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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

ESP32-S3 USB UAC

I turned my new ESP32‑S3 board into a USB Audio device. After a ninja LED fix and confirming the IMU and charging, I streamed mic audio over Web Serial (with a slick AI-made ‘Audio Studio’) and then via USB UAC. The mic sounds great, but the speaker is crackly over UAC—even though I2S WAV playback is perfectly clean. ESP-IDF worked; Arduino didn’t. Bonus annoyance: macOS vs Windows is a toggle, not a combo. Still, this board passes QA.
26 September 2025
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