December 7, 2025
Caffeine, code, and comment wars
Minimum Viable Arduino Project: Aeropress Timer
Coffee nerd’s 30‑sec timer ignites brew-time brawl, safety scolds, and 'use a cheap chip'
TLDR: A maker built a plug-in, 30‑second Aeropress timer with a buzzer and blinking light to dodge phone timer fumbles. Comments exploded over whether coffee needs 30 seconds or two minutes, whether the hardware is overkill or unsafe, and the classic 'just use a 555' jab.
Brian built a tiny, single‑purpose gadget: a 30‑second Aeropress timer with a shiny metal button, a chirping buzzer, and a blinking light, powered by USB. It’s based on an Adafruit Trinket M0 (a small Arduino‑like board), tucked into a 3D‑printed case after his laser cutter quit mid‑prototype. Simple, cute, and very caffeinated.
The comments? Absolute latte foam fight. One user asks, “Wait, 30 seconds?” while another drops the authority card: James Hoffmann says two minutes and shares a recipe. Cue the brew‑time civil war: speed‑pressers versus slow‑steepers. Then a classic hardware meme hits—someone just posts “555”, the old‑school timer chip, like it’s a holy text. Meanwhile, a safety scold warns that driving a buzzer straight from the board pin could toast it, turning “minimum viable” into “minimum survivable.”
Fans cheer the dedicated button because phone timers and voice assistants keep fumbling—Siri, we’re side‑eying you—while purists ask why not… a stopwatch. The blinky LED shining onto the counter gets dubbed “vibe light,” and everyone agrees the trill is polite, not panic‑alarm. Verdict from the crowd: adorable build, spicy debate, and proof that coffee people and hardware nerds will argue about literally everything. Grab popcorn, then pick your plunge time. And sip.
Key Points
- •A dedicated 30-second timer was built using an Adafruit Trinket M0, a button on Pin 0, and a piezo buzzer on Pin 1.
- •The enclosure was designed in OpenSCAD and 3D printed on an Ultimaker, after a laser-cut plan with Glowforge was dropped.
- •The device is USB-powered; battery power was avoided to reduce complexity (charging, deep sleep, and indicators).
- •Software uses delay-based timing, provides chirps at start/end, and blinks the NeoPixel LED each second.
- •PWM control of the buzzer was attempted but it behaved in a binary on/off manner; code was provided inline rather than on GitHub.