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IWR6443: Frameless chirping configuration

Joshua Sendall
Prodigy 91 points
Part Number: IWR6443


Hi,

We've got a need to keep a constant stream of equally spaced chirps in time, and the current minimum inter-frame time limitation will cause a break in this. Is there any way to configure an endless frame? For example using continuous mode with some settings?

"Frame repitition period

                  PERIOD >= Sum total time of all chirps + InterFrameBlankTime,
                  where, Sum total time of all chirps = Num Loops * Num chirps * Chirp Period. 
                  InterFrameBlankTime is primarily for sensor calibration/monitoring, thermal
                  control, transferring out any safety monitoring data if requested, hardware
                  reconfiguration for next frame, re-triggering of next frame.
                  InterFrameBlankTime >= 300 μs typically.
                  Add 150 us to InterFrameBlankTime if data-path reconfiguration needed in frame
                  boundary due to change in profile."
What happens if you disobey this limitation?

Thanks!

  • 0
    TI__Mastermind 20520 points

    Hello.

    What you are suggesting sounds like continuous mode, but I just wanted to clarify if you were looking to use continuous mode or if you had tried that and it did not meet what you were looking to do.  If you are looking to do continuous wave mode, our devices support CW mode but do not have any support for it in the OOB demo or any of our other demos.  However, there are some APIs in the mmwave link layer that you can explore/utilize for CW mode purposes.  CW mode is also something that is more easily supported through mmWave studio and the DCA1000 when doing raw data capture.  I have linked some E2E's below for reference.

    https://e2e.ti.com/support/sensors-group/sensors/f/sensors-forum/952410/iwr6843isk-continuous-transmit-mode-single-frequency

    https://e2e.ti.com/support/sensors-group/sensors/f/sensors-forum/1164289/iwr6843isk-configure-single-point-frequency-continuous-mode-in-the-mmwave_demo_visualizer-using-the-iwr6843isk-board

    Sincerely,

    Santosh

  • 0 in reply to Santosh Krishnan
    Prodigy 91 points

    Hi Santosh, thanks for the quick response.

    I was under the impression that continuous mode doesn't create FMCW sweeps, but maybe that is wrong?

    I think what we're looking for would be "Continuous Framing Mode". Essentially if we could have a normal configuration but set "num loops" to 0 for an infinitely long frame.

    Alternatively, is there a way to disable some of the interframe stuff to reduce the 300 us interframe time? In our application only need to run like this for a few seconds so I hope we can get away with forgoing with some of the longer-term calibration steps.

  • 0 in reply to Joshua Sendall
    TI__Mastermind 20520 points

    Hello Joshua.

    Joshua Sendall said:
    I think what we're looking for would be "Continuous Framing Mode". Essentially if we could have a normal configuration but set "num loops" to 0 for an infinitely long frame.

    I understand.  There is a way to run for an endless number of frames, but not for one infinitely long frame.  Let me look into this further and get back to you by Friday on this.

    Joshua Sendall said:
    Alternatively, is there a way to disable some of the interframe stuff to reduce the 300 us interframe time? In our application only need to run like this for a few seconds so I hope we can get away with forgoing with some of the longer-term calibration steps.

    Could you clarify what you mean by disabling some of the interframe steps?  Is there a specific step you want to disable?  Let me check if this is possible and I will provide a follow up by Friday.

    Sincerely,

    Santosh

  • 0 in reply to Santosh Krishnan
    Prodigy 91 points

    Thanks very much! I think that answers my initial question.

    As for disabling the interframe steps, I'm just wondering if all of them are necessary for our specific use case, or if we can forgo some of them to reduce the inter-frame time to < 300us.

  • 0 in reply to Joshua Sendall
    TI__Mastermind 20520 points

    Hello.

    I think most of those steps are necessary, especially the calibration, but the calibration will run once and store the values in memory to be accessed later(for factory calibration).  You can definitely try disabling them, but it may result in unintended consequences.  According to the document you were referring to, the interframe time is typically 300 us, but it can be reduced in certain situations as suggested by the note.  I believe the valid range that is referred to is for the overall frame time.

    Santosh Krishnan said:
    I understand.  There is a way to run for an endless number of frames, but not for one infinitely long frame.  Let me look into this further and get back to you by Friday on this.

    You can run the application for an endless number of frames by setting the numFrames parameter in the frameCfg to 0.

    Sincerely,

    Santosh.