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Re: Unable to access the DAP

Santosh PG
Expert 1590 points

Hi Everyone,

Please help to unlock the JTAG access as it might be blocked.

Scenario: For HW1

  1. First time we connected through JTAG successfully.
  2. Then we loaded our application code (we built this upon the sample codes provided by TI) through JTAG.
  3. Next time onward we are unable to connect to JTAG.
  4. Attached is the error we are seeing.

 

We tried on another HW - HW2 - with a change to the source code and change was to comment below code:

// Set the clocking to run directly from the crystal.

    ROM_SysCtlClockSet(SYSCTL_SYSDIV_4 | SYSCTL_USE_PLL | SYSCTL_XTAL_16MHZ | SYSCTL_OSC_MAIN);

 

After this change, we are able to successfully connect to HW2 every time. Is above code responsible for the behavior of HW1?

If yes, how do we correct HW1?

Attached the error screen shot for your reference.

Best Regards,

Santosh.

  • 0
    Expert 1590 points

    Attaching the screen shot once again.

    Best Regards,

    Santosh

  • 0 in reply to Santosh PG
    TI__Mastermind 21285 points

    Santosh,

    Lm Flash Programmer has a "debug port unlock" utility which mass erases the NV memory of the device.  You can download LM Flash Programmer from here; http://www.ti.com/tool/lmflashprogrammer

    The debug port unlock option is on the fourth tab, "Other Utilities".  Make sure to select "Fury, DustDevil, and Blizzard" classes.

  • 0 in reply to Michael S
    Expert 1590 points

    Hi Michael,

    Thanks for the mail, I am using LM4F232 device on the custom board and as LM4F evk doesnt support debugging we are using XDS100V2 emulator along with CCSv5.3.

    I believe LM flash programmer cannot be used for unlocking LM4F deviceson the custom board using LM4F evk.

    So correct me if I am wrong. Also let me know the alternative option if my understanding is right.

    Best Regards,

    Santosh.

  • 0 in reply to Santosh PG
    TI__Mastermind 21285 points

    Santosh,

    You are correct.  If there were an available LM3S evaluation kit, that could be used as an ICDI interface to the LM4F board.

    There are two alternatives that come to mind; use the flash resident bootloader and LM Flash to bring in another .bin via UART or perform the manual debug unlock procedure.  I've clipped this from the LM4F datasheet.  Sections 4.3.4.3 and onward are the sections of importance.

    6560.Manual Debug Unlock LM4F.pdf

     

  • 0 in reply to Michael S
    Expert 1590 points

    Hi Michael,

    I got LM3S9D96 evk but at the unlock time we need to select the type of the series so not getting what to select.

    so please let me know the procedure to do unlock the LM4F232 on custom board from LM3S9D96 evk.

    Best Regards,

    Santosh.

  • 0 in reply to Santosh PG
    TI__Mastermind 21285 points

    Hi Santosh,

    First, I apologize for the quality of the photo but all I had was my phone.  Below is an image of the setup however, since you are using a custom board, the cable between the DK and your board might be different.  I used an EK-LM4F232 for the image.

    First, connect the USB cable to the ICDI USB connection and make sure that the power jumper is set to ICDI (just below the 5VDC connector).  Also, remove all jumpers next to the large 20-pin JTAG connector EXCEPT for GND.

    MAke the required cable connection between the DK and your target board and open LM Flash and use the settings shown below.

    Next, select the "other utilities" tab and select the "Fury, DustDevil, and blizzard classes" option in the Debug port unlock section and click "unlock".  Follow the on-screen prompts and you should be able to unlock the device.

    As I previously mentioned, since you are using a custom board, I don't know what JTAG header you put in place.  However, since you're using XDS100 primarily, there are a few possible options.  Please let me know which header you are using on your board as there may have to be some cable adaption involved.

  • 0 in reply to Michael S
    Expert 1590 points

    Hi Michael,

    I was able to unlock the device really thanks for the support.

    Best Regards,

    Santosh.