How to interface LCD with PIC18F4550 Microcontroller

The character LCDs are the most commonly used display modules. These LCDs are used to display text using alphanumeric and special characters of font 5×7/5×10. 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 16×2 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 16×2 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 5×7 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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