Andy Warburton's GR3ML1N Is a Handheld Espressif ESP32 Cyberdeck You Can Build Yourself

Maker Andy Warburton has turned an Espressif ESP32 microcontroller into a handheld, wide-format, pocket-friendly cyberdeck "built for chaos:" the GR3ML1N.

"I've built a few cyberdecks over the years. Pelican case jobs mostly, the kind that look great on a desk but are a pain to actually use in the wild. Too bulky, awkward power setups, not really something you'd pull out in a coffee shop without feeling like you're assembling a field operations kit," Warburton explains by way of background to the project. "The idea was simple: all of the fun, none of the bulk. Something genuinely handheld that I could use without a desk, whip out anywhere and not feel ridiculous doing it."

A self-described "child of the '80s" who was raised on a diet of media like Blade Runner, WarGames, and Tron, Warburton took inspiration for the build from the Gremlins franchise. "Small," he explains, "mischievous, a little bit dangerous and absolutely not to be trusted around water after midnight. After about a month of tinkering and an absolutely unreasonable number of test prints, here we are."

The heart of the GR3ML1N is a WaveShare ESP32-S3 2.8" Display Development Board, which combines a 2.8" 240×320 full-color LCD panel with Espressif's ESP32-S3 dual-core Tensilica Xtensa LX7 wireless microcontroller — picked, Warburton explains, over a more powerful single-board computer like the Raspberry Pi Zero for rapid boot time and low power draw. The display and microcontroller combo sits in the middle of a 3D-printed handheld case, between the keys of a hand-wired compact keyboard based on tactile non-keyboard-specific switches to keep the size down. This, in turn, is wired to a Waveshare RP2040 Zero, a compact development board built around Raspberry Pi's dual-core in-house RP2040 microcontroller.

"The whole thing runs off a single 18650 [lithium] cell," Warburton says of the gadget's remaining hardware, "and there are three USB-C ports: center for power, right for direct keyboard access, and left as a dedicated add-on port for snapping in custom expansion modules without pulling anything apart (currently wired to I2C)." The software is an in-house pseudo-operating system written in CircuitPython, with a modular design that can load applications dubbed "Gizmos" from microSD Card, including a text editor, chiptune keyboard, network clock, diagnostic tests, and scanners for Bluetooth Low Energy (BLE) and Wi-Fi connections."

Warburton details the project further on his website, with 3D-print files available on Printables under the Creative Commons Attribution-NonCommercial 4.0 International license; code is available on GitHub, but Warburton confesses that it's the product of a generative large-language model — about which he says "still feel[s] vaguely gross."