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MiciMike drop-in PCB replacement for Google Nest Mini
MiciMike Nest Mini is a drop-in PCB replacement for the "Google Nest Mini" (Google's second-generation smart speaker with a barrel connector charging port)), but is based on ESP32 and XMOS microcontrollers to run open-source firmware.
Tip! If you are instead looking for a similar drop-in PCB replacement for the "Google Home Mini" (Google's first-generation smart speaker hardware with a Micro-USB charging port) then check out the sister project at https://github.com/iMike78/home-mini-v1-drop-in-pcb
Both of these are fully open-source hardware projects, taking some conceptual inspiration from the Onju Voice but aiming to follow Open Home Foundation's open voice assistants standard with Home Assistant Voice Preview Edition as reference for PCB designs and specifications.
Project scope
The goal of this project and repository (which is similar to the Onju Voice but under a fully open-source hardware license) is to design a drop-in replacement PCB (Printed Circuit Board) with hardware schematics that anyone can make/build or order from a one-stop PCB manufacturer as a custom drop-in replacement PCB for the Google Nest Mini (2nd Gen).
This is primarily targeting people looking to convert/repurpose their old Google Nest Mini smart speakers into open-source hardware for Voice Control of Home Assistant and/or media player speaker output for Music Assistant, (the hardware can however probably also be used with other applications as well with other firmware as it is based on the popular Espressif ESP32 platform).
The hardware design will (similar to Home Assistant Voice Preview Edition) integrate an ESP32-S3 SoC for WiFi, BLE, and onboard wake-word detection (using no-code ESPHome firmware) + an XMOS xCORE XU316 chip for advanced audio processing (with custom firmware for microphone cleanup offloading for better voice recognition capabilities by using locally running algorithms for Noise Suppression, Acoustic Echo Cancellation, Interference Cancellation, and Automatic Gain Control).
Functionality-wise it is made to be mostly hardware compatible with the Home Assistant Voice Preview Edition (a.k.a. Home Assistant Voice PE reference design (which has been released as open-source hardware design from Open Home Foundation in collaboration with Nabu Casa). The main difference will be due to constraints defined by the Google Nest Mini enclosure and components, (i.e. the nest-mini-drop-in-pcb project hardware design will be limited by the same type of physical capacity inputs as the original hardware from Google).
As such the scope of this project/repository is not to develop new features/functions for the ESPHome firmware, so if you want that then you instead need to turn to the firmware development of the Home Assistant Voice Preview Edition as well as to the upstream ESPHome mainline code:
- https://github.com/esphome/home-assistant-voice-pe
- https://github.com/esphome/esphome
- https://github.com/esphome/feature-requests
Request for collaboration
If you have some experience with PCB layout design, (and especially with PCB routing, ground pouring, or noise-sensitive digital+analog layouts), your help is highly appreciated! Please feel free to open a new issue, submit suggestions/requests, and add input/feedback to existing issues, or fork this repository.
For more information about the concept/idea see and contribute to related discussion also see this Home Assistant community forum thread:
- https://community.home-assistant.io/t/any-news-on-alternative-to-onju-voice-pcb-repacement-design-for-google-nest-home-mini-speakers-with-added-xmos-chip-to-match-official-home-assistant-voice-preview-edition-reference-hardware/860001/
Current status
- ✅ Schematic completed
- ✅ Component placement done
- ✅ Routing is done
- ✅ Ground pour, shielding strategy, and EMI considerations done
- ⚠️ 1st test batch failed on two errors - fixed
- 🕓 waiting for the 2nd test batch
Tools used
- 🛠️ KiCad 9
- 🧰 SnapEDA / LCSC for footprint sourcing
Known hardware specifications
- 4-layer PCB
- ESP32-S3R8 bare chip (ESP32-S3 for WiFi, BLE, and onboard wake-word detection)
- XMOS XU316-1024-QF60B-C32 (XMOS XU316 xCORE DSP audio processing)
- Dual SPI flash
- Dual I²S buses (to allow I2S interfaces at the same time, i.e. simultaneous audio output and audio input)
- MAX98357 for speaker output (I2S Class-D Mono Audio Amplifier)
- 2x MEMS microphones (MSM261DHP)
- SK6812 LEDs
- Custom USB-C and 14V power input
⚠️ Flashing via USB-C requires disconnecting the main 14V power input. See silkscreen note on PCB for details.
References
Home Assistant Voice Preview Edition resources including PCB design files
- https://www.home-assistant.io/blog/2024/12/19/voice-preview-edition-the-era-of-open-voice/
- https://voice-pe.home-assistant.io/resources/
- https://support.nabucasa.com/hc/en-us/articles/26195279589277-Home-Assistant-Voice-Preview-Edition-PCB-design-files
- https://raw.githubusercontent.com/NabuCasa/support/refs/heads/main/static/docs/voice/home_assistant_voice_pe_schematic_v1.0_241009.pdf
- https://github.com/esphome/home-assistant-voice-pe
- https://esphome.github.io/home-assistant-voice-pe/
- https://voice-pe.home-assistant.io/
XMOS xCORE DSP (XU316-1024-QF60B-C32) MCU IC chip
- https://www.xmos.com/download/XU316-1024-QF60B-xcore.ai-Datasheet(3).pdf
- https://www.xmos.com/software-tools/
- https://www.xmos.com/develop/xcore-voice
- https://www.xmos.com/usb-multichannel-audio/
- https://www.xmos.com/xcore-ai
- https://github.com/esphome/voice-kit-xmos-firmware
- https://github.com/esphome/xmos_fwk_rtos
- https://github.com/esphome/xmos_fwk_io
License
This project is licensed under the [CERN Open Hardware License Version 2 - Strongly Reciprocal (CERN-OHL-S v2)] Any modified version of this hardware must also be distributed under the same license.
☕ If you’d like to support this project, feel free to buy me a coffee on Ko-fi!
--- Tranlated By Open Ai Tx | Last indexed: 2025-10-06 ---