Update (10/10/2022): Joey Castillo has shown off a few more features of the Open Book Abridged Edition, including support for the Raspberry Pi Pico W — "which means, I regret to inform you, that despite my best efforts the book can have Wi-Fi," Castillo jokes.
"[It also has] two STEMMA ports for accessories. Here it’s a pot controlling an LED reading light, but imagine a mic for voice commands, or a foot pedal for accessibility. This is the vision."
A video demonstrating the STEMMA QT ports in action is available on Castillo's Twitter thread.
The original article continues below.
Oddly Specific Objects' Joey Castillo is officially rebooting the Open Book project, retiring the Adafruit Feather-compatible original design in favor of a new board, which hosts a Raspberry Pi Pico instead: the Open Book Abridged Edition.
"The Open Book was my first real electronics project; the earliest designs date to late 2019. I have learned a lot since those early days, and as such, here three years later, I am hitting reset," Castillo explains. "This [new] version of the book is the quickest path to getting hardware in people's hands so that we can start hacking on firmware together."
Castillo unveiled the Open Book project three years ago, initially building the design as an oversized carrier board for Adafruit Feather-compatible microcontroller boards. The full-size design was followed by the ultra-compact Tiny Book, which replaced the 4.2" ePaper display of its predecessor with a compact 2.7" equivalent — but the new Raspberry Pi Pico-powered variant represents a complete redesign.
The redesigned open-hardware eReader uses a 4.2" four-gray ePaper display chosen for its low cost, driven by the popular Raspberry Pi Pico's RP2040 dual-core microcontroller. The design takes a two-module approach: the Open Book Main Board holds the microcontroller, display, controls, external flash, and power, and is designed to be manufactured as a bare PCB for hand population and assembly; the Castellated E-Paper Driver, meanwhile, is a compact custom driver board for the ePaper display which Castillo advises should be populated and assembled at the factory owing to challenging surface-mount parts.
While older Open Book designs used lithium batteries, the new Open Book Abridged Edition goes in a different direction — packing a pair of triple-A alkaline or rechargeable batteries at the rear. "It's optimized for low part count and easy hand assembly," Castillo explains, "and may not be as svelte as some folks might prefer. At a later date, I hope to design a follow-up with built-in LiPo charging and a slimmer profile."
As with other models in the Open Book project, the new design is open source — and ready for hacking, using a firmware dubbed "libros," which Castillo warns is "a goddamn mess in some ways, and in dire need of documentation, but for the moment […] does the job of presenting a list of books stored on an SD Card and letting you read them."
The hardware design files for the new Open Book Abridged Edition are available on the project's rebooted GitHub repository under the reciprocal Creative Commons Attribution-ShareAlike 4.0 International license; the firmware is under development in a separate repository under an unspecified license.