2 replies to this topic

[Larsey]

Hello all (my first post!) :-) I have this project in mind, where I want to monitor and log temperature in my house and present them in several ways (smart phone, smart tv, plain website +++). It would be cool if I could browse a site on my iPad and get visual presentation of the temperature in the house right now and for the last 7 days (for instance). I'm not worried about the presentation part of the project. I'll do a website on my server (Windows 7 running webserver and database) with different layout to target the different clients... but what I'm struggling with is what I should buy. I want Netdunio because I know C#. But I don't know what to buy, I've been browsing Sparkfun and such but there is too much stuff out there that I can’t make a sound decision. For instance, by not having access to ethernet in all the places I want to log temperature, I decided to go for the regular Netduino. But for data transmission to my server should I go for wifi or radio? Wifi is somewhat expensive, but would allow me to connect directly to the server as they are on the same net. A possible cheaper solution is buying radio shields but then I would also need a receiver (another netduino) connected by USB to the server feeding it with data from the senders. Does anyone have some smart thoughts about it? For instance what hardware I could buy... and let’s not forget I also need a probe to measure temperature. -Lars

[JerseyTechGuy]

I cannot give you recommendations on the communication as my projects log to an SD card and use a COM port to hook to Windows as it is a portable device.

I have however used the SHT15 temperature sensor (SparkFun has a breakout for it SEN-08257). This measures both Temp and Humidity which is a nice combo. Allows you to easily then calculate DewPoint if needed. SparkFun also carries a Barometric Pressure sensor that works well and also measures temp. I am using both of these and logging the average temp between the devices (SEN-09694).

My windows application graphs out the temp, hum, dewpoint and barometric pressure using the Microsoft Chart Control (which is also available for asp.net). This may work well for your reporting purposes.

Good luck with your project.

[gbreder]

Hi Lars,
welcome to the forum. I've already build a temperature logging of all my rooms. There are a few things I want to point out:
Netduino needs energy. At least 40mA if I'm correct. This meens every battery will be depleted in about 2 days. You will need a regular (wall) power supply for each Netduino.

My own layout is as following:
Each room has one Arduino driven by a coin cell (CR2025).
The Arduino sleeps 3 minutes and after that it takes the temperature.
The sleep state takes a current of 0,000005Ampere (5 mircoAmps).
The measurement of the temperature takes 4ms and the send procedure takes about 13ms.
During the measurement the circuit takes about 0,015A (15milliAmps).
My coin cell batteries are depleted in approximately one year. (You can also replace the coin cells by "Super Cap" capcitors.)

The Arduino was not my first choice because I'had to learn (a little bit of) C language first but there are some advantages:
The things takes next to no energy.
You don't need 8 power supplies.
The hardware cost next to no money. (Arduino 328P 3,87$; Freeduino Runtime board 2,69$).
You don't have to write a large program. Everything the Arduino does is: sleep, measure temperature, send the temperature to the serial port, sleep again.

The real program to process the data is on a Netduino board.

The used temerature sensor TMP102 can also be operated in a low power sleep mode.
The wireless link is currently provided by the Nordic RFD21733 chip. But they have a very bad indoor range and they get brocken all the time (they really don't like 24/7 operation). All my RFD21733 will be replaced by XBee (XBee XB24-Z7WIT-004) chips. The whip antenna has a good range, the firmware supports low power sleep modes.

I hope this helps a little bit.

Regards
Guido