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:
For SS V4, the hardware set up for the EFM8, EFM32, EFR32 or BGM 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.
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/EFR32/BGM MCU using Simplicity Studio V4.