The Timegrapher HAT is the carrier PCB for the Timegrapher Studio wristwatch timegrapher. It mates with the Waveshare ESP32-S3-Touch-LCD-3.5 dev board via its 2×16 (J8) expansion header and carries the two things the timegrapher needs that the base board doesn’t provide cleanly:
- a ±2 ppm DS3231SN TCXO as the timing reference (the onboard PCF85063 is only ±20–50 ppm — inadequate as the discipline source), and
- a PCM1808 24-bit I²S ADC for the escapement audio (a dedicated line-level ADC; the onboard codec’s mic input isn’t broken out to a header).
Signal chain
piezo → preamp (at the sensor) → 3-pin shielded lead → AUDIO_IN → PCM1808 → I²S → ESP32-S3
The piezo preamp lives off-board, right at the pickup, and feeds the carrier through a short shielded 3-conductor lead — keeping the amplifier at the high-impedance source is the single biggest SNR win.
Build approach
A discrete, fab-assembled (JLCPCB PCBA) 2-layer board with the DS3231SN and PCM1808 placed as bare ICs and only the support parts the timegrapher actually uses — a single low-profile board not much bigger than the J8 footprint.
See DESIGN.md and BOM.md in the repository for the full design notes and bill of
materials, and bench_module_wiring.md for breadboard bring-up before the HAT is
fabricated.
License
Released under CC BY-NC-SA 4.0.
