Interfacing JHD404A (40×4) lcd with Microcontroller

This post covers how to interface JHD404A 40×4 lcd with microcontroller (89c51, Pic16f877, Arduino etc). JHD404A is a 40×4 Character lcd. 40×4 means it has 40 coulombs and 4 rows. On each row of lcd we can display 40 characters/numbers etc. Total characters which we can display on 40×4 lcd is equal to (40×4=160) 160.

Like all other character lcd’s JHD404A also has a controller in it which controls its internal functions. 40×4 contains HD44780 lcd controller by hitachi in it. Which means same commands are used to initialize 40×4 lcd that are used to initialize 8×1, 16×1, 16×2 ,20×2 character lcd’s. The only difference between JHD404A and his siblings when compared is, it has two enable pins (en1 & en2). This is because a single HD44780 controller can handle up to 80 characters. To handle 160 characters we need an extra HD44780 controller.

Why two enable ports?

Consider a 40×1 or 40×2 lcd they have one enable (en) pin. In contrary to 40×1 and 40×2, 40×4 lcd has two enable (en1 & en2) pins. Actually 40×4 is comprised of two 40×2 lcd’s stacked on each other. We have to initialize 40×4 lcd two times. One initializing is using en1 pin and second is using en2 pin. We have to initialize both HD44780 controllers. First two rows of 40×4 lcd are initialized using en1 pin and then third fourth rows are initialized using en2 pin.

Some tutorials which might help you if you are new and don’t know much about character lcd’s and their working. These tutorials will help you in understanding this post.

I made a PLC(programmable logical controller) in which i used 40×4 lcd to show input and output status. You can also build yours just take a look at it its not a hard task.

DIY PLC using Pic microcontroller and 40×4 lcd

Interfacing JHD404A (40×4) Lcd with 89c51 Microcontroller

Interfacing 40×4 lcd with 8051 series microcontrollers is not a hard task. If you have already done interfacing of any other character lcd with 8051 microcontrollers you can easily interface 40×4 lcd with 89c51. I made a simple project the circuit diagram is below.

#include <reg52.h>

sbit rw =P3^0; //Read/Write Pin

sbit en1=P3^1; //Enable for First 80 Characters

sbit rs =P3^2; //Register select (RS)

sbit en2=P3^3; //Enable for Second 80 Characters

void delay(unsigned int time) //Time delay function

{

unsigned int i,j;

for(i=0;i< time;i++)

for(j=0;j< 5;j++);

}

//Function for sending values to the command register of LCD

void lcdcmd1(unsigned char value)

{

P1=value;

rs = 0;

rw = 0;

en1 = 1;

delay(50);

en1=0;

delay(50);

}

//Function for sending values to the command register of LCD

void lcdcmd2(unsigned char value)

{

P1=value;

rs = 0;

rw = 0;

en2 = 1;

delay(50);

en2=0;

delay(50);

}

//Function for sending values to the data register of LCD

void display1(unsigned char value)

{

P1=value;

rs = 1;

rw = 0;

en1 = 1;

delay(500);

en1=0;

delay(50);

}

//Function for sending values to the data register of LCD

void display2(unsigned char value)

{

P1=value;

rs = 1;

rw = 0;

en2 = 1;

delay(500);

en2=0;

delay(50);

}

//function to initialize the registers and pins of LCD

//always use with every lcd of hitachi

void lcdint1(void)

{

P1=0x00;

P3=0x00;

delay(15000);

display1(0x30);

delay(4500);

display1(0x30);

delay(300);

display1(0x30);

delay(650);

lcdcmd1(0x38);

delay(50);

lcdcmd1(0x0F);

delay(50);

lcdcmd1(0x01);

delay(50);

lcdcmd1(0x06);

delay(50);

}

void lcdint2(void)

{

P1=0x00;

P3=0x00;

delay(15000);

display2(0x30);

delay(4500);

display2(0x30);

delay(300);

display2(0x30);

delay(650);

lcdcmd2(0x38);

delay(50);

lcdcmd2(0x0F);

delay(50);

lcdcmd2(0x01);

delay(50);

lcdcmd2(0x06);

delay(50);

}

void main()

{

unsigned int count=0;

char st[]=“Its 40×4 Lcd microcontroller-project.com“;

P1=0x00; //Port-1 as Output

P3=0x00; //Port-2 as Output

lcdint1();

lcdint2();

while(1){

lcdcmd1(0x80);

while(count!=40){

display1(st[count]);

count++;

}

count=0;

delay(5);

lcdcmd1(0xC0);

while(count!=40){

display1(st[count]);

count++;

}

count=0;

delay(5);

lcdcmd2(0x80);

while(count!=40){

display2(st[count]);

count++;

}

count=0;

delay(5);

lcdcmd2(0xC0);

while(count!=40){

display2(st[count]);

count++;

}

count=0;

}

}