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TMS320F28379D: SPI - GPIO input qualification

Aditya Ghule1
Intellectual 440 points
Part Number: TMS320F28379D

Hi,

I have been experiencing some noise on the input channels for an SPI port for the 28379D. Would adding a sample window using the GPIO input qualification potentially reduce noise? Do I need to take into account any timing differences if I enable input qualification for (3 or 6 samples) for the SPI input port?

Thank you,

Aditya

  • 0
    TI__Genius 10645 points

    Hi Aditya,

    Aditya Ghule1 said:
    Would adding a sample window using the GPIO input qualification potentially reduce noise?

    Yes, adding a sample window would reduce noise

    Aditya Ghule1 said:
    Do I need to take into account any timing differences if I enable input qualification for (3 or 6 samples) for the SPI input port?

    TRM Section 8.4  and Datasheet Section 8.9.6 describe the timing and how exactly to do the input qualification in detail if you haven't looked at both already.

    Aishwarya

  • 0 in reply to Aishwarya Rajesh
    Intellectual 440 points

    Hi Aishwarya,

    Thanks for the information on the timing setup. 
    section 8.4.1 (aynchronous mode) mentions that some peripherals might cause unexpected behavior so I was curious if there was still a way to use input qualification or if it would cause problems if used as an SPI. 

    TRM(SPRS880O) section 8.4.1:

     

    Thanks,

    Aditya

  • 0 in reply to Aditya Ghule1
    TI__Genius 10645 points

    Aditya,

    This note was included to emphasize that the GPIO pin has to be configured in asynchronous mode to avoid unexpected behavior because the peripheral itself (SPI in this case) is configured to be synchronous already. In other words, in async mode, you should not have any problems.

    To amend to my first reply, you can technically use input qualification, but it is recommended to not use it since the SPI peripheral performs synchronization internally. When you are referring to noise, is this causing issues with any of the SPI signals? I've attached this thread that can be helpful in debugging the noise you are seeing.

    Aishwarya