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Calibration for TDC7200

ttd
Mastermind 7670 points
Other Parts Discussed in Thread: TDC7200

Dear Technical Support Team,

I have a question about TDC7200 Caribration.

1.)
When CALIBRATION1 and CALIBRATION2 registers are updated?
Datasheet describes following. Are these mesured from "START" signal?

-------------
The first is a measurement of a single clock cycle period of the external clock.

the second measurement is for the number of external CLOCK periods set
by the CALIBRATION2_PERDIOS in the CONFIG2 register.

2.)
Is it possible that START_MEAS is "1" and  CALIBRATION1/2 are updated at the same time.
I worry that CALIBRATION1/2 are reset before readout.

3.)
Are CALIBRATION1 and CALIBRATION2 updated while FORCE_CAL=0 except for interrupted measurement like counter overflow or missing STOP signal?
Dose it mean that caliblation is not perfomed only causing illegal situation?

4.)
What setting of CALIBRATION2_PERIOD is better for minimizing vary?
measuring 40CLOCK periods?

Best Regrds,
y.i

  • 0
    TI__Mastermind 21685 points
    1. Calibration1 and Calibration2 measurements are done every time after a measurement is done. A measurement is started when start bit is set and it is done or completed when the programmed number of stop pulses are received. After a measurement is done, the internal time base is used to measure 1 clock period and CALIBRATION2_PERIOD of the external clock.

    2/3. If Calibration1 and Calibration2 are zero implies the measurement is not complete. Either the programmed number of stop pulses did not come or the counters overflow and the measurement is interrupted.


    4. In general, higher calibration2_period improves accuracy. To begin you should go with the default value of 10.
  • 0 in reply to Vishy Viswanathan
    Prodigy 10 points
    Hello, thanks for your answer.
    Just to further clarify:
    1. If there's no interrupt/error/timeout happens during measurement, Calibration 1 and 2 are always conducted at the end of each successful measurement even when FORCE_CAL = 0, right?
    2. so setting FORCE_CAL = 1 only makes sure the calibration procedure is conducted when a measurement is interrupted.
  • 0 in reply to Yue Lu
    TI__Mastermind 31655 points
    Hi Yue,

    You are correct on both points.

    Regards,