15.3.1 Overview

All peripherals are composed of one digital bus interface, which is connected to the APB or AHB bus and clocked using a corresponding synchronous clock, and one core clock, which is clocked using a generic clock. Access between these clock domains must be synchronized. As this mechanism is implemented in hardware the synchronization process takes place even if the different clocks domains are clocked from the same source and on the same frequency. All registers in the bus interface are accessible without synchronization. All core registers in the generic clock domain must be synchronized when written. Some core registers must be synchronized when read. Registers that need synchronization has this denoted in each individual register description.

Note: Due to asynchronicity between the main clock domain and the peripheral clock domains, all Read-Synchronized registers must ensure synchronization is completed before accessing them after waking up from standby sleep mode. The respective bit in the Synchronization Busy register (SYNCBUSY) will be cleared when the write-synchronization is complete.