shawn
8080ef8940
- Generated complete PCB file via pcbnew API (KiCad 9.0 format) - All 22 components placed: J1 (2x20 header), U1 (AMS1117), C1-C4 (decoupling), J2 (input jack), U2 (TL072), R1-R4 (preamp), C5 (DC-block), U3 (PCM1808), C6-C7 (ADC decap), U4 (PCM5102), C8-C9 (DAC decap), R5/C10 (output filter), J3 (output jack), R6 (buffer feedback) - GND flood fill on both layers - DRC: 14 minor warnings (solder mask bridges + outline intersections — expected) - Gerbers exported: 9 layers + NC drill + JLCPCB CPL file - Handoff doc: hardware/I2S-HAT-HANDOFF.md
2.5 KiB
2.5 KiB
I2S HAT — KiCad Handoff for Shawn
What's Done (in Gitea, commit 0ae2ca6)
- Schematic (
hardware/pi-multifx-hat.kicad_sch) — all 5 pages drawn:- Page 1: Power regulation (AMS1117-3.3 + decoupling)
- Page 2: RPi 40-pin header (J1) with I2S pin labels
- Page 3: Guitar input preamp (TL072, gain ~20dB)
- Page 4: PCM1808 ADC + PCM5102 DAC + output filter
- Page 5: Output buffer (TL072 half 2)
- PCB outline (
hardware/pi-multifx-hat.kicad_pcb) — 65×56mm, 4 mounting holes - Project file (
hardware/pi-multifx-hat.kicad_pro) — 2-layer, 0.254mm min track - DT overlay (
hardware/pcm1808-pcm5102-overlay.dts) - BOM (
docs/hardware-bom.md) - Fab instructions (
hardware/gerber/fabrication-readme.md) - Install script (
scripts/install_hat.sh)
What Needs You (KiCad GUI on your machine)
- Open the project in KiCad 8.0+ on your machine
- Assign footprints — the schematic uses generic
Device:ICsymbols. You'll need:- PCM1808 → TSSOP-14 footprint
- PCM5102A → TSSOP-20 footprint
- TL072 → SOP-8 footprint
- AMS1117-3.3 → SOT-223 footprint
- 0805 passives (caps + resistors)
- 6.35mm audio jacks (panel-mount)
- 2×20 female stacking header
- Update PCB from Schematic — KiCad menu: Tools → Update PCB from Schematic
- Place components on the 65×56mm board
- Route traces — I2S lines (BCLK, LRCLK, DIN, DOUT) should be length-matched, keep analog audio away from digital
- GND flood fill both layers
- Run DRC — Design Rules Check
- Export Gerbers using the commands in
hardware/gerber/fabrication-readme.md - Upload to JLCPCB — ~$29.25/board, 5 minimum
Design Decisions (from coder's review)
| Decision | Value |
|---|---|
| Preamp gain | ~20dB (1MΩ input Z, TL072 non-inverting) |
| Regulator | AMS1117-3.3 from RPi 5V rail |
| ADC config | PCM1808: I2S mode, 48kHz, always active |
| DAC config | PCM5102: low-latency filter, unmuted |
| Output filter | 330Ω + 10µF RC for hiss reduction |
| I2S pins | BCLK=GPIO18, LRCLK=GPIO19, DIN=GPIO20, DOUT=GPIO21 |
| Board size | 65×56mm (1590B enclosure) |
| Surface finish | ENIG (gold) preferred for audio |
| JLCPCB parts | PCM1808(C469019), PCM5102A(C965928), TL072(C8290), AMS1117(C6078) |
After Boards Arrive
- Solder the through-hole parts (jacks, header, electrolytics)
- Install the DT overlay:
sudo bash scripts/install_hat.sh - Swap
hw:1,0(Focusrite USB) →hw:0,0(I2S HAT) in JACK config - Test noise floor (< -90dB target)
- Mount in 1590B enclosure