How to interface LCD with PIC18F4550 Microcontroller- (Part 5/25)

The character LCDs are the most commonly used display modules. These LCDs are used to display text using alphanumeric and special characters of font 5x7/5x10. For basic working and operations of a character LCD, refer LCD interfacing with 8051. Here PIC18F4550 has been used to display a single character on a 16x2 character LCD.

For basic details and operations of character LCD, refer LCD interfacing with 8051. Here LCD has been interfaced in 8-bit mode* with data pins (D0-D7) connected to PortB of PIC18F4550. The LCD control pins RS, R/W and EN are connected to PortA pins RA0, RA1 and RA2 respectively.

*Character LCD can also be interfaced by using only 4 data lines. Refer LCD interfacing in 4-bit mode.

Programming Steps:

Before displaying anything on LCD, it needs to be configured with proper instructions. The following programming steps explain the procedure of configuring the LCD and display a character on it.

Step 1: Initialize the LCD.

The LCD must be initialized the by following pre-defined commands of character LCD.

· 0x38, to configure the LCD for 2-line, 5×7 font and 8-bit operation mode

· 0x0C, for Display On and Cursor Off

· 0x01, to Clear Display screen

· 0x06, to increment cursor

· 0x80, to set cursor position at first block of the first line of LCD.

The above set of commands is written in lcd_ini() function of the adjoining code.

Step 2: Send the commands to LCD.

· Send the command byte to the port connected to LCD data pins

· RS=0, to select command register of LCD

· RW=0, to set the LCD in writing mode

· EN=1, a high to low pulse to latch command instruction

· Delay of 1ms

· EN=0

The above set of commands is written in lcdcmd(unsigned char) function.

Step 3: Send data to LCD.

· Send data at the port which connected to LCD data pins

· RS=1, register select to select data register of LCD

· RW=0, this set the LCD in writing mode

· EN=1, a high to low pulse to latch data

· Delay of 1ms

· EN=0

The lcddata(unsigned char) function has the above set of instructions.

Step 4: Display character on LCD.

The functions lcdcmd() and lcddata() are user-defined functions. They are used to send a character (E in this case) to be displayed on LCD.

lcdcmd(0x38); // send command 0x38 to LCD

lcddata(‘E’); // send character E to LCD

Project Source Code

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// Program to interface 16x2 LCD and display single character using PIC18F4550 Microcontroller

// Configuration bits
/* _CPUDIV_OSC1_PLL2_1L,  // Divide clock by 2
   _FOSC_HS_1H,           // Select High Speed (HS) oscillator
   _WDT_OFF_2H,           // Watchdog Timer off
   MCLRE_ON_3H            // Master Clear on
*/

//LCD Control pins
#define rs LATA.F0
#define rw LATA.F1
#define en LATA.F2

//LCD Data pins
#define lcdport LATB

void lcd_ini();
void lcdcmd(unsigned char);
void lcddata(unsigned char);
unsigned int i=0;

void main(void)
{
	TRISA=0;		// Configure Port A as output port
	LATA=0;
	TRISB=0;		// Configure Port B as output port
	LATB=0;
	lcd_ini();		// LCD initialization
	lcddata('E');		// Print 'E'
	Delay_ms(1000);
	lcdcmd(0x85);		// Position 1st Line, 6th Column
	lcddata('G');		// Print 'G'

}
void lcd_ini()
{
	lcdcmd(0x38);		// Configure the LCD in 8-bit mode, 2 line and 5x7 font
	lcdcmd(0x0C);		// Display On and Cursor Off
	lcdcmd(0x01);		// Clear display screen
	lcdcmd(0x06);		// Increment cursor
	lcdcmd(0x80);		// Set cursor position to 1st line, 1st column
}

void lcdcmd(unsigned char cmdout)
{
	lcdport=cmdout;		//Send command to lcdport=PORTB
	rs=0;						
	rw=0;
	en=1;
	Delay_ms(10);
	en=0;
}

void lcddata(unsigned char dataout)
{
	lcdport=dataout;	//Send data to lcdport=PORTB
	rs=1;
	rw=0;
	en=1;
	Delay_ms(10);
	en=0;
}

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