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Universal HD44780 LCD interface

March 29, 2023 by Dilshan Jayakody

This project provides a universal interface to drive the popular Hitachi HD44780 LCD controller. It offers open hardware module and C/C++ library for the HD44780 controller.

YALI (Yet Another LCD Interface) is an open-source project to provide a universal interface to drive the popular Hitachi HD44780 LCD controller. This module supports 3.3V and 5V MCUs and hardware development platforms, including Arduino, STM32, PIC, and ESP8266.

The hardware module of this project consists of a 74HCT08 CMOS AND gate and a 74HC595 8-bit serial-in, parallel-out shift register. This module uses the MP1540 step-up converter to power the LCD unit connected to the system. The module has the jumper to select 3.3V or 5V DC power input.

Bottom side of the YALI hardware module.

The YALI library is developed using C and is designed to be easily integrated with any C/C++ embedded toolchain. At the initial design stages, this library was successfully tested with all Arduino development boards, NodeMCU, STM32 Blue Pill, etc. The target system must have three digital output lines with 5V or 3.3V logic levels to interface with the YALI module. As mentioned earlier, this module works successfully with 5V or 3.3V power sources and logic levels.

The YALI library provides a unified API to control the HD44780 LCD controller. It has functions to handle cursor control, custom character loading, LCD backlight control, etc.

The PCBWay sponsored this project. PCBWay offers high-quality PCB manufacturing and assembling services. Also, they offer CNC and 3D printing services. The PCB of the YALI module is available to order from PCBWay. Check out the PCBWay website for its manufacturing capabilities and pricing.

YALI hardware module with Standard 1602 LCD display.

The dimensions of the YALI hardware module are 69mm × 21mm. This module is designed using SMD components and can be connected directly to the LCD unit.

This project is an open-source hardware project. All its design files, BOM, schematics, and firmware source codes are available at

The PCB design, schematic, and other design files of this project are covered with a Attribution-ShareAlike 4.0 International license. The library source code is released under the terms of the MIT license.

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