ESP32 Rainbow QA - A tale of three boards We’ve shipped a few hundred ESP32 Rainbow boards-most are perfect - but a few failed QA. Here’s how we tracked down and fixed three real-world faults: no sound from lifted headphone jack pads, USB not enumerating due to a mis-seated ESD IC pin, and a flaky touch keyboard from poor ESP32 module joints. A bit of microscope work and reflow brought two boards back to life (one’s now a donor), and it’s a great reminder why we do final assembly and full QA here in Scotland. 02 January 2026
1 touch pin 8 touch pads To make my ESP32 ZX Spectrum touch keyboard work even better, I needed to ensure every key was independent. The ESP32-S3 only has 14 touch pins, so I’ve been using a matrix approach. While this works well, it struggles with key combinations, critical for the ZX Spectrum. I explored touch detection and experimented with analog multiplexer ICs (4051 series) to expand the touch pins. Initial tests were promising. After prototyping with breadboard-friendly versions and ordering parts, the new keyboard was not only functional but exceeded my expectations. Scanning the keyboard now takes around 20ms, and the solution is ready for... 28 July 2024