Welcome to the STM32 Keypad-LCD Interface project! This repository demonstrates how to interface a 4x4 matrix keypad with a 16x2 Character LCD using the STM32F103C6 microcontroller.
Whether you're building a calculator, a security system, or just learning the ropes of GPIO polling and 4-bit LCD communication, this project serves as a solid foundation.
The goal of this project is to create a seamless user input interface. The system polls a 4x4 matrix keypad and instantly reflects the pressed keys onto a 16x2 LCD display. It handles debouncing and includes a specific "Clear" function to reset the display, providing a smooth user experience.
Microcontroller: STM32F103C6 (ARM Cortex-M3)
Display: 16x2 Character LCD (LM016L)
Input: 4x4 Matrix Keypad
Others: 10kΩ Potentiometer , 8MHz Crystal, and decoupling capacitors.
4-Bit LCD Control: Optimized pin usage by driving the LCD in 4-bit mode rather than 8-bit.
Keypad Polling & Debouncing: A robust scanning algorithm that identifies key presses and releases while filtering out mechanical noise.
Custom Commands: Implemented a special 'C' key function that clears the screen and resets the cursor position.
Modular Code: The project is organized into dedicated drivers (lcd.c/h and keypad.c/h), making it easy to port these libraries to other STM32 projects.
Keypad: Connected to GPIOA. Rows are configured as Outputs, and Columns are configured as Inputs with Pull-Up resistors.
LCD: Connected to GPIOB. Control pins (RS, EN) and Data pins (D4-D7) are mapped to facilitate 4-bit communication.
To help with the hardware setup, here is the schematic designed and tested in Proteus. This shows the specific pin mapping for the STM32F103C6, the LCD's 4-bit connection, and the keypad matrix.
Note: Ensure the 10k pull-up resistors on the keypad columns and the contrast potentiometer (RV2) for the LCD are connected as shown to ensure reliable operation.
Create the Proteus project and point the STM32 component to the .hex file in the assets folder to see it in action!
I built this project to explore embedded I/O interfacing, and I’d love to hear your thoughts!
Found a bug? Open an Issue.