Lesson nr.15-Alphanumeric LCD in 4-bit mode

Hardware setup:
The purpose of this experiment is to interface an LCD 2x16 characters (compatible with standard HD44780) to PIC16F628A in 4-bit mode. This means the data transfer will use just 4 pins of the microcontroller. No additional hardware configuration is required. In the current experiment we are displaying a text, on the 2 x16 LCD. The circuit diagram is presented below.













Circuit Diagram:
For those who want to build it on their own breadboard or other platform, here is the electronic scheme built in Eagle Cad, free version:

Software:
Here is the C program written for MikroC PRO for PIC 2010 (version v4.15).

/*
'*******************************************************************************
'  Lesson nr.15:
'          Alphanumeric LCD in 4-bit mode.
'  Done by:
'          Aureliu Raducu Macovei, 2010.
'  Description:
'          In this experiment we will work with alphanumeric LCD. Communication 
'          with LCD will be performed through 4-bits and connections is made as
'          follows: D4 with RB0, D5 with RB1, D6 with RB2, D7 with RB3;
'                   RS with RB4 and EN with RB5.
'  Test configuration:
'    MCU:                        PIC16F628A
'    Test.Board:                 WB-106 Breadboard 2420 dots
'    SW:                         MikroC PRO for PIC 2010 (version v4.15)
'  Configuration Word
'    Oscillator:                 INTOSC:I/O on RA.6, I/O on RA.7
'    Watchdog Timer:             OFF
'    Power up Timer:             Disabled
'    Master Clear Enable:        Enabled
'    Browun Out Detect:          Enabled
'    Low Voltage Program:        Disabled
'    Data EE Read Protect:       Disabled
'    Code Protect:               OFF
'*******************************************************************************
*/
// LCD module connections
sbit LCD_RS at RB4_bit;
sbit LCD_EN at RB5_bit;
sbit LCD_D4 at RB0_bit;
sbit LCD_D5 at RB1_bit;
sbit LCD_D6 at RB2_bit;
sbit LCD_D7 at RB3_bit;
sbit LCD_RS_Direction at TRISB4_bit;
sbit LCD_EN_Direction at TRISB5_bit;
sbit LCD_D4_Direction at TRISB0_bit;
sbit LCD_D5_Direction at TRISB1_bit;
sbit LCD_D6_Direction at TRISB2_bit;
sbit LCD_D7_Direction at TRISB3_bit;
// End LCD module connections

// Define Messages
 char text1[] = "Testing LCD";
 char text2[] = "using PIC16F628A";
 char text3[] = "Test successful";
 char text4[] = "in 4-bit mode";
 
void main() {
  Lcd_Init();                        // Initialize LCD
  do {
      Lcd_Cmd(_LCD_CLEAR);           // Clear display
      Lcd_Cmd(_LCD_CURSOR_OFF);      // Cursor off
      Lcd_Out(1,3,text1);            // Write message1 in 1st row
      Lcd_Out(2,1,text2);            // Write message1 in 2nd row
      Delay_ms(3000);                // delay 3s
      Lcd_Cmd(_LCD_CLEAR);           // Clear display
      Delay_ms(1000);                // delay 1s
      Lcd_Out(1,2,text3);            // Write message3 in 1st row
      Lcd_Out(2,3,text4);
      Delay_ms(3000);                // delay 3s
      } while(1);
}