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