IWR6843ISK: Locating and sending raw data over UART

C Grebe

Part Number: IWR6843ISK

Hello,

I would like to know how to transmit raw ADC (IQ) data over the USB-UART for the IWR6843ISK. I am running an example project for vital signs with people tracking, that sends the post-processed data (point cloud, target list, target index, presence indication) to be shown on screen via an executable GUI.

I am looking for suggestions as to where:

- the size of the ADC array is set (via number of chirps per frame?)

- the raw data is located after the above array is filled

- to add the raw data to the UART buffer (the demo places the post processed data in MmwDemo_uartTxTask)

I do believe the above questions are generic to most of the TI example code, so the specific demo I am using shouldn't matter too much - I am open to looking at other demo projects if that will help me find what I am looking for. We plan to do our data processing on our own processor.

I understand that using the DCA1000 board would make this process much easier, but the SWAP constraints for this project prevent that. I am fine with decreasing the sample rate, and chirps per frame; I am aware the UART on-board cannot keep up with the data output at the default configuration.

Regards,

9 months ago

0 Abhishek Karkisaval 9 months ago

TI__Genius 9140 points

Thanks for your query. Please allow us a couple of days to respond

Regards

0 Pedrhom Nafisi 9 months ago in reply to Abhishek Karkisaval

TI__Mastermind 18057 points

Hello C,

If you must avoid the use of a DCA1000, then our suggested protocol for data transfer is SPI. It is impossible to transfer raw data over UART. You have every ADC sample taken on every chirp, across many chirps per frame, across multiple antennas, many times per second. On the high end it can take over 50mbps to dump this raw data, so even with SPI you have to limit your configuration substantially as well.

Best Regards,

Pedrhom

0 C Grebe 9 months ago in reply to Pedrhom Nafisi

Prodigy 30 points

Hello Pedrhom,

So in the case of the case of the IWR6843ISK, I would be able to access the SPI bus over the 60 pin connector J1? It looks like this is a Samtec QSH-030-01-L-D-A. Thank you for pointing that out.

Can you elaborate on my other questions?

1. Where the size of the ADC array gets set? I know that the CLI takes an argument to set this, but I haven't been able to find where this is processed in the code. If I do not set a value via the CLI, does the default value get set automatically? I understand I will need to significantly decrease the chirps per frame to be able to output over SPI.

2. Where can the raw data be found prior to being sent to the DSP? I am using the Vital Signs with People Tracking lab, but I think the program control of raw ADC --> Range --> Velocity --> CFAR --> AoA --> Point Cloud is common to several labs. I think I may just be unclear on how data is passed between the R4F and DSP.

Thank you for your help,

0 Pedrhom Nafisi 9 months ago in reply to C Grebe

TI__Mastermind 18057 points

Hello C,

1. The calculations of the size can be found in this post here: https://e2e.ti.com/support/sensors-group/sensors/f/sensors-forum/792677/dca1000evm-how-to-calculate-the-number-of-adc-data-of-iwr1642-using-dca1000evm

2. We have a very good and detailed flow diagram of how our demo works from start to finish with the relationship of MSS and DSS within our SDK at the following directory

C:\ti\mmwave_sdk_03_06_00_00-LTS\packages\ti\demo\xwr68xx\mmw\docs\doxygen\html\index.html

Best Regards,

Pedrhom

0 C Grebe 8 months ago in reply to Pedrhom Nafisi

Prodigy 30 points

Hello,

Thank you for the suggestions. In the interim, the scope of what I am trying to access has changed. This is partially due to the throughput limitations of the UART, discussed above.

I have asked a question about this here: https://e2e.ti.com/support/sensors-group/sensors/f/sensors-forum/1357913/iwr6843isk-accessing-the-range-fft-output-to-transmit-over-uart

Thanks,

Sensors

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IWR6843ISK: Locating and sending raw data over UART