Dan Jones' Appliance HAT Gives Your Raspberry Pi Six Quick-Connect Relays with a Smart Web GUI

Maker Dan Jones has launched an add-on for the Raspberry Pi - and compatible single-board computers — which aims to make home automation and industrial control projects as simple as possible: the Appliance HAT.

"The Appliance HAT is an I/O automation board for Raspberry Pi with six opto-isolated quick connect power relays," Jones explains. "Designed for switching household appliances, industrial control or home automation. Unlike similar products, the Appliance HAT does not require any screw terminals or PCB wire connections. Instead it uses quick connect power relays with integrated spade terminals, which allows six 16A / 250V AC rated power relays to fit onto a single HAT."

Based around the Microchip MCP23017 16-channel input/output expander, the Appliance HAT communicates with the host device over I2C and supports 3.3V or 5V logic. Six of the expander's channels are used for the on-board relays, while the remaining 10 are left free for other uses.

The project isn't purely about the hardware, though: Jones has also developed a graphical user interface which runs in a borwser, allowing for code-free development on the platform. "It is designed to be both a user guide & quick reference to the Appliance HAT pinout," Jones explains. "The GUI is fully responsive and adapts to any screen size."

The HAT is primarily designed for the Raspberry Pi family of single-board computers and has been tested on the family from the original Raspberry Pi through to the latest Raspberry Pi 4 and compact Raspberry Pi Zero; it's also compatible with other boards which boast the same pinout, including the Asus Tinker Board, Orange Pi range, and Odroid family, and has also been tested on the ATMegaZero microcontroller board.

The Appliance HAT is now available from Jones' Tindie store at $70, with Python example code and documentation available on the project's GitHub repository. Jones has also published a live demo of the web GUI.