15.1.3. Retention

The core state, including the debug settings, is preserved in low-power structures, enabling the core to be at least partially turned off. Changing from low-power retention to running operation does not require a reset of the core. The saved core state is restored on changing from low-power retention state to running operation. From an operating system point of view, there is no difference between a retention state and standby state, other than method of entry, latency and use-related constraints. However, from an external debugger point of view, the states differ as External Debug Request debug events stay pending and debug registers in the core power domain cannot be accessed.

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