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ADC3569: <Question> PRBS register setting and ports for ADC3569

shuhei hayashi
Prodigy 80 points
Part Number: ADC3569


Tool/software:

Hi All,

I have two questions about PRBS register settings and ports for ADC3569.

1. I confirmed the "8.3.9.6 Output Scrambler" in data sheet.

     The scrambled output data is stated to be sent with PRBS bits consisting of 0x146.

     However, 0x146 is related to enabling GPIO and does not include PRBS.

     Would you kindly tell me whether the PRBS register and port are correct to be 0x116 and not 0x146?

2. Please tell me the seed value for PRBS23.

Best Regards,
Hayashi

  • 0
    TI__Intellectual 1910 points

    Hi Hayashi-san,

    1) Thank you for catching this, this is atypo in the datasheet. The correct register address is 0x116.

    2) Ideally, the scrambled data can be reconstructed by XORing the output data with the PRBS bit output by the ADC. Can I ask why you want to know the seed value used to generate the PRBS?

    Best,

    Luke Allen

  • 0
    Prodigy 80 points

    Hi Luke-san,

    Thank you so much for your answer.

    1)We understood that the PRBS register value is 0x116.
    　The PBRS of the ADC3569 can be set using register 0x116, but is it necessary for the user to configure the receiving side?

    2)About seed values
    　We are confirming to customer why they want to know the seed value.
    　We will get back to you after confirming the reason from the customer.
    　Also, if a customer uses PRBS23, is the seed value a fixed value?
    　If the seed value is fixed, would you kindly tell me what value is.

    Best Regards,
    Hayashi

  • 0 in reply to shuhei hayashi
    TI__Intellectual 1910 points

    Hi Hayashi-san,

    I believe there is some confusion about how the scrambling works. Yes, you do need to configure the receiving side to unscramble the data. The ADC scrambles the data by generating a singular PRBS bit for each sample. Every data bit for each sample is then XORed with the PRBS bit. The PRBS is sent to the receiver by the ADC, as it is inserted into the sample. You can chose where this bit is insterted using register 0x116. To unscramble the data, the receiver must extract the PRBS bit (based on where you chose to insert it in the sample) and XOR each data bit with the PRBS bit. You do not need to know the seed of the PRBS generator because the PRBS bit is sent to the receiver.

    Best,

    Luke Allen