• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 31 subscribers
  • Views 164 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TDC7200: Minimum Time requiriered between STOP and next START signal during Multi-Cycle averaging in measurement Mode 2

Luca Frei1
Prodigy 30 points
Part Number: TDC7200

Hi, 

I am using a TDC7200 with a configured multicycle averaging of 64. Calibration register 2 is set to 2 clock periods.

As I understand it, calibration 2 is always performed after the last STOP signal is received. So with a multi-cycle averaging of 64, it is performed 64 times, did I understand that correctly? When I observe the signals (diagram below), I see that the time (delta_t_max) between the last STOP signal and the TRIGG signal is about 8 clock cycles. This is too much for my application, I expected 2 since I configured it to 2.

Is there any way to turn off or shorten calibration 2? A formula/explanation for the measured delta_t_max would also help tremendously.

Thank you very much

  • 0
    TI__Mastermind 19610 points

    Hello Luca,
    Thank you for posting to the sending forum! Please allow me to review your question and I will get back to you as soon as possible.

    Best,

    Isaac

  • +1 in reply to Isaac Lara
    TI__Mastermind 19610 points

    Hey Luca,

    Thanks for the patience, that is correct the calibration is performed after each last STOP signal is received. So a calibration is performed 64 times in a 64 measurement cycles.

    Please note that this is a two-point calibration method, so the device will sample the external clock a two separate instances. The first time it will sample a single clock cycle and the second time it will sample the number of requested calibration periods.

    This is then compared to the internal clock that is used for the measurements and the results of the calibration are stored in the CALIBRATION1 and CALIBRATION2 registers, all of these calibration transactions take time to perform hence why the TRIGG is not updated immediately after the sampling of the external clock is completed. Unfortunately I do not have a formula for calculating the max time it may take for the TRIGG pin to be update after the last stop. I believe using the two measurement cycles is the shortest configuration available on the device.

    Best,

    Isaac