Interfacing PIC18F4520 microcontroller with an HD44780 LCD


Being able to display data from a microcontroller visually has many advantages. It allows for menus, status indicators, and instructions to be intuitively shown to users. When paired with an LCD, a microcontroller becomes a powerful tool for building interactive electronic devices and systems. One excellent combination is interfacing an HD44780 LCD with PIC18F4520 microcontrollers. This pairing provides an affordable and resource-efficient solution for all sorts of projects.
In this article, I will discuss how to set up the connection between these two components and get text displayed on the screen. More importantly, I will explore the diverse applications this interface enables, with a focus on promising areas like home automation and the Internet of Things (IoT). By understanding real use cases, the concepts covered take on practical relevance beyond basic tutorials. So let’s dive into the technical details first before exploring where this small yet mighty microcontroller-LCD setup can take us!

Wiring the HD44780

HD44780-based LCDs have 14 pins, 11 of them are for interfacing with the LCD, and the others for power and screen contrast. To save I/O pins on the microcontroller only 6 pins to successfully interface with the LCD, as opposed to 11

Interfacing PIC18F4520 microcontroller with an HD44780 LCDSince the LCD will be used in 4-bit mode, pins DB0 to DB3 can be grounded. We only wish to write to the microcontroller so the R/W pin can also be grounded, which leaves us with the enable pin, the register select pin, and the DB4 to DB7 pins needed for the PIC.

The LCD interface will be set up on portD of the microcontroller, wire the LCD DB4 to DB7 on portD_0 to PortD_3, the enable pin to portD_4, and the register select to pin PORTD_5.

Initializing the Display

To send instructions to the LCD the data bits of the LCD are set and a pulse on the enable pin allows the LCD to read the data. The register select pin also plays a role, when it is low, the LCD interprets the data sent as an instruction to execute. When the register select pin is high, the LCD interprets the data pins as data.
Before the LCD can be used as a display, it needs to be initialized. The datasheet for the HD44780 has a process for initializing the LCD and it involves configuring the type of display attached to the HD44780. A flowchart of this initialization can be followed below

Interfacing PIC18F4520 microcontroller with an HD44780 LCD




X = Don’t Care
N = # Display lines; 0 = 1 line; 1 = 2 lines
F = font type; 0=5×7 display; 1 = 8×10 display
D = Display status; 0 = off ; 1 = on C = Cursor status; 0 = off; 1 = on B = Cursor Blinking; 0 = off; 1 = on
ID = Character Increment; 0 = off; 1 = increment +1 after character
S = Increment; 0 = off; 1 = on



Applications for Embedded Systems

Now that we have a functional microcontroller-LCD interface, there are endless possibilities for applications. Early embedded systems relied on LEDs and switches alone but lacked the rich interactivity of graphical displays. An LCD expands the kinds of products they can enhance, from industrial equipment to scientific instruments and beyond. Even basic functions like monitoring live readings and toggling between preset configurations become more approachable.

Other options include numeric keypads for data entry, menu structures built dynamically based on sensor feedback, and status indicators that provide operational awareness at a glance. A visually engaging interface makes embedded systems more approachable for non-technical users too. When considering projects both big and small, an LCD opens creative doors that were previously closed without a display option.

Uses in Home Automation

One burgeoning field ideally suited to microcontroller-LCD pairs is home automation. A thermostat, for instance, benefits tremendously from an intuitive menu for schedules, settings, and current conditions shown brightly on its face. Beyond temperature control, other smart home essentials like alarms, lighting, door locks, and more leverage similar display concepts.

Interacting with devices becomes seamless using icon-driven touchscreens reminiscent of mobile phones. Physical controllers shrink while capabilities multiply. Even DIY appliances and fixtures enter the ‘smart’ era with sensor monitoring and preset options selected via built-in menus. Advanced features integrate disparate systems for sophisticated yet cohesive home experiences. All told, an LCD elevates any automation installation from set-it-and-forget-it to actively engaged.

Benefits of IoT Applications

When internet connectivity enters the picture, possibilities multiply further. Everything from environmental sensors and security cameras to thermostats, refrigerators, and fitness trackers stands to gain an LCD interface for IoT functionality. Remote access, firmware updates, usage insights – graphical displays convey data in accessible formats versus relying on serial terminals alone.

Learning thermodynamic processes becomes an engaging interactive simulation versus dry textbook readings. Parameters tune intuitively via sliders and physical controls instead of remembering complex multiline commands. Communities even share custom ‘sketches’ for Arduino and PIC microcontroller displays like online artwork repositories. Taken together, IoT breathes a new purpose into the simplest of embedded designs through open-ended connectivity.

Advanced Thermostat Functions

A smart thermostat enabled by a microcontroller and LCD could provide many more advanced features beyond basic temperature control. Integrated sensors would allow for ambient light, humidity, CO2 levels, and other environmental factors to be monitored and influence settings. Meanwhile, geofencing using a home’s WiFi could detect when occupants leave or return, automatically adjusting temperatures accordingly.

Voice control via Alexa, Siri, or Google Assistant brings simplicity to complex schedules. Spoken commands adjust the thermostat from anywhere instantly. Historical energy usage data analyzed over time also informs smarter settings proposals to the user through the LCD interface. Patterns are found between external conditions, system runtimes, and individual comfort preferences to progressively offer finer-tuned efficiency.

Remote sensors around the home enhance zone-based temperature management as well. Bedrooms upstairs may need slightly warmer nights versus the main floor for optimal comfort all around. With an LCD at the thermostat plus remote sensor readouts on a phone app, more tailored comfort is achievable. Advanced thermostats truly improve the quality of life right in users’ own homes.

Real-World Examples

To better visualize where this interface leads, let’s explore some real product implementations.

Smart Thermostat

The Sensi touchscreen thermostat brings modern HVAC control to any home. Its PIC microcontroller pairs with LCD to show schedules, historical energy usage, geofencing integrations, and more through an elegant menu structure.

Environmental Sensor

The Blom soil moisture monitor tracks conditions for optimal indoor plant care. Its LCD-guided setup fosters an understanding of hydroponic principles through interactive calibration.

Security System

The SimpliSafe alarm combines PIR sensors with an LCD keypad to arm, disarm, and view camera pre-roll directly from the wall mount control center.

Smart Display

Raspberry Pi-powered MagicMirror transforms any mirror surface into a glanceable heads-up display using an HD44780 controller and customizable modules.

Beyond prototyping, innovative companies increasingly leverage PIC–LCD building blocks for polished consumer offerings. Their success reflects how even humble components when combined creatively, inspire technology to improve lives worldwide. Understanding this starting point fosters such progress.

IoT Garden Monitoring

A backyard weather station combining sensors, microcontroller, and LCD presents a fun educational project. Temperature, humidity, rainfall, UV index, and more environmental readings populate dynamic graphs on the display over time. Notifications of approaching storms or extreme heat warnings help care for plants appropriately.

Integrating with supplementary sensors allows comprehensive hydroponic or soil analysis as well. pH, EC, and nutrient levels guide hydroponic dosing amounts to optimal ranges viewable on the station’s LCD. Automated watering and fertigation schedules activate via relays based on real-time hydration needs. External solar panels ensure truly wireless, off-grid operation nurturing the garden seamlessly. All measurement data logs to an online database for analyzing seasonal trends.

Smart Agriculture Applications

Monitoring conditions critical to crop yields taps the strengths of microcontroller and LCD-based systems. Sensor networks across fields track moisture, nutrients, pests, and more, with readings centralized on an LCD interface. Historical comparisons aid proactive management like adjustable irrigation based on rainfall predictions.

Drones capture hyperlocal aerial imagery analyzed by computer vision to automatically detect diseased plant clusters or nutrient deficiencies down to the square foot. Targeted treatments minimize waste while maximizing outputs. RFID-chipped seeds, plus growth stage cameras autonomously measure and report individual plant maturity for optimizing harvest schedules.

Livestock systems benefit as well through interconnected enclosures. Automated feeders provision tailored rations adjusted by weight sensors. If illness in one is detected by abnormal vitals, isolation, and early treatment prevent disease spread across herds. Thermal cameras detect heat anomalies indicating distress, bruising, or injury from a centralized monitoring station.

Makerspaces and Education

Microcontroller prototyping platforms foster hands-on learning beyond traditional textbooks. Community maker spaces provide equipment for joint projects while guide curriculum explores programming fundamentals through physical computing.

Motion sensors trigger LCD animations teaching core concepts simply. Light-sensitive plant growth simulations visualize photosynthesis. Automated data logging stations record experimental variables over weeks. Tactile construction and troubleshooting build rapid intuition versus simulation alone.

Curricula extend to all ages and abilities through accessible goals and an iterative design process. Early electronics spark STEM interests that last lifetimes. With remote pandemic schooling emphasizing experiential lessons came new importance for these resources sparking engagement remotely too. Once daunting circuits become approachable tools for communities everywhere.

Smart Building Integration

Comprehensive automation emerges from seamless control system integration. Microcontrollers read the temperature, light, and occupancy throughout structures, controlling HVAC, shades, and more centrally for comfort and efficiency. Touchscreen interfaces keep settings easily personalized.

Intercom stations double as emergency panic buttons are answered immediately for worker safety assurance. Asset tracking tags allow locating any inventory on sprawling campuses in an instant whether warehouse shipping or hospital equipment. Motion-triggered security cameras live stream to guard stations and apps for ultra-convenience. Connected access control bolsters authentication with no touch.

Open platforms foster bespoke IoT devices tailored exactly to facility needs. All streamline sophisticated yet intuitive operations empowering any space – whether corporate campus, university district, or bustling downtown – to reach its full potential sustainably.

Printing to the Display

With initialization complete, it’s now possible to send character data through the microcontroller’s I/O port pins to the LCD. Since ASCII codes represent characters, passing them to our display writing function is straightforward. And because the LCD reads 4-bit nibbles twice per byte, a small delay between nibbles ensures reliable reception of each character on screen. From here, projects can populate the display dynamically based on sensor readings, menu navigation, or whatever else the application requires.

Prototyping Platform

For beginners exploring embedded systems design, a development board centered around easily programmable microcontrollers like PIC and interfacing peripherals empowers creativity. Built-in headers break out MCU pins conveniently while on-board components handle power regulation, debugging, and more.

LCD modules connect for interactive input/output without complicated wiring. Sensors, antennas, buttons, and other I/O expand functionality. Well-documented code libraries simplify common tasks so users focus on their unique applications. Online communities share custom “sketches”, and version control revisions and collaborate on open-source projects. Such platforms foster exploration that moves embedded design forward.


In closing, interfacing an HD44780 LCD with a PIC18F4520 microcontroller provides an affordably capable foundation for diverse applications. Menu-driven interfaces elevate everything from industrial machinery to home appliances when paired with a microcontroller’s logic and I/O abilities. Projects enter new spheres through graphical representations of complex processes on an LCD screen. Areas like home automation and IoT especially benefit, bridging the digital and physical worlds through interactive touch displays. With continued exploration of creative implementations, exciting innovations are sure to emerge from this simple yet powerful microcontroller-LCD combination.

Source Code:

#include <p18cxx.h> #include <string.h> #include <stdio.h>

#pragma config WDT=OFF long int count;
char c; //Character to be printed to LCD

#define LCD_D4 PORTDbits.RD0 #define LCD_D5 PORTDbits.RD1 #define LCD_D6 PORTDbits.RD2 #define LCD_D7 PORTDbits.RD3 #define LCD_EN PORTDbits.RD4 #define LCD_RS PORTDbits.RD5

// Functions
void LCD_Init ( void );
void LCD_SetPosition ( unsigned int c ); void LCD_PutCmd ( unsigned int c ); void LCD_PulseEnable ( void );
void delay(void);
void upper (unsigned int c); void lower(unsigned int c);
void LCD_PutChar ( unsigned int c );

void LCD_Init ( void ) //Initialize display
PORTD = 0; TRISD = 0x00;
delay (); /* wait enough time after Vdd rise */ delay ();
delay ();
delay(); LCD_RS =0 ; PORTD = 0x03;
LCD_PulseEnable(); delay (); LCD_PulseEnable(); delay (); LCD_PulseEnable();
PORTD = 0x02 ; /* set 4-bit interface */ LCD_PulseEnable();
LCD_PutCmd ( 0x2C ); /* function set (all lines, 5x7 characters) */ LCD_PutCmd ( 0x0C ); /* display ON, cursor off, no blink */ LCD_PutCmd ( 0x01 ); /* clear display */
LCD_PutCmd ( 0x06 ); /* entry mode set, increment & scroll left */
void LCD_SetPosition ( unsigned int c )
/* this subroutine works specifically for 4-bit Port A */ upper ( c | 0x08 );

LCD_PulseEnable(); lower ( c ); LCD_PulseEnable();

void LCD_PutCmd ( unsigned int c )
/* this subroutine works specifically for 4-bit Port A */ upper ( c ); /* send high nibble */ LCD_PulseEnable();
lower ( c ); /* send low nibble */ LCD_PulseEnable();

void LCD_PulseEnable ( void )
LCD_EN = 1;
delay(); // was 10 LCD_EN =0;
delay(); // was 5

void delay(void)
for(count = 1; count < 10000; count++);
void upper (unsigned int c)
if(c & 0x80) LCD_D7=1; else LCD_D7=0; if(c & 0x40) LCD_D6=1; else LCD_D6=0; if(c & 0x20) LCD_D5=1; else LCD_D5=0; if(c & 0x10) LCD_D4=1; else LCD_D4=0;

void lower(unsigned int c)
if(c & 0x08) LCD_D7=1; else LCD_D7=0; if(c & 0x04) LCD_D6=1; else LCD_D6=0; if(c & 0x02) LCD_D5=1; else LCD_D5=0; if(c & 0x01) LCD_D4=1; else LCD_D4=0;

void LCD_PutChar ( unsigned int c )
/* this subroutine works specifically for 4-bit Port A */

LCD_RS =1;
upper ( c ); /* send high nibble */ LCD_PulseEnable();
lower ( c ); /* send low nibble */ LCD_PulseEnable();
LCD_RS =0;



About The Author

Ibrar Ayyub

I am an experienced technical writer holding a Master's degree in computer science from BZU Multan, Pakistan University. With a background spanning various industries, particularly in home automation and engineering, I have honed my skills in crafting clear and concise content. Proficient in leveraging infographics and diagrams, I strive to simplify complex concepts for readers. My strength lies in thorough research and presenting information in a structured and logical format.

Follow Us:

Leave a Comment

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.