The Open Book (DIY e-reader)

Joey Castillo’s open-source DIY e-reader, running since late 2019 and recently reworked for easier assembly: a Raspberry Pi Pico at the centre, a GDEW042T2 grayscale e-paper display, a custom main PCB plus an e-paper driver module, AAA cells, microSD, flash, and buttons. Deliberately low part count so it can be hand-soldered, with fab files ready for JLCPCB or PCBWay. The firmware, libros, renders plain-text books off the SD card. Per-component licensing. Parked in the hub _inbox on 2026-07-14 under open-hardware; migrated here at the spin-out.

The device is an argument

Castillo’s stated position is that people should control their own reading devices rather than depend on proprietary platforms — a right-to-read stance expressed as a schematic. That makes this the spoke’s clearest instance of open-hardware as a political project rather than a licensing choice: the design is published so the object can be rebuilt, repaired, and modified by whoever holds it, which is precisely what a commercial e-reader forecloses.

Why it belongs beside a metrology MCU and an x86 SBC

It’s the same field seen from the finished-object end. The Pico is an MCU board — the same layer as the Nuvoton part, one rung of integration up — and everything above it is the constraint work embedded-systems describes: a display chosen because e-paper holds an image without power, AAA cells because a coin cell won’t drive a refresh, a part count chosen for a soldering iron rather than a pick-and-place. The awesome-iot catalog lists both the Pico and the ESP32-based DIY platforms this sits among.

Note what it doesn’t do: no radio, no cloud, no protocol stack. It’s an embedded device that is emphatically not an IoT device, which is a useful boundary marker for a spoke holding both words in its name.

Tier

T3 — a project README for a hobbyist hardware design. Self-described, no production data, no independent build reports collected here. Its value is as an artifact of the open-hardware practice rather than as a specification.

Related

open-hardware · microcontroller · embedded-systems · awesome-iot · synthesis