I will configure the circuit with EFM8SB1. And debugging will use the USB Debug-Adapter. I do not know how to configure the circuit to use JTAG. the document("EFM8SB1_BRD5101A-A02-schematic") have a "Control MCU" and is it necessary? I think "Control MCU" is for Jlink. But when I use JTAG with USB Debug-Adapter, do I need all the circuits in the document?
EFM8SB1 don't support JTAG, it use C2 that developed by Silabs.
The UDA was ok to used to debug the EFM8SB1.
Basically speaking the EFM8SB1 STK included a JLINK debugger (C2 interface) that support debug/program EFM8SB1 and you don't need a external standalone UDA. As far as I know the integrated JLINK debugger in the EFM8SB1 STK was developed by Silabs and cooperation with Segger.
The integrated JLINK debugger on EFM8SB1 use a separate "Control MCU" and it was from another MCU vendor, it support C2 to debug our 8-bit EFM8 MCU (in fact also some of C8051Fxxx, you could see the support list in Segger website) and SWD to debug our 32-bit EFM32 MCU.
My views are my own and do not necessarily represent the views of Silicon Labs
Mainly refer to the sheet 4 of the EFM8SB1 STK schematic, including power supply, C2 debug interface.
Also, please see the section 5 (page 31) of EFM8SB1 Datasheet for the typical power and debug connection.