Arm TrustZone Technology for Armv8-M

Arm TrustZone for Cortex-M technology is an optional core extension, which enables the system and the software to be partitioned into Secure and Non-Secure domains.

Secure software can access both Secure and Non-Secure memories and resources, while Non-Secure software can only access Non-Secure memories and resources.
Figure 1. TrustZone for ARMv8-M

If the TrustZone is implemented (SAM L11 devices), the system starts up in Secure state by default.

The security state of the processor can be either Secure or Non-Secure.
Important: For additional information, refer to “TrustZone Technology for ARMv8-M Architecture”, which is available on the Arm web site (