Often peripherals can be clocked not only from internal peripheral bus, but also from variety of alternative clock sources, such as dedicated asynchronous clock generator or any other system clock source. Although, the way how such selection is implemented is component-specific and might be common for all clock configurations, it is common practice that high-level and LDD components allow selecting input clock source for each clock configuration independently, switching between them during the application runtime (during SetClockConfiguration() method call). If peripheral input clock is not available, for example, because the clock configuration is set to disable the required reference clock source, the Processor Expert notifies the user about this.