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DSA serial reception for CD player display

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  • DSA serial reception for CD player display

    Hi, I've been trying, for a few days now, to implement the DSA protocol into my µLCD 35DT (reception only). The objective of this task is to display properly the data sent by a CD player (especially time).

    First I thought I could use the SPI fonctions of the Diablo16 but my signal frequency is 125kHz (not available in SPI mode...) so I assumed that it's not possible to see it as SPI. Is it ?

    Today I use the "bus_SetChangeInterrupt()" instruction to detect a change on my clock signal (more precisely a rising edge) then I store my 8 first bit in my byte 1, the 8 bit next in byte 2 etc... then I display what I need to display.
    The problem is that the display is kind of "freestyle" for now ^^ Data are not read correctly and I'm pretty sure it's a problem of timing. Indeed the interrupt seems to by quite slow and I need it every 8µs.

    Do you think it is possible to read properly this signal using only the Diablo16 on Visi ? Do you have any clue about that ? Thanks.

    I've attached below the shape of my DSA signal (with some timings) + Datasheet of DSA protocol :
    Attached Files

  • #2
    Hmm, never heard of DSA and google doesn't seem to know much about it either.

    I wouldn't expect you to be able to read it, it's just too high a frequency for that sort of 'decoding'.

    Is there such a thing as a DSA to UART converter?


    • #3
      It's a Philips protocol only used in their CD players, so yes it's a pain to get information about it...

      Ok. But i don't understand, the operating fréquency of a diablo16 is quite high, I expected it to be fast enough (because i juste have to take one good frame every second).

      Do you think I could 'decode' that with a µC (PIC) and then send serial instructions to my display ? I really hope so because if not I don't see any other alternative.


      • #4
        Yeah, I reckon you should be able to so that without too much dufficulty