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JTAG Communication Failures

It is possible to run code on a Stellaris device that causes the device to lose JTAG communication.  The two most common causes are:

  1. Changing the system clock speed to something that the target system does not support.
  2. Changing the function of the Port C[3:0] pins, which are muxed with the JTAG pins.

If you accidentally do either of these things, you can restore communication with your target device by running the Debug Port Unlock utility in LMFlash Programmer as shown below.  Select the appropriate product class for your device.  If you don't know the class for your device, you can find it by reading the Device Identification 0 (DID0) register at address 0x400F.E000.  Then click on the "Unlock" button.

On Tempest- and Firestorm-class devices, the MAC address is erased by the Debug Port Unlock utility, so be sure to write down the number before running the utility.

Regards,

Sue

36 Replies

  • For further advice on bringing up a board with JTAG, see this post from cb1.

    Regards,

    Sue

  •  

    I use  a XDS 100v2 JATG emulator to connect the board. The emulator is made by Blackhawk. It has a cTI 20-pin header.

    I ues a 20e_cTi-20t_ARM pin converter to connect it to a MDL-ADA210-pin to 20-pin JTAG adapter module, and then connect to Board.

    The configuration is shown as below:

     

  • In reply to alex yu:

    Alex,

    You cannot use the XDS100 with LMFlash programmer.  You need to use another Stellaris evaluation board to do a debug port unlock sequence.

    Regards,

    Sue

  • In reply to Sue Cozart:

    Sue,

    Could you recommend me what kind of Evakuation board that is duitable for that application ?

    thanks

    Alex

  • In reply to alex yu:

    Hi Alex,

    Any one will work, except for the EK-LM4F232 board.  The EK-LM3S811 is the cheapest at around $50.

    Regards,

    Sue

  • In reply to Sue Cozart:

    Hi Sue,

    Is it suitable for febuging and programming LM3s9B92 based applications?

    Alex

  • In reply to alex yu:

    Yes it is, Alex.

    Regards,

    Sue

  • In reply to Sue Cozart:

    Hi Sue,

    I have the EKS-LM3S811. And I tried to unlock the board, but it shows an error: unable to initialize target -1! as shown below:

    Could you please tell me what cause the problem. and how to solve it?

    Thanks

     

  • In reply to alex yu:

    Hi Alex,

    I'm sorry for the delay in responding - I was on vacation.  What is your configuration on the front tab?  You have to configure for the target (use EK-LM3S9B92), not the emulator.

    Regards,

    Sue

  • In reply to Sue Cozart:

    Hi Sue,

    Yes, I used LM3SB92 Evaluation Board as the target in confiuration.

    Alex

     

     

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