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Original question:

DCA1000EVM: The lvds data obtained by running the lua script is empty, what should I do?

DCA1000EVM: How to calculate the number of ADC data of IWR1642 using DCA1000EVM?

user5874743
Intellectual 340 points
Part Number: DCA1000EVM
Other Parts Discussed in Thread: IWR1642

The DCA1000EVM is used to acquire the ADC data of the IWR1642. Using the matlab to obtain the data of the four receiving antennas through the readDCA1000() function, it is a 4*262144 matrix, 4 represents 4 receiving antennas, and 262144 represents 262144 points. So how does this 262144 get? My settings are shown below.

The Ramp End Time is 60us and the ADC Start Time is 6us. The ADC Sampling Time should be 54us. The Sampling Rate is 10000ksps and the ADC Samples is 256. Does it mean that my data should be 54*10^-6*10000*10^3*256=138240? But the final number of data points is 262,144 data. Where is my fault?

  • 0
    TI__Guru 70050 points
    Hi,
    Here is a formula to calculate the size of raw ADC data sent from the device over LVDS interface. (same applicable for CSI-2 also for other mmwave sensor variants).
    numOfSample * numOfRx * sampleSize [2 bytes] * complex_real [2 bytes: complex, 1: real] * total_numOfChirp_inFrame * numOf_Frame_dataCaptured.

    Let's take an exmaple:
    ADC sample = 256, 4 Rx, complex2X, 16Bit each sample, chirpStartIdx = 0, chirpEndId=63, numOfLoop = 4, numOfFrame = 8.
    Then total ADC data captured to a file from DCA1000EVM (if only ADC data is configured not CP/CQ along with it)
    256 * 4 * 2* 2 * ((63-0 +1)*4) * 8 = 8388608 bytes.

    When you capture using DCA1000EVM it adds up its own seqNum to it, so you need to click the PostProc button which invokes packet-reordering and zero filling utility that chunks off these extra data and generate a new file raw_data.bin. Thus look for this file size (having only raw ADC data) to verify above calculated byte numbers.


    Regards,
    Jitendra