reTerminal Sticky ePaper Runs Four Open Firmwares

One Panel, Four Personalities

The reTerminal Sticky is a 3.97-inch magnetic touch ePaper display built on an ESP32-S3, and what makes it worth writing about is not the hardware so much as the software situation around it. Four separate open-source firmware projects already target the device: Crosspoint for e-reader duty, TRMNL for live dashboards, and both ESPHome and OpenDisplay for Home Assistant integration. That is an unusual amount of community support for a device this new.

• 3.97-inch monochrome ePaper, 800 x 480 resolution with 4-level grayscale and touch input
• ESP32-S3R8 dual-core MCU up to 240 MHz, 8MB PSRAM, 32MB flash, microSD slot
• 106 x 65.5 x 7.3 mm and 70 grams, with a 750 mAh battery charged over USB-C and roughly 7 days average standby
• $49.90, with an early-bird price of $39.90 for the first 500 units; four open-source firmware projects supported so far

Why Four Firmwares Beats One Good One

A single vendor firmware forces the hardware into one job. Four community firmwares mean the same $50 panel is a different product depending on what you flash, and none of those products required Seeed to build them.

The four cover genuinely distinct use cases. Crosspoint turns it into a pocket e-reader, which the 235 PPI panel and microSD slot support well. TRMNL drives it as an always-on information dashboard — transit times, calendar, weather. ESPHome and OpenDisplay both wire it into Home Assistant, either as a status surface or a control panel. Buying one device and deciding later is a materially better proposition than buying the right device first time.

Does ePaper Make Sense for a Dashboard?

For this class of information, it is the correct display technology and it is not close. A dashboard showing your next train, today's meetings, and the indoor temperature changes a handful of times an hour. An LCD burns power continuously to hold that image; ePaper draws power only when the image changes.

That is what produces roughly a week of standby from a 750 mAh cell, and the week is what makes the form factor viable. A magnetic panel you charge every other day gets left on the charger. One you charge weekly stays on the fridge. The 4-level grayscale is a real constraint — no photos, no color coding — but for text and simple graphics it is enough, and readers of our mini computer coverage who followed the Xteink X4 Pro pocket eReader will recognize the tradeoff.

What Would You Actually Build With It?

The obvious one is a household information panel, and ESPHome makes that close to trivial if you already run Home Assistant — the display becomes another entity, and rendering is templated the same way as everything else on the network. Our low-power wireless MCU guide covers why the ESP32-S3 is a sensible base for that sort of always-connected, mostly-asleep device.

The less obvious one is a written-note surface. The touch layer plus 8MB of PSRAM is enough for jotting and re-rendering, which is what the "sticky" in the name is reaching for. Whether that beats a paper sticky note is a genuinely open question, and the answer probably depends on whether the note needs to be readable from another room or synced to a phone.

The Practical Notes

Wireless is Wi-Fi 4 and Bluetooth 5.0, which is the right call for a battery device that wakes up briefly to fetch a small payload — Wi-Fi 6 would add cost and radio complexity for nothing this device needs. Charging is USB-C at 5V/1A.

At $49.90 the value proposition rests on the firmware ecosystem rather than the bill of materials, and that is the healthier place for it to rest. Hardware that gets four community firmwares in its first months tends to keep getting them.

Sources: CNX Software — July 31, 2026; Seeed Studio — July 2026; Liliputing — July 2026.