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 followsPowering LCD .Wait for abour 20mSSend the first init value (0x30) Wait for about 10mSSend second init value (0x30) Wait for about 1mSSend third init value (0x30)Wait for 1mSSelect bus width (0x20) so we give 0x20 and selected as 4 bit modeWait for 1mSThen, 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.
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
#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
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.
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
#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
compiler - sdcc ,XC8.
#define _XTAL_FREQ 8000000 // setting the crystal frequency
#include <xc.h> // Header file inclusion ,to add function like _delay_ms()
#pragma config PWRTE = OFF // Power-up Timer Enable bit (PWRT disabled)
#pragma config CP = OFF // FLASH Program Memory Code Protection bits (Code protection off)
#pragma config BOREN = ON // Brown-out Reset Enable bit (BOR enabled)
#pragma config LVP = ON // Low Voltage In-Circuit Serial Programming Enable bit (RB3/PGM pin has PGM function; low-voltage programming enabled)
#pragma config CPD = OFF // Data EE Memory Code Protection (Code Protection off)
#pragma config WRT = ON // FLASH Program Memory Write Enable (Unprotected program memory may be written to by EECON control)
int main()
{
TRISB0 = 0; //RB0 as Output PIN
while(1) // endless loop
{
RB0 = 1; // LED ON
__delay_ms(1000); // 1 Second Delay
RB0 = 0; // LED OFF
__delay_ms(1000); // 1 Second Delay
}
return 0;
}
LED Blinking By using 8051 in Keil IDE
/led-blinking-program-by-using-atmega32
compiler - sdcc ,XC8.
#define _XTAL_FREQ 8000000 // setting the crystal frequency
#include <xc.h> // Header file inclusion ,to add function like _delay_ms()
#pragma config PWRTE = OFF // Power-up Timer Enable bit (PWRT disabled)
#pragma config CP = OFF // FLASH Program Memory Code Protection bits (Code protection off)
#pragma config BOREN = ON // Brown-out Reset Enable bit (BOR enabled)
#pragma config LVP = ON // Low Voltage In-Circuit Serial Programming Enable bit (RB3/PGM pin has PGM function; low-voltage programming enabled)
#pragma config CPD = OFF // Data EE Memory Code Protection (Code Protection off)
#pragma config WRT = ON // FLASH Program Memory Write Enable (Unprotected program memory may be written to by EECON control)
int main()
{
TRISB0 = 0; //RB0 as Output PIN
while(1) // endless loop
{
RB0 = 1; // LED ON
__delay_ms(1000); // 1 Second Delay
RB0 = 0; // LED OFF
__delay_ms(1000); // 1 Second Delay
}
return 0;
}
LED Blinking By using 8051 in Keil IDE
/led-blinking-program-by-using-atmega32
sbit LED1 = P2^0; // P2.0 of the pin name cahnged to LED1
void delay(); // a delayis used to give some delay in between turn ON and OFF
void main()
{
while(1)
{
LED1 = 0;
delay();
LED1 = 1 ;
delay();
}
}
void delay()
{
int j;
for(j=0; j<500; j++)
;
}
sbit LED1 = P2^0; // P2.0 of the pin name cahnged to LED1
void delay(); // a delayis used to give some delay in between turn ON and OFF
void main()
{
while(1)
{
LED1 = 0;
delay();
LED1 = 1 ;
delay();
}
}
void delay()
{
int j;
for(j=0; j<500; j++)
;
}
LCD 4-BIT MODE with 8051
TO know the Basic of LCD go to the previous post click here . There are many reasons why sometime we prefer to use LCD in 4-bit mode instead of 8-bit. One basic reason is lesser number of pins are needed to interface LCD.
In 4-bit mode the data is sent in nibbles, first we send the higher nibble and then the lower nibble. To enable the 4-bit mode of LCD, we need to follow special sequence of initialization that tells the LCD controller that user has selected 4-bit mode of operation. We call this special sequence as resetting the LCD. Following is the reset sequence of 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(0x30 - for 8-bit and 0x20 for 4-bit)
- Wait for 1mS
The busy flag will only be valid after the above reset sequence. Usually we do not use busy flag in 4-bit mode as we have to write code for reading two nibbles from the LCD. Instead we simply put a certain ammount of delay usually 300 to 600uS. This delay might vary depending on the LCD you are using, as you might have a different crystal frequency on which LCD controller is running. So it actually depends on the LCD MODULE you are using. So if you feel any problem running the LCD, simply try to increase the delay. This usually works. For me about 400uS works perfect.
LCD connections in 4-bit Mode
Above is the connection diagram of LCD in 4-bit mode, where we only need 6 pins to interface an LCD. D4-D7 are the data pins connection and Enable and Register select are for LCD control pins. We are not using Read/Write (RW) Pin of the LCD, as we are only writing on the LCD so we have made it grounded permanently. If you want to use it.. then you may connect it on your controller but that will only increase another pin and does not make any big difference. Potentiometer RV1 is used to control the LCD contrast. The unwanted data pins of LCD i.e. D0-D3 are connected to ground.
LCD connections in 4-bit Mode
We will now look into the common steps to send data/command to LCD when working in 4-bit mode. As i already explained in 4-bit mode data is sent nibble by nibble, first we send higher nibble and then lower nibble. This means in both command and data sending function we need to saperate the higher 4-bits and lower 4-bits.
The common steps are:
- Mask lower 4-bits
- Send to the LCD port
- Send enable signal
- Mask higher 4-bits
- Send to LCD port
- Send enable signal
Program lcd.c file
#include<reg51.h>
#include<stdio.h>
#define LCDPORT P2
sbit RS = LCDPORT ^ 0;
sbit RW = LCDPORT ^ 1;
sbit E = LCDPORT ^ 2;
#include "lcd.h"
void main()
{
lcd_init();
lcd_com(15);
lcd_puts("test");
lcd_com(0XC0);
lcd_puts("World");
while (1);
}
---------------------------------------------------------------------------------------------------------------------------
lcd.h file .
bit status = 0;
#define lcd_delay 400
void delay(unsigned int j)
{
unsigned int i = 0;
for (; i < j; i++);
}
void_lcd_init_write(unsigned char a)
{
RS = 0;
RW = 0;
LCDPORT = a;
E = 1;
delay(lcd_delay);
E = 0;
}
void lcd_com(unsigned char a)
{
unsigned char temp;
if (status) {
status = 0;
gotonext;
}
RS = 0;
next:
RW = 0;
temp = a;
temp &= 0xf0;
LCDPORT &= 0x0f;
LCDPORT |= temp;
E = 1;
delay(lcd_delay);
E = 0;
temp = a << 4;
temp &= 0xf0;
LCDPORT &= 0x0f;
LCDPORT |= temp;
E = 1;
delay(lcd_delay);
E = 0;
}
void lcd_data(unsigned char a)
{
status = 1;
RS = 1;
lcd_com(a);
}
void lcd_init(void)
{
delay(lcd_delay);
lcd_init_write(0x30);
delay(lcd_delay);
lcd_init_write(0x30);
delay(lcd_delay);
lcd_init_write(0x30);
delay(lcd_delay);
lcd_init_write(0x20);
delay(lcd_delay);
lcd_com(0x28);
delay(lcd_delay);
lcd_com(4);
delay(lcd_delay);
lcd_com(0x85);
delay(lcd_delay);
lcd_com(6);
delay(lcd_delay);
lcd_com(1);
delay(lcd_delay);
}
void lcd_puts(char *aaa)
{
unsigned int i = 0;
for (; aaa[i] != 0; i++)
lcd_data(aaa[i]);
}
Download here the Proteus and Keil File Click Here
Till now whatever we discussed in the previous part of ths LCD tutorial, we were dealing with 8-bit mode. Now we are going to learn how to use LCD in 4-bit mode. There are many reasons why sometime we prefer to use LCD in 4-bit mode instead of 8-bit. One basic reason is lesser number of pins are needed to interface LCD.
In 4-bit mode the data is sent in nibbles, first we send the higher nibble and then the lower nibble. To enable the 4-bit mode of LCD, we need to follow special sequence of initialization that tells the LCD controller that user has selected 4-bit mode of operation. We call this special sequence as resetting the LCD. Following is the reset sequence of 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 (0x30 - for 8-bit and 0x20 for 4-bit)
- Wait for 1mS
- See more at: http://www.8051projects.net/lcd-interfacing/lcd-4-bit.php#sthash.MwfMgDYA.dpuf Till now whatever we discussed in the previous part of ths LCD tutorial, we were dealing with 8-bit mode. Now we are going to learn how to use LCD in 4-bit mode. There are many reasons why sometime we prefer to use LCD in 4-bit mode instead of 8-bit. One basic reason is lesser number of pins are needed to interface LCD.
In 4-bit mode the data is sent in nibbles, first we send the higher nibble and then the lower nibble. To enable the 4-bit mode of LCD, we need to follow special sequence of initialization that tells the LCD controller that user has selected 4-bit mode of operation. We call this special sequence as resetting the LCD. Following is the reset sequence of 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 (0x30 - for 8-bit and 0x20 for 4-bit)
- Wait for 1mS
- See more at: http://www.8051projects.net/lcd-interfacing/lcd-4-bit.php#sthash.MwfMgDYA.dpuf
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