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Need a remote control technology.

Discussion in 'Embedded' started by Mike V., Jan 28, 2004.

  1. Mike V.

    Mike V. Guest

    Hi,
    I want to build in a receiver into an 8-bit microcontroller based
    system, and be able to program it via some type of wireless technology
    using a battery operated handheld as small as a garage door opener
    remote control.

    Here's more info:
    1. the data to be transferred over is not big. Probably just 100
    bytes.
    2. Nice to have: i want the communication to be able to penetrate
    aluminum.

    I've looked into IrDa infrared. It won't penetrate aluminum.

    What about the KeeLoq devices from Microchip Technology? Can it be
    used for lightweight data communication?

    How about WLAN? Perhaps i can turn this device into a networked
    device. are there any WLAN chips out there, and does WLAN penetrate
    aluminum?

    Thanks,
    Mike
     
    Mike V., Jan 28, 2004
    #1
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  2. Although it won't go through Ali, infra-red is hard to beat on cost - using a modulated protocol (as
    used on TVs etc.), you can get an integrated receiver module for < 50 cents that handles all the
    analogue stuff and gives you a clean demodulated signal, and the transmitter is a few cents' worth
    of IR LED.
    Data rates of the order of 2Kbit/sec can easily be done - you can get modules which will handle
    faster rates. Look at www.vishay.com TSOP series devices

    Anything else will be much more complicated and expensive.
     
    Mike Harrison, Jan 28, 2004
    #2
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  3. 1. the data to be transferred over is not big. Probably just 100
    It's also highly directional. You might want to try ultrasonic
    communications, using basically the same encoding methods as for
    infra-red signals, maybe.
    You don't want these hassles. It is a major undertaking to add 802.11b
    to a product.
     
    Lewin A.R.W. Edwards, Jan 29, 2004
    #3
  4. Mike V.

    Robert Scott Guest

    You are barking up the wrong tree. All these things are examples of
    protocols. A protocol does not penetrate aluminum. What you want is
    the physical communication channel. Nothing based on EM waves is
    going to penetrate aluminum except for very low frequency magnetic
    waves. I would look into ultrasonics. Sound will penetrate aluminum
    quite well.


    -Robert Scott
    Ypsilanti, Michigan
    (Reply through this forum, not by direct e-mail to me, as automatic reply address is fake.)
     
    Robert Scott, Jan 29, 2004
    #4
  5. Mike V.

    Gary Kato Guest

    Sound will penetrate aluminum
    How about the data transmitter using a digitized voice yelling the numbers out
    and the receiver using voice recognition? I can imagine people looking around
    trying to figure out where the voice is coming from. :)
     
    Gary Kato, Jan 29, 2004
    #5
  6. Mike V.

    Mike V. Guest

    Thanks everyone for their input. It looks like i'll be doing either an
    infrared or cheap RF solution, AND probably requiring that some holes
    or vents be cut into the aluminum to expose the receiver.

    As for garykato's proposal...
    I thought i was the only one being over-imaginative =)
    At one point i was thinking of putting a voice prompt, thinking of
    putting a DTMF generator/decoder, etc. to respond to user input, and
    probably putting a modem into the box. I guess that's what happens
    when i'm trying to make a simple device too high tech. Thanks for the
    thought though!
     
    Mike V., Jan 29, 2004
    #6
  7. For minimum attenuation, the went should be more than a half
    wavelength long, but it can be quite narrow (1 mm). Thus, on 2.45 GHz
    (WLAN, Bluetooth etc.) the went should 8-10 cm long.

    If this is too much, install a BNC socket facing outward in a small
    hole, solder a 1/4 wavelength wire to the to the centre of the socket
    (inside the container). Take a BNC plug and solder a 1/4 wavelength
    wire to it. Insert the plug into the socket and you have a passive
    repeater :). With suitable BNC or N sockets, even moisture can be
    kept on one side of the wall, however, these do not usually tolerate
    any high pressure differences.

    This works best if either station is close to this passive repeater,
    and even better, if at least one end of the link can be connected
    directly by a cable to this "repeater".

    Paul
     
    Paul Keinanen, Jan 29, 2004
    #7
  8. Hi,

    The best one I heard about was Ali Baba solution: "Open Sesame"
    No need to carry anything...
     
    Ulf Samuelsson, Jan 30, 2004
    #8
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