30.5.2.6 Tamper Full Erase

Tamper full erase bit (CTRLA.TAMPERS) must be configured before CTRLA.ENABLE is set. This setting cannot be changed while the module is enabled. When this feature is enabled, the RTC Tamper Event (RTC_TAMPER) will trigger the full erase equivalent to a TRAM software reset and the reset of the Data Scramble Key (DSCC.DSCKEY) register. All TRAM registers are reverted to the default reset value. Data inside the security RAM is written to ‘0’ for all address locations.

Note: Tamper events are connected directly from the RTC to the TRAM, without going through the Event System.

The tamper full erase routine operates at the highest priority. If a remanence routine executing when a tamper full erase occurs, the remanence routine is immediately terminated. If the CPU attempts to write a new scramble key at the same time the tamper key erase routine is active, the CPU data is ignored, but no bus error will occur. If a CPU security routine access is requested during a tamper full erase, the CPU transaction will be ignored and treated as a bus error similar to accessing the module during a software reset.

Important: In STANDBY low power mode, it is mandatory to enable the dynamic power gating feature (STDBYCFG.DPGPDSW) to ensure TrustRAM erasing when the power domain PDSW is in a retention state.