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Me Here 367951c903 PM_K-1 hardware: SIG/CLIP indicator + monitor speaker amp (both DNP) 
indicator.py: peak-detect (Schottky+RC) on STAGE1_OUT (signal-present) and MIX_OUT (clip)
-> LM393 (powered from +15V) vs tunable threshold dividers -> open-collector outputs pulled
to +3V3 = SIG_LED/CLIP_LED (drive face LEDs + read on GPIO19/20).
speaker.py: PAM8302A filterless class-D (pinout verified, Diodes SO-8) fed from MIX_OUT
(single-ended, RIN=68k -> ~+5.7dB), SD pulled high, BTL out -> SPK_P/SPK_N.
Both ERC 0 errors; netlists 0 errors. Threshold/gain values tunable; DNP per form factor.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
2026-05-30 23:49:18 -05:00
..
circuits PM_K-1 hardware: SIG/CLIP indicator + monitor speaker amp (both DNP) 2026-05-30 23:49:18 -05:00
sim PM_K-1 hardware: Stage 4 -- balanced output driver (completes the audio chain) 2026-05-30 20:27:04 -05:00
Containerfile PM_K-1 hardware: Stage 1 input receiver as SKiDL (code-defined schematic) 2026-05-30 19:43:07 -05:00
README.md PM_K-1 hardware: reproducible EDA container (KiCad 9 + ngspice) 2026-05-30 19:17:54 -05:00
run.sh PM_K-1 hardware: reproducible EDA container (KiCad 9 + ngspice) 2026-05-30 19:17:54 -05:00

README.md

PM_K-1 EDA environment

A reproducible container with the tools to design, check, and simulate the core board — so the work doesn't depend on whatever happens to be installed on a given machine, now or in 50 years.

What's inside

  • KiCad 9 — schematic capture + PCB layout, and a CLI (kicad-cli) that can run ERC (Electrical Rules Check) and DRC, and export netlists/PDF/Gerbers.
  • ngspice — SPICE simulator for validating the analog audio circuits before we commit copper (op-amp stages, filters, input loading, etc.).
  • python3 — scripting, BOM munging, optional code-defined-schematic helpers.

Why a container?

The system KiCad here is 7.0, whose CLI can't run ERC (that arrived in KiCad 8). Rather than fight the host, we pin a known toolchain. Anyone — including future-you — rebuilds the exact environment with one command.

Use it

cd hardware/eda
./run.sh                                   # interactive shell, lands in hardware/kicad/
./run.sh kicad-cli version                 # confirm KiCad 9
./run.sh kicad-cli sch erc pm_k1_core.kicad_sch   # run ERC on the schematic
./run.sh ngspice -b ../eda/sim/input_loading.cir  # run a simulation (cwd is kicad/)

run.sh builds the image on first use, then mounts the whole repo at /work (so KiCad sees hardware/). Use RUNTIME=docker ./run.sh … to use Docker instead of Podman.

Layout

eda/
  Containerfile      # the pinned toolchain (KiCad 9 + ngspice + python)
  run.sh             # build-if-needed + run with the repo mounted
  sim/               # ngspice decks (SPICE simulations of the analog circuits)