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AM6442: Operating Frequency on Tap mode of OSPI

Hideaki Matsumoto
Expert 8770 points
Part Number: AM6442

Hi,

My customer would like to confirm about the frequency on OSPI tap mode. Could you please answer their questions below.

    Q1: Can the PHY mode not be used if SDR 8S-8S-8S is used ?

           It seems like the driver is configured that way.

    Q2: The customer believes that tap mode is activated when PHY mode is disabled (OSPI_CONFIG_REG Register bit3 = 0). Are they correct?

    Q3: If Q2 is yes, is it impossible to achieve 50MHz or higher with SDR in tap mode?

          (Actually, with PHY mode disabled, 100MHz can be set and it seems to be working.)

          Is it prohibited by some reason ? Actually, it can work at >50MHz on SDR.

 

 They’re asking you above question by referring Chapter 7.10.5.14 OSPI in the datasheet. 

 From the description in this Chapter, the software support is still needed in order to achieve DDR due to Errata. .Instead it looks like it's finally possible.to achieve with SDR 100MHz.

 

Thanks and regards,

Hideaki

  • 0
    TI__Mastermind 32274 points

    Hello Hideaki,

    Thanks for reaching out via TI E2E Support forum.

    Please expect delayed responses due to the holidays.

    Thanks for your patience.

    Regards,

    Vaibhav

  • 0 in reply to Vaibhav Kumar
    TI__Expert 4445 points

    Q1: Can the PHY mode not be used if SDR 8S-8S-8S is used ?

    A1: The PHY mode can be used in both SDR 8S-8S-8S and DDR 8D-8D-8D, the restriction may be what's in S/W currently. For anything not in S/W you will need to evaluate if it's worth adding on to the S/W we provide.

    Q2: The customer believes that tap mode is activated when PHY mode is disabled (OSPI_CONFIG_REG Register bit3 = 0). Are they correct?

    A2: The customer is correct.

    Q3: If Q2 is yes, is it impossible to achieve 50MHz or higher with SDR in tap mode?

              (Actually, with PHY mode disabled, 100MHz can be set and it seems to be working.)

              Is it prohibited by some reason ? Actually, it can work at >50MHz on SDR.

    A3: We only recommend and support using 50 MHz SDR Tap Mode for robust operation; it's possible the customer can see it working in one instance, but it's not guaranteed across operating conditions. Please see the AM6442 datasheet for our device timings and frequency limits ( for this they can start in OSPI0 Switching Characteristics – Tap SDR Mode): https://www.ti.com/lit/ds/symlink/am6442.pdf 

    Sincerely,

    Lucas