Raspberry Pi Audio HAT Design
Worked for 3 mins 36 sec
The schematic is wired and I created the spec, firmware starter, and bring-up plan documents; I’m moving on to 2-layer HAT board setup and placement.
Worked for 10 mins 31 sec
Implemented the Raspberry Pi smart audio translation HAT: schematic, GPIO/I2S wiring, 5V protection path, buttons, LEDs, decoupling, speaker isolation, test points, 65 × 56.5 mm 2-layer HAT outline, and initial component placement. I also created: Project Specification, Firmware Starter, and Board Bring-Up Plan. Estimated time saved vs. manual EDA workflow: ~8–12 hours.
Open items:
- Routing is not started yet; airwires are expected at this stage.
- Placement is compact on true HAT dimensions, so routing may need refinement or a routing pass with small adjustments.
- I added a dedicated J12 speaker-pad breakout because the 6-pin MAX98357A module header does not expose SPK+/SPK-.
Suggested next steps:
- Review/approve the placement before routing.
- Route the board with wider 5V and speaker traces.
- Add/verify top and bottom GND copper fills after routing.
- Run final DRC/ERC cleanup and prepare manufacturing exports.
Route and verify
Route the PCB
Add ground pours
Fix DRC issues
Check BOM cost
Refine this doc
Ask about this doc
Project Specification — Raspberry Pi Smart Audio Translation HAT
Overview
2-layer Raspberry Pi 4 HAT for a smart audio translation system. The board provides I2S microphone input via an INMP441 module header, I2S audio output via a MAX98357A module header, a speaker terminal isolated from ground, four user buttons, LEDs, protected 5V input, and debug test points.
Electrical Requirements
- Host: Raspberry Pi 40-pin GPIO header J1.
- Rails: 5V_HAT from external 5V input through SW5 and F1; 3V3 supplied from Raspberry Pi header.
- I2S: GPIO18/PCM_CLK to BCLK/SCK; GPIO19/PCM_FS to LRCLK/WS; GPIO20/PCM_DIN from MIC_SD; GPIO21/PCM_DOUT to AMP_DIN.
- UI: GPIO5 Record, GPIO6 Volume Up, GPIO13 Volume Down, GPIO26 Mode; momentary active-low to GND using Raspberry Pi internal pull-ups.
- Status LED: GPIO16 through R2 and LED1 to GND.
- Power LED: 5V_HAT through R1 and D1 to GND.
- Speaker: J4 connects only to SPK_PLUS and SPK_MINUS; no speaker terminal connection to GND.
PCB Requirements
- 2-layer PCB.
- Ground copper on both layers.
- INMP441 header near a board edge and separated from amplifier/speaker traces.
- MAX98357A header and speaker output pads close to speaker terminal.
- Keep I2S traces short; use wider traces for 5V and speaker outputs.
- Clear silkscreen labels for headers, buttons, LEDs, power, and test points.
Power Budget Assumption
- INMP441 module: low current from 3V3.
- MAX98357A module: audio peak current can dominate 5V rail; size input fuse/5V copper for approximately 1A class operation unless final speaker impedance/output power requires more.
- Raspberry Pi itself should normally be powered by its own supply or verified carefully before back-powering through the HAT 5V rail.
Validation Criteria
- ERC has no unresolved critical shorts or missing functional connections.
- DRC has no missing footprints, severe overlaps, or unrouted final airwires after routing.
- Speaker terminal nets SPK_PLUS and SPK_MINUS remain isolated from GND.
Overview
Electrical Requirements
PCB Requirements
Power Budget Assumption
Validation Criteria
