- Hex CodeCommand to LCD Instruction Register1Clear screen display2Return home4Decrement cursor6Increment cursorEDisplay ON, Cursor ON80Force the cursor to the beginning of the 1st lineC0Force cursor to the beginning of the 2nd line38Use 2 lines and 5x7 matrix
DESCRIBTION
- It is very important to keep a track of the working of almost all the automated and semi-automated devices, be it a washing machine, an autonomous robot or anything else. This is achieved by displaying their status on a small display module. LCD (Liquid Crystal Display) screen is such a display module and a 16x2 LCD module is very commonly used. These modules are replacing seven segments and other multi segment LEDs for these purposes. The reasons being: LCDs are economical, easily programmable, have no limitation of displaying special & even custom characters (unlike in seven segments), animations and so on. LCD can be easily interfaced with a microcontroller to display a message or status of a device. This topic explains the basics of a 16x2 LCD and how it can be interfaced with AT89C51 to display a character.
CODE
/Program to test LCD. Display single character "A"
#include<reg51.h>
#define cmdport P3
#define dataport P2
#define q 100
sbit rs = cmdport^0; //register select pin
sbit rw = cmdport^1; // read write pin
sbit e = cmdport^6; //enable pin
void delay(unsigned int msec) // Function to provide time delay in msec.
{
int i,j ;
for(i=0;i<msec;i++)
for(j=0;j<1275;j++);
}
void lcdcmd(unsigned char item) //Function to send command to LCD
{
dataport = item;
rs= 0;
rw=0;
e=1;
delay(1);
e=0;
}
void lcddata(unsigned char item) //Function to send data to LCD
{
dataport = item;
rs= 1;
rw=0;
e=1;
delay(1);
e=0;
}
void main()
{
lcdcmd(0x38); // for using 8-bit 2 row mode of LCD
delay(100);
lcdcmd(0x0E); // turn display ON for cursor blinking
delay(100);
lcdcmd(0x01); //clear screen
delay(100);
lcdcmd(0x06); //display ON
delay(100);
lcdcmd(0x86); // bring cursor to position 6 of line 1
delay(100);
lcddata('A');
}
