Interfacing 16×2 LCD with 8051

In this project, we’ll go through how to connect a Interfacing 16×2 LCD with 8051 module to an AT89C51, a microcontroller from the 8051 series. We utilise LCD displays to show messages in a more interactive fashion, such as while operating the system or when displaying error messages. Interfacing a 162 LCD with an 8051 microcontroller is simple if you understand how LCDs work.

As a result, in this project, I will not only share knowledge about the LCD, but also code written in C that is error-free.

Outline

• A Brief Note on Interfacing 16×2 LCD with 8051
• Interfacing 16×2 LCD with 8051 Circuit Diagram
• Components Required 
• Circuit Explanation
• Programming LCD to 8051
  • Initializing LCD
  • Sending Commands to the LCD
  • Writing the Data to the LCD
• Code 
• Additional Codes 
  • Code 1
  • Code 2

A Brief Note on 16×2 LCD

162 Liquid Crystal Display that displays 32 characters in two rows at a time (16 characters in one row). The size of each character in the display is a 57% pixel matrix. This matrix varies depending on the 162 LCD module you choose; for example, if you use JHD162A, this matrix is 58%. The LCD module has 16 pins, and the pin configuration is shown below.

PIN NO	NAME	FUNCTION
1	VSS	Ground pin
2	VCC	Power supply pin of 5V
3	VEE	Used for adjusting the contrast commonly attached to the potentiometer.
4	RS	RS is the register select pin used to write display data to the LCD (characters), this pin has to be high when writing the data to the LCD. During the initializing sequence and other commands this pin should low.
5	R/W	Reading and writing data to the LCD for reading the data R/W pin should be high (R/W=1) to write the data to LCD R/W pin should be low (R/W=0)
6	E	Enable pin is for starting or enabling the module. A high to low pulse of about 450ns pulse is given to this pin.
7	DB0
8	DB1
9	DB2
10	DB3
11	DB4	DB0-DB7 Data pins for giving data(normal data like numbers characters or command data) which is meant to be displayed
12	DB5
13	DB6
14	DB7
15	LED+	Back light of the LCD which should be connected to Vcc
16	LED-	Back light of LCD which should be connected to ground.

So, after reading the table above, you should have a good concept of how to show a character. To display a character, first enable the enable pin (pin 6) with a 450ns pulse, then pick the register select pin (pin 4) in write mode. To enable write mode, set the register select pin to high (RS=1), and then set the R/W to low (R/W=0).

Follow these simple steps for displaying a character or data

• E=1; enable pin should be high
• RS=1; Register select should be high
• R/W=0; Read/Write pin should be low.

To send a command to the LCD just follows these steps:

• E=1; enable pin should be high
• RS=0; Register select should be low
• R/W=0; Read/Write pin should be low.

Commands: There are some preset commands which will do a specific task in the LCD. These commands are very important for displaying data in LCD. The list of commands given below:

COMMAND	FUNCTION
0F	For switching on LCD, blinking the cursor.
1	Clearing the screen
2	Return home.
4	Decrement cursor
6	Increment cursor
E	Display on and also cursor on
80	Force cursor to beginning of the first line
C0	Force cursor to beginning of second line
38	Use two lines and 5×7 matrix
83	Cursor line 1 position 3
3C	Activate second line
0C3	Jump to second line position 3
0C1	Jump to second line position1

Interfacing 16×2 LCD with 8051 Circuit Diagram

Components Required 

• AT89C51 (8051 Microcontroller)
• 16X2 LCD Display
• 11.0592MHz Crystal
• 2 X 33pF Capacitors 
• 2 X 10 KΩ Resistors
• 1 KΩ X 8 Resistor Pack 
• 10 KΩ Potentiometer 
• 330Ω Resistor 
• Push Button 
• 10μF/16V Capacitor 
• 8051 Programmer 
• 5V Power Supply 
• Connecting Wires

Circuit Explanation

The crystal oscillator is connected to XTAL1 and XTAL2, which will give the system clock to the microcontroller, along with two 33pF capacitors.

With the help of a 10K resistor, the RST Pin is pulled-low. You can reset the 8051 Microcontroller using a 10F Capacitor and a Push Button. With the help of a 10K resistor, EA is pulled-HIGH.

The LCD data pins are connected to PORT0 (with the help of a 1K Resistor Pack, the PORT0 pins must first be pulled-HIGH). Pins P2.0 and P2.1 on PORT2 are used to connect RS and E.

The LCD contrast is adjusted with a 10K potentiometer.

Programming LCD to 8051

Coming to the programming you should follow these steps:

• STEP1: Initialization of LCD.
• STEP2: Sending commands to LCD.
• STEP3: Writing the data to LCD.

Initializing LCD

To initialize LCD to the 8051 the following instruction and commands are to be embed in to the functions

• 0x38 is used for 8-bit data initialization.
• 0xoC for making LCD display on and cursor off.
• 0X01 for clearing the display of the LCD.
• 0x80 for positioning the cursor at first line .

Sending Commands to the LCD

• E=1; enable pin should be high
• RS=0; Register select should be low for sending commands
• Placing the data on the data registers
• R/W=0; Read/Write pin should be low for writing the data.

Writing the Data to the LCD

• E=1; enable pin should be high
• RS=1; Register select should be high for writing data
• Placing the data on the data registers
• R/W=0; Read/Write pin should be low for writing the data.

Code 

	#include<reg51.h>
	#define lcd P0
	sbit rs=P2^0;
	sbit e=P2^1;
	void delay (int);
	void cmd (char);
	void display (char);
	void custom (void);
	void string (char *);
	void init (void);
	unsigned char custom_char[]= {0x00,0x04,0x0E,0x04,0x15,0x0E,0x04,0x00,
	0x00,0x04,0x0E,0x0E,0x0E,0x1F,0x04,0x00,
	0x00,0x0A,0x15,0x11,0x11,0x0A,0x04,0x00,
	0x0E,0x11,0x11,0x1F,0x1B,0x1B,0x1B,0x1F,
	0x0E,0x11,0x10,0x1F,0x1B,0x1B,0x1B,0x1F,
	0x00,0x0E,0x15,0x1B,0x0E,0x0E,0x00,0x00,
	};
	void delay (int d)
	{
	unsigned char i;
	for(;d>0;d–)
	{
	for(i=250;i>0;i–);
	for(i=248;i>0;i–);
	}
	}
	void cmd (char c)
	{
	lcd=c;
	rs=0;
	e=1;
	delay(5);
	e=0;
	}
	void display (char c)
	{
	lcd=c;
	rs=1;
	e=1;
	delay(5);
	e=0;
	}
	void custom (void)
	{
	int k;
	cmd(0x40);
	for(k=0;k<48;k++)
	display(custom_char[k]);
	cmd(0x80);
	}
	void string (char *p)
	{
	while(*p)
	{
	display(*p++);
	}
	}
	void init (void)
	{
	cmd(0x38);
	cmd(0x0c);
	cmd(0x01);
	cmd(0x80);
	}
	void main()
	{
	init();
	custom();
	string(“Electronics Hub “);
	cmd(0xc0);
	string(” Presents “);
	delay(2000);
	cmd(0x01);
	cmd(0x80);
	string(” Custom Chars “);
	cmd(0xc0);
	string(” on 16×2 LCD “);
	delay(2000);
	cmd(0x01);
	cmd(0x80);
	string(“ABCDEFGHIJKLMNOP”);
	cmd(0xc0);
	string(“1234567890”);
	cmd(0xca);
	display(0);
	display(1);
	display(2);
	display(3);
	display(4);
	display(5);
	while(1);
	}

Additional Codes 

The programs given below will use above functions and display the complete string which is given by the programmer to display the data. We have provided two demo codes working properly and easy to understand.

Code 1

	#include <REG51.H>
	#include <string.h>
	#include <stdio.h>
	sfr  LCD=0x80;
	sbit EN=P2^1;
	sbit RS=P2^0;
	void nop(void);
	void delay_1s(unsigned char t);
	void initial_lcd(void);
	void delay(void);
	void string_to_lcd(unsigned char *s);
	void write_lcd(unsigned char dat,unsigned int com);
	void delay_50ms(unsigned char x);
	void main()
	{
	P1=0xff;
	P2=0xff;
	P3=0xff;
	delay_50ms(4);
	initial_lcd();
	write_lcd(0x80,0);
	string_to_lcd(”   Welcome to   “);
	write_lcd(0xc0,0);
	string_to_lcd(“Electronics Hub “);
	}
	void nop(void)
	{
	unsigned char n;
	for(n=0;n<20;n++);
	}
	//………………delay routine……………..//
	void delay_1s(unsigned char t)
	{
	unsigned char i,j;
	for(i=0;i<t;i++)
	{
	for(j=0;j<20;j++)
	{
	TMOD=0x01;
	TH0=0x3c;              //for 12MHz   (12/12MHZ)=1u>per cycle operation
	TL0=0xb0;            //50ms delay get (50m/1u)=50000;
	TR0=1;                 //Load value is =65536-50000=15536(=3cb0H)
	while(TF0!=1);  //wait for overflow flag
	TF0=0;
	}
	}
	}
	void initial_lcd(void)
	{
	write_lcd(0x38,0);
	write_lcd(0x0c,0);
	write_lcd(0x01,0);
	}
	void write_lcd(unsigned char dat,unsigned int com)
	{
	RS=com;
	LCD=dat;nop();
	EN=1;nop();
	EN=0;
	nop();
	}
	void string_to_lcd(unsigned char *s)
	{
	unsigned char i,l;
	l=strlen(s);
	for(i=0;i<l;i++)
	{
	write_lcd(*s,1);delay_50ms(1);
	s++;
	}
	}
	void delay_50ms(unsigned char x)
	{
	unsigned char i;
	for(i=0;i<x;i++)
	{
	TMOD=0x01;
	TH0=0x3c;
	TL0=0xb0;
	TR0=1;
	while(!TF0);
	TF0=0;
	TR0=0;
	}
	}

Code 2

	#include<reg51.h>
	#define cmdport P2
	#define dataport P0
	sbit rs = cmdport^0;        //register select pin
	sbit e = cmdport^1;        //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;
	e=1;
	delay(1);
	e=0;
	}
	void lcddata(unsigned char item)    //Function to send data to LCD
	{
	dataport = item;
	rs= 1;
	e=1;
	delay(1);
	e=0;
	}
	void main()
	{
	lcdcmd(0x38);    //for using 8-bit 2 row mode of LCD
	delay(100);
	lcdcmd(0x0C);    //turn display ON and cursor OFF
	delay(100);
	lcdcmd(0x01);    //clear screen
	delay(100);
	lcdcmd(0x86);    //bring cursor to position 6 of line 1
	delay(100);
	lcddata(‘A’);
	}