• 1
    Build Instructions

    Video

  • 2
    Building the Hardware

    Gather all of the materials listed in the parts list above. We will start with the simplest circuits and build our way up to the harder ones (DHT11 → Damper → Control Unit).

    The DHT11 circuit is by far the simplest circuit to assemble for this build. You will only need 1 Builder Base, 5 MM jumper wires, and a DHT11 temperature sensor.

    Use the schematic and breadboard views listed below as a reference.

    Start by attaching the 3.3V and GND ports on the breadboard to the GND and VCC rails on the breadboard.

    Place your DHT11 on the breadboard and attach a jumper from the 3.3V rail to the furthest left pin on the DHT11. Next attach a wire from the GND rail on the breadboard to the furthest right pin on the DHT11.

    Lastly, connect the pin second from left on the DHT11 to the GP0 port on the Builder Base.

    Your DHT11 circuit is now finished. This will be used to sense the temperature of your heating/cooling zone.

    Now let’s assemble the damper circuit. The damper is the vent that is open and closed depending wether the system is heating or cooling. You will need 1 builder base, an L293D H-bridge, a DC motor, and a number of MM jumper wires.

    Wire the H-bridge to the Builder Base as follows:

    We then wired the Motor to the H-bridge as follows:

    We purchased a motorized damper and modified it by bypassing its ECU and connecting it directly to our system using the above circuit . You should be able to do the same with any motorized damper that you purchase, but you need to make sure that the motor used in the damper is a brushed DC motor. Otherwise, you will have to design a circuit that differs from the one above.

    In the video we built the damper circuit without the damper attached. We did this so it would be easier to show you exactly how the circuit is assembled.

    Here is a photo of the internals of our damper. You can see that the circuit we use is the same.

    With the circuit in place inside of the damper we then chose to cut a hole in the back of the damper and run the wires through it.

    And here it is wired to the client.

    The damper circuit is now complete. Let’s move onto the Control Unit.

    Note: All of the following electronics are connected to one builder base. We split the diagrams up to make the wiring process easier to follow.

    The control unit is where you set the temperature Heat/Cool point.

    What you will need to assemble this portion of the project is a Builder Base, an I2C LCD (both 2x16 and 4x16 displays will work), and rotary encoder, and three LEDs (Green, Blue, and Red).

    Let’s start by connecting the LCD to the Builder Base.

    On the back of your LCD you should have four pins labeled SDA,SCL,VCC, and GND.

    You should use MF jumper wires to attach the LCD to the Builder base

    You should attach the LCD to the Builder Base as follows:

    Now let’s move onto the LEDs (Red,Blue,Green). Each of the GND leads on the LEDs should be attached to the GND port on the Builder Base, and the positive leads should be attached as follows:

    You should attach the LEDs to the Builder Base as follows:

    If you followed the above wiring diagram you should now have your LEDs properly connected.

    Let’s move onto the rotary encoder. What you will need are 5 MF jumper wires and your rotary encoder.

    You should attach the rotary encoder to the Builder Base as follows:

    Congratulations! All of the circuits needed for the HVAC system are now complete!

  • 3
    Build the Firmware

    Since we use three clients in this project we will need to build three separate firmware files.

    Start by navigating to the firmware builder and create a new firmware named “Temperature Probe”.

    Click on the “+Add Hardware” button and add a Temperature sensor.

    Click the “Add Hardware” button and once the device has been added to your firmware select the DHT11 temperature sensor from the driver drop down menu.

    Configure the driver as follows:

    Pin: GP0

    Resolution (F): 1

    Our system is set to imperial, so the resolution is in ˚F. If you want it to be in ˚C change your measurement units under your system settings.

    Save this firmware file, and create another named "Damper".

    Now, click the “+ Add Hardware” button and add a Damper to your firmware file.

    Select the H-bridge from the driver drop down menu.

    Configure the driver as follows:

    Enable Pin: GP3

    DC 1 Pin: GP2

    DC 2 Pin: GP1

    Save your firmware file and add another named “ROTARY+LCD+LED”.

    Use the “+Add Hardware” button to add an LCD, a Forced Air Unit, and a Rotary Encoder to your firmware file.

    Now let’s configure the LCD. Click on the LCD and select the “Generic LCD2004Display(I2C)” from the driver dropdown menu.

    Now we will configure the driver as follows:

     I2C Address: 0x27

    Layout: 2x16

    Your LCD device is now configured. We will now configure the rotary encoder.

    Select the Rotary Encoder driver from the driver dropdown menu.

    Now we will configure the driver as follows:

     CLK Pin: GP5/TX

    DT Pin: GP4

    BTN Pin: GP3

    Now let’s configure the FAU.

    Note that for the FAU there are three services. Each service represents either Heat, Cool, or Fan, and each service has to be configured individually.

    Start by selecting the GPIO driver from the driver drop down menu for each service.

    Now we will configure the services as follows.

    Heat:

    Cool:

    Fan:

    That’s it, this firmware file is now complete. Save and upload your firmware files to the appropriate clients!

    Upload the Damper firmware file to the builder base that the damper is attached to; the temperature probe file to the builder base that the DHT11 is attached to; the Rotary+LCD+LED file that the Control unit is attached to.