Some SAM devices include an ERASE pin which is asserted to perform a complete chip erase and unlock devices on which the security bit is set. This feature is coupled to the device itself as well as the Flash controller and is not part of the Arm core.
The ERASE pin is NOT part of any debug header, and the Atmel-ICE is thus unable to assert this signal to unlock a device. In such cases the user should perform the erase manually before starting a debug session.
JTAG Interface
The RESET line should always be connected so that the Atmel-ICE can enable the JTAG interface.
SWD Interface
The RESET line should always be connected so that the Atmel-ICE can enable the SWD interface.