Nest Audio Drop-In PCB Replacement

Open-source hardware replacement PCB for the Google Nest Audio smart speaker with Home Assistant integration.

Overview

This project provides a drop-in replacement PCB for the Google Nest Audio, converting it into a fully open-source Home Assistant voice assistant. The design is inspired by the nest-mini-drop-in-pcb project and follows the Home Assistant Voice Preview Edition hardware specification.

Features

• ESP32-S3R8: Dual-core WiFi & Bluetooth with wake-word detection
• XMOS XU316: DSP audio processing with AEC, noise suppression, and beamforming
• High-power amplifier: Upgraded for Nest Audio's larger speaker drivers
• USB-C + 14V barrel power: Flexible power input options
• Drop-in replacement: Fits original Nest Audio enclosure
• Home Assistant compatible: Native Voice Assistant support
• Open source hardware: CERN-OHL-S v2 licensed

Hardware Specifications

PCB Dimensions

• Length: [TBD - from your scan]
• Width: [TBD - from your scan]
• Thickness: 1.6mm (standard)
• Mounting: Compatible with original T6 screw holes

Components

Component	Model	Purpose
MCU	ESP32-S3R8	WiFi, BLE, wake-word
DSP	XMOS XU316-1024-QF60B	Audio processing
Amplifier	[TBD - higher power than mini]	Speaker driver
Microphones	Dual MEMS	Far-field voice capture
LEDs	[TBD]	Status indication
Power	USB-C + 14V barrel	Power input

Audio Chain

1. Dual MEMS microphones → XMOS DSP (AEC, beamforming)
2. XMOS → ESP32-S3 (I2S)
3. ESP32-S3 → WiFi → Home Assistant
4. Home Assistant response → ESP32-S3 → Amplifier → Speaker

Getting Started

1. Order PCB

• Download KiCad files from hardware/kicad/
• Upload to PCB manufacturer (JLCPCB, PCBWay, etc.)
• Recommended: 1.6mm thickness, ENIG finish

2. Order Components

• See hardware/bom/bill-of-materials.csv
• Available from Digi-Key, Mouser, LCSC

3. Assemble

• Follow docs/assembly-guide.md
• Requires hot air station for QFN packages
• Test points provided for debugging

4. Flash Firmware

• Follow docs/flashing-guide.md
• Uses ESPHome configuration
• OTA updates supported

5. Install

• Remove original Nest Audio PCB
• Install this PCB using original mounting screws
• Connect speakers and power

Documentation

• Assembly Guide
• Flashing Guide
• Measurements
• Troubleshooting

Hardware Design

KiCad Project

• Open hardware/kicad/nest-audio-pcb.kicad_pro in KiCad 9.0+
• Schematics in hardware/kicad/*.kicad_sch
• PCB layout in hardware/kicad/*.kicad_pcb

Key Design Files

• audio.kicad_sch - Audio processing and amplification
• power.kicad_sch - Power management and regulation
• mcu.kicad_sch - ESP32-S3 and XMOS connections
• io.kicad_sch - Connectors and interfaces

Firmware

ESPHome Configuration

# See firmware/esphome/nest-audio.yaml
esp32:
  board: esp32-s3-devkitc-1
  variant: esp32s3
  flash_size: 8MB
  
# Home Assistant Voice Assistant
voice_assistant:
  microphone: mic_array
  speaker: amp_output

Features

• Wake word detection ("Hey Jarvis", "OK Google", custom)
• Local voice processing with Wyoming protocol
• OTA firmware updates
• WiFi provisioning via BLE
• Status LED control
• Volume control

Project Status

• Project initialization
• Hardware measurements from 3D scan
• KiCad schematic design
• PCB layout and routing
• Prototype testing
• Documentation complete
• First release

Contributing

We welcome contributions! Please see CONTRIBUTING.md for guidelines.

Areas needing help:

• PCB measurements and verification
• Audio amplifier selection for larger drivers
• Thermal management testing
• Enclosure modifications guide
• Firmware optimizations

Credits

• Inspired by: nest-mini-drop-in-pcb by @iMike78
• Hardware reference: Home Assistant Voice Preview Edition
• Community: Home Assistant Community Thread
• Teardown reference: iFixit Nest Audio Teardown

Similar Projects

• nest-mini-drop-in-pcb - Google Nest Mini v2 replacement
• Onju Voice - Original inspiration
• Home Assistant Voice PE - Official hardware reference

License

This project is licensed under the CERN Open Hardware Licence Version 2 - Strongly Reciprocal (CERN-OHL-S v2).

See LICENSE file for full text.

Disclaimer

This is an independent open-source project and is not affiliated with or endorsed by Google LLC. "Google Nest Audio" is a trademark of Google LLC.

Use at your own risk. Modifying electronic devices can be dangerous. Ensure you understand the risks before proceeding.

Support

• Issues: GitHub Issues
• Discussions: GitHub Discussions
• Community: Home Assistant Voice Assistant thread

Roadmap

Phase 1: Hardware (Current)

• Initial project setup
• Complete measurements from 3D scan
• Finalize component selection
• Complete PCB design
• Order prototypes

Phase 2: Testing

• PCB bring-up and testing
• Audio quality verification
• Thermal testing
• Long-term stability testing

Phase 3: Release

• Documentation completion
• Manufacturing files
• Assembly guide video
• First stable release

Phase 4: Enhancements

• Alternative amplifier options
• Different enclosure compatibility
• Advanced audio features
• Community contributions

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