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EK-TM4C129EXL: Error connecting to the target

Part Number: EK-TM4C129EXL

Hello,

Recently we buy new EK-TM4C129EXL Evaluation Board in the first attempt we successfully upload the code, after few days we try to upload code it shows the CORTEX_M4_0: Error connecting to the target: Unable to communicate with the device. Please check your connection.

we tried the Blinky code at first time still controller in that state only now we unable to upload the code,

here i am attached images of connection setup of ccs studio error image and present state of Evolution board,

we think controller are going unknown state, we need support for how to recover to older state.  

Regards,

Pavan

  • Hi,

      My understanding from your description is that you still have the project0 code on the board? Is that correct?

      Is the project0 code that you first programmed the stock example from TivaWare or is it your own code? 

      If it is your own code, how is it different from the stock blinky example?

      Are both boards having the same problem or just one of them?

      Can you restart CCS and try again? Will it make a difference?

      Can you use LM flash programmer to program the code? Download LM flash programmer from https://www.ti.com/tool/LMFLASHPROGRAMMER

      If LM flash programmer still fails to program/erase the flash, you can try to unlock the device. It will bring the device to its factory settings. 

     Normally, a debugger becomes unable to connect to the target for the below possible reasons. I just wanted to know if you modify your code that may have put the device in such as state. I don't think you have done as follows but just wanted to bring them up for possible reasons that can prevent the debugger if it is not a hardware issue. 

      1. You repurpose JTAG pins for GPIO. When this happens the debugger can no longer access the target through the JTAG port. 

      2. The device is put into deepsleep or hibernate mode without a mechanism to wake up. In these low power modes, the clock is completely turned off. Without a means to wake up, the debugger is unable to synchronize with the un-clocked processor. 

      3. BOOTCFG register is programmed to lock out JTAG access. 

      

      

  • Hi,

    1. My understanding from your description is that you still have the project0 code on the board? Is that correct?

    --Yes 

    2. Is the project0 code that you first programmed the stock example from TivaWare or is it your own code?

    -- Its is stock example of tivaware after that we tried to our own code it still doesn't work. 

    3. Are both boards having the same problem or just one of them?

    -- both boards have same problem after that we buy another one in that we have not found any issue such that.

    4.  Can you restart CCS and try again? Will it make a difference?

    -- yes we restart several times but shows that same error. we observed that when we reset the controller it successfully resting but we can 't upload the code.

    5. we tried the LM Flasher to unlock the debug port it still shows  unable to find the target and we try program through the LM flasher still fails we have attached images of we getting error images below

    Regards

    Pavan 

  • Hi,

    We have tried unlock the debug port it shows the unlock completed but we couldn't upload the code.

    please look at images we have tried procedure.

    It shows the unlock successful

    It shows the unlock successful after we tried to flash below error pop-up

     

    Regards,

    Pavan 

  • Hi,

      Today is a US public holiday. Please expect delayed response. 

  • Hi,

      After you unlock, did you do a power cycle?

      I still see a valid MAC address. I don't know if that was left from the previous session. An unlock is supposed to do a mass-erase that will also wipe out MAC address which is stored in a non-volatile register. Can you click the Get Current MAC address? If it is still showing a MAC address then it did not unlock successfully.  Since you have the project0 example programmed before, the board is supposed to blink LED. If you successfully unlock the device then the LED should not blink anymore because there is no code in the flash. If you see LED continue to blink then the unlock wasn't successful.   

  • Hello,

    After you unlock, did you do a power cycle?

    --Yes i do the power cycle.

    when i clicking on the Get Current MAC Address but it shows the unable to connect target .

    when i do the unlock it shows that unlock is successful in that time i observed blinky code is erased because now the LED is not glowing.

    but still i am unable to upload code when do the upload the code it shows unable to connect target  

    my observations is that i think unlock is successful but it connect the target.

    Regards,

    Pavan 

  • Hi,

      Unless it is a PCB issue, I can't image a simple project0 example can cause the board to lock up. Earlier you said you ran the stock project0 example but from your first screenshot, see below, it does not look like a stock project0 example. Did you modify the code? I see some header file for ssd1386_spi.h. This is not part of project0. In any case, I don't see a reason that a software should lock up the device if the software didn't do anything accidently to prevent JTAG access as I described before-  such as putting the device in hibernate/deepsleep mode, repurpose JTAG pins for GPIO or disable JTAG via BOOTCFG. 

    -- both boards have same problem after that we buy another one in that we have not found any issue such that.

     How many boards do you have? It seems like you have three boards. Is it correct?

     Do you have one board that is working but not the others two?

     Do you have a debug probe like XDS200 or XDS110 or XDS100? If you do, can you try to unlock per instructions in section 5.3..2 in the app note below using dbgjtag.exe? 

    https://www.ti.com/lit/pdf/spma075

  • Hello,

    We tried in new PC with latest LM Flasher tool and CCS studio after that we tried to flash the code and we successfully uploading the code to the board. 

    After that we uninstall the CCS studio and LM flasher in our other system and installing the latest tools now we able flash the code. and we tried several times we couldn't find such that issue again.

    Thanks for the support

    Regards,

    Pavan N