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[FAQ] CCS/TDA4VM: TDA4VM: How to get Console traces on Lauterbach/Trace32 using DCC?

Genius 17910 points

Replies: 1

Views: 58

Part Number: TDA4VM

Tool/software: Code Composer Studio

I do not have any UART instances. How can i get the u-boot console logs on DCC(Debug Communication Channel) using Lauterbach/Trace32?

  • Hi,

    DCC: DCC stands Debug communication channel. ARM processors provide very useful utility
    to divert all the console prints to a debug channel.  More details here: https://developer.arm.com/documentation/ddi0210/c/Debug-Interface/Debug-Communications-Channel/Communications-through-the-DCC

    This is very useful for the following cases:

    • No UART instances available on board.
    • UART Instances are broken
    • UART instance somehow not functional.


    Please use the below patch on top of latest 7.0 SDK: 0001-j721e-Enable-DCC-on-T32.patch

    The patch does the following:

    • Enables the DCC Config option.
    • Adds DCC device tree node.
    • Add serial3 as dcc alias in device tree.
    • Replace stdout-path from UART2(SoC UART) to DCC. So that all the console logs get routed to DCC.
    • Lastly adds an infinite loop at the beginning of R5 SPL.

    The user needs to compile the u-boot binaries using:

    make u-boot
    cp board-support/u-boot_build/a53/u-boot.img board-support/u-boot_build/a53/tispl.bin board-support/u-boot_build/r5/tiboot3.bin board-support/prebuilt-images/sysfw.itb /media/$USER/boot/


    Open 32 bit arm Trace32 version:

    t32mamrm

    As mentioned the patch adds an infinite loop. So we need to connect to MCU-R5F using the cmm script: j721e_evm_r5.cmm


    After running the above CMM script.

    Open the DCC window by running the following commands in the trace32 command window:

    TERM.MODE String
    TERM.METHOD DCC
    TERM.SIZE 100. 1024.
    TERM.SCROLL ON
    TERM.view

    The above should open a DCC Terminal

    Now Set PC to immediate next instruction. As example in the below screenshot the infinite loop is at 0x41c00524 so Set the PC to 0x41c00526
    to get out of while loop. Press run.

    One should see DCC window with R5 SPL booting:


    Now we are done with R5 SPL now close t32 and open 64 bit mode using t32marm64 and run a72 cmm script: j721e_evm_a72.cmm

    Run commands mentioned above to open DCC window and then press run. You Should see a72 SPL & u-boot prints like below.
    Press enter to get to u-boot command prompt.


    The same should work for DRA820, DRA829 processors with just the changes in DTs and config files.

    Best Regards,
    Keerthy

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