If Simplicity Studio V3.3 is being used, then the following knowledge base articles explain how one can debug an EFM8/EFM32 product on a custom board:

Debugging for EFM8 devices

Debugging for EFM32 devices


For SS V4, the hardware set up for the EFM8 and EFM32 devices remains the same and can be referred to from the Knowledge Base articles listed above. The Simplicity Studio configuration, however, has been modified to make changing debug modes easier. There is no Kit Manager in V4, and debug modes can be changed directly from the Launcher perspective. 


To prepare your setup:

1. Connect the debug pins between the debugger and the target board as described in the Knowledge Base articles above.

2. Power the custom board.

3. Connect the STK to the host and move the switch to the AEM or Debug position or connect a JLink debugger to the host.


In Simplicity Studio, perform the following steps to connect to a target board using an STK in debug OUT mode:


1. Launch Simplicity Studio V4 and select the root element in the Device view of the STK.debug_1.PNG


2. The Launcher perspective shows the Debug mode, and there is a link next to it to change the debug mode.




3. Click on Change. In the subsequent J-link window, under the Adapter Configuration tab, change Debug Mode to OUT.





4. Go to the Device Hardware tab in the same window. Change the Target Part to the target MCU. Leave the Target Interface as SWD. Click OK.




5. The device information will be updated in the Device view in the Launcher perspective.




6. These steps may need to be repeated after closing and reopening Simplicity Studio.


An alternative way to get the J-link window (Step 3) open would be to right click the root element and select Device Configuration. Steps 3 - 6 will remain the same. 



Now you can debug the external EFM8/EFM32 MCU using Simplicity Studio V4. 


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  • 32-bit MCUs
  • Development Environments
  • Knowledge Base Articles
  • Simplicity Studio
  • Hi,


    This does not work for me anymore since my upgrade to Simplicity Studio 4. I can't change Debug mode of the STK board (whatever type of STK LG,GG or TG), the Debug OUT led on the board does not switch on and the Studio Launcher screen still shows MCU.

    (All this worked fine with Studio 3)

    What can I do?





  • Hi OM,


    What exactly are you seeing when you try to change the Debug Mode through V4? Can you share some screenshots?



  • Easy: Nothing !

    In other words, the screen shows that the SDK Debug mode is MCU mode. You click on 'change' link to see the 'Adapter Configuration' dialog box that contains a listbox to change the Debug Mode (see attached screen1 file).


    Choose OUT, after a little while the listbox becomes valid again and the word 'applied' is shown beside it (see attached screen 2 file), however the SDK did not change mode and the OUT led on the SDK is not on.


    Obviously, this means that the SDK debug mode is not in OUT mode and trying to debug an external board with it does not work.


    Hope this helps,





  • I experienced this issue, but it was resolved by updating the adapter firmware from the launcher in SS4.

  • @ryanco Are you using Studio V4 on an XP machine?

  • nope, windows 7

  • I could not upgrade STK firmware from SS4 as well. It just does not work and is just ignored by the STK board.

    Is there a way to "uncompress" the .emz package and copy it directly on the STK "virtual disk" to manually upgrade it?


  • You are seeing this issue because an executable which is responsible for changing the debug mode of the MCU is not working as expected on XP. This is happening because one of the visual studio c runtime files in XP is of an incompatible version on V4. For now, I would suggest you to continue using V3.3 on your system. We are looking into this internally and once we have an update I will let you know. 



  • Hi, marao


    Which EFM32 family devices is it possible to externally debug with an specific Starter Kit? For instance, a Tiny Gecko Starter Kit (STK3300) can debug an external EFM32LG micro?


    Best regards,


  • Hi Marao,


    Any news regarding V4 version and XP?


    Best Regards,