16x2 LCD with 16F877A

In this exercise lets look at how can we interface a LCD display with 16F877A PIC microcontroller. 


The mikroC PRO for PIC provides a library for communication with LCDs (with HD44780 compliant controllers) through the 4-bit interface. 


HD44780 Pinout

1. Vss (Ground)
2. VCC (5V)
3. Contrast (use a potentiometer for variable contrast, or just connect to GND)
4. Register Select (RS), 0 = command write, 1 = data write
5. Read/Write (R/W), 0 = write to display, 1 = read from display
6. Enable (EN) - used to clock in data
7. DB0 (not used in 4-bit mode) - LSb
8. DB1 (not used in 4-bit mode)
9. DB2 (not used in 4-bit mode)
10. DB3 (not used in 4-bit mode)
11. DB4 - LSb in 4-bit mode
12. DB5
13. DB6
14. DB7 - MSb
15. Backlight + (5V)
16. Backlight - (GND)

4-bit and 8-bit modes

An HD44780 LCD can be operated in two different modes: 4-bit mode and 8-bit mode. In 8-bit mode, pins 7-14 of the LCD are connected to eight I/O pins on the microcontroller; while in 4-bit mode, pins 11-14 on the LCD are connected to four I/O pins on the microcontroller. The advantage to operating in 8-bit mode is that the programming is a bit simpler and data can be updated more quickly. The obvious reason to operate in 4-bit mode is to save four I/O pins on the PIC microcontroller.

Circuit Diagram for 16x2 LCD

Complete Circuit Diagram with PIC Microcontroller

MikroC Code:

// 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

void main() {

  int i=0;

  char text[]="16x2 LCD Disply";

  ADCON1=0x06; // Configure all input and output in to digital

  Lcd_init();  // Initialize LCD

  Lcd_Cmd(_LCD_CLEAR);               // Clear display

  Lcd_Cmd(_LCD_CURSOR_OFF);          // Cursor off

  do{

     Lcd_Out(1,1,"   Electronic   ");  //Write text on raw 1, column 1

     Lcd_Out(2,1,"   Work Space   ");  //Write text on raw 1, column 1

     Delay_ms(1000);  // Delay 1 second

     Lcd_Cmd(_LCD_CLEAR);               // Clear display

 

     for(i=0;i<16;i++){

       Lcd_Chr(1,i+1,text[i]);            //Display charactor by charactor

       Delay_ms(500);

     }

   }while(1); // continue  infinite loop

}