15.11.2.2 Operation From a Debug Adapter

Debug adapters should access the DSU registers in the external address range 0x100 – 0x2000. If the device is protected by the NVMCTRL security bit, accessing the first 0x100 bytes causes the system to return an error. Refer to Intellectual Property Protection.

References:

NVMCTRL – Non-Volatile Memory Controller

Security Bit