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Original question:

TMS320C6748: Error connecting to the target through the XDS110

TMS320C6748: Error connecting to the target through the XDS110

Juan Encinas
Intellectual 510 points
Part Number: TMS320C6748

Hi,

Some moths ago I posted this problem related to TMS320C6748:

As we told you, we found a short in some pins of the JTAG connector and we had to buy a new one. We have been working with the new board with no problems whatsoever until yesterday. Similarly to the post I have referred to, without apparent reason it stopped working showing the same error:

Error connecting to the target:
(Error -2131 @ 0x0)
Unable to access device register. Reset the device, and retry the operation. If error persists, confirm configuration, power-cycle the board, and/or try more reliable JTAG settings (e.g. lower TCLK).
(Emulation package 7.0.48.0)

We checked the same affected pins of the JTAG connector and we found no short in this case. We tried with a different debug probe but the problem persists. Also, we have followed all the steps you suggested in the previous post with no result. 

Additionally, we have tried to load the .bin in the Flash memory and run the program without the debug probe and it works normally, so the problem seems to be only related to the JTAG interface.

Since it is the second board we have this problem with, we would want to know if there is a potential reason to be causing this failure. Do you have any idea about what could be happening?

Best regards,

Juan

  • 0
    TI__Guru**** 161600 points
    Hi Juan,

    As I understand this is a custom board. Could you post the JTAG parts of your schematics? Maybe there is an error in your design.

    Best Regards,
    Yordan
  • 0 in reply to Yordan Kovachev
    Intellectual 510 points

    Hi,

    First, thanks for your quick response.

    We are not using a custom board, but the C6748 Development Kit (LCDK): http://processors.wiki.ti.com/index.php/L138/C6748_Development_Kit_(LCDK), the same as the previous post.

    Thanks,

    Juan

  • 0 in reply to Juan Encinas
    TI__Guru**** 161600 points
    Hi,

    Ok, sorry for the misunderstanding. Let me check that on my side.

    Best Regards,
    Yordan
  • 0 in reply to Yordan Kovachev
    TI__Guru 55325 points

    The problem you described above could be caused by an Electrical Over Stress (EOS) event. 

    Are you performing your work at an ESD workstation and following appropriate ESD safeguards like wearing an ESD wrist strap? 

    It may be helpful to understand if the problem was found after a specific action was taken.  Do you recall any action that was taken before the problem occurred?  For example, did you cycle power to the development kit, connect/disconnect the debugger, connect/disconnect anything else to the development kit, or simply touch the development kit? 

    If any of the above is the case, please describe details how this action was taken.  For example, describe how power is cycled or things connected?  Do you hot plug the power supply to connector J1 or the debugger to header J6? 

    Please describe everything connected to the development kit.

    Regards,
    Paul

  • 0 in reply to peaves
    Intellectual 510 points

    Hi,

    We are not using any ESD equipment, since we thought the board would not be so delicate, considering it is a development kit. Nevertheless, the problem in both cases showed up with no apparent reason: all was was working fine, we left the workplace for a while with the board powered up and when we came back the JTAG connection was not responding anymore.

    We had connected to the development kit the power supply, the debugger through the JTAG interface and some dupont cables to the GPIOs pins, to monitor those signals using an oscilloscope.

    Kind regards,
     
    Juan

  • 0 in reply to Juan Encinas
    TI__Guru 55325 points

    My first recommendation - Setup an ESD workstation and follow industry standard ESD handling safeguards.

     

    My second recommendation - Never hot plug the DC power plug. Always use a switch on a plug strip to cycle the AC input to the DC power source with the DC plug already connected to the board. We have seen cases where the positive polarity center contact in the barrel connector makes connection before the negative/ground outer contact. Current may flow through unexpected paths if the negative/ground output of the DC power source has an internal connection to earth ground and the center contact makes contact first. When this happens an inrush of current seeks other paths to earth ground through connected devices trying to get back to the power source. This problem doesn’t occur while the board is isolated from everything else.

     

    Regards,

    Paul