The One File That Didn't Belong on Amazon
I open sourced a hardware project. Then I realised the book explaining it was the only part still locked behind a paywall.
The hardware files were already on GitHub under CERN Open Hardware Licence. The firmware was MIT. The PCB design was OSHWA certified — UK000086, publicly verified. Everything that made the project was already open, except the book. And it was hurting my soul. It didn't fit the spectrum, neither the Spectrum One.
I could have kept the print edition on Amazon and only pulled the digital. But this wasn't about format.
I dislike Amazon. Not as a shop — as a machine. A company that dictates terms to the world, monopolises markets, replaces workers with robots, and invests the cut you give them into making more people redundant. Something about that isn't right, and I didn't want to carry it with me. So I pulled everything. Digital and print. All editions. The KDP account can collect dust.
I love holding a printed book. It's one of those things I don't want to lose in my life. But I don't know how to solve this without print-on-demand, and I'm not going back there. So for now, remains digital only.
I need to pay bills like everyone else. But no one has ever been able to bribe me into anything. The book is free. If it helps you and you want to give something back — there's a donation option and a membership on the homepage.
What the book covers
Most of the book lives on the breadboard. That's where the decisions were made, the wiring was tested, and the behaviour was understood. The PCB came after, built directly from that prototype. Nothing is cleaned up or idealised — the design is presented as it developed, including the constraints and trade-offs that shaped it.
What the last chapter opens up
Strip the WiFi firmware away and the hardware is still a complete instrument. An ESP32, a 16×2 LCD, a 10-segment LED bar, and a single button. That same pattern has existed in test equipment and lab instruments for decades. The final chapter explores what else the platform can become — counters, timers, environmental observers, tools for learning embedded systems. Not a roadmap. Just proof that the hardware doesn't end where the WiFi story does.
Where everything lives
The book is a free download in PDF and EPUB, licensed CC BY-NC-SA 4.0.
Download and project page — https://currenari.com/spectrum-one
The hardware files, firmware source, schematics, and assembly docs are all on GitHub. The hardware is CERN-OHL-S-2.0. The firmware is MIT.
GitHub — https://github.com/currenari/spectrum-one
What comes next
My plan is to take it further and expand it. Version 0.2.0 will open up more GPIO access and add connectors for external components — sensors, inputs, whatever the project calls for. The work has already begun, at least in my mind.
The project is open. Fork it, adapt it, take it somewhere nobody expected.