Tom Beraducci's SensorNode Makes Adding Low-Cost Smart Home Sensors to Home Assistant a Cinch

Self-described technologist and inventor Tom Beraducci is looking to make it easier to deploy a wide variety of sensors for ingestion into Home Assistant with the SensorNode — a credit card-sized board powered by a Raspberry Pi Pico W.

"SensorNode is a simple credit-card sized PC [Printed Circuit] board with a Raspberry Pi Pico W installed on it," Beraducci explains of his creation. "The Pico is loaded with software that enables many common home automation sensors to be interfaced to Home Assistant, one of the most popular open-source home automation software solutions available. All you do is attach sensors to it, configure it through the built-in Wi-Fi Access Point, and run. Although all the code is open-sourced, you don't need to write code to use SensorNode."

As Beraducci says, the SensorNode board itself is built around Raspberry Pi's Pico W development board and its dual-core Arm Cortex-M0+ RP2040 microcontroller — hosted on headers, rather than surface-mounted, making it removable if required. Elsewhere on the board is a 7.5–24VDC power input jack, screw terminals for two sensors — a two-wire dry contact sensor and a three-wire sensor — and physical switches for enabling a Wi-Fi access point for configuration, powering on and off, and turning off the status lights if desired.

The board itself has no on-board sensors, though a high-speed latch chip is included to make sure the Raspberry Pi Pico doesn't miss anything. Instead, the SensorNode is designed to interface with external hardware: a two-wire sensor like push-button switches, magnetic door and window sensors, float sensors, vibration sensors and the like, and/or a three-wire motion, temperature, and moisture sensor, with early support for human presence detection sensors. There's also an I2C interface, which at the time of writing exclusively supported the ASAIR AHT20 temperature and humidity sensor.

"The main reason I came up with SensorNode was, as I was setting up my home automation system, I had the need for several dry contact switches (garage doors, fountains, push buttons, etc.) and found that there were few options available," Beraducci explains. "The ones that were available were expensive and battery-powered. Neither of which I wanted. So, as any good engineer would do, I built my own. The design is complete. I have over 20 units up and running around my house, several of them for many months non-stop. Some for over 1 year. The hardware is very simple so I'm confident it will be robust."

Beraducci is crowdfunding the SensorNode project on Kickstarter, with rewards starting at $10 for a bare PCB or $15 for a PCB and all components excluding the Raspberry Pi Pico W and rising to $49 for "early bird" pricing on a complete ready-to-run assembled unit with housing and power supply or $100 for a pack of three.