F, 'M

$7F,$04,$08,$10,$7F, 'N

$3E,$41,$41,$41,$3E, 'O

$7F,$09,$09,$09,$06, 'P

$3E,$41,$51,$21,$5E, 'Q

$7F,$09,$19,$29,$46, 'R

$46,$49,$49,$49,$31, 'S

$01,$01,$7F,$01,$01, 'T

$3F,$40,$40,$40,$3F, 'U

$1F,$20,$40,$20,$1F, 'V

$3F,$40,$38,$40,$3F, 'W

$63,$14,$08,$14,$63, 'X

$07,$08,$70,$08,$07, 'Y

$61,$51,$49,$45,$43, 'Z

$3E,$51,$49,$45,$3E, '0

$00,$42,$7F,$40,$00, '1

$42,$61,$51,$49,$46, '2

$21,$41,$45,$4B,$31, '3

$18,$14,$12,$7F,$10, '4

$27,$45,$45,$45,$39, '5

$3C,$4A,$49,$49,$30, '6

$01,$71,$09,$05,$03, '7

$36,$49,$49,$49,$36, '8

$06,$49,$49,$49,$3E, '9

$00,$00,$00,$00,$00, '

$08,$08,$3E,$08,$08, '+

$08,$08,$08,$08,$08, '-

$00,$60,$60,$00,$00, '.

$14,$08,$3E,$08,$14, '*

$00,$36,$36,$00,$00 ':

)


In order to feel free for choosing your own characters and showing them on led-

matrix, you can implement normal or custom characters by drawing them and get

their constants array using: MikroElektronica GLCD Font Creator program.

Download it from here

Steps of work will be like this:

1. Create new font >> enter name and change size to 5x7

https://www.mediafire.com/?aqybdufjevcx9qm


2. Grid layout will appear like this

3. Draw your own character, then pess at its place to save it

To get a const for the char. Clear invert colors

Press

here


4. Your charcters is saved, get its constant array

5. Copy and baste the code in your project before the main

Addresses of

characters

Change them

according to your

characters addresses


Proteus

1. Write a basic program that displays the letters from A to H

on the led Matrix.

2. Simulate the circuit using Proteus ISIS program.

3. Connect the circuit at the hardware kit.

Lab Work 2


Code

After drawing letters A-F and getting their const. arrays, we must use a loop for

showing them on the led-matrix instead of traditional way for loading every value

to the port for every character.

Mikrobasic

‘ << ‘ shift number left

by one position

Portd: 00000001

00000010

00000100

00001000

00010000


If you inverse ports << If you use portb for columns, the same work will not give

the same results!!

- If you work with portb, cancel RB0 from your cade:

- RB0 have a problem with shift operator ’ << ‘.

- Start to enable the first column normally

by changing code and simulation like this:

Warning!


… Good Luck …

1. Write a basic program to display the following figure (use

your name & ID) on the GLCD (implement the design as much

as possible).

2. Write a basic program that displays the numbers from 0 to 9

on the led Matrix.

3. Do Application-Part2 and include it at the report.

Homework

Documents

March 2014 - Islamic University of Gaza