LCD 16*2 INTERFACING WITH LPC2148.

 

As given below the pin diagram of 16*2 lcd.

Pin description of 16*2 LCD

LCD Initialization:

 

• ·         RS=0 & RW=0 (Select Command mode)

• ·     E=1

• ·     Delay

• ·     E=0 (Latch data into input register)

 

Commands:

 

Sr.No.	Hex Code	Command to LCD instruction Register
1	01	Clear display screen
2	02	Return home
3	04	Decrement cursor (shift cursor to left)
4	06	Increment cursor (shift cursor to right)
5	05	Shift display right
6	07	Shift display left
7	08	Display off, cursor off
8	0A	Display off, cursor on
9	0C	Display on, cursor off
10	0E	Display on, cursor blinking
11	0F	Display on, cursor blinking
12	10	Shift cursor position to left
13	14	Shift cursor position to right
14	18	Shift the entire display to the left
15	1C	Shift the entire display to the right
16	80	Force cursor to beginning ( 1st line)
17	C0	Force cursor to beginning ( 2nd line)
18	38	2 lines and 5×7 matrix

 

 Interfacing Diagram:

LCD INTERFACING WITH LPC2148

 

 It is 8 bit data so there are D0 to D7 data pins.

RS=register select (If '1' then data register select else command register)

R/W= Read write 

E= Enable

 

Algorithm:

1. Start
2. Initially define hardware of interfacing Diagram
3. Initialize LCD by selecting functions of LPC2148 pins as GPIO, Set direction of pins as an output pins, Send Commands to LCD (0x38, 0x0E,0x0C, 0x06, 0x01, 0x80)
4. LCD Command function:- Clear command value available on data pins first ,shift the command value by 16 bits to left side to get available on P0.16 to P0.23 , Make RS pin=0, RW pin=0, High to low pulse on Enable pin
5. LCD Data function :- Clear data available on data pins first ,shift the data by 16 bits to left side to get available on P0.16 to P0.23 , Make RS pin=1, RW pin=0, High to low pulse on Enable pin
6. Pass character to data function until null character
7. End

 

Code: LCD 16*2 interfacing with LPC2148

/**************************************************************************************************
Expt. 2.: Interfacing 16x2 LCD to LPC2148
Platform:  LPC2148 Development Board.
College: PICT  

Hardware Setup:-
 LCD data pin :-P0.16-P0.23 
 RS-P1.16
 RW-P1.17
 EN-P1.18         
********************************************************************************/
//Include Controller specific header file
#include <lpc214x.h> 
#define RS (1<<16)
#define RW (1<<17)
#define E (1<<18)


void LCD_command(unsigned char command);
void  delay_ms(unsigned char time);
void LCD_data(unsigned char data);
void LCD_write_string(unsigned char *string);
void LCD_init() ;


int main(void)
{
 //PINSEL1 = 0x00000000;  //Configure PORT0 as GPIO
 //PINSEL2 = 0X00000000;  //Configure PORT1 as GPIO
 IODIR1= 0x07<<16; //Configure P1.18, P1.17, P1.16 as output
 IODIR0= 0xFF<<16;  //Configure P0.23 - P0.16 as output
 LCD_init();    //Initialize LCD 16x2
 LCD_command(0x01); 
 LCD_write_string("Welcome to PICT");
 LCD_command(0xc0);  //second line 1st position
 LCD_write_string("PUNE");
 delay_ms(10) ;
 while (1);
}


//Function to generate software delay
//Calibrated to 1ms
void  delay_ms(unsigned char time)    
{  
 unsigned int  i, j;
 for (j=0; j<time; j++)
 {
  for(i=0; i<8002; i++)
  {
  }
}
}

void LCD_command(unsigned char command)
{
 IOCLR0 = 0xFF<<16; // Clear LCD Data lines
 IOCLR1=RS;     // RS=0 for command
 IOCLR1=RW;     // RW=0 for write
 IOSET0=command<<16; // put command on data line
 IOSET1=E;   // en=1 
 delay_ms(10) ;   // delay
 IOCLR1=E;    // en=0
}

void LCD_data(unsigned char data)
{
 IOCLR0 = 0xFF<<16; // Clear LCD Data lines
 IOSET1=RS;     // RS=1 for data
 IOCLR1=RW;     // RW=0 for write
 IOSET0= data<<16;  // put command on data line
 IOSET1=E;   //en=1 
 delay_ms(10) ;    //delay
 IOCLR1=E;   //en=0
 }

void LCD_init()
{
 LCD_command(0x38); //8bit mode and 5x8 dotes (function set)
 delay_ms(10) ;   // delay
 LCD_command(0x0c); //display on, cursor off, cursor char blinking off(display on/off)
 delay_ms(10) ;   // delay
    LCD_command(0x0e);  //cursor increment and display shift(entry mode set)
    delay_ms(10) ;   // delay
 LCD_command(0x01);  //clear lcd (clear command)
 delay_ms(10) ;   // delay
 LCD_command(0x80); 
  delay_ms(10) ;//set cursor to 0th location 1st lne
 
}
 
void LCD_write_string(unsigned char *string)
{
int i=0;
  while(string[i]!='\0')
  {   //Check for End of String
  LCD_data(string[i]);
  i=i+1;  //sending data on LCD byte by byte
}
}