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AWR1843: reference design

Anthony Dobaj
Prodigy 230 points
Part Number: AWR1843

We are using the xWR1843-BOOST and associated Launchpad dev kit to develop a RADAR system, and are at the point where we need to miniaturize and simplify for the production unit. The BOOST design includes a XDS110 interface for PC connectivity but this seems overkill for implementing the RADAR functionality. What do we minimally need for PC connectivity for debug, production test and bringup for an AWR1843-based custom RADAR PCBA? Is there a reference design for this? In the datasheet there is reference to the BOOST schematic, but again this may be overkill. Please advise.

  • 0
    Prodigy 230 points

    The application is a safety device for micro mobility.

  • 0 in reply to Anthony Dobaj
    TI__Guru 58035 points

    Hello Anthony,

    The XDS110 is used for development and debug purpose. It provides JTAG interface to the PC and also UART interface for application flashing purpose and demonstration purpose ( we have the OOB demo application which send the object data over this UART interface) .

    In your end sensor you might not need this. You need build a block diagram of you complete system , look at the interfaces you  intend to use and if any of those are needed to be brought to the PC or are contained within the system. For debug purpose you can bring out JTAG interface lines and use external XDS110 emulator instead of having onboard XDS110. You would also need UART lines to flash your application to the serial flash. Again you can use some external UART to USB converter (like FTDI) instead of having one on the board. 

    Regards,

    Vivek 

  • 0 in reply to Vivek Dham
    Prodigy 230 points

    Hi Vivek, thank you for that insight. If you would, please walk us through your suggestions and answer a couple of follow-on questions:

    "For debug purpose you can bring out JTAG interface lines and use external XDS110 emulator instead of having onboard XDS110." - I understand exposing the JTAG interface lines, but what exactly does that mean "use external XDS110 emulator"?

    "You would also need UART lines to flash your application to the serial flash. " I understand exposing the UART lines, but it looks like there is a DSS and a BSS UART, the datasheet doesn't go into detail about the difference, please explain. And how would the serial flash be utilized in this case? Is this an external (to the AWR1843) device that we need to add? And if so, what utility or software would be used to "flash your application to the serial flash"? To be clear, are you suggesting that we purchase an FTDI device so we can implement this interface using a USB port? If so, which device exactly?

    The devil is in the details and I'm concerned that a lot of details are being glossed over. For example, are there test points we should expose for debugging the RADAR interface and function (power rails, clocks, ADC, etc). What about the CAN bus? What might we need that for? And what is the "Debug Interface (hardware in loop)"? I don't see any details in the datasheet about that. This would be the utility of a production reference design for this chip, I'm very surprised there isn't such a document for such a complex part. We don't have the time or budget to do this by trial and error. 

    One other question about the antenna. Do we have a stackup and layout for this? I've also recently learned of AOM parts, what are the tradeoffs of using such a part versus printing the antenna? Thanks for the information.

  • 0 in reply to Anthony Dobaj
    TI__Guru 58035 points

    Hello Anthony,

    Please find my inputs below.

    "For debug purpose you can bring out JTAG interface lines and use external XDS110 emulator instead of having onboard XDS110." - I understand exposing the JTAG interface lines, but what exactly does that mean "use external XDS110 emulator"?

    XDS110 emulators are available off the shelf. You just need to connect the wires to the appropriate signals. That way you dont need to put the device on your PCB and can connect it when ever its needed. You can find the link to one of the portals selling them here: https://www.mouser.in/ProductDetail/Texas-Instruments/TMDSEMU110-U?qs=34RfhUjJmKcb5um%252BgEm3Xw==&gclid=Cj0KCQiAi9mPBhCJARIsAHchl1wXD6o3cAHo9TX6g54TMHbo2ZNwNGvR0sRpJ-yAx3d-cJ024ZjcmBUaAopyEALw_wcB

    "You would also need UART lines to flash your application to the serial flash. " I understand exposing the UART lines, but it looks like there is a DSS and a BSS UART, the datasheet doesn't go into detail about the difference, please explain. And how would the serial flash be utilized in this case? Is this an external (to the AWR1843) device that we need to add? And if so, what utility or software would be used to "flash your application to the serial flash"? To be clear, are you suggesting that we purchase an FTDI device so we can implement this interface using a USB port? If so, which device exactly?

    BSS UART is used by the BSS core to send our debug logs around its code execution. This is done by the TI firmware. You could do a similar thing for your DSS application using the DSS UART, if you want to send out internal logs.  External Serial flash is used to save your application, when the device boots up it would load your application from the serial flash and start the execution.   Please refer to the AWR1843 EVM reference design for the external serial flash connections and the mmwave SDK documentation ( https://www.ti.com/tool/MMWAVE-SDK) for the details of the usage of the flash, tools used to load your application on the serial flash etc. You could use any USB to UART/RS232 converter, operating at 3.3V IO level. One such solution from FTDI is https://ftdichip.com/wp-content/uploads/2020/08/DS_UB232R.pdf

    The devil is in the details and I'm concerned that a lot of details are being glossed over. For example, are there test points we should expose for debugging the RADAR interface and function (power rails, clocks, ADC, etc)

    Please refer to the design guidelines checklist (https://www.ti.com/lit/zip/spracl2) that provides recommendation for debug connections. In general we dont recommend putting test points on power rails as they might cause radiation. We do not have Rx ADC outputs available for external access. Clocks, we do have an OSC CLKOUT signal which could be used by you to measure the internal reference clock frequency and adjust the external xtal caps to make sure the frequency is centered. Again this is captured in the guidelines document mentioned above.

    What about the CAN bus? What might we need that for?

    CAN is  standard communication bus typically used in vehicles. You can read more details about the interface online, maybe you can start of from Wikipedia (https://en.wikipedia.org/wiki/CAN_bus) . Incase you do intend to you use CAN bus in your system , you need a CAN PHY externally. Again, you can refer to the 1843 EVM reference design that shows the CAN PHY connections and the refer to the mmwave SDK code examples to use the CAN interface. The TRM document (https://www.ti.com/lit/pdf/swru520) also provides all the low level details to program this IP, but using the SDK example would make it easier for you. You dont have to start from scratch. 

    And what is the "Debug Interface (hardware in loop)"? I don't see any details in the datasheet about that.

     I assume you mean DMM interface. There is a section in the AWR1843 datasheet explaining this interface, section 8.10.12 . There is also a detailed chapter in the TRM document that explains how to program this interface and use it (https://www.ti.com/lit/pdf/swru520). Unless you want to implement a playback you dont need to use this interface.

    One other question about the antenna. Do we have a stackup and layout for this? I've also recently learned of AOM parts, what are the tradeoffs of using such a part versus printing the antenna? Thanks for the information.

    The complete schematic, layout, stackup etc. used for our EVM is available online for your reference and usage. In the following page refer to the design files section: https://www.ti.com/tool/AWR1843BOOST 

    We have mostly used PCB etched antennas for 80Ghz operation. They seem to be the most popular option. You can design the etched antenna based on your system requirements, ie range, FOV, etc. So that gives you flexibility and also they do not cost anything, only PCB area. Could you provide more details on the AOM antennas you are referring to ? 

    Regards,

    Vivek