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IWR1642: What is the functionality of SYNC_IN and SYNC_OUT?

Danny Braunshtein
Prodigy 110 points
Part Number: IWR1642

In order to use multiple IWR1642 devices, I need to know the functionality of sync_in and sync_out.
1) Does sync_in trigger an entire frame? 
2) Does sync_in trigger a single chirp? 
3) If SYNC_IN can be used to trigger chirps, can I re-program chirp parameters between chirps, 
     such that each next chirp will only start when triggered by SYNC_IN? 
4)   To what extent of consistency shall the IWR1642 perform:
      Assume two IWR1642 devices are triggered by the same SYNC_IN signal, and programmed with the same chirp & frame parameters.
      Assume the RF average phase difference between the two transmitters (of the 2 devices) is TETA radians. (Ideally TETA should be 0).
      a) What shall be the standard deviation of TETA following multiple triggers of SYNC_IN?
      b) What shall be the standard deviation (in nSec) of the timing difference between the  A/D clocking of the 2 devices - following multiple triggers of SYNC_IN?

Thanks in advance.

  • 0
    TI__Mastermind 27740 points

    Hi Danny,

    Danny Braunshtein said:
    1) Does sync_in trigger an entire frame? 
    2) Does sync_in trigger a single chirp?

    Sync_in triggers a frame, as noted in section 5.3 of this document, which you may find relevant.

    https://www.ti.com/lit/an/swra574b/swra574b.pdf

    Danny Braunshtein said:
    3) If SYNC_IN can be used to trigger chirps, can I re-program chirp parameters between chirps, 
         such that each next chirp will only start when triggered by SYNC_IN? 

    N/A because it triggers frames.

    Danny Braunshtein said:
    4)   To what extent of consistency shall the IWR1642 perform:
          Assume two IWR1642 devices are triggered by the same SYNC_IN signal, and programmed with the same chirp & frame parameters.
          Assume the RF average phase difference between the two transmitters (of the 2 devices) is TETA radians. (Ideally TETA should be 0).
          a) What shall be the standard deviation of TETA following multiple triggers of SYNC_IN?
          b) What shall be the standard deviation (in nSec) of the timing difference between the  A/D clocking of the 2 devices - following multiple triggers of SYNC_IN?

    Table 1 of the linked document above has similar information on the magnitude of uncertainty of the delays in nanoseconds. You could use them to form a model of your choice for the probability distribution of the delays.