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Extracting the infrared code of a remote control

Discussion in 'Electronic Basics' started by Infrared, Jun 29, 2004.

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  1. Infrared

    Infrared Guest

    ** This email address will self destruct in 72 hours. **

    The users of some digital cameras with infrared remote shutter release
    ability have discovered codes for universal television remote controls
    which will work on their cameras.

    I own a Nikon D70 and the ML-L3 infrared remote for this camera is
    scarcer than hen's teeth.

    Question #1: Is the procedure to read an IR pulse to attach
    oscilloscope probes to an IR receiver (such as from a used VCR) and then
    scope its terminals?
    [If I owned this remote, I would try this and share the result.]

    Question #2: Is there any way beyond brute force trial and error to
    cross-reference the result of said experiment to the brand and function
    of an appliance? (Such as IR pulse XYZ = Zenith, "Channel Up")

    Question #3: If the pulse information were provided to me, how much
    knowledge and overhead is required to create an IR emitter for this
    purpose? How about to make an intervalometer out of it, whereas it
    would trigger once every 3 minutes, for example? (time lapse
    photography, which the stock item does not do)
  2. Don Bruder

    Don Bruder Guest

    That's one way. Another would be to open the remote, and clip your
    o'scope probes (with suitable scaling) directly on the LED's leads.
    Sorta "cut out the middleman", doncha know.
    SOMEWHERE, someone has a list of how they map, I'm sure. But I'd be
    willing to bet that nobody is willing to give it up at anything that
    resembles a reasonable price. The fact that such a mapping is out there
    is demonstrated by the universal remotes that come with a list of "punch
    in the code for your TV/VCR/cable box/whatever-it-is" presets, as
    opposed to being what I call the "adaptive" type, where you "program" it
    by putting it in some kind of "learn" mode and shooting the existing
    remote at it (which is, of course, rather difficult to do, should the
    original remote be AWOL...)

    Just by the fact that they can be bought, the "punch in a code" remotes
    prove such a list (or at least, a substantial subset of such a list)
    DOES exist, but at the same time, they tell you why it's hard to get
    ahold of one. Why's company X, who has invested the last 3 years and 18
    bajillion East Elbonian Sheckels in the process of chasing down obscure
    VCR remote codings so that they could make *The Ultimate Universal
    Remote* going to let anybody else have the list, y'know?

    Knowledge? You need to know which end of a soldering iron to grab, and
    it would help a lot if you can draw/read a schematic.

    Overhead? A power source and 1 IR LED, plus the circuitry it takes to
    make it flash in the desired pattern(s), plus the timer (A 555 would
    probably work for what it sounds like you're trying to do) circuitry to
    control when it should make the pattern(s).

    Don't look at me for putting any of the above together, though! Like the
    "greedy" remote maker I spoke of above, I don't work for free! :)
    See above. Once you've got basic functionality, adding a timer to
    trigger it at a set interval shouldn't be that difficult.
  3. Si Ballenger

    Si Ballenger Guest

    The remotes seem pretty common for $17. The bottom link may give
    you an idea how to hack one for connection to a timer or such.
  4. John Fields

    John Fields Guest

  5. The simplest thing to do is simply purchase a learning remote like one
    of the ones from Radio Shack or the All-in-One type remotes sold at
    palced like WalMart. By learning remotes, I mean the ones that you can
    hold another remote head to head with it and teach the learning remote
    codes from the other, in this case your digital camera remote.

    You can also buld simple interfaces for these (search google for "JP1
    interface") and there are programs on the web that allow you to modify
    the programming of these remotes as well as access the codes learned
    from other remotes. Try this group for files and FAQ...
  6. Rick

    Rick Guest

    ** This email address will self destruct in 72 hours. **
    I did this exact thing for the new "toy" robot Robosapien. It is very easy,
    but somewhat time consuming. I used a junk box photodiode and my digital
    oscilloscope to capture the 40khz modulated data from the remote (by pressing
    each button and recording the data...uhg). I then used a simple atmel
    microcontroller's timer and output compare pin to generate the 40khz modulated
    codes. Very easy and cheap, and I can now do all sorts of things that were not
    possible with a standard remote. If you want to do things like trigger delays
    and such for your camera, I would suggest you take a similar route.
  7. Rich Grise

    Rich Grise Guest

    Yes, and yes.
    I worked at a place where a guy's job was to set remotes in his little
    fixture and push buttons all day. People sent in remotes from all over
    the world.

    The day they got a P.O. for 200,000 of their universal remotes, the
    company prez, in a meeting, said something like, 'We just sold
    200,000 of these things. We can pretty much do whatever we want to."

  8. John Fields

    John Fields Guest

    I did it for a Sony camcorder remote once, and the method I used was
    to use a small C clamp to hold down the button I wanted to decode,
    then to clamp that C clamp in a rubber-jawed Panavise so I could move
    the whole business around in a predictable way. Then I mounted a
    phototransistor and a pullup resistor on a small piece of perfboard
    and wired them up like this:


    Then I clamped the perfboard in another Panavise and oriented the
    transistor and the IR output of the remote so they were coaxial with
    and close enough to the transistor so that I got a good display on the
    scope. What I found was that instead of just the modulation envelope
    (the demodulated data) being displayed, the bursts of 40kHz carrier
    were being displayed, making it hard to sync the scope and decode an
    entire word. So I made a little detector, like this:

    +---[CR>]--+----+----->TO SCOPE VERTICAL IN
    | | |
    C | |
    IR>))))))B [C] [R]
    E | |
    | | |

    I don't recall what the values of the R and C were (smallish C and
    largish R, AFAIR) but, in conjunction with the holdoff control (analog
    scope) it worked. Once I could recognize the start of the pattern and
    sync to it with the scope horizontal in X1, I switched to X10 and then
    just counted off the ones and zeros as I moved the display across the
    screen with the horizontal position control. Pretty brute force and a
    huge PITA, but it worked!
    You might want to try some of the photography newsgroups; I got a
    pretty comprehensive list of Sony codes that way.

    Alternatively, you night want to try Nikon themselves. Email them;
    what's the worst they can do, not reply?
    Duck soup for both if you know how to talk to a small µC. If you
    don't, then you're talking about something like a 555 running at 40kHz
    which you turn on and off with a pattern you've got stored somewhere
    and another timer to start the sequence every three minutes, let it
    run for a while and then shut it down for the rest of the 3 minutes.
  9. sulphar


    Jul 21, 2010
    Need help for making Robosapien remote

    Hi Rick ,
    I have a robot Robosapien and i don,t have its original remote,i want to make it myself,which microcontroller i should use ,also tell me that Is Robosapien work with 40khz or with 38.2 khz??
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