LCD I2C Interfacing With PIC16f877A

Question

I am trying to interface an LCD using I2C but can't quite understand how to do it. I found this example Here's the code: i2c.h:

/* File: I2C_LCD.h */

#define _XTAL_FREQ             16000000

#define I2C_BaudRate           100000
#define SCL_D                  TRISC3
#define SDA_D                  TRISC4

#define LCD_BACKLIGHT          0x08
#define LCD_NOBACKLIGHT        0x00
#define LCD_FIRST_ROW          0x80
#define LCD_SECOND_ROW         0xC0
#define LCD_THIRD_ROW          0x94
#define LCD_FOURTH_ROW         0xD4
#define LCD_CLEAR              0x01
#define LCD_RETURN_HOME        0x02
#define LCD_ENTRY_MODE_SET     0x04
#define LCD_CURSOR_OFF         0x0C
#define LCD_UNDERLINE_ON       0x0E
#define LCD_BLINK_CURSOR_ON    0x0F
#define LCD_MOVE_CURSOR_LEFT   0x10
#define LCD_MOVE_CURSOR_RIGHT  0x14
#define LCD_TURN_ON            0x0C
#define LCD_TURN_OFF           0x08
#define LCD_SHIFT_LEFT         0x18
#define LCD_SHIFT_RIGHT        0x1E
#define LCD_TYPE               2       // 0 -> 5x7 | 1 -> 5x10 | 2 -> 2 lines

//-----------[ Functions' Prototypes ]--------------

//---[ I2C Routines ]---

void I2C__Init();
void I2C__Wait();
void I2C__Start();
void I2C__RepeatedStart();
void I2C__Stop();
void I2C_ACK();
void I2C_NACK();
unsigned char I2C__Write(unsigned char data);
unsigned char I2C_Read_Byte(void);

//---[ LCD Routines ]---

void LCD_Init(unsigned char I2C_Add);
void IO_Expander_Write(unsigned char Data);
void LCD_Write_4Bit(unsigned char Nibble);
void LCD_CMD(unsigned char CMD);
void LCD_Set_Cursor(unsigned char ROW, unsigned char COL);
void LCD_Write_Char(char);
void LCD_Write_String(char*);
void Backlight();
void noBacklight();
void LCD_SR();
void LCD_SL();
void LCD_Clear();

I2c.c

#include <xc.h>
#include "I2C.h"

unsigned char RS, i2c_add, BackLight_State = LCD_BACKLIGHT;

//---------------[ I2C Routines ]-------------------
//--------------------------------------------------
void I2C__Init()
{
  SSPCON  = 0x28;
  SSPCON2 = 0x00;
  SSPSTAT = 0x00;
  SSPADD = ((_XTAL_FREQ/4)/I2C_BaudRate) - 1;
  SCL_D = 1;
  SDA_D = 1; 
}

void I2C__Wait()
{
    while ((SSPSTAT & 0x04) || (SSPCON2 & 0x1F));
}

void I2C__Start()
{
    I2C__Wait();
    SEN = 1;
}

void I2C__RepeatedStart()
{
    I2C__Wait();
    RSEN = 1;
}

void I2C__Stop()
{
    I2C__Wait();
    PEN = 1;
}

void I2C_ACK(void)
{
    ACKDT = 0;          // 0 -> ACK
    I2C__Wait();
    ACKEN = 1;          // Send ACK
}

void I2C_NACK(void)
{
    ACKDT = 1;          // 1 -> NACK
    I2C__Wait();
    ACKEN = 1;          // Send NACK
}

unsigned char I2C__Write(unsigned char data)
{
    I2C__Wait();
    SSPBUF = data;
    while(!SSPIF);  // Wait Until Completion
    SSPIF = 0;
    return ACKSTAT;
}

unsigned char I2C_Read_Byte(void)
{
    //---[ Receive & Return A Byte ]---
    I2C__Wait();
    RCEN = 1;         // Enable & Start Reception
    while(!SSPIF);    // Wait Until Completion
    SSPIF = 0;        // Clear The Interrupt Flag Bit
    I2C__Wait();
    return SSPBUF;    // Return The Received Byte
}
//======================================================

//---------------[ LCD Routines ]----------------
//------------------------------------------------------

void LCD_Init(unsigned char I2C_Add) 
{
  i2c_add = I2C_Add;
  IO_Expander_Write(0x00);
  __delay_ms(30);
  LCD_CMD(0x03);
  __delay_ms(5);
  LCD_CMD(0x03);
  __delay_ms(5);
  LCD_CMD(0x03);
  __delay_ms(5);
  LCD_CMD(LCD_RETURN_HOME);
  __delay_ms(5);
  LCD_CMD(0x20 | (LCD_TYPE << 2));
  __delay_ms(50);
  LCD_CMD(LCD_TURN_ON);
  __delay_ms(50);
  LCD_CMD(LCD_CLEAR);
  __delay_ms(50);
  LCD_CMD(LCD_ENTRY_MODE_SET | LCD_RETURN_HOME);
  __delay_ms(50);
}

void IO_Expander_Write(unsigned char Data) 
{
  I2C__Start();
  I2C__Write(i2c_add);
  I2C__Write(Data | BackLight_State);
  I2C__Stop();
}

void LCD_Write_4Bit(unsigned char Nibble) 
{
  // Get The RS Value To LSB OF Data  
  Nibble |= RS;
  IO_Expander_Write(Nibble | 0x04);
  IO_Expander_Write(Nibble & 0xFB);
  __delay_us(50);
}

void LCD_CMD(unsigned char CMD) 
{
  RS = 0; // Command Register Select
  LCD_Write_4Bit(CMD & 0xF0);
  LCD_Write_4Bit((CMD << 4) & 0xF0);
}

void LCD_Write_Char(char Data)
{
  RS = 1;  // Data Register Select
  LCD_Write_4Bit(Data & 0xF0);
  LCD_Write_4Bit((Data << 4) & 0xF0);
}

void LCD_Write_String(char* Str)
{
    for(int i=0; Str[i]!='\0'; i++)
       LCD_Write_Char(Str[i]); 
}

void LCD_Set_Cursor(unsigned char ROW, unsigned char COL) 
{    
  switch(ROW) 
  {
    case 2:
      LCD_CMD(0xC0 + COL-1);
      break;
    case 3:
      LCD_CMD(0x94 + COL-1);
      break;
    case 4:
      LCD_CMD(0xD4 + COL-1);
      break;
    // Case 1  
    default:
      LCD_CMD(0x80 + COL-1);
  }
}

void Backlight() 
{
  BackLight_State = LCD_BACKLIGHT;
  IO_Expander_Write(0);
}

void noBacklight() 
{
  BackLight_State = LCD_NOBACKLIGHT;
  IO_Expander_Write(0);
}

void LCD_SL()
{
  LCD_CMD(0x18);
  __delay_us(40);
}

void LCD_SR()
{
  LCD_CMD(0x1C);
  __delay_us(40);
}

void LCD_Clear()
{
  LCD_CMD(0x01); 
  __delay_us(40);
}

main.c:

#include "I2C.h"

void main(void) {

    I2C__Init();
    LCD_Init(0x4E);    // Initialize LCD module with I2C address = 0x4E

    LCD_Set_Cursor(1, 1);
    LCD_Write_String("  Welcome To ");
    LCD_Set_Cursor(2, 1);
    LCD_Write_String("  MicroDigiSoft ");
    delay_ms(2500);

    while(1)
    {
     }
    return;
}

But I get these Errors: Screenshot of Error Screenshot of Error

I am using MikroC and one thing to note is that I have included the system libraries Lcd and Lcd Constants. How can I fix these errors, and are there any examples of interfacing LCD I2C with microcontrollers apart from this?

Answer 1

You must import the I2C system libray in the the MikroC Library Manager, at the right panel. See the attached image: