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TSP65950 / TWL4030 Data Format on the Voice PCM Serial Port?

Phil Evans51389
Prodigy 100 points
Other Parts Discussed in Thread: TPS65950


What is the format of the PCM Voice TX & RX data on the TSP65950 Serial Port?

 

 

  • 0
    Prodigy 100 points

    The Tech Manual (doc manual SWCU050e), section 14.4.4.1 says its 16 bit. What I'm seeing on the received is a 16 bit word, but only the 11 LSB's are valid. ie: typical Rx data: 0x07FE, 0x7FF. Upper 5 bits are always 0 - no sign extension. (which is OK, as long as we know). BIG QUESTION: How should the Tx Data be formatted. Assuming its an 11 bit data word, how should things be aligned, sign extended, etc.? Note we're using the OMAP35x EVM, which uses the TWL4030, which is supposed to be an early, functional equivalent to the TSP65950 device.]

     

  • 0 in reply to Phil Evans51389
    TI__Genius 15100 points

    Hi,

    Yes, TPS65950 is functionally equivalent to 4030.

    In the audio format the bits are 0-padded to complete the 16-bits. There shouldnt be any need for specific formatting when you use TPS65950. As long as you ensure that you have the padding as mentioned in the diagrams in document you should be good.

    Let me know if there are any specific concerns for this.

     

    Regards,

    Gandhar.

     

  • 0 in reply to Gandhar Dighe
    Prodigy 100 points

     

    Solved the problem.

    My concern was that we were receiving 11 bit 2's complement data on the McBSP serial port, and we were expecting 16 bit 2's comp.

    Problem was misconfiguration of the McBSP serial port.   It was configured for 12 bit rather than 16 bit operation.

    Now rx'ing 15 bit. 

    I think the 15 vs. 16 bit is related to the "bit delay" configuration.