ESP32 Powers Single-PCB ZX Spectrum Emulator

When word first got out that the Chinese board houses were experimenting with full color silkscreens, many in our community thought it would be a boon for PCB art. Others believed it would be akin to cheating by removing the inherent limitations of the medium. That’s not a debate that will be solved today, but here we have an example of a project that’s not only making practical application of the technology, but one that arguably couldn’t exist in its current form without it: a single-PCB ZX Spectrum emulator developed by [atomic14].

There basics here are, well, they’re pretty basic. You’ve got an ESP32-S3, a TFT display, a micro SD slot, and the handful of passives necessary to tie them all together. What makes this project stand out is the keyboard, which has been integrated directly into the PCB thanks to the fourteen pins on the ESP32-S3 that can be used as touch sensor input channels. There are issues with detecting simultaneous keypresses, but overall it seems to work pretty well.

The keyboard matrix takes 13 of the 14 touch input pins on the ESP32-S3.

But what makes the keyboard really special is that [atomic14] has used the color silkscreen capability to put all the necessary labels directly onto the keys. Technically this could have been done using a traditional single color silkscreen, but it would have been a hell of a lot harder to fit all the necessary information on there while keeping it readable. Plus, you’d miss the little rainbow in the corner.

As good as it looks already, the project is still in the early stages of development. Some components, such as the TFT display, still need to be better integrated into the board. In terms of software, the board is running a ZX Spectrum emulator that [atomic14] developed previously. Judging by the gameplay in the video below, it’s doing a solid job of bringing this classic system (and its games) back to life.

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