Typical processor or microcontroller allows multiple reference clock sources usage, contains clock synthesis modules to process these reference clocks and distribute them across the system. This system timing scheme provides a set of clocks produced by the system modules and is described as a clock path which starts at selected reference clock source, such as internal oscillator or external crystal, and ends at variety of processor internal clocks, such as core (instruction) clock or other clocks consumed by internal peripherals.
Clock configuration is feature allowing design time creation and management of multiple system timing schemes and is handled by a CPU (processor) component. This feature is derived from the Speed modes used by the high-level components. For more details, see Speed modes support topic.
The following schematic illustrates a simple system timing scheme. It consists of internal and external reference clock, general clock generator module and several internal modules that can consume variety of clocks. The orange block represents modules involved in clock generation and distribution whereas, blue and green blocks denote clock consumers. For example, core module and all internal peripherals can be clocked from divided clock generator output or from divided internal or external reference clock. Additionally, internal peripheral 3 can be fed directly from internal reference clock and internal peripheral 2 also directly from external reference.
In Processor Expert, the orange blocks represents clock configuration and the green blocks represents embedded components.
As mentioned, clock configurations are configured in the CPU (processor) component. There user can make selection of used reference clock and specify configuration of clock generator modules and dividers. Finally, in CPU component user always select frequency of all major processor clocks, such as core, system or flash memory frequencies that is clock, which define speed of the whole system, or peripheral bus clocks, which influence timing characteristics of chip internal peripherals. embedded components relies on these values and use them as the input value for timing features they encapsulate. The relationship between clock configurations set in the CPU (processor) component and embedded components is explained in Support of clock configurations in embedded components topic.
There is always at least one clock configuration in the project - Clock configuration 0. However, it is possible to use more clock configurations in the same project. For example, use case of multiple clock configuration is in Multiple clock configurations topic.