Tindie’s blog rounded up three open-source KiCad hardware projects worth knowing about this week — none finished products, all with real schematics and PCB layouts published on GitHub for anyone who wants to build, fork, or just learn from them.
NeoCalculator Rev A: a handheld calculator you can build
The most immediately fun of the three is NeoCalculator, built by El-EnderJ around an ESP32-S3, a 50-key matrix, and a display connector, with lithium-ion charging and power circuitry handled on-board. It’s explicitly alpha hardware — the designer is asking people to hold off ordering PCBs or printing the enclosure until the design settles further. For anyone who’s wanted a hackable calculator platform rather than a locked-down graphing calculator, this is the kind of project worth bookmarking and revisiting once it stabilizes.
IV-DCY: a USB reference design stripped to essentials
hkr-ypt’s IV-DCY is a more utilitarian board: a compact USB reference design around an STM32F042, with USB-C, ESD protection, a boot button, and an SWD header. Its firmware provides a virtual serial port. It’s the kind of small, well-documented reference design that’s genuinely useful as a starting point for a custom USB device — the sort of board you fork rather than admire.
Cardea Key: an early, unaudited security-key concept
The most speculative of the three is shosoin’s Cardea Key, pairing an RP2354A microcontroller with an NXP SE051C2 secure element, with connections for an external fingerprint sensor. The project’s own documentation is upfront about its status: the PCB is only a placement draft, not routed or validated, and the firmware is experimental and unaudited. Worth watching as an idea, not yet worth trusting with anything security-sensitive.
Why this matters beyond the three boards
All three publish full KiCad schematics and PCB files, which is the real value of a roundup like this for a maker audience — not polished products, but inspectable, forkable starting points at exactly the early stage where community feedback is most useful.