4. Debugging
The Thunderboard EFM32GG12 contains an on-board fully functional SEGGER J-Link Debugger that interfaces to the target
EFM32GG12 SWD debug interface. The debugger allows the user to download code and debug applications running in the target
EFM32GG12. Additionally, it also provides a virtual COM port (VCOM) to the host computer that is directly connected to the target devi-
ce's serial port, for general purpose communication between the running application and the host computer.
An external Silicon Labs debugger can also be used with the board by connecting it to the Mini Simplicity connector. This allows ad-
vanced debugging features as described in section
4.3 Mini Simplicity Connector
. A Silicon Labs Starter Kit (STK) is a good example of
a debugger that can be used with the Thunderboard EFM32GG12 when connected through a debug adapter.
Note:
When using an external debugger, the "PWR" slide switch must be placed in the "DBG USB" position, and the debug USB cable
must be removed to ensure correct operation.
Figure 4.1 Thunderboard EFM32GG12 Debugging Possibilities on page 13
shows the possible debug options.
Figure 4.1. Thunderboard EFM32GG12 Debugging Possibilities
4.1 On-board Debugger Considerations
The on-board debugger is a SEGGER J-Link debugger running on an EFM32 Giant Gecko. The debugger is connected to the SWD
and VCOM pins of the target EFM32GG12 through a level shift and isolation circuit. When the debug USB cable is inserted, the on-
board debugger is automatically active and takes control of the SWD and VCOM interfaces. This means that debugging or communica-
tion will
not
work with an external STK connected through the Mini Simplicity connector at the same time.
When the debug USB cable is connected, the target EFM32GG12 voltage domain (VMCU) is used to power parts of the level shift and
isolation circuit. Furthermore, depending on the "PWR" slide switch position, the debugger itself may also be powered from the VMCU
rail. These considerations should be taken into account when trying to measure the EFM32GG12 current consumption on the kit while
using the on-board debugger.
When the debug USB cable is disconnected, the on-board debugger is powered down and the level shift and isolation circuit is put in a
partially powered down state, minimizing both leakage current and quiescent current from the target EFM32GG12 voltage domain
(VMCU). This means that high performance power measurements of the EFM32GG12 with either Advanced Energy Monitoring or other
external hardware should be obtained with the debug USB cable disconnected.
UG371: Thunderboard EFM32GG12 User's Guide
Debugging
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