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New home monitoring setup – part 1

Updated 26/2/2010
I have been looking at revisiting my home monitoring setup for some time. Whilst I have considered plug computers and other slugs as the hub for this I keep coming back to the Arduino. An Arduino has enough CPU power, is cheap, very low power and I can maintain it should it develop a fault.

For the sensor communications I have decided to standardize on the JeeLabs JN4. Most sensors will connect directly to the sensor controllers, but for the CC128 then I will use a bare board Arduino as a data concentrator.

new architecture for home monitoring

For the first part of this project I will build the data storage unit. This will have:

1) Seeeduino 328 – chosen due to the additional 3.3v power available.
Update 24/2/10: I am revising this decision as the Seeeduino has placed the 500mA fuse on the 5v line (not on the USB 5v line), I need more than this (it is the LCD back light that draws most of this) and the fuse keeps cutting power. I will probably end up with a standard Duemilanove and put a 3.3v regulator in for the 3.3v devices.
Update 25/2/10: Measured current required – 305mA (180mA without the LCD) – so it must be the regulator cutting out because the heat sink is not adequate. Moved to Duemilanove, with 100mA 3.3v LDO regulator and although the 5v regulator does get hot I do not have any cutout problems.

2) Arduino ethernet shield

3) XBee-pro 802.15.4 for serial wireless communications connecting to the Arduino via a XBee shield.
Update: Using the JeeLabs JN4 with RFM12B operating at 868MHz for the wireless communications

4) 128Kbyte I2C FRAM (RAMTRON) this will be used to hold message queues – this is 3.3v

5) 2GB SD card – initially with uALFAT controller (I2C 3.3v), but I intend to use a SD card directly for the final version.

6) I2C serial LCD – based upon my own ATTiny2313 I2C Serial LCD adapter

7) I2C battery backed RTC to use as a time stamp for all readings.

I am using my own level converter (based upon this) to drive the 3.3v I2C bus from 5v.

I have gathered the necessary hardware and will start detailed design at the weekend.

6 comments to New home monitoring setup – part 1

  • And the process towards the police state at home continues….
    How long until you tag us with microchips (or has it already happened!)

  • Now there is a thought!

  • Nick

    I agree with the setup. It is what I was planning.

    Some of the things that were on my plan are this.

    1. Fault tolerance. It’s clear that links can go down.

    What that means to me is that the sensor controllers have to store information, in case the link goes down and forward it on when it comes back up.

    Same with the data logger, and the connection on.

    2. Push or pull?

    Do you push data, or do you pull data?

    My view, data logger pulls data from sensor and pushes out.

    3. Control. If you put a clock on the sensors, then you need to set them remotely. That means sending commands down to the sensors.

    a) Get data
    b) Set clock

    4. Data format. My view is that it could all be xml. The data logger then records xml.

    5. What about a remote viewer?

    6. What about controllers?

    Nick

  • Wondering about the RFM12B instead of the XBee. @andrewdlindsay is doing some range tests and his results may encourage me to change. RFM12B is available for around £4, whilst XBee-pro costs around £22 so there is quite a saving. The Jee Labs node uses the RFM12B. http://shop.jeelabs.com/products/jeenode

  • [...] waiting for part 2!via [John Rambilngs Blog] [...]