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TMS320F28027: Flashing via SPI - issue

Jens G
Expert 3365 points
Part Number: TMS320F28027


Hi TI- Team,

my customer has problems with flashing via SPI. The Issue is, that receives and sends dates are NOT synchronous (shifts between the bits).

If he changes the recommended capacitor on Vdda from 2.2uF up to 4.7uF the communication is working.

Now, we have to find an answer, what the root cause for this behavior is!

Thanks and best regards,

Jens

  • 0
    Guru 30330 points
    Jens,

    To be clear, If he changes the capacitance on the VDDA pin, and only the VDDA pin, we is successfully able to program the device?

    Are VDDA and VDDIO coming from the same supply? Is there also a 2.2uF on VDDIO?
    Is the customer using Internal VREG?
    If using Internal VREG, does VDD have a minimum of 1.2uF per pin to GND?

    Can you send screen captures of a good signal transmission and also during a bad transmission?

    Thanks,
    Mark
  • 0 in reply to Mark Labbato
    Guru 30330 points
    Jens,

    Based on the schematic which I received offline, there is nothing outstanding. All of the decoupling caps are present in the schematic, and the customer is using the Internal VREG.

    What debug steps has the customer done?
    Does this failure occur for all devices tested? Does this occur on only one board or multiple devices?

    Can you please share some captures of a bad transmission vs good transmission?

    Thanks,
    Mark
  • 0 in reply to Mark Labbato
    TI__Expert 3365 points

    Hi Mark ,

    there are no screenshots of this behavior. The issue was visible on multiple boards. What could be important is, that this issue occurs only in time of flashing. In the normal application, the SPI works like expected.

    Which kind of test could/should we can do to validate the root cause?

    Best regards,

    Jens