Joey Castillo’s Open Book reboot is a new open-hardware e-reader revision built around a Raspberry Pi Pico—not a refresh of the original SAMD51 design. Its priorities are a low component count and hand assembly, with documented firmware that can list and read books from an SD card. It is a build-it-yourself project, and its firmware remains under development.
What changed in the Pico reboot
The creator’s repository calls this revision “The Open Book: Project Reboot” and centers it on a Raspberry Pi Pico. Castillo says the design was reset after lessons from his first electronics project, with the new version optimized for fewer parts and easier hand assembly. That accessibility comes with a form-factor tradeoff: it uses AAA batteries and may be thicker than some readers would prefer. No battery-runtime measurement is stated.
The earlier Open Book was a separate 2019 design based on a SAMD51J19A microcontroller and a Feather-compatible architecture. Its documentation described a broader set of ambitions, including audio, multilingual language data, microSD storage and Feather expansion. Those features should not be assumed to apply to the Pico reboot. Castillo says the original won Hackaday’s Take Flight with Feather contest in early 2020, but the planned manufacturing run with Adafruit did not happen. Castillo’s history of the original Open Book Project describes that earlier concept and platform.
What you need to build the reboot
This is not a ready-made consumer e-reader: the documented build requires custom boards and electronics assembly. The repository names the main-board fabrication file and a castellated e-paper driver module, alongside the following parts:
#1 Best Overall
- RP2040 microcontroller chip designed by Raspberry Pi in the United Kingdom
- Dual-core Arm Cortex M0+ processor, flexible clock running up to 133 MHz
- 264KB of SRAM, and 2MB of on-board Flash memory
- Castellated module allows soldering direct to carrier boards
- 26 × multi-function GPIO pins
- One Raspberry Pi Pico board.
- One GDEW042T2 grayscale e-paper display. The repository specifically warns builders not to buy the tri-color version.
- Seven through-hole slim tactile buttons, 3 mm by 6 mm, TL1107 type.
- One 1µF capacitor with an 0805 footprint and a voltage rating of at least 6.3V.
- One custom Open Book main board and one castellated e-paper driver module.
Custom board fabrication
The repository specifies a two-layer, 1 mm-thick main board. It documents two e-paper driver versions and says one was successfully fabricated through JLCPCB’s economic PCBA service and another through PCBWay’s PCBA service. These are prior documented fabrication routes, not confirmation of current service availability, pricing or turnaround times. The project repository contains the board files, component list and assembly details.
Plan for soldering and board assembly rather than assuming the parts arrive as a finished reader. Castillo’s Open Book Documentation wiki includes soldering strategies and assembly guidance.
Rank #2
- The Raspberry Pi Pico is a beginner-friendly microcontroller board that uses MicroPython to give you a taste of the Internet of Things and microcontrollers. The RP2040 is a well-designed microprocessor that can be utilized in almost any Internet of Things project. It has enough power to complete the task quickly.
- 【Raspberry Pi RP2040 Microcontroller】Raspberry Pi Pico features Dual-core ARM Cortex M0+ processor, flexible clock running up to 133 MHz. With 264KB of SRAM, and 2MB of on-board Flash memory.Supports up to 16 MB of off chip flash memory via a dedicated QSPI bus
- 【Multiple Software Support】Pico has rich and complete software support, it comes with a complete Rasberry Pi official C/C++ SDK, Micropython SDK.The programming and burning of Pico need to be carried out on the computer. Supported operating systems and computers include:Raspberry Pie with Raspberry Pi OS,Other platforms equipped with Debian based Linux system Computer with MacOS, Computers with Windows, etc.
- 【Rich Hardware Interface】Raspberry Pi Pico has 30 GPIO pins, 4 pins for analog signal input and 26 × multi-function GPIO pins, 2 × SPI, 2 × I2C, 2 × UART, 3 × 12-bit ADC, 16 × controllable PWM channels.USB 1.1 supported by host and device, The installation mode can be flexibly selected by users to facilitate welding with other development boards.
- 【Build Project in Tiny Size】Only 2.1cm*5.1cm ( as small as your thumb). Pico has been designed to use either soldered 0.1" pin-headers or can be used as a surface-mountable 'module'.
What the firmware can do—and what is still in progress
The repository calls the firmware “libros” and says it remains under development. Its documented basic workflow is to show a list of books stored on an SD card and let the reader open and read them. The canonical book format is plain text with the title on the first line; optional front matter and ASCII control codes can provide chapter breaks and formatting.
The project materials do not establish a complete, finished e-reader feature set for this revision. In particular, do not carry over capabilities described for the original SAMD51 project—such as audio or its broader multilingual and expansion ambitions—as specifications of the Pico build.
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Rank #3
- with pre-soldered header Raspberry Pi Pico. RP2040 microcontroller chip designed by Raspberry Pi in the United Kingdom
- Dual-core Arm Cortex M0+ processor, flexible clock running up to 133 MHz. 264KB of SRAM, and 2MB of on-board Flash memory.
- Castellated module allows soldering direct to carrier boards. USB 1.1 with device and host support. Low-power sleep and dormant modes. Drag-and-drop programming using mass storage over USB. 26 × multi-function GPIO pins.
- 2 × SPI, 2 × I2C, 2 × UART, 3 × 12-bit ADC, 16 × controllable PWM channels.Accurate clock and timer on-chip.Temperature sensor.
- Accelerated floating-point libraries on-chip.8 × Programmable I/O (PIO) state machines for custom peripheral support
How to distinguish it from other Open Book projects
Castillo’s project index separately lists the 2019 Open Book Project and a 2026 entry called Open Book Touch, described there as a pocketable, front-lit open-source e-reader. The available project descriptions do not establish that Open Book Touch is the same device as this Pico reboot, so they should not be treated as interchangeable names or as a direct hardware comparison. Castillo’s Objects index lists the projects separately.
The reboot’s current hardware choices, assembly emphasis and documented reading workflow are the clearest way to identify it: Pico-based, assembled from custom boards and components, and built around reading text files from an SD card. There is no stated cost, performance benchmark or battery-life figure for this revision.
Quick Recap
Best Value
- Raspberry Pi Pico: A tiny, fast, and versatile board built using dual-core Arm Cortex-M0+ processor (Comes with pinout card and stickers)
- Detailed Tutorial: Provides step-by-step guide with MicroPython, C and Processing (Java) Code (The download link can be found on the product box) (No paper tutorial)
- Example Projects: Each project has schematics, wiring diagrams, complete code and detailed explanations (Need extra items)
- Easy to Use: Just connect the board to your computer (installed IDE) with the USB cable to program it
- Get Support: Our technical support team is always ready to answer your questions
Rank #4
- New Flexible Microcontroller Board --- Raspberry Pi Pico is a tiny, fast, and versatile board. It's based on RP2040 chip, which features a dual-core Arm Cortex-M0+ processor with 264KB internal RAM and support for up to 16MB of off-chip Flash, flexible clock running up to 133 MHz.
- Multi-Function GPIO Pins---It has 26 multifunction GPIO pins, including 3 analogue inputs, 2 × UART, 2 × SPI controllers, 2 × I2C controllers, 16 × PWM channels.
- Rich Peripheral Set---A wide range of flexible I/O options includes I2C, SPI, and — uniquely —8 × Programmable I/O (PIO) state machines for custom peripheral support.
- Multiple Software Support---Raspberry Pi Pico has rich and complete software support and community resources. Programmable in C and MicroPython. Drag-and-drop programming using mass storage over USB.
- Low-power sleep and dormant modes; Accurate on-chip clock; Temperature sensor; Accelerated integer and floating-point libraries on-chip
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