Introduction
Back in 2017, Google launched the first generation Google Home Mini as an affordable smart speaker that gave users voice access to the Google Assistant. For around $50, you could ask questions, set reminders, control smart home devices, and stream music. However, the convenience came at a cost: every voice command was sent to Google's servers for processing, raising privacy concerns among users who wanted a local, offline alternative. Now, an open-source hardware project offers a compelling solution by replacing the Mini's internal board with a custom drop-in board that runs Home Assistant, turning the device into a privacy-focused smart speaker that operates entirely on your own network.
Why Replace the Google Home Mini’s Brains?
The original Google Home Mini relies on cloud-based voice recognition and processing. While this enables powerful features, it also means constant internet connectivity and data transmission to Google. Many smart home enthusiasts prefer a local voice assistant that doesn't require cloud services for basic tasks. Home Assistant, the popular open-source home automation platform, can integrate with voice assistants like Rhasspy or wake word detection to provide on-device voice control. By swapping out the Mini's original board, you gain full control over your data, reduce latency, and can even operate without an internet connection for local automations.
Meet the Drop-In Board: Specifications and Cost
This $85 drop-in board is an open hardware design that fits perfectly into the Google Home Mini's chassis. It consists of a main processor module (often based on the Raspberry Pi Compute Module 4 or similar) combined with a dedicated audio codec, microphone array interface, and power regulation circuitry. The board is designed to reuse the original Mini's speaker, microphones, and power supply, making for a clean and simple upgrade. The project files—including PCB schematics, firmware, and case modifications—are available on GitHub under an open license, so you can purchase assembled boards from sellers or build your own if you have the skills.
Installation Process
Upgrading your Google Home Mini is surprisingly straightforward and requires no soldering. Simply open the device, disconnect the ribbon cables from the original logic board, and replace it with the new drop-in board. The board aligns with existing screw mounts and connectors. After closing the case, you flash a custom firmware based on Home Assistant OS or a dedicated voice assistant image. The whole process can be completed in under 30 minutes, even by a beginners with basic electronics experience.
What Home Assistant Brings to Your Mini
With the new board installed, your Google Home Mini becomes a fully local smart speaker running Home Assistant. This means:
- Offline voice control – Process voice commands locally using project Rhasspy or Picovoice.
- Advanced automations – Integrate with hundreds of smart home devices and create routines without cloud dependencies.
- Full privacy – Your voice data never leaves your home network.
- Open-source flexibility – Customize the software to your exact needs, add new sensors or services.
- Cost-effective upgrade – Instead of buying a new smart speaker, breathe life into an old Google device and gain far more control.
Is It Worth the Investment?
At $85 plus the cost of a used Google Home Mini (often $15-25 on the second-hand market), you end up with a powerful, private smart speaker for about $100-110. That's comparable to a new Amazon Echo Dot or Nest Mini, but with the advantage of full local processing and open-source flexibility. However, it's not for everyone. The setup requires some technical comfort with opening electronics and configuring software. You also lose direct access to Google Assistant services like Google Play Music or Google Calendar sync, though you can often replace them with local alternatives. For privacy-conscious users and smart home tinkerers, this drop-in board offers a unique way to reclaim your device.
Conclusion
This open-source drop-in board transforms a humble Google Home Mini into a cornerstone of a private, local smart home. With a clear path from cloud-dependent speaker to fully owned hardware, it represents the best of the maker community and the Home Assistant ecosystem. If you're ready to take control of your voice assistant, grab a used Google Home Mini, order the board, and start building your own private smart speaker today.