PIC18F4550 and HD44780 LCD Interfacing Example using MikroC

Overview

The HD44780 alphanumeric display has been using for many years now. In early years, it is commonly found in some electronic and control system, laser printers, etc. At that time, interfacing this LCD with an 8-bit micro-controller and programming in Assembly language was common. This display controller uses the Motorola 6800 data bus with three control signals, Register Select (RS), Read/Write (R/W), and Enable (E). However it support a 4-bit data transfer mode that split the 8-bit data into higher nibble and lower nibble, in which the higher nibble sent and latched first.

 

A Blue Back LED 16x2 Character LCD

A Blue Back LED 16x2 Character LCD

 

Currently, this display controller still in used. It is very popular among students, engineer, hobbyists, and small electronic control projects. There are a lot of replacement controllers available at very low cost and riches in dimensions. Using this LCD with and Arduino is very popular due to its ready-to-use module and libraries. This display can be converted into a serial communication interface such as I2C or SPI.

 

PIC18F4550 and a 16x2 LCD Example

MikroC has a lot of hardware libraries even in free mode. We can follow its example programs in its reference manual. To get started, I repeat an example code in its Lcd Libary. There are some library functions that we need to know especially the LCD pins declaration.

Library Routines

• Lcd_Init
• Lcd_Out
• Lcd_Out_Cp
• Lcd_Chr
• Lcd_Chr_Cp
• Lcd_Cmd

The LCD pins declaration such as R/S, E, and D7:4 must be putted first at the head of C source code before these functions can be called. For more information please see its Help file in the compiler IDE. 

Schematic

 

Schematic

 

 

MikroC Source Code

1. 
   
2. 
   
3. // LCD module connections
4. sbit LCD_RS at RD2_bit;
5. sbit LCD_EN at RD3_bit;
6. sbit LCD_D4 at RD4_bit;
7. sbit LCD_D5 at RD5_bit;
8. sbit LCD_D6 at RD6_bit;
9. sbit LCD_D7 at RD7_bit;
10. 
    
11. sbit LCD_RS_Direction at TRISD2_bit;
12. sbit LCD_EN_Direction at TRISD3_bit;
13. sbit LCD_D4_Direction at TRISD4_bit;
14. sbit LCD_D5_Direction at TRISD5_bit;
15. sbit LCD_D6_Direction at TRISD6_bit;
16. sbit LCD_D7_Direction at TRISD7_bit;
17. // End LCD module connections
18. 
    
19. char txt1[] = "mikroElektronika";
20. char txt2[] = "EasyPIC6";
21. char txt3[] = "Lcd4bit";
22. char txt4[] = "example";
23. 
    
24. char i; // Loop variable
25. 
    
26. void Move_Delay() { // Function used for text moving
27. Delay_ms(500); // You can change the moving speed here
28. }
29. 
    
30. void main(){
31. 
    
32. 
    
33. Lcd_Init(); // Initialize LCD
34. 
    
35. Lcd_Cmd(_LCD_CLEAR); // Clear display
36. Lcd_Cmd(_LCD_CURSOR_OFF); // Cursor off
37. Lcd_Out(1,6,txt3); // Write text in first row
38. 
    
39. Lcd_Out(2,6,txt4); // Write text in second row
40. Delay_ms(2000);
41. Lcd_Cmd(_LCD_CLEAR); // Clear display
42. 
    
43. Lcd_Out(1,1,txt1); // Write text in first row
44. Lcd_Out(2,5,txt2); // Write text in second row
45. 
    
46. Delay_ms(2000);
47. 
    
48. // Moving text
49. for(i=0; i<4; i++) { // Move text to the right 4 times
50. Lcd_Cmd(_LCD_SHIFT_RIGHT);
51. Move_Delay();
52. }
53. 
    
54. while(1) { // Endless loop
55. for(i=0; i<8; i++) { // Move text to the left 7 times
56. Lcd_Cmd(_LCD_SHIFT_LEFT);
57. Move_Delay();
58. }
59. 
    
60. for(i=0; i<8; i++) { // Move text to the right 7 times
61. Lcd_Cmd(_LCD_SHIFT_RIGHT);
62. Move_Delay();
63. }
64. }
65. }

 

DIY PIC18F4550 Prototype Board

I tested this example on my DIY PIC18F4550 Prototype Board.

 

PIC18F4550 Prototype Board

PIC18F4550 Prototype Board

 

 

On-board Switches and LCD Example

In this example, when one of two on-board push buttons is pressed it will shows its state - Press or Released. The schematic is shown in the example above.

MikroC Source Code

 

#define SW4 RB4_bit
#define SW5 RB5_bit

// LCD module connections
sbit LCD_RS at RD2_bit;
sbit LCD_EN at RD3_bit;
sbit LCD_D4 at RD4_bit;
sbit LCD_D5 at RD5_bit;
sbit LCD_D6 at RD6_bit;
sbit LCD_D7 at RD7_bit;

sbit LCD_RS_Direction at TRISD2_bit;
sbit LCD_EN_Direction at TRISD3_bit;
sbit LCD_D4_Direction at TRISD4_bit;
sbit LCD_D5_Direction at TRISD5_bit;
sbit LCD_D6_Direction at TRISD6_bit;
sbit LCD_D7_Direction at TRISD7_bit;
// End LCD module connections


void main(){

  /// PORTB AS INPUT
  PORTB = 0;
  LATB = 0;
  TRISB = (1<<5)|(1<<4);
  
  // ENABLE PORTB PULL-UP
  INTCON2 &=~(1<<7);
  // DISABLE ANALOG INPUTS
  ADCON1 = 0x0F;
  
  Lcd_Init();                        // Initialize LCD

  Lcd_Cmd(_LCD_CLEAR);               // Clear display
  Lcd_Cmd(_LCD_CURSOR_OFF);          // Cursor off

  Lcd_Out(1,1,"PIC18F4550 LCD");
  Lcd_out(2,1,"Buttons Example");

  Delay_ms(7000);
  Lcd_Cmd(_LCD_CLEAR);               // Clear display
  Lcd_Out(1,1, "Press on SW4.");
  Lcd_Out(2,1, "Press on SW5.");
  while(1){
    if(SW4==0){
      Lcd_Out(1,1, "SW4 is Pressed.");
      while(SW4 == 0);
      Lcd_Out(1,1, "SW4 is Released.");
    }
    if(SW5==0){
      Lcd_Out(2,1, "SW5 is Pressed.");
      while(SW5 == 0);
      Lcd_Out(2,1, "SW5 is Released.");
    }
  }
}

 

Example Pictures

I tested this example on my DIY PIC18F4550 Prototype Board.

 

My DIY PIC18F4550 Prototype Board

My DIY PIC18F4550 Prototype Board

My DIY PIC18F4550 Prototype Board