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I2C LCD

 
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sshahryiar



Joined: 05 May 2010
Posts: 92
Location: Dhaka, Bangladesh

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I2C LCD
PostPosted: Sat Sep 05, 2015 4:18 am     Reply with quote

PCF8574.h

Code:
#define PCF8574_address 0x40

#define PCF8574_write_cmd PCF8574_address             
#define PCF8574_read_cmd (PCF8574_address + 1)   

#define SDA_pin pin_A5
#define SCL_pin pin_A4     


#use I2C(Master, SDA = SDA_pin, SCL = SCL_pin)

             
unsigned char PCF8574_read();               
void PCF8574_write(unsigned char data_byte);


PCF8574.c

Code:
#include "PCF8574.h"
     
                                       
unsigned char PCF8574_read()
{
    unsigned char port_byte = 0;       
    i2c_start();                             
    i2c_write(PCF8574_read_cmd);       
    port_byte = i2c_read(0);             
    i2c_stop();
    return port_byte;
}                                                         


void PCF8574_write(unsigned char data_byte)                     
{
    i2c_start();
    i2c_write(PCF8574_write_cmd);               
    i2c_write(data_byte);
    i2c_stop();
}



LCD.h

Code:
#include "PCF8574.c"


#define clear_display 0x01
#define goto_home 0x02
         
#define cursor_direction_inc (0x04 | 0x02)
#define cursor_direction_dec (0x04 | 0x00)
#define display_shift (0x04 | 0x01)
#define display_no_shift (0x04 | 0x00)

#define display_on (0x08 | 0x04)
#define display_off (0x08 | 0x02)
#define cursor_on (0x08 | 0x02)                           
#define cursor_off (0x08 | 0x00)
#define blink_on (0x08 | 0x01)
#define blink_off (0x08 | 0x00)
                                   
#define _8_pin_interface (0x20 | 0x10)
#define _4_pin_interface (0x20 | 0x00)
#define _2_row_display (0x20 | 0x08)
#define _1_row_display (0x20 | 0x00)
#define _5x10_dots (0x20 | 0x40)
#define _5x7_dots (0x20 | 0x00)
                                                   
#define dly 0x01


unsigned char data_value = 0x00;
                                           
                                                                         
void LCD_init(); 
void LCD_command(unsigned char value);
void LCD_send_data(unsigned char value);
void LCD_4bit_send(unsigned char lcd_data);                                     
void LCD_putstr(char *lcd_string);               
void LCD_putchar(char char_data);             
void LCD_clear_home();           
void LCD_goto(unsigned char x_pos, unsigned char y_pos);



LCD.c

Code:
#include "lcd.h"
                             

void LCD_init()
{                                     
    unsigned char t = 0x1A; 

    data_value = 0x08;
    PCF8574_write(data_value);     
    while(t > 0x00)
    {   
            delay_ms(dly);
            t--;
    };       
   
    data_value = 0x30;
    PCF8574_write(data_value); 
                             
    data_value |= 0x08;
    PCF8574_write(data_value);     
    delay_ms(dly);
    data_value &= 0xF7;
    PCF8574_write(data_value); 
    delay_ms(dly);
             
    data_value = 0x30;
    PCF8574_write(data_value); 
                   
    data_value |= 0x08;                     
    PCF8574_write(data_value); 
    delay_ms(dly);
    data_value &= 0xF7;
    PCF8574_write(data_value); 
    delay_ms(dly);

    data_value = 0x30;
    PCF8574_write(data_value); 

    data_value |= 0x08;
    PCF8574_write(data_value); 
    delay_ms(dly);
    data_value &= 0xF7;
    PCF8574_write(data_value); 
    delay_ms(dly);

    data_value = 0x20;
    PCF8574_write(data_value); 
                   
    data_value |= 0x08;
    PCF8574_write(data_value); 
    delay_ms(dly);
    data_value &= 0xF7;
    PCF8574_write(data_value); 
    delay_ms(dly);

    LCD_command(_4_pin_interface | _2_row_display | _5x7_dots);         
    LCD_command(display_on | cursor_off | blink_off);     
    LCD_command(clear_display);                           
    LCD_command(cursor_direction_inc | display_no_shift);       
}   


void LCD_command(unsigned char value)
{                                   
    data_value &= 0xFB;
    PCF8574_write(data_value); 
    LCD_4bit_send(value);           
}
   

void LCD_send_data(unsigned char value)
{                               
    data_value |= 0x04;
    PCF8574_write(data_value); 
    LCD_4bit_send(value);
}                                       
   

void LCD_4bit_send(unsigned char lcd_data)       
{
    unsigned char temp = 0x00;
     
    temp = (lcd_data & 0xF0);
    data_value &= 0x0F;   
    data_value |= temp;   
    PCF8574_write(data_value); 
                                         
    data_value |= 0x08;
    PCF8574_write(data_value); 
    delay_ms(dly);
    data_value &= 0xF7;
    PCF8574_write(data_value); 
    delay_ms(dly);
   
    temp = (lcd_data & 0x0F);
    temp <<= 0x04;     
    data_value &= 0x0F; 
    data_value |= temp;                           
    PCF8574_write(data_value); 
               
    data_value |= 0x08;
    PCF8574_write(data_value); 
    delay_ms(dly);
    data_value &= 0xF7;
    PCF8574_write(data_value); 
    delay_ms(dly);



void LCD_putstr(char *lcd_string)
{
    while (*lcd_string != '\0')   
    {
        LCD_send_data(*lcd_string);
        lcd_string++;
    };
}


void LCD_putchar(char char_data)
{
    LCD_send_data(char_data);
}


void LCD_clear_home()
{
    LCD_command(clear_display);
    LCD_command(goto_home);
}


void LCD_goto(unsigned char x_pos,unsigned char y_pos)
{                                                   
    if(y_pos == 0)   
    {                             
        LCD_command(0x80 | x_pos);
    }
    else
    {                                             
        LCD_command(0x80 | 0x40 | x_pos);
    }
}



Example

Code:
#include <12F675.h>


#device *= 16

                                 
#fuses NOWDT, PROTECT, CPD, NOMCLR, INTRC_IO, BROWNOUT, PUT

                               
#use delay (internal = 4MHz)   
#include "lcd.c"                         


void setup();                       
                                         
                               
void main()
{                       
    unsigned char i = 0;     
   
    char txt1[] = {"MicroArena"};
    char txt2[] = {"SShahryiar"};
    char txt[6];
                                   
    setup();                   

    while(TRUE)
    {                                                                                     
        LCD_clear_home();   
             
        for(i = 0; i <= 9; i++)
        {                 
           LCD_goto((i + 3), 0);   
           LCD_putchar(txt1[i]);
           delay_ms(99);
        }                                               
        for(i = 0; i <= 9; i++)                                   
        {           
           LCD_goto((i + 3), 1);                                                         
           LCD_putchar(txt2[i]);                                         
           delay_ms(99);
        }         
                                 
        delay_ms(4000);
       
        LCD_clear_home(); 
       
        LCD_goto(3, 0);
        LCD_putstr(txt1);               
        for(i = 0; i <= 100; i++)
        {
           LCD_goto(7, 1);
           sprintf(txt,"%02u", i);
           LCD_putstr(txt);   
           delay_ms(500);
        }
       
       
    };       
}                                       
           

                                         
void setup()
{
    disable_interrupts(GLOBAL);
    setup_comparator(NC_NC_NC_NC);                   
    setup_ADC(ADC_off);
    setup_ADC_ports(no_analogs);
    setup_timer_0(T0_internal);     
    setup_timer_1(T1_disabled);
    set_timer0(0); 
    set_timer1(0);
    LCD_init(); 
    delay_ms(100);       
}



More details:

http://www.libstock.com/projects/view/1530/i2c-lcd

https://www.youtube.com/watch?v=dBjV9LTCY1c
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SShahryiar
mahatia



Joined: 14 Nov 2016
Posts: 23

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PostPosted: Tue Nov 15, 2016 2:28 am     Reply with quote

hello! I am a student and the goal of my project is to interface date and hours from RTC DS1307 to the Lcd 16x2. I use PIC12F675 with an expander PCF8574. I ve used your codes to display something to the LCD and it works very well. Could you help me to do this? thank you very much! I really need it! please, help me![/img]
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