SPRUJ79 November 2024 F29H850TU
In addition to MPU specific configurations, the SSU can be used to add another level of security to the RTDMA system, optionally.
RTDMA MPU versus SSU
RTDMA is an independent bus initiator that is not directly governed by SSU access filters. RTDMA receives sideband signals from the SSU that determines LINK ownership of channel configurations. The MPU is used to actually protect data transfers initiated by a DMA channel.
How RTDMA utilizes the SSU
Only the privileged software executing from SROOT (CPU1 LINK2) and CPU1 LINK0/1 can read / write and define the RTDMA MPU registers. Safety and Security Unit (SSU) related checks are placed in a hardcoded region outside of the RTDMA to verify appropriate permissions. User can assign each channel to an AP region inside the SSU to define the channel ownership to a certain link / zone and prevent illegal accesses to channel specific registers from other sources.