Thermostat V3 Schematic

Posted 2012.06.19 9.45 in Computers/Internet/Technology, Hobbies by Stephanie

Here is a schematic for my Thermostat V3. It’s something of a ‘block diagram’ as I did for the ISEB6 layout, as it is another project that was mostly assembled from off the shelf modules.

You can download the PDF version here.

I have omitted the lux / luminosity sensor in the above schematic, because it’s not working very well and I find it’s fairly pointless. I’ll likley remove it from my thermostat next time I’m doing work on it.

For something of a BOM and assembly instructions, please download the zip file that was linked in the original Thermostat post.



  1. Nagaki says:

    Hello Stephanie,

    You probably sick of seeing my name, but please help; Subject: Thermostat V3

    I got questions for you:
    I could not up load the sketch into the Arduino Pro (even though the file complied with no error)
    How did you upload yours? You had to use FTDI, correct?
    What baud rate is your setting?
    I keep being the message: avrdude: stk500_recv(): programmer is not responding.
    Could you please, help?
    Thanks so much

    1. Stephanie says:

      Hello Nagaki – no worries at all! 🙂

      I used an FTDI cable. The Arduino Pro of course has no ftdi chip, just the header. Oh, one other thing, if you have fully assembled it like the schematic, there is that DPDT switch to the XBee adaptor – that has to be ‘off’ or it will interfere with the sketch upload.

      The XBee and the FTDI port share the one and only serial port on the ATMega328 so for normal running use, the serial port is connected to the XBee but when you are doing uploads you flip the switch and that disconnects the XBee.

      Hope that helps!

      1. Nagaki says:

        Thank you for helping me.
        I did not have the anything assembled,
        all I did was hooking-up the FTDI board (Adafruit ID 284) to the Arduino pro and tried to upload.
        From the Tools menu > Board> Arduino pro 5V,16Mhz w/328, is it correct? or something else? I tried to select board as Duemilanove w/328 but I got the same error.
        I have Mac Lion 10.7.2 Mini Mac

        I am stuck,
        Should I get the FTDI cable?
        Thank you.

        1. Stephanie says:

          I use the Adafruit FTDI friend as well. The only other thing I can suggest is the obvious, make sure you have the correct serial port selected.

          Apart from that, the problem you’re having has nothing to do with the sketch itself, it’s a communications issue between your computer and the FTDI board.

          I’d suggest making sure your build environment is able to function normally, i.e. make sure you can upload any of the basic sketches (blink etc) and if not, debug that before proceeding with the rest of the thermostat build.

          Good luck!

          1. Nagaki says:

            You’re right, Stephanie.
            There is nothing wrong with the sketch, it was the communication between the Mac and the FTDI.
            I finally figured out, I got it to work. Loaded the sketch and I saw Day/date and RH%.

            I still have a bit to go as far as relay, switches, and Xbee. I have no idea how Xbee work, but I could do some readings.

            Thank you for helping me, you’re very kind.

  2. Stephanie says:

    Hi Nagaki,

    Glad you got the sketch loaded and running!

    The Xbee’s purpose is to talk with another Arduino that I have hooked up with an ethernet shield. So I can remotely monitor or adjust the thermostat settings.

    I communicate via network / internet to the networked Arduino and send commands to it, then that arduino relays the data to the thermostat.


    1. Nagaki says:

      Wow, Xbee is Cool !

      So how do I adjust the time and date for the clock on the thermostatV3? ( I do not have any arduino network)

      I plan to complete the “home made” board (which contains relays and transistors) this weekend.

      1. Stephanie says:

        You can set the time and date through the serial port / XBee. Easiest way (without the XBee network in place) is to hook up the FTDI board and use Arduino’s serial monitor.

        The other thing you can do is you can have an XBee in the thermostat, and have a second XBee attached to your computer – Adafruit and Sparkfun both have XBee -> USB boards. Either way it boils down to just sending serial data to the thermostat.

        If you do that, you could probably even write up software on your computer to handle all the communications, so you’d have the thermostat control available on your desktop (or laptop or wherever you have the xbee plugged in.)

        There’s a full list of commands in the build notes (txt) file that was with the sketch file, but to set the time the command is “scHHMM” and to set the date it’s “sdYYMMDD”


        1. Nagaki says:

          Thank you so much, Stephanie.
          I will try that this evening.

          This is silly question for you:
          did you have a degree in Electrical Engineer? Your works are awesome!
          I mean it.


          1. Stephanie says:

            Nagaki, you’re quite welcome!

            I have no degree, I’m just a self-taught hobbiest. I’ve been interested in electronics for a good long time, but have not had any formal education in the field.

            I just read a lot, experiment a lot, and am very lucky that I never had people in my life telling me that I can’t do these things. (I.e. “girls don’t do electronics” and “that’s too hard, it’ll never work.”)


  3. Chris says:

    May I ask where you got the Star Trek TOS Comm panel?

    1. Stephanie says:

      Hello Chris,

      It comes from – originally it played some sound effects and blinked some lights.


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