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Application Design
Basic Principles
Figure 3.8 Clock configuration example in application low-power state
This example also shows that some peripherals allow using multiple clock sources (for
instance clock generator output, raw output from reference clock source or other
alternative clocks). Clock configuration in such case can be used to switch clock source of
the peripheral clock input. Furthermore, the example demonstrates possibility to enable or
shut down entire peripheral during clock configuration switch. For more information
about clock configuration options available in the embedded components, see Support of
Clock Configurations in Embedded Components topic. Clock configuration switch is
explained in the topic below.
Changing active clock configuration
CPU (processor) component SetClockConfiguration(ConfigurationID)
method is used to change active clock configuration. This method will switch to clock
configuration defined by ConfigurationID passed as input parameter. The required
configuration has to be predefined in the processor component, otherwise the method
returns an error.
Clock configuration change is done during CPU SetClockConfiguration()
method call in the following order:
1. It is checked whether required clock configuration number was defined in the CPU
(processor) component. If not, method returns with an error.
2. System timing is configured according to new clock configuration, including reference
clock source selection, clock generator modules and system dividers.
3. All LDD components which support clock configuration feature are called to
configure their underlying peripherals - global internal
LDD_SetClockConfiguation() method is invoked which in return invokes
internal SetClockConfiguration() method of the LDD components.
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