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PGA460: USART spec

Yasushi Fujiwara
Genius 12725 points
Part Number: PGA460

Tool/software:

Hello Experts,

My customer has question as follows. Would you answer it, please?
1. A following figure is for PGA460 side or Host side?


2. Would you provide AC characteristics such as setup/hold time, delay time and so on, please?

Best Regards,
Fujiwara

  • 0
    TI__Mastermind 23045 points

    Hello Fujiwara,

    1.  A following figure is for PGA460 side or Host side?
      1. The capture shown above is for the PGA460 device side.
    2. Would you provide AC characteristics such as setup/hold time, delay time and so on, please?
      1. These specifications are not something that was characterized on the PGA460 because the UART interface standard does not define these specifications for standard UART operation since it relies on start/stop bits along with timing of the specific baud rate. Synchronous UART on the PGA460 is mainly used to extract raw data from the PGA460 and not for use as the standard communication method with the sensor. In this mode the PGA460 is the only one providing data while the host MCU simply provides a clock input to the device at 8MHz in order to extract the raw data.

    Best,

    Isaac

  • 0 in reply to Isaac Lara
    TI__Genius 12725 points

    Hello Isaac,

    Customer checked EVM and provided a following waveform. It seems that data is sampled by rising edge and data is shifted by falling edge. So it is opposite, compared with datasheet. Customer has changed a data sampling timing to falling edge, but it did not communicate. Would you clarify which one is correct, please?

    * Note that it seems noisy waveform but it does not care of this topic.
    * yellow: SCLK, Green: RXD, Magenta: TXD

    Best Regards,
    Fujiwara

  • 0 in reply to Yasushi Fujiwara
    TI__Genius 12725 points

    Hello Isaac,

    I understand you did not characterize AC timing. Would you tell typical value/target value of AC timing? Customer would like to know that for the reference to design MCU side.

    Best Regards,
    Fujiwara

  • 0 in reply to Yasushi Fujiwara
    TI__Mastermind 23045 points

    Hello Fujiwara,

    Let me look into your question and I will get back to you tomorrow.

    Best,

    Isaac

  • 0 in reply to Isaac Lara
    TI__Mastermind 23045 points

    Hello Fujiwara,

    I checked this on the EVM and it doesn't matter if I sample on the rising or the falling edge while the shift happens on the opposite of what I selected for the sampling. What I did notice was that the data has different formats depending on what selection is made.

    Such as when I did the bandpass filter output the data was in 2's complement but when I did the LP filter output the data just good as it was. I don't have any information the AC timing I will have to check with the team and get back to you.

    Best,

    Isaac

  • 0 in reply to Isaac Lara
    TI__Mastermind 21250 points

    Fujiwarea-san,

    Thank you for your patience while we look into more details regarding the AC timing.  Isaac is currently out of office for holiday travel, and the many others will be out of office largely until after the new year.  We thank you and will continue to look into this as soon as we can.

    Thanks,

    Scott