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Explorer II
November 5, 2025
Solved

Choosing a specific device in JTAG chain

  • November 5, 2025
  • 3 replies
  • 193 views

Hi,

I can't seem to find the launch configuration setting to specify a device in the JTAG chain by its position and IRpre length. I'm using a J-link programmer and I can usually do this from the command line by passing the -jtagconf x,y argument to the J-link executable. However, the debug console in VScode shows that the debug launch config called the Segger J-link GDB server without this argument. I can't seem to find how to make the debug config to append this to the J-link server call

 

Visques_0-1762305065631.png

Is this supported by the STM32Cube extension?

Thanks

    This topic has been closed for replies.
    Best answer by Florent V

    Hi Visques,

    The attribute serverJtagCfg will be available in the next delivery (planned for the end of November).

    In the meantime, you can use the generic debug configuration to pass the -jtagconf argument in the serverParameters attribute.

    Ex: 

     {
     "type": "stgdbtarget",
     "request": "launch",
     "name": "STM32Cube: STM32 Launch Generic GDB Server",
     "origin": "snippet",
     "cwd": "${workspaceFolder}",
     "preBuild": "${command:st-stm32-ide-debug-launch.build}",
     "program": "${command:st-stm32-ide-debug-launch.get-projects-binary-from-context1}",
     "gdb": "${command:st-stm32-ide-debug-launch.get-gdb-executable}",
     "serverExe": "JLinkGDBServerCL",
     "serverParameters": ["-s", "-if", "jtag", "-device", "STM32H723ZG", "-speed", "4000", "-endian", "little", "-novd", "-jtagconf", "9,2"],
     "serverHost": "localhost",
     "serverPort": "2331",
     "serverCwd": "<Path to your JLink installation>",
     "runEntry": "main",
     "imagesAndSymbols": [
     {
     "imageFileName": "${command:st-stm32-ide-debug-launch.get-projects-binary-from-context1}",
     "imageOffset": "",
     "symbolFileName": "${command:st-stm32-ide-debug-launch.get-projects-binary-from-context1}",
     "symbolOffset": ""
     }
     ],
     "verbose": true
     },

     
    (Note: Update the serverCwd attribute with your path)

    Best Regards,
    Flo

    3 replies

    Florent VAnswer
    ST Employee
    November 5, 2025

    Hi Visques,

    The attribute serverJtagCfg will be available in the next delivery (planned for the end of November).

    In the meantime, you can use the generic debug configuration to pass the -jtagconf argument in the serverParameters attribute.

    Ex: 

     {
     "type": "stgdbtarget",
     "request": "launch",
     "name": "STM32Cube: STM32 Launch Generic GDB Server",
     "origin": "snippet",
     "cwd": "${workspaceFolder}",
     "preBuild": "${command:st-stm32-ide-debug-launch.build}",
     "program": "${command:st-stm32-ide-debug-launch.get-projects-binary-from-context1}",
     "gdb": "${command:st-stm32-ide-debug-launch.get-gdb-executable}",
     "serverExe": "JLinkGDBServerCL",
     "serverParameters": ["-s", "-if", "jtag", "-device", "STM32H723ZG", "-speed", "4000", "-endian", "little", "-novd", "-jtagconf", "9,2"],
     "serverHost": "localhost",
     "serverPort": "2331",
     "serverCwd": "<Path to your JLink installation>",
     "runEntry": "main",
     "imagesAndSymbols": [
     {
     "imageFileName": "${command:st-stm32-ide-debug-launch.get-projects-binary-from-context1}",
     "imageOffset": "",
     "symbolFileName": "${command:st-stm32-ide-debug-launch.get-projects-binary-from-context1}",
     "symbolOffset": ""
     }
     ],
     "verbose": true
     },

     
    (Note: Update the serverCwd attribute with your path)

    Best Regards,
    Flo

    VisquesAuthor
    Explorer II
    November 5, 2025

    Thanks for your quick reply. I'll wait until the next update then

    ST Employee
    December 15, 2025

    Hi @Visques ,

    Thanks to the latest 3.7.0 release, the attribute for JTAG configuration is now available.

    "serverJtagCfg": "<IRPre>,<DRPre>",

    With the tooltip:

    FlorentV_1-1765817419976.png

     

    Regards,
    Flo

     

     

     

    VisquesAuthor
    Explorer II
    December 15, 2025

    Thanks so much! 

     

    Btw: Not sure if the information box should say TDO instead of TDI? Usually IRPre and DRPre are counted from TDO

    VisquesAuthor
    Explorer II
    January 6, 2026

    One more thing: How can I attach to a running STM32 target by using its specific JTAG address? If I select "attach" in "request" the "serverJtagCfg" option becomes invalid. 

    Thanks