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DIY automation and HVAC system runs Ubuntu Snappy on RPi

Dec 17, 2015 — by Eric Brown — 2,541 views

Cube-Controls has launched a “Pi Cubes” home automation and HVAC kit that runs Ubuntu Snappy on a Raspberry Pi.

Having furnished its Kickstarter backers with its Pi Cubes home automation system, Kitchener, Canada startup Cube-Controls has opened sales to the general public. The Raspberry Pi-driven system is designed like a commercial building HVAC automation system, says Cube-Controls. However, it is designed for the home, supporting control over furnaces, boilers, humidifiers, air handler units, dampers, valves, and any other HVAC equipment.

Pi Cubes mainboard bare (left) and with a Raspberry Pi
(click images to enlarge)

You can connect up to six I/O modules, from a selection of three types, with up to 24 combined I/O endpoints. By mixing and matching the I/O modules, you can extend the system to provide other home automation and DIY tasks, such as controlling garage doors and garden sprinklers, says the company. There’s also a smart thermostat (see farther below).

Pi Cubes board with six loaded I/O modules
(click image to enlarge)

You’re paying a bit more than the funders did, but it’s not a major difference. The basic kit with a mainboard, which acts as the hub, as well as one I/O module and a PVC PCB track, goes for $200 Canadian ($143 US). A second kit for $275 Canadian ($197) adds a second I/O module, and a $350 ($251) kit adds a third module. None of these prices include the cost of the Raspberry Pi. You can use either a Pi 1 B+ or a quad-core Pi 2 B SBC.

The Pi Cubes mainboard offers a 24VDC power supply, RTC, and a super capacitor backup. There’s also an RS485 based communication jack for the thermostats and an extension port for I/O modules. The board communicates with the Pi via I2C. Unlike most home automation systems, there’s no built-in wireless capability and no mobile app.

Pi Cubes I/O modules (left to right): DO4 Output, UI4 Input, and UO4 Output
(click image to enlarge)

The three I/O modules include:
  • DO4 Output — 4x relay outputs, with maximum current 2A and voltage 24V AC/DC
  • UI4 Input — 4x universal inputs, selectable as analog, resistive, or digital input
  • UO4 Output — 4x universal outputs, selectable as analog or digital output

Sample furnace controller project using Pi Cubes
(click image to enlarge)

An SDK for the Raspberry Pi runs on the transactionally enhanced Snappy Ubuntu Core, which is claimed to ease installation. Developers can write applications with Python, Node JS and Node RED, C/C++, and the commercial, extra-cost REX Control System for Raspberry Pi from Rex Controls.

Ubuntu Snappy SDK running a Node-RED routine (left) and a Rex Control System conceptual diagram
(click images to enlarge)

The Rex Control System provides a GUI programming environment for accessing a function block library with timers, comparators, filters, PID controllers, and other items. The software supports arbitrary dependencies between the sensors and actuators, enabling sophisticated commands like: “If excessive temperature is detected, engage the ventilation for 10 minutes.” The Pi Cubes site offers a forum, blog, and a number of tutorials and hardware projects.

Pi Cubes Communication Thermostat

Also available is a Pi Cubes Communication Thermostat for $100 Canadian ($72). The thermostat is configurable for different HVAC systems, and can also be controlled by an Arduino board, or any SBC that supports an RS485/Modbus RTU with an RJ45 adapter board, says Cube-Controls.

Pi Cubes Communication Thermostat
(click image to enlarge)

The wall-mounted device offers a temperature sensor and a rotary dial controlled room thermostat with set point. It also provides a monochrome LCD display with time and weather information, plus icons for HVAC mode, occupancy, and fan. Up to four thermostats can be connected to a single Pi Cubes mainboard via a Power-over-Ethernet connection, so no extra wiring is required.

The Raspberry Pi has also been spun into a number of other home automation and HVAC products. Some recent examples include:

Further information

A variety of Pi Cubes kits are available starting at $200 Canadian ($143 US) with one I/O module (see farther above for more pricing). More information may be found on the Cube-Controls website, as well as the earlier Pi Cubes Kickstarter page.

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