13.4 Secure and Secure Always On Region Types

A secure region type is non-programmable region with a secure filtering attribute. When the CPU or other bus master requests access to an address range that falls within a secure region address space, the request is rejected with bus slave error if the bus request is non-secure. Secure requests are not rejected within the region address space. This region is only active if CTRLA.ENABLE=1. If CTRLA.ENABLE=0, this region is exempt from security filtering.

For this type of region, the RSTATUSAn.Type=0 and RSTATUSBn.NONSEC=0, where n is a value between from 1 to STATUS.NBRG. The lower address of the region is given by RSTATUSAn. ADDR[31:10] * 2¹⁰ and the upper address by RSTATUSAn.ADDR[31:10] * 2¹⁰ + 2^{RSTATUSAn.SIZE} - 1, when RSTATUSAn.SIZE is greater than 0. All addresses from the lower to the upper address range are subject to filtering. Attempting to program this type of region through RCTRL sets the STATUS.CFGERR and the command is ignored.

A secure always on region is similar to a secure region type except that it is always active regardless of CTRLA.ENABLE state.