CCS/AWR6843: Problem configuring CAN-FD timing parameters for the CAN-FD interface

Frank Kuchenbrod

Intellectual 260 points

Part Number: AWR6843

Tool/software: Code Composer Studio

Dear Sir or Maddam,

could you please help me to configure the CAN-FD Interface?

I changed the CLK for the CAN module up to 80MHz:

    /* Configure the divide value for MCAN source clock */
    SOC_setPeripheralClock(gMmwMCB.socHandle, SOC_MODULE_MCAN, SOC_CLKSOURCE_240MPLL, 3U, &errCode);    // 80Mhz

    SOC_initPeripheralRam(gMmwMCB.socHandle, SOC_MODULE_MCAN, &errCode);

I found a tool to calculate the Timing Parameters for CAN-FD.

But now I need to know how I can calculate the dataPropSeg.

Can you help me to calculate the dataPropSeg for nominal bitrate and for data bitrate?

    /* 1MBit */
    mcanBitTimingParams.nomBrp      = 0x2U;
    mcanBitTimingParams.nomPropSeg  = 0x???;
    mcanBitTimingParams.nomPseg1    = 0x5U;
    mcanBitTimingParams.nomPseg2    = 0x2U;
    mcanBitTimingParams.nomSjw      = 0x2U;

    /* 5MBit */
    mcanBitTimingParams.dataBrp     = 0x2U;
    mcanBitTimingParams.dataPropSeg = 0x???;
    mcanBitTimingParams.dataPseg1   = 0x29U;
    mcanBitTimingParams.dataPseg2   = 0x10U;
    mcanBitTimingParams.dataSjw     = 0x10U;

Thank you very much in advance?

Regards,

Frank

over 5 years ago

0 Vaibhav Mahimkar over 5 years ago

TI__Mastermind 23725 points

Hello

Could you please help us know which tool for timing are your referring to?

Please take a look at identical CAN config tickets here.

https://e2e.ti.com/support/sensors/f/1023/t/717635?AWR1642-About-MCAN-test-issue

https://e2e.ti.com/support/sensors/f/1023/t/813737?RTOS-AWR1843-CANFD-demo-code-

https://e2e.ti.com/support/sensors/f/1023/t/778971?CCS-IWR6843ISK-IWR6843-CAN-FD-NETWORK

Please take a look at the register field description in the CAN FD chapter in TRM

AWR18xx/16xx/14xx/68xx Technical Reference Manual (Rev. E)

Thank you,

Vaibhav

0 Frank Kuchenbrod over 5 years ago in reply to Vaibhav Mahimkar

Intellectual 260 points

Hello,

I think there are two tools available:

- from vector informatics for example CANoe -> its part of the software

- from peak system there is a standalone windows app available:

https://www.peak-system.com/fileadmin/media/files/BitRateCalculationTool.zip

But to my problem I could find no informations: What does propseg mean and how can I find the right value?

Can you help once again?

Regards,

Frank

0 Frank Kuchenbrod over 5 years ago in reply to Frank Kuchenbrod

Intellectual 260 points

Hello,

I could find this calculations in swru520e on page 2422 and following:

0 Yogesh Siraswar over 5 years ago in reply to Frank Kuchenbrod

TI__Mastermind 21495 points

You can also refer to the following e2e post, different device but the MCAN IP is the same:

https://e2e.ti.com/support/processors/f/791/t/920090

0 Frank Kuchenbrod over 5 years ago in reply to Yogesh Siraswar

Intellectual 260 points

Hello,

but for me its still not clear how to calculate the propagation time segment parameters!

I found the two examples in swru520e for different baudrates which I posted before.

But for me the calculation it still not clear. Perhaps somebody could help again.

I can see that tq depends on CAN_CLK. The delays are specific from bus topology and from the selected transceiver.

Is there a fault in the example calculation? µs <->ns

Regards,

Frank

0 Yogesh Siraswar over 5 years ago in reply to Frank Kuchenbrod

TI__Mastermind 21495 points

Hi Frank,

Prop_Seg: Propagation Time Segment

This segment is used to compensate for the physical delay times within the network, such as signal propagation delay and delays within the actual CAN nodes, namely the receiver/transmitter circuits. The segment’s length must be twice these delay times to compensate for delays from sender to receiver and back to the sender

Yes, the tq parameter for the second case may have unit error.

If you read the documentation it clearly state that Several combinations may lead to the desired bit time, allowing iterations of the steps.

You may also try the calculator @https://www.ti.com/lit/an/sprac35/sprac35.pdf

Thanks

Yogesh

0 Yogesh Siraswar over 5 years ago in reply to Yogesh Siraswar

TI__Mastermind 21495 points

Hi Frank,

Did the calculator reference in the above document resolved your issue:

http://www.ti.com/lit/zip/sprac35

Thanks

Yogesh

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CCS/AWR6843: Problem configuring CAN-FD timing parameters for the CAN-FD interface