Last week, Bits & Pieces took a closer look at a smart thermostat in the Netherlands powered by an Arduino Mega 2560 (ATmega2560 MCU). Today, we’re going to be getting up close and personal with a three-zone thermostat built around an Atmel-based Arduino Uno (ATmega328).
The three zone system – which recently surfaced on Instructables courtesy of hbomb9000 – is also equipped with DS18B20 temperature sensors, DS1307 RT Clock, 16×2 character display, LCD keypad Arduino shield, along with various miscellaneous wire leads, connectors and resistors. On the software side, hbomb9000 used an add on for SublimeText known as Stino, as well as two libraries: OneWire and DallasTemperature.
“The first step in making the program actually work was to get the temp sensors working. They are at the heart of the thermostat. Without them, the furnace doesn’t know when to turn on or off,” hbomb9000 explained.
“The temperature sensor is pretty cool in that it uses a single wire to send data back to the Arduino. What’s more, each sensor has an address, a unique number which identifies the sensor. This is really exciting because it means you can have multiple sensors sending their inputs into the same pin on the Arduino.”
In terms of wiring, hbomb9000 described the process as “super simple.”
“Run one wire into the analog pin of your choice (my program reads from pin A0), and connect that to one side of the button array. The other side of the button array is connected to ground,” he said.
“From there, the buttons are simply chained together via a resistor network. An additional wire is added from each button to the analog input pin, so every button has a direct path to the analog pin.”
At this stage, hbomb9000’s three-zone thermostat is mostly theoretical, although he does intend on installing it after further soldering, tweaking and adding Internet connectivity.
“My next steps will be to fashion a housing for the main thermostat as well as the two remote temperature sensors. These housings will sit on the wall in their respective zones,” he concluded.
“I’ve decided I will be using hardwood maple for the housings, so they should look fairly sharp once attached to the wall. Beyond that, some simple soldering and affixing the components to permanent breadboards will be required, as again these breadboards are not designed for permanent use. I have to either procure or build out some zone dampers.”
Interested in learning more? You can check out the project’s official Instructables page here.