Interfacing LCD using AVRatmega32 with 4 bit mode

[BhanuKiran Chaluvadi]

 

Hai ,

I am using  PD3 for RS Register

                  PD6       R/W

                  PB4       Enable    and PB0-PB3 for Data Transfer. 

I am using the same code given in this website making few changes and the code is as follows. Nothing is being displayed on the LCD . Is it because the way i am transfering 4 bits of data .. Do i need to change masking because my Data Transfer ports are PB0 to PB3 not PB4 to PB7.

 

 

#include<avr/io.h>

#include<util/delay.h>

#include<inttypes.h>

 

#define rs PD3

#define rw PD6

#define en PB4

 

void lcd_init(void);

void dis_cmd(char);

void dis_data(char);

void lcdcmd(char);

void lcddata(char);

 

int main(void)

{

unsigned char data0[11]=”ENGINEERS”;

unsigned char data1[10]=”GARAGE”;

 

int i=0;

DDRB=0xFF;

DDRD=0xFF;

lcd_init(); 

 

while(data0!=’’)

{

dis_data(data0);

_delay_ms(200);

i++;

}

 

dis_cmd(0xC5);

 

i=0;

while(data1!=’’)

{

dis_data(data1);

_delay_ms(200);

i++;

}

 

while(1);

}

 

 

 

void lcd_init() // fuction for intialize 

{

dis_cmd(0x02); // to initialize LCD in 4-bit mode.

dis_cmd(0x28); //to initialize LCD in 2 lines, 5X7 dots and 4bit mode.

dis_cmd(0x0C);

dis_cmd(0x06);

dis_cmd(0x83);

}

 

void dis_cmd(char cmd_value)

{

char cmd_value1;

 

cmd_value1 = cmd_value & 0xF0; //mask lower nibble because PA4-PA7 pins are used. 

lcdcmd(cmd_value1); // send to LCD

 

cmd_value1 = ((cmd_value<<4) & 0xF0); //shift 4-bit and mask

lcdcmd(cmd_value1); // send to LCD

}

 

 

void dis_data(char data_value)

{

char data_value1;

 

data_value1=data_value&0xF0;

lcddata(data_value1);

 

data_value1=((data_value<<4)&0xF0);

lcddata(data_value1);

}

 

void lcdcmd(char cmdout)

{

PORTB=cmdout;

PORTD&=~(1<<rs);

PORTD&=~(1<<rw);

PORTB|=(1<<en);

_delay_ms(1);

PORTB&=~(1<<en);

}

 

void lcddata(char dataout)

{

PORTB=dataout;

PORTD|=(1<<rs);

PORTD&=~(1<<rw);

PORTB|=(1<<en);

_delay_ms(1);

PORTB&=~(1<<en);

}

 

[AJISH ALFRED]

Hi,

If your Data Transfer ports are PB0 to PB3 then mask the higher nibbles when writing, not the lower nibbles.In this case there is no left shifting of data is required, simply write it to port B with higher nibbles masked.

[BhanuKiran Chaluvadi]

Thank u Sir…

This is the final code and its working…

 

 

// Program to interface LCD in 4 bit mode with AVR microcontroller

//#define F_CPU 12000000UL

#include<avr/io.h>

#include<util/delay.h>

#include<inttypes.h>

 

#define rs PD3

#define rw PD6

#define en PB4

 

void lcd_init(void);

void dis_cmd(char);

void dis_data(char);

void lcdcmd(char);

void lcddata(char);

 

int main(void)

{

unsigned char data0[11]=”JAI”;

unsigned char data1[10]=”BALAYYA”;

 

int i=0;

DDRA=0xFF;

DDRD=0xFF; //modified

DDRB=0xFF; //modified

 

lcd_init();

 

while(data0!=’’)

{

dis_data(data0);

_delay_ms(200);

i++;

}

 

dis_cmd(0xC5);

 

i=0;

while(data1!=’’)

{

dis_data(data1);

_delay_ms(200);

i++;

}

 

while(1);

}

 

 

 

void lcd_init() // fuction for intialize 

{

dis_cmd(0x02); // to initialize LCD in 4-bit mode.

dis_cmd(0x28); //to initialize LCD in 2 lines, 5X7 dots and 4bit mode.

dis_cmd(0x0C);

dis_cmd(0x06);

dis_cmd(0x83);

}

 

void dis_cmd(char cmd_value)

{

char cmd_value1;

 

cmd_value1 = (cmd_value>>4) & 0x0F; //mask lower nibble because PA4-PA7 pins are used. 

lcdcmd(cmd_value1); // send to LCD

 

cmd_value1 = ((cmd_value) & 0x0F); //shift 4-bit and mask

lcdcmd(cmd_value1); // send to LCD

}

 

 

void dis_data(char data_value)

{

char data_value1;

 

data_value1=(data_value>>4)&0x0F;

lcddata(data_value1);

 

data_value1=((data_value)&0x0F);

lcddata(data_value1);

}

 

void lcdcmd(char cmdout)

{

PORTB=cmdout;

PORTD&=~(1<<rs);

PORTD&=~(1<<rw);

PORTB|=(1<<en);

_delay_ms(1);

PORTB&=~(1<<en);

}

 

void lcddata(char dataout)

{

PORTB=dataout;

PORTD|=(1<<rs);

PORTD&=~(1<<rw);

PORTB|=(1<<en);

_delay_ms(1);

PORTB&=~(1<<en);

}

 

 

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