6) What does it take to build a thermostat circuit?

For my project, in each room (zone) I installed a Honeywell Round on/off thermostat (T87G1006)
It's a power stealing thermostat, so no batteries needed.
I've made a small circuit to give a signal to the input port of arduino.

The benefit of this, is that I don't necesserally need a tablet to control the heating system, also I see the actual temperature on the thermostat.
The best way for mounting a thermostat/sensor: ca. 1.5 meters above floor, watch out for draught and lightbulbs (warmth).

You can't power the 1-wire bus with a mosfet, you need a pull-up resistor. Why shouldn't you use a pull-up resistor?
The data line of 1-wire pulls the (5V) line low, to prevent short-circuit you'll need a resistor.
See also http://playground.arduino.cc/Learning/OneWire

For question 1: just use the Rx and Tx pins, they are the UART pins. It's all serial, so use Serial.print or read for communication. You have to set the baudrate to a known speed, e.g 9600.

BUT: are you sure it's serial communication? I think they just use the DB9 connector because it has 9 pins, not for serial communication.
See: http://pinouts.ru/forum/index.php?topic=4679.0

While quite busy working on my Arduino home automation project, forgot to look at this forum.
And see what happened: lots of discussion and good tips, thanks everbody, I'm gonna study all comments!

Wat's exactly the problem?
I assume you've connected the relays to an output pin of your webserver (which you control by a webbrowser).
Now you've connected a pushbutton to your webserver, also to control the relays.
In that case you still know the position of the relay (i.e. the status of the output pin).

what happens: If switch 15 == LOW, you jump to afsluiten.
millis - starttijd is not greater then 5000, so nothing happens and void loop starts again.

Then again, starttijd = millis, we jump to afsluiten and again (and never will...) millis - starttijd is not greater then 5000.

So make sure you only update starttijd once.

Maybe this will help?

http://www.jayconsystems.com/forum/viewtopic.php?f=10&t=90

Yes, it's more or less the same as reading from the SDcard and write it to a webbrowser.
In this (opposite) case, you create a loop and write bytes to the SDcard while there are bytes available.
Instead of println you use print, because you write a stream of bytes and you don't want any cr/nl inserted.
When I've time, I'll look for and post an example.

Look for tinywebserver, it has an upload fuction.
It's based on the HTML command 'PUT'.
Altough PUT is a normal HTTP command, I found out that most webbrowser convert PUT into GET.
To bypass this, u can use Javasript, something like:

Code:

<script type="text/javascript">
    // Create the communications object.
    var xmlhttp;
    if (window.XMLHttpRequest) {
        // code for IE7+, Firefox, Chrome, Opera, Safari
        xmlhttp=new XMLHttpRequest();
    }
    else {
        // code for IE6, IE5
        xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
    }
   
    // Set up the request to send data to the server.
    // Make it synchronous, so we know how page rendering should proceed
    async = false;
    resource = "http://192.168.your webaddress";
    data = "your file";
   
    xmlhttp.open("PUT", resource, async);   
    xmlhttp.send(data);
 </script>

If you find tinywebserver to complicated, you can also use Ladyada's sketch: http://www.ladyada.net/learn/arduino/ethfiles.html, which is also often found on this forum.
In her sketch, you look for the GET command, but you can easily add a routine which looks for PUT.

If you're able to wire all lights and switches to Arduino, it's a good solution.
Depending on the amount of lights/ switches, you should choose between an Uno or a Mega.
In my case, I used Solid State relays, I didn't want to hear the click of the mechanic relays.

Hi,

I'm  also working on a similar project as you, hope to see some ideas from you!
For now, I've a Mega connected via I2C to the ethernet module (W5100 + arduino together), and the ethernet card has about 20 meter cable (cat 5e) to my router.
It's all working fine here, so I think the distance isn't the problem.

Maybe the power isn't enough? Have you tried a 7,5 volt power supply?

Hello guys,

Not a real problem, but could somebody explain why data transfer is so terribly slow:

I've an Arduino Ethernet card with 8GB SD card.
This SD card contains a complete html code including several jpg's and png's files.
It's all working fine: the webbrowser gives a request, arduino delivers the html page via the SD card, the webbrowser asks for the images (as put in the html file) and Arduino sent the files.
But an image of approx. 150kB takes about 20 seconds to load, what's the bottleneck around here?
(Arduino, Wiznet 5100, SD card, libraries..)

In all my simplicity I think: 8 MHz arduino, pick a byte from SD, sent it over the internet etc., 150kB shouldn't take 20 seconds?