CCS/AWR1642: how to know size fftOut1D of datapath obejct?

Hi,

Which demo are you using?

Usually the size of the fftOut1D is computed as size_fft (usually this is the size of ADC samples, also called Range Bins ) x 2 (since complex fft) x 4 bytes

In the mmave SDK 2.1 oob demo, this buffer is statically allocated as follows:

MMW_ALLOC_BUF(fftOut1D, cmplx16ReIm_t,
heapL2start, MMWDEMO_MEMORY_ALLOC_DOUBLE_WORD_ALIGN,
2 * obj->numRxAntennas * obj->numRangeBins);

Thank you
Cesar

You should use the mmWave SDK 1.2 OOB demo.

The output of the fftout1d is stored to the L3RAM, radar cube buffer.

It is possible to run the OOB demo with CCS and stop the execution with a breakpoint. Then, one can use the tools provided in CCS to save the radar cube to a file.

Notice that the size of the radar cube is proportional to the number of chirps and number of ADC samples for each chirp.

If you would like to retrieve this information at run time there are several challenges

1) The size of the radar cube
Since the data is transferred from sensor to PC through UART there is a limitation on the size that can be transferred. For larger number of chirps and ADC data samples there may not be sufficient time to transfer the data before the beginning of next frame

2) Code changes
The mmWave SDK 1.2 OOB demo does not support out of the box transferring the radar cube to PC host. The code would have to be modified. This should be simple update

3) GUI changes
The Visualizer would also have to be modified to support this feature

thank you
Cesar

Hi ZHG,

We do not have any code that outputs 1D and 2D FFT data on PC. We only allow the final object detection to be sent out of the device to the PC.

-Raghu