Debugging During Battery Operation - Silicon Laboratories EFR32xG21B User Manual

UG428: EFR32xG21B 2.4 GHz 10 dBm Wireless Starter Kit User's Guide
On-Board Debugger
Note: For "Debug IN" to work, the kit board controller must be powered through the Debug USB connector.

8.3 Debugging During Battery Operation

When the EFR32 is powered by battery and the J-Link USB is still connected, the on-board debug functionality is available. If the USB
power is disconnected, the Debug IN mode will stop working.
If debug access is required when the target is running off another energy source, such as a battery, and the board controller is powered
down, the user should make direct connections to the GPIO used for debugging. This can be done by connecting to the appropriate
pins of the breakout pads. Some Silicon Labs kits provide a dedicated pin header for this purpose.
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