The serial wire debug (SWD) pins can be used as GPIO pins when debugging is not active.
These pins default to SWD functionality at reset, and can be configured as GPIO pins using the PROTECT.GPIOSWD signal protector interface of TAMPC. Once configured as GPIO pins, the SWD functionality and all SWD-related debug operations are disabled until the next reset. The debugger will not be able to wake the device from sleep or from System OFF mode through the SWD interface, but must instead use the pin reset (nRESET) to reset the device.
The pins shall only be used as outputs, connected to high impedant loads. This ensures that the pins do not load the debug interface when debugging is enabled. Failure to do so can cause the device SWD operations to malfunction.
The debugger can prevent the device from using the SWD pins as GPIOs by holding SWDCLK high when nRESET is de-asserted. This forces the device to keep the SWD functionality enabled.