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OEM chips for X-10 available?

Discussion in 'Electronic Design' started by Eduardo Gimeno, Feb 8, 2005.

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  1. mike

    mike Guest

    Well, if you've got a wire...
    PIC16F87Xa. Builtin serial port, whether you need level translator
    depends on length and noise. Onechip, lots of i/o.
    Probably can find a cheaper more current part with enough capability.
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  2. Brian

    Brian Guest

    I don't know about an "all-in-one" chip. It would have to handle 120V
    or 220V power input to synchronize with the zero crossing. The PL513,
    TW523, LM465 and CM17A units that X-10 sells are fairly cheap. But
    you'll need a TW723 (or is it TW7223?) for 220V, 50Hz systems, if
    that's what Spain uses.

    There's an article in the current Circuit Cellar about using a CM17A
    with an RS232 UART.

    - Brian
  3. John Fields

    John Fields Guest

    Somehow, I seem to be missing something here.

    What, specifically, do you want?

    Somewhere upstream I thought I heard you ask for a way to transmit the
    state of eight dipswitches to a remote location using the power line
    as a communications medium. Is that all you want, or is there more to
  4. John, what I need is the following:

    I need to find some IC, Chip, module, etc... which performs all the
    protocol/signal processing/... for transmitting control information
    over a line. At first I was proposing PLC, because I read something
    about X-10 and seemed OK. But now, I can assume using a dedicated line
    because I have an empty spare electrical tube along all the house.

    I just want to have all the stuff X-10 does. I.e: Remote
    lamp/appliance switching, remote IR detection, automated house control
    from a computer, etc...

    I will not make any commercial product. I just want to spend my time
    doing some useful installation at my own home.

    I would like to find a small and cheap module/ic which I can fit in a
    reduced size PCB of my own with a microcontroller (programmed by me)
    to install in the wall switches and plugs. I can use SMD components.

    What I said about using dipswitches an so on was: I would like to find
    a very simple to use IC, which, for example, would have some pins to
    select the station (ie 8 external dipswitches), 2 pins for the signal
    from the line, and some pins for the processed command, which I could
    feed to my microcontroller. I now I am asking for too much... but
    maybe someone knows something which seems to this.

    I do not discard using the microcontroller itself to implement the
    whole protocol over a serial port, anyhow.

    Regards and thanks to everyone for your replies!

  5. Brian, if I use TW-XXX I cannot embed it into the wall switch or plug,
    due to the huge size of the module. As I stated before, I can use a
    dedicated line, so I can avoid all the stuff about zero-crossing and
    so on. I have quite much experience on ATMega microcontrollers, also
    quite much on SGS-Thomson (ST-62XX) and some on PICs. I would need to
    find the simplest and smallest one having serial port and at least 12
    IOs (8 for station ID dips), 2 for serial port, and 2 for command

  6. John Fields

    John Fields Guest

    If you already know how to work with microcontrollers, why not roll
    your own?

    As far as getting the signal on the line goes, it's pretty simple;
    just capacitively couple a high-frequency tone burst signal onto the
    mains using a frequency far enough displaced from the mains frequency
    that the capacitor looks like a very large reactance to the mains
    frequency while being small enough to let your signalling frequency
    pass, like this:

    Here's a link to some X10 technical documents:
  7. I'd think this through some more.

    1. House resale. X-10 stuff is pretty normal these days. X-10 outlets
    and switches wouldn't scare anyone away. I'd not buy a house that had
    DIY electrical components in it.

    2. Legalities. Many areas have laws regarding what can be tied into
    the mains. Your widgets aren't going to be UL/CSA/whatever approved.

    3. Liability. If the house catches on fire or someone gets hurt...

    4. Insurance. If the house catches on fire you don't have any. If the
    insurance company even finds out you have a modified system and
    unapproved equipment, you don't have any.

    Personally, I'd find another hobby or at least stick with X10/Leviton
    devices connected into the mains. I wouldn't be so worried about
    things that plug in, though even here I'd be using approved wall warts,
    if at all possible.
  8. Can you do this without a transformer?
    And if not, can you use a cheap off the shelf or surplus xfmr?
  9. Rich Grise

    Rich Grise Guest

    Then install an ethernet. Run Cat 5 UTP through all of the conduit - you
    could even use all 4 pairs, and have two actual RJ45s at each outlet, if
    you want. You'd have to decide where your main hub is, and mount a jack
    there for each one around the house, of course. (You can't daisy-chain

    I can't imagine not being able to find some kind of simple ethernet
    interface-on-a-chip, or for that matter, since they're your wires, you
    could send something as simple as a contact closure, or 12 VDC to operate
    a relay at the remote end.

    Your boxes at the lamp end would just plug in like an X-10 box or RS
    remote lamp box, but have just a relay, that plugs into the RJ45 jack that
    you're using just to send 12V on one of the sets that doesn't use ethernet.

    Or, you could plug in a computer and have a real live network. :)

    And since the wall plates just have RJ45s, and it's cat 5 in the conduit,
    there's no code to worry about, and you might even _increase_ the
    resale value of the house! ("... and this is the Server Room..." ;-) )

    Have Fun!
  10. Reg

    Reg Guest

    Interestingly, I just got finished with a San Francisco city inspector
    looking at some new AC wiring, and the project also involved running some

    According to them, the 2002 NEC regs will take effect in August. They
    said that had the work taken place after that I would be required to get
    specific permits for the "communications" wire.
  11. John Fields

    John Fields Guest


    MAINS>--+-----+-------------/ /-----+-----+------------------
    | | | |
    | [C] | [C]
    | | | |
    | +--+--+ | +--+--+
    +--| TX | +--| RX |--[LOAD]--+
    | | | | |
    +--| | +--| |----------+
    | +-----+ | +-----+
    | |
    | |
    MAINS>--+------------------/ /------+------------------------

    Looking at the caps connected to the mains, if inside the TX box we
    have something like this,:

    | |
    +--+--+ [C1]
    |TONE | |
    | GEN | |
    +--+--+ [R1]
    | |

    what we'll want to do is keep the 170V peak AC from damaging the tone
    burst generator, while at the same time allowing the generator to
    couple bursts of a high frequency tone to the mains. Just for grins,
    let's say that we'd like to keep the 60Hz down to about +/- a volt at
    the R1C1 junction, and we'd like R1 to be about 100 ohms. That means
    that we'll have to limit the 60Hz current through R1 to

    E 1V
    I = --- = ------ = 0.01A
    R 100R

    With 170V on the mains, that means that the impedance of R1C1 has to
    look like:

    Z = ------- = 17000 ohms

    Now, since

    Z = sqrt (R² + Xc²)

    and we need to find the value of C1, we can rearrange to get the
    reactance of C1:

    Xc = sqrt (Z² - R²) = sqrt (17000² - 100²) ~ 17000R

    And the capacitance will be:

    C = ---------- ~ 0.156µF
    2pi f Xc

    So now we have this:

    | |
    +--+--+ [0.15µF]
    |TONE | |
    | GEN | |
    +--+--+ [100R]
    | |

    and we want to place a signal on the mains. First we'll choose a nice
    high frequency (say 100kHz) so that the reactance of C1 will be nice
    and low to it, allowing it to pass through and onto the mains without
    attenuating it too much.

    At 100kHz the reactance of 0.15µF will be

    Xc = --------- ~ 10 ohms
    2pi f C

    So that looks pretty good, and the last thing that needs to be done is
    to decide on the output amplitude of the tone burst generator.

    If we say that our receiver has a sensitivity threshold of 100mV at
    100kHz during the mains zero-crossings, and we want the receiver to
    work with a 10kW load on the mains, then our circuit starts to look
    like this:

    | | |
    +--+--+ [10R] |
    |TONE | | |
    |BURST+-------+ [1.44R]
    | GEN | | |
    +--+--+ [100R] |
    | | |

    Which is essentially this:

    |TONE |
    | GEN | | |
    +--+--+ [100R] [10R]R1
    | | |
    | | +---E2
    | | |
    | | [1.44R]R2
    | | |

    In order to have E2 be 0.1V, we'll need E1 to be

    (R1 + R2)
    E1 = E2 ----------- = 0.794V

    and the generator will have to pump current into the impedance formed
    by everything across the mains, which reduces to:

    | |
    | [10R]
    [100R] |
    | [1.44R]
    | |

    and, finally, to:


    which is close enough to 10 ohms for our purpose, which is to
    determine how much current the tone burst generator has to supply into
    10 ohms to get a drop of 0.794 across it, and since

    E 0.79V
    I = --- = ------- = 0.079A ~ 80mA
    R 10R

    it'll be eminently doable, and as a matter of fact, upping it to 1V
    would get us better receiver operation and only require 100 mA out of
    the tone burst generator.
  12. John, thanks for your calculation for the adapter part. Maybe I will
    have to use them in short (converted to 50Hz and 220 V...)

    Some comments about the replies:

    1.-Cabling all the house with Ethernet would be the most profitable
    solution, but would also involve making a really big project of the
    design, and filling the tubes up with lots of cables. Suppose I need
    to have control over ALL the lamps and from all the switches. My house
    (2 floors) would have several hubs/switches at given places, and some
    tubes would carry more cables than expected due to design of network
    (avoid more switches)

    2.-I don't know yet the legal problems I would have here in Spain if I
    modify the electrical installation, or from the assurance company in
    case of fire... I should ask about it before doing anything.

    3.-I think I will consider two choices:
    a) Using a dedicated cable with a low level protocol, i.e. with
    RS485, and a top level protocol of my own in a PIC, for example. The
    cable would only have to go through all the switches one time, like a

    b) Using a home-made X10-like protocol, with the indications from
    John Fields. Positive: I would avoid using the dedicated cable.
    Negative: I would have to train for a while until building the right
    "interface" module.

    Once again, thanks to everyone for all the replies and help!
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