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LM49352: "SOMETHING CLIPPED" GPIO output

Jonathan9420
Expert 2056 points
Part Number: LM49352


Can you explain how the GPIO is used?

GPIO_MODE register lets us set it to any of these:

ADC CLIPPED (out)
DAC CLIPPED (out)
SOMETHING CLIPPED (out)

Does this mean it will toggle to light an LED when the ADC signal is clipping?  Is it a pulse or does it stay latched forever?

Does this happen at 0 dBFS,  -1 dBFS, etc.? 

Does "SOMETHING" mean "either ADC or DAC" or does it include any internal circuitry?  (Since near-clipping channels could be summed to produce a clipping signal)

How does it handle the stereo channels?  (Maybe it's in sync with the LRCK signal so the two channels can be separated digitally?)

Can GPIO be used at the same time as PORT2 if port 2 is input-only?

  • 0
    TI__Mastermind 30220 points
    Jonathan,

    I recommend the GPIO not be used to drive an LED directly. you can use a simple FET or Transistor do do this. as for the behavior of the GPIO in this situation I will have to look deeper into this.
    "Something clipped" likely includes all of the clipping monitors in registers 0x9A (ADC FXCLIP) and 0xBA (DAC FXCLIP) while The ADC clip or DAC clip only refers to the ADC or DAC.

    I believe that PORT2 SDI is still functional, it is only PORT2_SDO that is not available. I will have to look into this to be certain, but there is no good reason why the GPIO register should disable the entire port2 block.

    We are in the process of creating an EVM for this device as the original EVM was discontinued a few years back due to some supporting devices being discontinued and no pin-pin compatible devices being available.
    This device remains popular, and we do receive a fair number of questions like yours, and so we have recently brought the design files out of the archive for our own reference. once we have an EVM again it will be easier to check on some of this without diving into the design files.

    Best regards,
    -Steve Wilson
  • 0 in reply to Steve-Wilson
    Expert 2056 points
    Oh I hadn't noticed FXCLIP, that would be helpful in itself
  • 0 in reply to Jonathan9420
    TI__Mastermind 30220 points
    Jonathan,

    I had a family emergency today (Monday, July 30th) and didn't return to the office as I had planned. I will be in tomorrow. My apologies for the delay

    best regards,
    -STeve Wilson
  • 0 in reply to Steve-Wilson
    Expert 2056 points

    No problem, it's not urgent