Seeed Studio Simplifies Home Assistant Mains Control with a XIAO ESP32C3 Two-Channel Wi-Fi Relay

Driven by Seeed's compact Espressif ESP32-C3 RISC-V dev board, this compact relay board includes power measurement and two channels.

Seeed Studio has announced a compact gadget designed to make it easier to get mains-powered devices integrated into your Home Assistant or other smart home control system: the Espressif ESP32-C3-based Two-Channel Wi-Fi AC Relay.

"Our Seeed Studio XIAO ecosystem has been growing steadily with tap-on accessories like Grove expansion boards, sensors, connectivity modules, and actuators to complement our thumb-sized dev boards," says Seeed's Lily Li of the new launch. "But one thing kept coming up in our XIAO Open Roadmap: you wanted more relays! Well, we heard you, and here’s our answer: the new Seeed Studio Two-Channel AC Wi-Fi Relay."

Seeed has launched an ESPHome-flashed Espressif ESP32-C3-powered smart relay, ready for use with Home Assistant. (📹: Seeed Studio)

The compact relay box is built around Seeed's XIAO ESP32C3 compact microcontroller development board, which in turn features an Espressif ESP32-C3 system-on-chip — delivering a single 32-bit RISC-V processor core running at up to 160MHz, 400kB of static RAM, 4MB of flash memory, and a radio with IEEE 802.11b/g/n Wi-Fi and Bluetooth 5.0 Low Energy (BLE) connectivity plus Bluetooth Mesh support.

To this, the company has added a pair of 100-250VAC relays good to 10A, with a combined maximum load of 2,400W at 240V, with the outputs and the power inputs on screw terminals. There's a Shanghai Belling BL0942 power-metering chip, delivering a claimed power usage measurement error of just 0.1 per cent — and the microcontroller comes pre-flashed with the ESPHome firmware, meaning it rapidly integrates into Home Assistant for control, automation, and both live and historical power draw measurements.

"The relay comes in a white 3D-printed enclosure (which you can download and customize from Thingiverse for free)," Li adds. "And for all you makers and developers who want to DIY with your existing XIAO boards — stay tuned! We’re working on a universal relay add-on that’ll be compatible with all XIAO dev boards."

The Two-Channel Wi-FI AC Relay is listed on the Seeed store at $19.90 before volume discounts, with availability estimated in early January 2025. More information is available on the Seeed wiki, where Li says schematics will soon be uploaded under an unspecified open source license.

Gareth Halfacree
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire: freelance@halfacree.co.uk.
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