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Device core is hung for C6678 with JTAG

bing zhou
Prodigy 130 points

Hi Sir

        We have a question for C6678,our project is four DSPs on board,JTAG connection is fly by topology，

Device core is hung for C6678 with JTAG，we find that core0 is hung of every DSP，others core are  normal with JTAG link，

please give us some advices to solve it，thanks！

  • 0
    TI__Guru* 81335 points
    I understand that you are using custom board with four C6678 connected on fly topology. Please confirm.

    Are you trying to connect/emulate with core0 of C6678 DSP for first time or it was worked earlier got broken now?

    Have you verified the board schematics for JTAG connectivity?

    Thank you.
  • 0 in reply to Raja
    Prodigy 130 points
    Hi Raja
    Our DSP should not work earlier,because we did not burn any fireware to flash for loading，i don't think there will be any disruption，i think DSP didn't do anything before JTAG connecting，thanks!
  • 0
    TI__Mastermind 43660 points
    Hello,

    May i know what is the boot mode on all four DSPs ? Please try to connect with no boot mode.

    Regards,
    Senthil
  • 0 in reply to Senthilkumar Srinivasan
    TI__Mastermind 46460 points

    I do not know what is meant by fly-by JTAG connectivity.  Do you mean that all four C6678 devices are in a single JTAG chain?  This is valid but it does slow down JTAG performance.  You might try modifying a board so that only a single C6678 is in the JTAG chain to see if this changes the symptoms.

    Did you buffer the JTAG TCK?  It is mandatory to implement JTAG TCK buffering when putting multiple devices into a single chain.  The JTAG link may work initially but instability will be seen due to reflections on the clock routing.  Please refer to recommendations in www.ti.com/.../spru655i.pdf.

    Based on the observation that JTAG emulation cannot connect to core 0 but it can connect to the other cores, this appears to be a BOOTMODE issue as highlighted by Senthil.  You can set the DSPs to NOBOOT or any of the BOOTMODES that are waiting for packets to arrive such as EMAC boot.  CCS should be able to reliably connect to core while the boot code is executing its idle loop.

    Make sure that the DSP is properly powered, has proper clocks and it is out of reset.  These are the basic requirements for JTAG emulation.  Proper power -> clock -> reset sequencing is mandatory as shown in the Data Manual.

    Tom

  • 0
    Intellectual 920 points

    Hi sir,

    did u get the solution for the above issue? or what is the reason behind the issue...

    we also facing same issue with our custom board.

  • 0 in reply to Noufal P
    TI__Mastermind 46460 points

    Noufal,

    The same guidance provided above needs to be followed.  There is a board or software error preventing CCS connect.  Please post answers to the questions asked above.  In general you should be setting the boot mode to one of the packet boot modes that are waiting for packets.  CCS can reliably connect while the BOOTROM is polling for received packets.  Instead, if you are in a boot mode where custom code is loaded and executed immediately, corrupt code can hang the core such that you cannot connect.

    Another avenue for test is to use an EVM and load into it code that fails to debug it.

    Tom