Today we stopped talking about the crystal build as a future thing and put the first sensing circuit on the desk.
The piezos are glued to the discs. The Waveshare ESP32-S3 screen is the temporary hub. Its header gives us a practical little bridge between the physical discs and the POP software: one pin to drive the resonator, one pin to listen, and the screen waiting to show what the crystal tells us.
The breadboard now has the first conditioned sensing path: a protected ADC input, a biased signal node, and a separate drive path through a 10kΩ resistor. The objective is deliberately simple. We are not trying to power the hub from the piezos yet. We are trying to make the discs hum, measure their response, find their resonance profile, and then register that crystal on-chain and in the little POP hub.
The wiring is complete and has been checked. The next step is firmware: flash a small test mode that drives the disc around 403 Hz, reads the response, and reports the signal safely. The machine’s file-edit runner misbehaved before we could flash it, so the hardware is resting unplugged and the setup is recorded for the next session.
That is still a beginning. The disc is attached, the hub is waiting, and the first physical identity is almost ready to answer back.