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Original question:

CCS/TMS320F28377D: The debug problem of 28377D or 28377s about CLA

TMS320F28377D: questions about setting "OSR" and "Sinc"

Yuan Tan63
Expert 3280 points

Part Number: TMS320F28377D

Hi team,

Customer have some questions about "OSR" and "Sinc" setting for F28377D filters.

1 Can I change the OSR to numbers which is not 2^n, I mean OSR_125，or OSR_136? is there any influence to the accuracy?

2 From the parameter below, the OSR  has a corresponding SINC, what's the relationship behind that? can I set OSR=128 with sinc=6?

Thank you!

  • 0
    TI__Genius 10845 points

    Hi Yuan,

    2 From the parameter below, the OSR  has a corresponding SINC, what's the relationship behind that? can I set OSR=128 with sinc=6?

    The values in above table are the shift values which need to be configured to keep the result in valid range. For OSR = 128 & Sinc3 filter, shift value of 7 should be used.

    Thanks

    Vasudha

  • 0
    TI__Guru 55700 points
    Yuan,

    1) Yes, you can use OSR = 125 etc. It doesn't necessarily have to be 2^N

    2) Shift value mentioned in Table 13-5 is based on the maximum possible digital output value for a given OSR in 32 bit mode. With OSR = 128, it is possible to get same 16-bit digital value when using shift value of 6 when SD modulator is operating the saturation region. If customer can make sure he will operate only in the linear range of SD-modulator he can use shift value of 6 for OSR = 128.

    Regards,
    Manoj