Home Assistant launches Connect AUX-2 open hardware bridge for legacy devices

Home Assistant has released the Connect AUX-2, an open hardware accessory intended to bridge the gap between modern smart home controllers and older or untrusted hardware. The device serves as a localized interface for equipment that lacks native smart capabilities, has had its cloud services discontinued, or poses privacy risks due to network-connected monitoring features.

By providing physical connection points for serial and audio interfaces, the gadget allows users to control legacy hardware like solar inverters, hi-fi systems, and smart TVs without exposing those devices directly to the internet. The hardware is built around an Espressif ESP32-S3 microcontroller and supports various expansion methods including Z-Wave and RS485 via USB.

Hardware specifications and connectivity

• Core Processing: Powered by an Espressif ESP32-S3 microcontroller featuring 8MB of flash storage and 8MB of pseudo-static RAM (PSRAM).
• Audio and Networking: Integrates a Texas Instruments PCM5122 audio chip for 3.5mm analog and optical S/PDIF outputs, alongside a WIZnet W5500 Ethernet controller supporting Power-over-Ethernet (PoE).
• Wireless Protocols: Supports single-band 2.4GHz Wi-Fi and Bluetooth 5 Low Energy (BLE), with the ability to act as a proxy for up to three active BLE device connections.
• Legacy Interfaces: Includes two RS232 serial ports for programmatic control of older hardware and a USB Type-A port for peripherals like the ZWA-2 Z-Wave adapter or Waveshare USB-to-RS485 adapters.

Why it matters

This release promotes hardware sustainability by enabling the continued use of functional but 'dumb' or cloud-dependent electronics. For the open-source community, the fully open nature of the device allows for custom driver development and expanded use cases in local-first home automation.