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
PDM Microphone Mystery I was puzzled that ESP-IDF’s PDM I2S config has no LR pin—until I actually read the mic’s datasheet. On PDM mics, LR isn’t a word-select clock at all; it picks which clock edge the mic drives and tri-states on the opposite edge. Tie one mic’s LR low and the other high and both share the same data line for stereo—no extra GPIO needed. I scoped it with some nice pogo probes to confirm, and it matches the timing diagrams perfectly. Net win: one fewer pin in the next design. 10 October 2025