25.6.7 Security Features

When an undefined register access occurs, the URAD bit in the Interrupt Status Register (ISR) is set if unmasked. Its source is then reported in the Undefined Access Status Register (UASR). Only the first undefined register access is available through the UASR.URAT field.

Several kinds of unspecified register accesses can occur:

• Unspecified structure member set to one detected when the descriptor is loaded
• Configuration register (CFG) modified during active monitoring
• Descriptor register (DSCR) modified during active monitoring
• Hash register (HASH) modified during active monitoring
• Write-only register read access

The URAD bit and the URAT field can only be reset by writing a ‘1’ to the CTRL.SWRST bit.