ARM7 LPC2148 1

How to Interface LCD with LPC2148 ARM

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.

NXPs 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

CONTROL

RS P0.16

RW P0.17

E P0.18

DATA

LINES

D0-D3 NC

D4 P0.19

D5 P0.20

D6 P0.21

D7 P0.22

Make switch SW28 to LCD label marking

position

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.

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

******************************************************************************

*********

Title : Program to 4 bit LCD display

******************************************************************************

*********

#include

#include

#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 int i,j;

for(i=0;i

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

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.

How to Interface Sensor with LPC2148 ARM Evaluation Board

ARM7 LPC2148 Evaluation Board

The ARM7 LPC2148 Evaluation 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.

NXPs ARM7 (LPC2148), ARM Evaluation Kit is proposed to smooth the progress of developing

and debugging of various designs encompassing of High speed 32-bit Microcontrollers. Temperature Sensor

DS1820 is a temperature sensor which is small sensor. The output of sensor converted to digital

that easy connecting with microcontroller. Interfacing ds1820

Fig. 1 shows how to interface the ds1820 to microcontroller. As you can see the first pin is

connected to GND, the third pin is connected to VCC & the second pin is connected to the

Microcontroller. So when the temperature is sensing, it give the sensor reading to controller.

Fig. 1 interfacing ds1820 to Microcontroller

Interfacing ds1820 with LPC2148

We now want to read the temperature in LPC2148 Evaluation Board from temperature sensor

ds1820. The ARM7 LPC2148 Evaluation board uses the ADC pin for reading temperature from

temperature sensor ds1820. The reading output is displayed into PC through UART1.

The 10 bit ADC used to read temperature. Basic clocking for the A/D converters is provided by

the VPB clock. A programmable divider is included in each converter, to scale this clock to the

4.5 MHz (max) clock needed by the successive approximation process. A fully accurate

conversion requires 11 of these clocks. Pin Assignment with LPC2148

On-Chip ADC ADC Inputs LPC2148 ADC Select

POT (R28) ADC0.1 P0.28

Circuit Diagram to Interface ds1820 with LPC2148

Source Code

The Interfacing ds1820 with LPC2148 program is very simple and straight forward, that read

temperature from temperature sensor ds1820 and it display into PC through serial port. C Program to read temperature using LPC2148

******************************************************************************

*********

Title : Program to read temperature using ARM7 Evaluation Board

******************************************************************************

*********

#include // Define LPC2148 Header File

#include

#define DONE 0x80000000

#define START 0x01000000

#define PRESET 0x00230600

void main ()

{

unsigned long Val;

VPBDIV = 0x02;

Serial_Init ();

PINSEL1 = 0x01 > 6) & 0x3FF);

printf (">> Current Temperature : %4d ", Val);

printf ("\xF8 \F \r");

}

}

void Delay ()

{

unsigned int i,j;

for (i=0;i

printf (" 2009 Pantech Solutions Pvt Ltd \n\r");

printf ("-----------------------------------------

---------------\n\r");

printf ("*** Temperature Sensor Interfacing with

Tyro Kit ***\n\r");

printf ("-----------------------------------------

---------------\n\r");

printf (">> Put Jumper J in 'E' Mode to Enable

Temp Sensor Block \n\r");

printf (">> Connect UART1 to COM Port @ 9600 Baud Rate\n\n\r");

printf ("***************************************

*****************\n\r");

printf ("************************* Result ***********************\n\r");

printf ("***************************************

*****************\n\n\r");

}

void Serial_Init ()

{

PINSEL0|= 0x00050000; //Configure TxD1 and RxD1

U1LCR = 0x83;

U1DLL = 195;

U1LCR = 0x03;

}

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 Evaluation Board.

The Flash Magic software is used to download the hex file into your LPC2148 Evaluation Board

through UART0.

Testing the ds1820 with LPC2148

Give +3.3V power supply to LPC2148 Evaluation Board; the serial cable is connected between

the controller and PC. Open the Hyper Terminal screen, select which port you are using and set

the default settings. Now the screen should show the current temperature readings.

Bri