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How to set a known overflow of TDC7200?

Eric Tian61
Intellectual 890 points
Other Parts Discussed in Thread: TDC7200

Hi,

I the section 8.3.3.2 in the user's guide of TDC7200, I know I can write to COARSE_CNTR_OVF to set the overflow of TDC7200, but if I want to set a 300ns overflow in mode 1, how do I calculate the value should be written to COARSE_CNTR_OVF? Do I need todo the following steps?

(1) Read calCount

(2) Calculate normLSB = CLOCKperiod/calCount

(3) COARSE_CNTR_OVF = 300ns/normLSB

Can I set a 300ns overflow without reading calCount? Thanks.

Regards,

Eric

  • 0
    TI__Mastermind 21685 points
    You should use

    COARSE_CNTR_OVF = 300ns / (normLSB * 63).

    where 63 is the number of delay cells in the internal ring oscillator.

    You can use the typical normLSB value of 55ps but if you want higher accuracy, then you can measure normLSB (once every minute or so as your application permits) and update the COARSE_CNTR_OVF register.

    Thanks,
    Vishy