feat: PCM1808+PCM5102 I2S HAT design files
Custom I2S HAT for Pi Multi-FX Pedal — full hardware package:
- KiCad project: schematic (kicad_sch), PCB layout (kicad_pcb), project file
- Custom DT overlay: pcm1808-pcm5102-overlay.dts (no upstream overlay exists for PCM1808)
- docs/hardware-bom.md: BOM (9.25 HAT + 1.75 with enclosure), wiring diagram, PCB design notes
- docs/config-audio.md: DT overlay build, ALSA config, JACK integration, troubleshooting
- scripts/install_hat.sh: One-command install + test suite (6 tests)
- hardware/gerber/: JLCPCB fab instructions and assembly notes
Circuit: Guitar input → TL072 preamp (gain ~20dB) → PCM1808 ADC → RPi I2S
→ PCM5102 DAC → RC filter → output jack
I2S: BCLK/GPIO18, LRCLK/GPIO19, DIN/GPIO20, DOUT/GPIO21
Stacking header passes all 40 GPIO pins for footswitches/LEDs/display
shawn
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