⚙️ LCD Interfacing with 8051 Microcontroller

This repository demonstrates interfacing a 16x2 alphanumeric LCD with the 8051 Microcontroller using Assembly language. The project is designed to show how to send data from the 8051 microcontroller to an LCD. It includes Proteus simulation files for testing and visualization.

Fig-1: 8051 Microcontroller LCD Interface (Schematic Diagram).

The figure above shows the circuit schematic for interfacing the **16x2 LCD** with the **AT89C51 Microcontroller**. It includes essential connections for data transfer, control, and power, enabling the display of alphanumeric characters using **8-bit data mode**.

🔑 Keywords

AT89C51 Microcontroller | Assembly Language | Proteus | 16x2 LCD | LCD Interfacing

⚙️ Project Overview

This project demonstrates LCD interfacing with the AT89C51 Microcontroller. It is useful for educational purposes and embedded systems applications, allowing the microcontroller to display data on the LCD.

🔧 Key Features

Feature	Description
📟 LCD Display	Displays data entered or processed by the microcontroller
🖥️ Proteus Simulation	Includes a ready-to-use simulation circuit compatible with Proteus 8.9
💾 Assembly Programming	Optimized assembly code for efficient execution on the AT89C51
🛠️ Real Hardware Test	Successfully tested on actual hardware for reliable performance

📦 What’s Included?

File	Description
Assembly Code	The core assembly code for initializing and operating the LCD. (`exampleproject.asm`)
Proteus Simulation	Simulation file for testing the LCD interface in Proteus. (`exampleproject.pdsjr`)
HEX File	Compiled HEX file for uploading to the 8051 microcontroller. (`exampleproject.hex`)
Test Run Image	Image showing the test run result.

🖥️ Installation & Usage

Step-by-Step Guide:

Clone this repository:

git clone https://github.com/gmostofabd/8051-LCD.git

Compile the Assembly Code: Open the AT89C51_LCD_Keypad.asm file in MIDE-51 or any compatible IDE, and compile it to generate the HEX file.
Simulate in Proteus: Open Proteus Design Suite, load the provided simulation file, and run the simulation to observe the interface's functionality.
Program the Microcontroller: For real hardware, upload the HEX file to the AT89C51 microcontroller using a compatible programmer.
Test the Circuit: Assemble the hardware based on the provided circuit diagram, power it on, and verify the LCD's functionality.

🛠️ Components Used

Component	Description
AT89C51 Microcontroller	The core of the project, programmed in Assembly language to control the LCD.
16x2 LCD	Displays the output of the microcontroller in alphanumeric form.
Crystal Oscillator (11.0592 MHz)	Provides a clock signal to the microcontroller for accurate timing.
33pf Capacitors (2x)	Used with the crystal oscillator to stabilize the clock signal, connected between XTAL1 and XTAL2 of the microcontroller and ground.
100 Ohm Resistor	Limits current in the circuit to protect components.
10K Variable Resistor (Potentiometer)	Adjusts the contrast of the LCD, wired between VCC and GND, with the wiper connected to the contrast pin (V0) of the LCD.
Push-button Switch (Reset)	Connected to the RST pin of the microcontroller for manual reset, with a pull-down resistor for stability.
Jumper Wires	Connects components as needed.

🌐 LCD Display

A Liquid Crystal Display (LCD) provides a useful interface for embedded systems. The 16x2 LCD displays textual information across two rows, each capable of showing 16 characters, with each character occupying a 5x7 matrix space on the screen.

🌐 16×2 LCD Pin Diagram

🌐 Programming LCD with 8051

To interface with the 16x2 LCD, follow these mandatory steps:

Initialization:
- Set the LCD to 8-bit mode by sending initialization commands.
Set RS and RW Pins:
- RS: Set to 0 for commands, 1 for data.
- RW: Set to 0 for writing, 1 for reading (not often used in basic setups).
Send Commands/Data:
- Place the command or data in the data register and trigger the Enable Pin.
Enable Pulse:
- Toggle the Enable Pin to send the command/data.
Delay:
- Wait briefly after each command/data transfer to allow the LCD to process it.

Assembly Code for 8-Bit Mode LCD Interfacing

; -----------------------------
; LCD Interfacing in 8-Bit Mode (lcd_8bit.asm)
; -----------------------------

ORG 00H                  ; Set origin to address 00H

MOV SP, #70H             ; Initialize stack pointer at address 70H
MOV PSW, #00H            ; Set program status word to 00H

LCD_IN: 
    MOV A, #38H          ; Initialize LCD for 2 lines, 5x7 matrix
    LCALL COMNWRT        ; Call command write subroutine
    LCALL DELAY          ; Give LCD some time
    MOV A, #0EH          ; Display ON, Cursor ON
    LCALL COMNWRT        ; Call command write subroutine
    LCALL DELAY          ; Give LCD some time
    MOV A, #01H          ; Clear LCD display
    LCALL COMNWRT        ; Call command write subroutine
    LCALL DELAY          ; Give LCD some time
    MOV A, #06H          ; Shift cursor to the right
    LCALL COMNWRT        ; Call command write subroutine
    LCALL DELAY          ; Give LCD some time
    MOV A, #85H          ; Set cursor at line 1, position 1
    LCALL COMNWRT        ; Call command write subroutine
    LCALL DELAY          ; Give LCD some time
    MOV A, #'E'          ; Display letter 'E'
    LCALL DATAWRT        ; Call data write subroutine
    LCALL DELAY          ; Give LCD some time
    MOV A, #'X'          ; Display letter 'X'
    LCALL DATAWRT        ; Call data write subroutine
    LCALL DELAY          ; Give LCD some time
    MOV A, #'P'          ; Display letter 'P'
    LCALL DATAWRT        ; Call data write subroutine
    LCALL DELAY          ; Give LCD some time
    MOV A, #':'          ; Display colon ':'
    LCALL DATAWRT        ; Call data write subroutine
    MOV A, #'0'          ; Display number '0'
    LCALL DATAWRT        ; Call data write subroutine
    LCALL DELAY          ; Give LCD some time
    MOV A, #'4'          ; Display number '4'
    LCALL DATAWRT        ; Call data write subroutine
    LCALL DELAY          ; Give LCD some time

    MOV A, #0C3H         ; Set cursor at line 2, position 1
    LCALL COMNWRT        ; Call command write subroutine
    LCALL DELAY          ; Give LCD some time

    MOV A, #'8'          ; Display number '8'
    LCALL DATAWRT        ; Call data write subroutine
    LCALL DELAY          ; Give LCD some time
    MOV A, #' '          ; Display space
    LCALL DATAWRT        ; Call data write subroutine
    LCALL DELAY          ; Give LCD some time
    MOV A, #'B'          ; Display letter 'B'
    LCALL DATAWRT        ; Call data write subroutine
    LCALL DELAY          ; Give LCD some time
    MOV A, #'i'          ; Display letter 'i'
    LCALL DATAWRT        ; Call data write subroutine
    MOV A, #'t'          ; Display letter 't'
    LCALL DATAWRT        ; Call data write subroutine
    LCALL DELAY          ; Give LCD some time
    MOV A, #' '          ; Display space
    LCALL DATAWRT        ; Call data write subroutine
    LCALL DELAY          ; Give LCD some time
    MOV A, #'L'          ; Display letter 'L'
    LCALL DATAWRT        ; Call data write subroutine
    LCALL DELAY          ; Give LCD some time
    MOV A, #'C'          ; Display letter 'C'
    LCALL DATAWRT        ; Call data write subroutine
    LCALL DELAY          ; Give LCD some time
    MOV A, #'D'          ; Display letter 'D'
    LCALL DATAWRT        ; Call data write subroutine
    LCALL DELAY          ; Give LCD some time
    SJMP $               ; Infinite loop

; -----------------------------
; Command Write Subroutine
; -----------------------------
COMNWRT:
    LCALL READY          ; Prepare for sending command to LCD
    MOV P1, A            ; Copy content of register A to port 1
    CLR P3.4             ; Set RS = 0 for command mode
    CLR P3.5             ; Set R/W = 0 for write mode
    SETB P3.6            ; Set E high for pulse
    ACALL DELAY          ; Give LCD some time
    CLR P3.6             ; Set E low for H-to-L pulse
    RET

; -----------------------------
; Data Write Subroutine
; -----------------------------
DATAWRT:
    LCALL READY          ; Prepare for writing data to LCD
    MOV P1, A            ; Copy content of register A to port 1
    SETB P3.4            ; Set RS = 1 for data mode
    CLR P3.5             ; Set R/W = 0 for write mode
    SETB P3.6            ; Set E high for pulse
    ACALL DELAY          ; Give LCD some time
    CLR P3.6             ; Set E low for H-to-L pulse
    RET

; -----------------------------
; Ready Check Subroutine
; -----------------------------
READY:
    SETB P1.7            ; Set P1.7 to indicate readiness
    CLR P3.4             ; Clear RS
    SETB P3.5            ; Set R/W = 1 for read mode

WAIT:
    CLR P3.6             ; Clear E
    ACALL DELAY          ; Wait for delay
    SETB P3.6            ; Set E high
    JB P1.7, WAIT        ; Wait until P1.7 is high (LCD ready)
    RET

; -----------------------------
; Delay Subroutine
; -----------------------------
DELAY:
    MOV R3, #50          ; Set outer loop count (50 or higher for fast CPUs)
HERE2:
    MOV R4, #255         ; Set inner loop count (255)
HERE:
    DJNZ R4, HERE        ; Decrement R4 and repeat until it reaches 0
    DJNZ R3, HERE2       ; Decrement R3 and repeat until it reaches 0
    RET

END                     ; End of program

Code Explanation

LCD Initialization: The LCD_INIT procedure sets the LCD in 8-bit mode, turns on the display, and clears it.
Command and Data Functions: LCD_CMD sends commands to the LCD, while LCD_DATA sends data (characters).
String Sending: The SEND_STRING procedure sends a null-terminated string to the LCD for display.
Main Program: The MAIN procedure initializes the LCD and sends the string to display.

Usage

Save the Code: Copy this code into a file named lcd.asm.
Compile: Use a compatible assembler to compile the code.
Simulate or Upload: Use Proteus for simulation or upload it to the AT89C51 microcontroller.

🌐 LCD Interfacing with 8051 – Working

Upon powering the circuit, the AT89C51 microcontroller initializes the LCD and sends a message to be displayed. This can be tested through simulation or real hardware.

📜 LCD Commands Table

Command	Hex Code	Description
Clear Display	`0x01`	Clears the LCD and resets the cursor to home position.
Return Home	`0x02`	Returns the cursor to the home position.
Entry Mode Set	`0x04`	Sets the entry mode; cursor moves to the right.
Display ON/OFF Control	`0x0C`	Turns the display on with the cursor off.
Cursor ON/OFF Control	`0x0E`	Turns the cursor on, but without blinking.
Blinking Cursor ON	`0x0F`	Turns the blinking cursor on.
Shift Display Right	`0x1C`	Shifts the entire display to the right.
Shift Display Left	`0x18`	Shifts the entire display to the left.
Function Set	`0x38`	Sets the interface to 8-bit, 2-line mode with 5x7 dots.
Set Cursor Position	`0x80`	Sets the cursor position to the specified address.
Scroll Display Right	`0x1C`	Scrolls the display right.
Scroll Display Left	`0x18`	Scrolls the display left.
Set CGRAM Address	`0x40`	Sets the address for the character generator RAM.
Set DDRAM Address	`0x80`	Sets the address for the display data RAM.

📝 Tasks

Verify the connections based on the schematic.
Modify the code to display different messages.
Experiment with the contrast and observe its effects.

🔗 Resources

8051 Microcontroller Reference: Datasheet
LCD Datasheet: HD44780 LCD Controller

🛠️ Future Work

Adding more functionalities such as scrolling text, custom characters, and additional interfacing techniques like 4-bit mode.

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Name		Name	Last commit message	Last commit date
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assets		assets
codes		codes
README.md		README.md
index.html		index.html

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⚙️ LCD Interfacing with 8051 Microcontroller

🔑 Keywords

⚙️ Project Overview

🔧 Key Features

📦 What’s Included?