Operate Switches with Creative iNFRA CD-ROM remote control

Discussion in 'General Electronics Chat' started by VBIT, Oct 27, 2007.

  1. VBIT

    Thread Starter New Member

    Oct 25, 2007
    2
    0
    I want to operate my bedroom light and fan switches with my old Creative iNFRA CD-ROM infra read remote control.
    My First Problem is how can I decode information coming from remote? Is there any simple way to detect it? The best in my mind is some how I able to find some standard IC that decode it for me.

    What you people say?
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    It's very easy if you have an oscilloscope. Simply set up a phototransistor to receive the pulses from the control and use the o'scope to visualize them.
     
  3. VBIT

    Thread Starter New Member

    Oct 25, 2007
    2
    0
    Thanks for reply

    First I don’t have oscilloscope
    And second how can I find standard IC that can decode the waveform I found on oscilloscope?
     
  4. GS3

    Senior Member

    Sep 21, 2007
    408
    35
    This is more complex than you may think and the best way is to find the receiver circuit which matches the transmitter. The place to find it would be in the discarded DVD player or whatever it was. Other than that you may have difficulty.

    To give you an example, I have run into a similar problem recently. I wanted to have a second remote control for my satelite TV receiver so I could control it from another room but I have no idea what transmitter it is.

    So I spent a whole afternoon identifying the information sent. Believe me, this is tricky because pulses are modulated on a ~38 Khz carrier. I spent an entire afternoon and this is what I found:

    The modulating signal has 27 bits of 8.8 ms (112.5 bps) so that the complete instruction takes about 240 ms. As long as a key is pressed the command is repeated about 4 times per second.
    Code ( (Unknown Language)):
    1.  
    2.           bits: 1  2  2         10           12
    3. 01  AV          1 01 XX 1001010101 010101101010
    4. 02  Red         1 01 XX 1001010101 010110010101
    5. 03  Green       1 01 XX 1001010101 010110010110
    6. 04  Blue        1 01 XX 1001010101 010110011010
    7. 05  Yellow      1 01 XX 1001010101 010110100110
    8. 06  Exit        1 01 XX 1001010101 011001011001
    9. 07  i-epg       1 01 XX 1001010101 011001011010
    10. 08  List        1 01 XX 1001010101 011001100110
    11. 09  Swap        1 01 XX 1001010101 011010100110
    12. 10  Ch-down     1 01 XX 1001010101 011010101001
    13. 11  CH-up       1 01 XX 1001010101 011010101010
    14. 12  Vol-down    1 01 XX 1001010101 100110101001
    15. 13  Vol-up      1 01 XX 1001010101 100110101010
    16. 14  Mute        1 01 XX 1001010101 101001011001
    17. 15  On/Off      1 01 XX 1001010101 101001011010
    18. 16  9           1 01 XX 1001010101 101001101001
    19. 17  8           1 01 XX 1001010101 101001101010
    20. 18  7           1 01 XX 1001010101 101010010101
    21. 19  6           1 01 XX 1001010101 101010010110
    22. 20  5           1 01 XX 1001010101 101010011001
    23. 21  4           1 01 XX 1001010101 101010011010
    24. 22  3           1 01 XX 1001010101 101010100101
    25. 23  2           1 01 XX 1001010101 101010100110
    26. 24  1           1 01 XX 1001010101 101010101001
    27. 25  0           1 01 XX 1001010101 101010101010
    28. 26  OK          1 10 XX 1001010101 100110010101
    29. 27  Menu        1 10 XX 1001010101 100110100110
    30. 28  TV          1 10 XX 1001010101 101010011001
    31. 29  Radio       1 10 XX 1001010101 101010011010
    First bit is always "1"(start).
    Bits 2 and 3 are always "01" except keys OK, TV, Radio and Menu in which case they are "10". I have no idea as to the whyness of this.
    Bits 4 and 5 alternate between "10" and "01" when the same key is pressed repeatedly. This tells the receiver that the same key was pressed again and that it is not receiving the same key pressing. first press sends "10", next pressing "01"etc.
    The next 10 bits, from 6 to 15 are always "1001010101". I imagine this is a product ID so that one remote does not interfere with other remotes for other products.
    The next 12 bits, from 16 to 27 carry a different code for each key.
    In all these codes there are never more than two ones or two zeros consecutively.

    This is just one particular example but it shows how these things are complex and it is not trivial to generate or decode the signals. You would need something programmable as even the generic IC would need to be programmed with the product code etc.
     
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