Arduino and GCBASIC: Control a Character LCD With Built-In Commands

If you have ever wired an LCD to an Arduino and fumbled through the LiquidCrystal library, GCBASIC offers a cleaner alternative. Chuck Hellebuyck, better known as CHEP from Filament Friday, posted a full breakdown of the built-in LCD commands available in the free GCBASIC compiler. The video is aimed at the 3D printing community, but the advice applies to any embedded project.

What GCBASIC Adds

GCBASIC is a free, open-source compiler for PIC and AVR microcontrollers. Unlike Arduino C++, which requires you to load a separate library and configure pin mappings manually, GCBASIC includes LCD support directly in the language. Built-in commands handle initialization, cursor positioning, character writing, custom character creation, and display control without extra header files.

The compiler targets the same hardware the 3D printing community already uses: ATmega328P on the Arduino Uno and Nano, ATmega2560 on the Mega, and most 8-bit AVR boards. If you can flash an Arduino sketch, you can compile GCBASIC code for the same chip.

Built-In LCD Commands Covered

Hellebuyck's video demonstrates every command the compiler exposes for character displays. The list includes basic text output, cursor control, display on/off toggling, cursor blinking, and custom character generation. The custom character workflow is the most useful part. GCBASIC stores character bitmaps directly in the source code as byte arrays, which mirrors the Arduino approach but with less boilerplate.

For 3D printer firmware tinkerers, this matters. Octoprint plugins, boot screens, filament runout detectors, and enclosure status displays all rely on character LCDs. GCBASIC compiles to smaller binaries than Arduino C++ for the same task, which matters when you are fitting firmware onto a board with limited flash space.

Getting Started

The GCBASIC compiler is free to download from the project website. Supported programmers include the PICkit 2 and 3, the AVR ISP mkII, and USBasp clones. Hellebuyck uses a Chipino module in the video, but the code compiles and runs on a standard Arduino Uno with no hardware changes.

If you want to experiment without buying hardware, the GCBASIC IDE includes a simulator that renders the LCD output on screen. That is a fast way to confirm your cursor math and custom characters before you ever connect a real display.

Why This Matters for the 3D Printing Community

Most 3D printer owners interact with firmware through the slicer or Octoprint. Few venture into the source. But firmware modifications are how you add boot logos, filament sensor warnings, temperature alarms, and custom status screens to printers that ship with locked-down stock firmware. GCBASIC lowers the entry point for those changes.

Hellebuyck has been posting electronics tutorials alongside his filament reviews for years. This one is a practical reference. The video is available on the Filament Friday YouTube channel, and the GCBASIC compiler is free to download.