A Sonoff Switch Repurposed As A Thermostat

May 25, 2019 by Jenny List 14 Comments

Underfloor heating is a wonderfully luxurious touch for a bedroom and en-suite bathroom, and [Andy] had it fitted so that he could experience the joy of walking on a toasty-warm floor in the morning. Unfortunately after about a year it stopped working and the culprit proved to be its thermostat. A replacement was eye-wateringly expensive, so he produced his own using an ESP8266-powered Sonoff wireless switch.

The thermostat has a thermistor as its temperature sensor, embedded in the floor itself. This could be brought to the ESP’s solitary ADC pin, but not without a few challenges along the way. The Sonoff doesn’t expose the pin, so some very fine soldering was the first requirement. A simple voltage divider allowed the pin to be fed, but through it he made the unfortunate discovery that the ESP’s analogue input has a surprisingly low voltage range. A new divider tying it to ground solved the problem, and he was good to go.

Rather than using an off-the-shelf firmware he created his own, and with a bit of board hacking he was able to hard wire the mains cabling and use one set of Sonoff terminals as a sensor connector. The whole fit neatly inside an electrical fitting box, so he’s back once more to toasty-warm feet.

This isn’t the first ESP thermostat we’ve featured, nor will it be the last. Here’s a particularly nice build from 2017.

Hack My House: Raspberry Pi As A Touchscreen Thermostat

February 27, 2019 by Jonathan Bennett 49 Comments

Your thermostat is some of the oldest and simplest automation in your home. For years these were one-temperature setting and nothing more. Programmable thermostats brought more control; they’re alarm clocks attached to your furnace. Then Nest came along and added beautiful design and “learning features” that felt like magic compared to the old systems. But we can have a lot more fun. I’m taking my favorite single-board computer, the Raspberry Pi, and naming it keeper of heat (and cool) by building my own touchscreen thermostat.

Mercury thermostats started it all, and were ingenious in their simplicity — a glass capsule containing mercury, attached to a wound bi-metal strip. As the temperature changes, the contraption tilts and the mercury bead moves, making or breaking contact with the wiring. More sophisticated thermostats have replaced the mercury bead with electronics, but the signaling method remains the same, just a simple contact switch.

This makes the thermostat the prime target for an aspiring home automation hacker. I’ve had this particular project in mind for quite some time, and was excited to dive into it with simple raw materials: my Raspberry Pi, a touchscreen, and a mechanical relay board.

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Add Nest Functionality To Your Thermostat For $5

November 6, 2018 by Bryan Cockfield 39 Comments

The Nest Thermostat revolutionized the way that people control the climate in their homes. It has features more features than even the best programmable thermostats. But, all of the premium features also come at a premium price. On the other hand, for only $5, a little coding, and the realization that thermostats are glorified switches, you can easily have your own thermostat that can do everything a Nest can do.

[Mat’s] solution uses a Sonoff WiFi switch that he ties directly into the thermostat’s control wiring. That’s really the easy part, since most thermostats have a ground or common wire, a signal wire, and a power wire. The real interesting work for this build is in setting up the WiFi interface and doing the backend programming. [Mat’s] thermostat is controlled by software written in Node-RED. It can even interface with Alexa. Thanks to the open source software, it’s easy to add any features you might want.

[Mat] goes through a lot of detail on the project site on how his implementation works, as far as interfacing all of the devices and the timing and some of the coding problems he solved. If you’ve been thinking about a Nest but are turned off by the price, this is a great way to get something similar — provided you’re willing to put in a little extra work. This might also be the perfect point to fall down the home automation rabbit hole, so be careful!

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Doomed Thermostat

May 22, 2017 by Inderpreet Singh 25 Comments

It is amazing how the game Doom has been ported to so many things. Enter one more port, where the hardware in question is a Honeywell Prestige thermostat.

In his video, [cz7asm] shows us the game running quite nicely on the 480 x 272 LCD with an NES controller plugged into the USB port originally intended for software updates. The thermostat runs on a STM32F429 which is an ARM9 processor that has the juice to pull it off. The Doom engine being used is based on Chocolate Doom, an open source port of the game, and the binaries can be downloaded for Windows and Mac. The source code is also available as a download for your tinkering pleasure. This project by [cz7asm] is extended from a code on GitHub by [floppes] that was meant for the STM32F429IDISCOVERY evaluation board.

The author shares his code for the STM32F4 on Dropbox as a zip and in order to compile it, the Atmel BSP for GNU GCC is used. The video below demonstrates the hack in action and, though there is no sound yet, the satisfaction that comes from such modifications is its own reward.

What else can you run Doom on? How about a calculator or maybe the Intel Edison or even an ATM machine! If there is a processor with enough muscle power, hackers will find a way to run Doom on it. So have you seen any alien computers lately that you think can be hacked? Continue reading “Doomed Thermostat” →

SST Is A Very Tidy ESP8266 Smart Thermostat

January 1, 2017 by Jenny List 15 Comments

The smart thermostat has become in a way the public face of the Internet of Things. It’s a demonstration that technological uptake by the general public is driven not by how clever the technology is, but by how much use they can see in it. A fridge that offers your recipes or orders more eggs may be a very neat idea, but at street level a device allowing you to turn your heating on at home before you leave work is much cooler. Products like Nest or Hive have started to become part of normal suburban life.

There is no reason though for an IoT thermostat to be a commercial product like the two mentioned. Our subject today demonstrates this; SST is a Wi-Fi smart thermostat using an ESP8266 that can be controlled by an app, thanks to its use of the open-source Souliss IoT Framework.

The build is very well finished, with PCBs, colour display and other components in a neat 3D-printed box. It’s a project that you could put in front of an end-user, it’s finished to such a high standard. Physical entity files are available from the hackaday.io page linked above, while its firmware is available in a GitHub repository. THere is a video showing some of the device’s capabilities, which we’ve put below the break.

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Arduino Replaces Bad AC Thermostat, Hacker Stays Cool

August 5, 2016 by Dan Maloney 16 Comments

Most of North America has been locked in a record-setting heat wave for the last two weeks, and cheap window AC units are flying out of the local big-box stores. Not all of these discount units undergo rigorous QC before sailing across the Pacific, though, and a few wonky thermostats are sure to get through. But with a little sweat-equity you can fix it with this Arduino thermostat and temperature display.

We’ll stipulate that an Arduino may be overkill for this application and that microcontrollers don’t belong in every project. But if it’s what you’ve got on hand, and you’re sick of waking up in a pool of sweat, then it’s a perfectly acceptable solution. It looks like [Engineering Nonsense] got lucky and had a unit with a low-current power switch, allowing him to use a small relay to control the AC. The control algorithm is simple enough – accept a setpoint from an encoder, read the temperature sensor, and turn the AC on or off accordingly. Setpoint and current temperature are displayed on an OLED screen. One improvement we’d suggest is adding a three-minute delay between power cycles like the faceplate of the AC states.

This project bears some resemblance to this Arduino-controlled AC, but it seems more hackish to us. And that’s a good thing – hackers have to keep cool somehow.

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DEFCON Thermometer

August 5, 2016 by James Hobson 22 Comments

Redditor [mulishadan] — a fan of the movie WarGames — has created a singular thermostat in the form of a Defcon alert meter.

Looking to learn some new skills while building, [mulishadan] tried their hand at MIG welding the 16g cold-rolled plate steel into the distinctive shape. A second attempt produced the desired result, adding a 1/4-inch foam core and painting the exterior. Individual LEDs were used at first for lighting, but were replaced with flexible LED strips which provided a more even glow behind the coloured acrylic. A Particle Photon board queries the Weather Underground API via Wi-Fi in five-minute intervals.

Each escalation in the Defcon alert signals an increase of 10 F, starting at Defcon 5 for 69 F and below, up to Defcon 1 for 100+ F. The final build looks like a true-to-life prop with some useful functionality that can be adapted to many different purposes — proof that a relatively simple project can still produce fantastic results for entry-level makers. So why not try making this thermostat scarf as well?