ARM HOW-TO GUIDE Interfacing LCD with LPC2148 ARM · 12/1/2014 · Interfacing LCD ... Liquid Crystal Display also called as LCD is very helpful ... Tutorial of how to create & Debug

ARM HOW-TO GUIDE

Interfacing LCD with

LPC2148 ARM

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Contents at a Glance

ARM7 LPC2148 Primer Board ........................................... 3

LCD (Liquid Crystal Display) .............................................. 3

Interfacing LCD ................................................................ 4

Interfacing 4 bit LCD with LPC2148 ................................... 5

Pin Assignment with LPC2148 .......................................... 5

Circuit Diagram to Interface 4 bit LCD with LPC2148 ......... 6

Source Code .................................................................... 6

C Program to display a text in 4 bit LCD using LPC2148 ..... 7

Testing the LCD Module with LPC2148 ........................... 10

General Information ...................................................... 11



ARM7 LPC2148 Primer Board

The ARM7 LPC2148 Primer board is specifically

designed to help students to master the required skills in

the area of embedded systems. The kit is designed in such

way that all the possible features of the microcontroller will

be easily used by the students. The kit supports in system

programming (ISP) which is done through serial port.

NXP’s ARM7 (LPC2148), ARM Primer Kit is proposed to

smooth the progress of developing and debugging of

various designs encompassing of High speed 32-bit

Microcontrollers.

LCD (Liquid Crystal Display)

Liquid Crystal Display also called as LCD is very helpful

in providing user interface as well as for debugging purpose.

A liquid crystal display (LCD) is a flat panel display that uses

the light modulating properties of liquid crystals (LCs). LCD

Modules can present textual information to user.



Interfacing LCD

Fig. 1 shows how to interface the LCD to

microcontroller. The 2x16 character LCD interface card with

supports both modes 4-bit and 8-bit interface, and also

facility to adjust contrast through trim pot. In 4-bit interface

7 lines needed to create 4-bit interface; 4 data bits (D0 –

D3), three control lines, address bit (RS), read/write bit

(R/W) and control signal (E).

Fig. 1 Interfacing 4 bit LCD to Microcontroller



Interfacing 4 bit LCD with LPC2148

We now want to display a text in LPC2148 Primer Board

by using 4 bit LCD module.

The ARM7 LPC2148 Primer board has seven numbers of

LCD connections are needed to create 4-bit interface;

connected with 4 data bits (P0.19 – P0.22, D4-D7), address

bit (RS-P0.16), read/write bit (R/W-P0.17) and control signal

(E-P0.18) to make LCD display.

Pin Assignment with LPC2148

LCD MODULE LPC2148 LINES 2x16 LCD Selection

CO

NTR

OL

RS P0.16

RW P0.17

E P0.18

DA

TA L

INES

D0-D3 NC

D4 P0.19

D5 P0.20

D6 P0.21

D7 P0.22

Make switch SW28 to ‘LCD’

label marking position

+5V

ONOFF

SW28

PWR ON/OFF

1234

8765

LCD7SEG

GLCDSM/RL

GN

D

VC

C

VEE

RS

R/W

E D4

D5

D6

D7

LED

+

LED

-



Circuit Diagram to Interface 4 bit LCD with LPC2148

Source Code

The Interfacing 4 bit LCD with LPC2148 program is very

simple and straight forward, which display a text in 2 X 16

LCD module using 4 data lines only. Some delay is occurring

when a single command / data is executed.

RS

C52

22pf

3.3V

C53

22pf

X21

12MHz

LPC2148

U16

VSS16 V

DD

A7

VSS218

VD

D3

23

VSS325

VD

D2

43

VSS442

VR

EF

63

XT

AL1

62

XT

AL2

61

VSSA59

VD

D1

51

VSS550

P0.222P0.211P0.2055P0.1954

P0.1853P0.1747P0.1646

RW

JP12

2X16 LCD

11

22

33

44

55

66

77

88

99

1010

1111

1212

1313

1414

1515

1616

1717

1818

1919

2020

D7

+5V

EN

R30 10K1 3

2

D4

D6D5



C Program to display a text in 4 bit LCD using LPC2148 ***************************************************************************************

Title : Program to 4 bit LCD display ***************************************************************************************

#include <lpc214x.h>

#include <stdio.h>

#define RS 0x10000

#define RW 0x20000

#define EN 0x40000

void lcd_cmd (unsigned char);

void lcd_data (unsigned char);

void lcd_initialize (void);

void lcd_display (void);

void LCD4_Convert(unsigned char);

const unsigned char cmd[4] = {0x28,0x0c,0x06,0x01};

unsigned char msg[] = {">PS-Primer 2148<"};

unsigned char msg1[]= {":: LCD Demo! ::"};

void main()

{

PINSEL1 = 0;

IODIR0 = 0xFF << 16;

lcd_initialize();

lcd_display();

while(1);

}

void delay(unsigned int n)

{

unsigned int i,j;

for(i=0;i<n;i++)

for(j=0;j<12000;j++);

}



void lcd_cmd(unsigned char data)

{

IOCLR0 |= RS; //0x1000; //RS

IOCLR0 |= RW; //0x2000; //RW

LCD4_Convert(data);

}

void lcd_initialize(void)

{

int i;

for(i=0;i<4;i++)

{

IOCLR0 = 0xF << 19; //IOCLR 0/1

lcd_cmd(cmd[i]);

delay(15);

}

}

void lcd_data (unsigned char data)

{

IOSET0 |= RS; //0x1000; //RS

IOCLR0 |= RW; //0x2000; //RW

LCD4_Convert(data);

}

void lcd_display (void)

{

char i;

/* first line message */

lcd_cmd(0x80);

delay(15);

i=0;

while(msg[i]!='\0')

{

delay(5);

lcd_data(msg[i]);

i++;

}



delay(15);

/* second line message */

lcd_cmd(0xc0);

delay(15);

i=0;

while(msg1[i]!='\0')

{

delay(5);

lcd_data(msg1[i]);

i++;

}

delay(15);

}

void LCD4_Convert(unsigned char c)

{

if(c & 0x80) IOSET0 = 1 << 22; else IOCLR0 = 1 << 22;




IOSET0 = EN;

delay(8);

IOCLR0 = EN;





IOSET0 = EN;

delay(8);

IOCLR0 = EN;

}



To compile the above C code you need the KEIL

software. They must be properly set up and a project with

correct settings must be created in order to compile the

code. To compile the above code, the C file must be added

to the project.

In Keil, you want to develop or debug the project

without any hardware setup. You must compile the code for

generating HEX file. In debugging Mode, you want to check

the port output without microcontroller Board.

The Flash Magic software is used to download the hex

file into your microcontroller through UART0.

Testing the LCD Module with LPC2148

Give +3.3V power supply to LPC2148 Primer Board; the

LCD is connected with microcontroller LPC2148 Primer

Board. When the program is downloading into LPC2148 in

Primer Board, the screen should show the text messages.



If you not reading any text from LCD, then you just

check the jumper connections & adjust the trim pot level.

Otherwise you just check it with debugging mode in Keil. If

you want to see more details about debugging just see the

videos in below link.

How to Create & Debug a Project in Keil.

General Information

For proper working use the components of exact values

as shown in Circuit file. Wherever possible use new

components.

Solder everything in a clean way. A major problem

arises due to improper soldering, solder jumps and

loose joints.

Use the exact value crystal shown in schematic.

More instructions are available in following articles,

User Manual of LPC2148 Primer Board.

Tutorial of how to create & Debug a project in Keil.

http://youtu.be/EzOCple4POk

http://www.pantechsolutions.net/index.php?option=com_k2&view=item&layout=item&id=686&virtuemart_category_id=1&Itemid=19

http://www.pantechsolutions.net/index.php?option=com_k2&view=item&layout=item&id=313&virtuemart_category_id=1&Itemid=19



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ARM HOW-TO GUIDE Interfacing LCD with LPC2148 ARM · 12/1/2014 · Interfacing LCD ... Liquid Crystal Display also called as LCD is very helpful ... Tutorial of how to create & Debug