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AWR6843AOP: Using LIN bus with AWR6843AOP

Duygu
Prodigy 20 points
Part Number: AWR6843AOP
Other Parts Discussed in Thread: , MMWAVEICBOOST

Hello Team,

I am preparing a design in which I use 2 CAN-FD lines using AWR6843AOP. In the design, I want to use one of the CAN bus to read CAN data. I want to use the other CAN bus to write data to a LIN line.
I created the CAN transceiver (TCAN1042HGVDRBRQ1) connection with AWR6843AOP. I gave the CANH and CANL pins of 2 transceivers out of the board via a connector.


Can I use one of the CANH and CANL lines as a LIN line? What do I need for this? Is it enough to connect a CAN to LIN converter to the CAN output (if such a solution is possible)? Do you have a suitable solution, product or design?


I'm a little new to this. Thanks in advance for your suggestions.

  • 0
    TI__Expert 3530 points

    Hey Duygu,

    Thanks for reaching out on E2E regarding your question on a hybrid CAN-LIN solution! I will need to check with another one of our engineers to confirm this, but it should be possible to address a LIN node using a CAN node on a CAN bus. You might be able to find more information in ISO 15765-2 or ISO 17987-4, but give me a day or two to dig up some more specific information. You might also be able to find information in LIN documentation under the keyword "backbone bus" or "backbone network."

    Regards,

    Kristien

  • 0 in reply to Kristien Everett
    Prodigy 20 points

    Hi Kristien,

    Thank you for your response. I am waiting for your definitive answer. In addition to this question, I would like to ask a few additional questions to confirm the design.

    1- The pin outputs I gave via AWR to use CAN lines are as follows. Is there any harm in using these pins as CAN data lines? As far as I see in the document, AWR pins D2 and B4 are recommended as CAN2_FD data lines. Is there a problem with the pinouts I used in the design below?

    2- If I cannot use the LIN line over CAN lines, I have to go for another design. Which of the AWR pins are suitable for connection to a LIN converter? I thought about using U16 and V16 pins, but in the current design, U16 and V16 are not idle.

  • 0 in reply to Duygu
    TI__Expert 3530 points

    Hey Duygu,

    There shouldn't be any issues using those pins for CAN, besides limiting the SPI ports to only one, but I will need to check with one of our hardware engineers to confirm if there are no other concerns. Likewise, I'll need to run your second question by them as well.

    Thank you for your patience,

    Kristien

  • 0 in reply to Kristien Everett
    Prodigy 20 points

    Hi Kristien,

    There is no problem for the project in limiting the SPI ports to only 1.


    What confuses me is, do I need to use  resistors in CAN connections?


    In the TI AWR6843AOPEVM design, the choice was made between SPI and CAN and these resistors were included in the design. Since I am currently directing these outputs (D2, C2) only to the CAN transceiver, do I still need to use resistors? Why did TI include these resistors in the design?

    Thank you for your interest.

  • 0 in reply to Duygu
    TI__Expert 3530 points

    Hey Duygu,

    You should not need the resistors for CAN connections. These are pullup resistors that are only needed for the SPI signals. 

    Also, I have an update on the CAN-to-LIN concept: due to differences in the physical layer and electrical signals of CAN and LIN, it would be difficult to use a CAN transceiver on a LIN bus and vice versa. LIN uses an open drain architecture on a single wire with an external pullup source to the Vbat supply such as 12 V. CAN uses a differential signal with a common mode or recessive voltage level of 2.5 V with CANH swinging between 2.5V - 4.5V and CANL swinging between 2.5V-0.5V. At best, you would need an MCU to translate the data between the CAN and LIN transceivers which may not be the simplest solution to work with.

    Your best bet would be to use a LIN transceiver, such as the TLIN1039-Q1, with the AWR6843AOP. As for selecting suitable pins for the transceiver, I would highly recommend looking over Section 7.3 Pin Attributes of the AWR6843AOP Datasheet if you haven't already. I would consider using U6 and V5 for LIN TX  and RX, but keep in mind that these pins are normally used for the DCA1000 or MMWAVEICBOOST.

    Regards,

    Kristien