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Compiler/IWR1642BOOST: change samples per chirp

Marc Bjelkanovic
Prodigy 20 points
Part Number: IWR1642BOOST

Tool/software: TI C/C++ Compiler

Hello there,

I'm trying to change the samples per chirp in a config to higher values. All values to 512 work without problems, but after 512  the mmWave Demo Visualizer plots don't start and the console gives the message: 

mmwDemo:/>sensorStart
DSS Exception: dss/dss_data_path.c, line 3791.

I looked in the dss_data_path code and it seems like "MmwDemo_dssAssert(heapUsed <= SOC_XWR16XX_DSS_L3RAM_SIZE);" is the problem.

My questions are: - what exactly does this part of the dss_data_path code?

  - do I have to change other values in my configuration too, to get a higher sample per chirp rate without errors?

Thanks

  • 0
    TI__Mastermind 30405 points

    Hi Marc,

    As you increase the number of samples, the memory required to store the radar cube goes up and at some point, the memory requirement will exceed the available L3 memory as indicated by the exception you see here.

    Please look at the following thread for a similar discussion: IWR1642: L3 Memory Calculation

    Based on the above calculation, you can try reducing the number of chirps for a given scenario to fit the resulting radar cube in the available L3 memory. But please note that you may also run into processing time limitation since it will take longer to process the larger number of samples for each chirp (and each virtual antenna).

    I'm not sure what your objective is but if your aim is to increase the range accuracy by using a higher order FFT, there are other ways to achieve this instead of  increasing the number of ADC samples. Please look at the 16xx - High Accuracy Range Measurement lab which demonstrates the zoom FFT technique for higher accuracy. The lab includes complete source code and CCS project along-with a step-by-step user guide.

    Lab : 16xx - High Accuracy Range Measurement

    Regards

    -Nitin