Interfacing Old Burglar Alarm Sensors Into HomeAssistant

October 28, 2024 by Lewin Day 14 Comments

The annoying thing about commercial smart home gear is its lack of interoperability. HomeAssistant is very flexible though, and it’s easy to use all kinds of gear—even stuff you bodge together yourself. [Jeff Sandberg] demonstrates that ably with his project to use ancient 1990s burglar alarm sensors in his modern smarthome setup.

The sensors in question are from an old GM Interlogix security system. The sensors themselves sit on doors or windows. They use magnets and a reed switch to sense if the door or window is opened. If so, they send out a radio message saying as much. All [Jeff] had to do was catch those messages and translate them for HomeAssistant.

To listen in on the sensors, [Jeff] employed a Nooelec NESDR—a software defined radio that could pick up the 319.5 MHz signals. The NESDR runs a tool called RTL_433, which can decode the sensor signals, and spit out MQTT messages to interface with HomeAssistant.

Much of the hard work was done already for [Jeff]—he just had to lace together the components. This is just a testament to the hard work by people in the HomeAssistant and SDR communities for figuring all this out and putting the tools online.

We’ve seen some neat HomeAssistant builds before, like this neat home control terminal. If you’re cooking up your own smarthome hacks, don’t hesitate to let us know!

Hackaday Prize 2023: AutoDuct Smart Air Duct

September 15, 2023 by Bryan Cockfield 13 Comments

Modern building techniques are relying more and more on passive elements to improve heating and cooling efficiencies, from placing windows in ways to either absorb sunlight or shade it out to using high R-value insulation to completely sealing the living space to prevent airflow in or out of the structure. One downside of sealing the space in this fashion, though, is the new problem of venting the space to provide fresh air to the occupants. This 3D printed vent system looks to improve things.

Known as the AutoDuct, the shutter and fan combination is designed to help vent apartments with decentralized systems. It can automatically control airflow and also reduces external noise passing through the system using a printed shutter mechanism which is also designed to keep out cold air on windy days.

A control system enables features like scheduling and automatic humidity control. A mobile app is available for more direct control if needed. The system itself can also integrate into various home automation systems like Apple’s HomeKit.

A 100% passive house that’s also as energy-efficient as possible might be an unobtainable ideal, but the closer we can get, the better. Some other projects we’ve seen lately to help climate control systems include this heat pump control system and this automatic HVAC duct booster fan system.

Smart Powermeter Uses E-Paper Display

July 20, 2023 by Lewin Day 17 Comments

In most places around the world, electricity is getting ever more expensive. Cutting back on your usage is one of the easier ways to escape this pain. This smart powermeter from [JGAguagdo] may prove a useful tool to achieve that goal.

The project uses an ESP32-S2 as the brains of the operation. It’s capable of reading up to six current-transformer clamps for measuring current draw in AC devices. It also features an embedded BMP280 temperature and air pressure sensor. Live data is displayed on a 2.9-inch e-Paper display, making it clear and easy to read under normal lighting conditions. By default, it’s set up to display graphs of power usage both over the last 24 hours, and the last ten days. It can even be set up with the prevailing energy rates in your area to display a realistic figure for what you’ll pay for your daily usage.

It can even be set up to work with Home Assistant for more logging and control options. We can imagine that, with a little work, you could even do some fancy plotting of energy use versus temperature to determine the performance and cost of your home HVAC setup.

If you want one with a minimum of fuss, you can score one on Tindie. Alternatively, design files are available on GitHub, too. We’ve featured some other great power meters over the years, and if you’re cooking up your own smart designs, don’t hesitate to let us know!

Tiny Microcontroller Uses Real-Time Operating System

May 10, 2023 by Bryan Cockfield 51 Comments

Most of the computers we interact with on a day-to-day basis use an operating system designed for flexibility. While these are great tools for getting work done or scrolling your favorite sites, they have a weakness when it comes to interacting quickly with a real-world environment. For these kinds of low-latency, high-reliability systems you may want to turn to something like freeRTOS which is optimized for this kind of application and which [Parikshit Pagare] has used to build his home automation system.

This build is based around an ESP32 for which freeRTOS, designed specifically for embedded systems, is uniquely suited. There are several channels built in capable of monitoring temperature, functioning as a smoke alarm, and sensing whether someone is at the front door. All of these are reported to a small OLED screen but are also updated on an Android app as well, which happens nearly instantaneously thanks to the real-time operating system. There are a number of user-controllable switches as well that are capable of turning lights or fans on and off.

For a home automation system, it’s one of the most low-cost and fully-featured we’ve seen and if you’re still having trouble coming across a Raspberry Pi as they sort out supply issues, something like this might make an excellent substitute at a fraction of the price. If you’re looking to expand even beyond this build, one of the gold standards for ESP32-based automation design is this build from [Marcus] which not only demonstrates how to build a system like this but goes into great detail on the ESPHome environment.

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When Your Smart Light Switches Stop Working, Build Your Own

April 30, 2023 by Lewin Day 14 Comments

If you want smart light switches in your house, you can buy from any one of hundreds of manufacturers. [Brian Boyle] had kitted out his home with TP Link devices, but after a few years of use, he found they all suddenly failed within a few months of each other. Decrying the state of things, he set about building his own instead.

[Brian]’s switches use the ESP32 for its handy in-built WiFi hardware. His aim was to produce smart switches that would fit neatly into standard “Decor” style switch boxes. The design uses two PCBs. One is charged with handling the mains power side of things. It carries an SPDT relay for switching AC power, and a DC power supply to run the ESP32 itself. The controller board holds the microcontroller, a Neopixel as a status indicator, and a pair of buttons — one for switching the lights on and off, the other for resetting to default settings. The physical housing is 3D printed, and looks great with the glowing status indicator in the middle of the switch.

[Brian]’s switches are triggerable via MQTT, a web interface, and the physical button onboard the device itself. Having built the devices on his own, he’ll be well-placed to troubleshoot any usability or reliability issues that crop up in the future. That’s a lot more than we can say about most smart devices on the market!

Pi Pico Calculates Water Usage

February 25, 2023 by Bryan Cockfield 18 Comments

Modern WiFi-enabled microcontrollers have made it affordable and easy to monitor everything from local weather information to electricity usage with typically no more than a few dollars worth of hardware and a little bit of programming knowledge. Monitoring one’s own utility data can be a little bit more difficult without interfering with the metering equipment, but we have seen some clever ways of doing this over the years. The latest is this water meter monitoring device based on a Raspberry Pi Pico.

The clever thing here isn’t so much that it’s based on the tiniest of Raspberry Pis, but how it keeps track of the somewhat obscured water flow information coming from the meter. Using a magnetometer placed close to the meter, the device can sense the magnetic field created as water flows through the meter’s internal sensors. The magnetic field changes in a non-obvious way as water flows through it, so the program has to watch for specific peaks in the magnetic field. Each of these specific waveforms the magnetometer detects counts to 0.0657 liters of water, which is accurate for most purposes.

For interfacing with a utility meter, this is one of the more efficient and elegant hacks we’ve seen in a while. There have, of course, been other attempts to literally read the meter using web cams and computer vision software, but the configuration for these builds is much more complex than something like this. You can interface with plenty of utility meters other than water meters, too, regardless of age.

Automating The Most Analog Of HVAC Equipment

February 20, 2023 by Bryan Cockfield 35 Comments

Burning wood, while not a perfect heating solution, has a number of advantages over more modern heating appliances. It’s a renewable resource, doesn’t add carbon to the atmosphere over geologic time scales like fossil fuels do, can be harvested locally using simple tools, and it doesn’t require any modern infrastructure to support it. That being said, wood stoves aren’t something that are very high-tech and don’t lend themselves particularly well to automation as a result, at least with the exception of this wood stove from [jotulf45v2].

While this doesn’t automate the loading or direct control of a modern pellet stove, it does help [jotulf45v2] know when the best times are for loading more wood into the stove and helps keep the stove in the right temperature range to avoid the dangerous formation of creosote on the inside of his chimney caused by low temperature burns. Two temperature sensors, one on the stovetop and the other on the stove pipe, monitor the stove exhaust temperature. They feed data to a Node-RED system running on a Raspberry Pi which automatically notifies the user by text message when certain stove temperatures are reached.

For anyone heating with wood, tools like this are indispensable to help avoid spending an otherwise unnecessary amount of time getting a fire up to temperature quickly without over-firing the stove. Modern pellet stoves have some more modern conveniences like this built in, but many of the perks of using cord wood are lost with these devices. There are plenty of other ways to heat with wood too; take a look at this custom wood boiler which serves as a hot water heater.