| /** | |
| * \file | |
| * | |
| * \brief SAM D20 System Clock Driver Quick Start | |
| * | |
| * Copyright (C) 2012-2013 Atmel Corporation. All rights reserved. | |
| * | |
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| * | |
| * \page License | |
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| * modification, are permitted provided that the following conditions are met: | |
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| * this list of conditions and the following disclaimer in the documentation | |
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| * Atmel microcontroller product. | |
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| */ | |
| /** | |
| * \page asfdoc_samd20_system_clock_basic_use_case Quick Start Guide for SYSTEM CLOCK - Basic | |
| * | |
| * In this case we apply the following configuration: | |
| * - RC8MHz (internal 8MHz RC oscillator) | |
| * - Divide by 4, giving a frequency of 2MHz | |
| * - DFLL (Digital frequency locked loop) | |
| * - Open loop mode | |
| * - 48MHz frequency | |
| * - CPU clock | |
| * - Use the DFLL, configured to 48MHz | |
| * | |
| * \section asfdoc_samd20_system_clock_basic_use_case_setup Setup | |
| * | |
| * \subsection asfdoc_samd20_system_clock_basic_use_case_setup_prereq Prerequisites | |
| * There are no special setup requirements for this use-case. | |
| * | |
| * \subsection asfdoc_samd20_system_clock_basic_use_case_setup_code Code | |
| * Copy-paste the following setup code to your application: | |
| * \snippet qs_clock_source.c setup | |
| * | |
| * \subsection asfdoc_samd20_system_clock_basic_use_case_setup_flow Workflow | |
| * -# Create a EXTOSC32K module configuration struct, which can be filled | |
| * out to adjust the configuration of the external 32KHz oscillator channel. | |
| * \snippet qs_clock_source.c config_extosc32k_config | |
| * | |
| * -# Initialize the oscillator configuration struct with the module's default | |
| * values. | |
| * \note This should always be performed before using the configuration | |
| * struct to ensure that all values are initialized to known default | |
| * settings. | |
| * | |
| * \snippet qs_clock_source.c config_extosc32k_get_defaults | |
| * | |
| * -# Alter the EXTOSC32K module configuration struct to require a start-up time | |
| * of 4096 clock cycles. | |
| * \snippet qs_clock_source.c config_extosc32k_change_defaults | |
| * | |
| * -# Write the new configuration to the EXTOSC32K module. | |
| * \snippet qs_clock_source.c config_extosc32k_set_config | |
| * | |
| * -# Create a DFLL module configuration struct, which can be filled | |
| * out to adjust the configuration of the external 32KHz oscillator channel. | |
| * \snippet qs_clock_source.c config_dfll_config | |
| * | |
| * -# Initialize the DFLL oscillator configuration struct with the module's | |
| * default values. | |
| * \note This should always be performed before using the configuration | |
| * struct to ensure that all values are initialized to known default | |
| * settings. | |
| * | |
| * \snippet qs_clock_source.c config_dfll_get_defaults | |
| * | |
| * -# Write the new configuration to the DFLL module. | |
| * \snippet qs_clock_source.c config_extosc32k_set_config | |
| * \section asfdoc_samd20_system_clock_basic_use_case_use_main Use Case | |
| * | |
| * \subsection asfdoc_samd20_system_clock_basic_use_case_code Code | |
| * | |
| * Copy-paste the following code to your user application: | |
| * \snippet qs_clock_source.c main | |
| * | |
| * \subsection asfdoc_samd20_system_clock_basic_use_case_flow Workflow | |
| * -# Configure the external 32KHz oscillator source using the previously | |
| * defined setup function. | |
| * \snippet qs_clock_source.c config_extosc32k_main | |
| * | |
| * -# Enable the configured external 32KHz oscillator source. | |
| * \snippet qs_clock_source.c enable_extosc32k_main | |
| * | |
| * -# Configure the DFLL oscillator source using the previously defined setup | |
| * function. | |
| * \snippet qs_clock_source.c config_dfll_main | |
| * | |
| * -# Enable the configured DFLL oscillator source. | |
| * \snippet qs_clock_source.c enable_dfll_main | |
| * | |
| * -# Switch the system clock source to the DFLL, by reconfiguring the main | |
| * clock generator. | |
| * \snippet qs_clock_source.c set_sys_clk_src | |
| */ |