LCD 4-bit Mode Interfacing

In  LCD 4-bit Mode Interfacing  we need to connect only 4+3 wire to LCD from Microcontroler . So we save 4 pins of micro controller.But we need to send 8 bit data or command to lcd by using   4 wire How ?
 By spiting the data or command  into two parts (4 bit nibble) ie ,lower 4 bits and higher 4 bits (the technique is called masking ). 
We need first initialize the LCD  as 4 bit according to the data sheet .
that is as follows
Powering LCD . Wait for abour 20mS
Send the first init value (0x30) 
Wait for about 10mS
Send second init value (0x30)  
Wait for about 1mS
Send third init value (0x30)
Wait for 1mS
Select bus width  (0x20) so we give 0x20 and selected as 4 bit mode
Wait for 1mS

Then, we send higher4bit  and then lower 4bit . This means in both command and data sending function we need to separate the higher 4-bits and lower 4-bits.




Mask lower 4-bits
Send to the LCD port (that to 4 pins of the LCD )
Send enable signal  
Mask higher 4-bits
Send to LCD port
Send enable signal

 Programming section as follows 

I am using the controller 8051  with the compailer Keil  and with C language .

The port 2 of the 8051  is used . the circuit as follows




                         LCD.h header File


 #include"delay.h"
 #define LCDPORT P2  // named the Port2 as LCDPORT
 sbit RS=LCDPORT^2;  // P2.2 named RS
 sbit E=LCDPORT^3;  // P2.3 named as E
 #define LINE2 lcd_cmd(0xc0);   // used to display the second line oxc0 is 
 
 
 void latch(void)  // used to a high to low pulse the pin E 
{
    E = 1;
    delay(1);
    E = 0;
}

void lcd_cmd(unsigned char c)   // used to send the command / Instruction to the lcd port 
{          
RS = 0;    // send a '0' value to select to send command
delay(1);     
LCDPORT = c & 0xf0;  //  send  the command c only 4 bit by masking the lower bit 
latch();
delay(1); 
LCDPORT =  (c << 4); // giving the lowerbit  by shifting the 4 bit to left 
latch(); 
}

 void lcd_data(unsigned char c)
 {
 RS =1;    // send 1 to send data 
 delay(1);
LCDPORT = c & 0xf0 | 0x4; //send  the data  only  4 bit by masking the lower bit and also making the RS pin high by giving 0x04 .
delay(1);
latch();

LCDPORT = (c << 4)| 0x4; ; // giving the lower bit  by shifting the 4 bit to left 
latch(); 
}
 
void lcd_init()
{
  delay(20);
    lcd_cmd(0x30);  //as per data sheet
  delay(20);
    lcd_cmd(0x30);    //as per data sheet
  delay(4);
    lcd_cmd(0x32);    //as per data sheet
 delay(4);
    lcd_cmd(0x28);            // Function set (4-bit interface, 2 lines, 5*7Pixels)
    lcd_cmd(0x28);            // Function set (4-bit interface, 2 lines, 5*7Pixels)
    lcd_cmd(0x0c);            // Make cursorinvisible
    lcd_cmd(0x6);            // Set entry Mode(auto increment of cursor)
}

 void string(const char *q)    // used to send single charcter to display the lcd 
{
    while (*q) {
        lcd_data(*q++);
    }
}



Finaly The code is lcd.c

#include <REGX51.H>   
#include "lcd.h"


void main(){
lcd_init();
string("Lcd Testing ");
LINE2
string("its displaying ");
while(1);
}

Download the full project including Proteus File Clik here

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