SWCU195A December 2024 – May 2025 CC2744R7-Q1 , CC2745P10-Q1 , CC2745R10-Q1 , CC2745R7-Q1 , CC2755R10
The Trustzone Control Module (TCM) holds protected registers intended to configure the system outside the CPU.
Each register has the following form:
31: Parity covering bits 23:16
30: Parity covering bits 15:8
29: Parity covering bits 7:0
28:24: 0
23:0: Data
The data field contains either control bits for all gaskets or sets the watermark for memories.
If the parity is wrong at the time of writing or at any time during operation, the device will perform a security reset as this is evidence of external tampering with security features.
Watermark has a limited resolution, providing a granularity of 1024 bytes for SRAM and 8kB for Flash.
If the TCM is not reconfigured from its initial state, then the entire system is operating in Secure mode. This is the correct backward-compatible mode of operation with non TrustZone-M systems, and is the expected mode if no TrustZone-M features are needed.
Bootcode can configure TCM securely based on user configuration.
As the TCM changes the system address map, special precautions must be taken to ensure no data corruption occurs when it is modified. Please refer to TI-provided code or the code already deployed in the system in ROM to reconfigure TCM safely.