/** | |
* \file | |
* | |
* \brief SAM D20 Generic Clock Driver Quick Start | |
* | |
* Copyright (C) 2012-2013 Atmel Corporation. All rights reserved. | |
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*/ | |
/** | |
* \page asfdoc_samd20_system_gclk_basic_use_case Quick Start Guide for SYSTEM CLOCK - GCLK Configuration | |
* | |
* In this use case, the GCLK module is configured for: | |
* \li One generator attached to the internal 8MHz RC oscillator clock source | |
* \li Generator output equal to input frequency divided by a factor of 128 | |
* \li One channel (connected to the TC0 module) enabled with the enabled generator selected | |
* | |
* This use case configures a clock channel to output a clock for a peripheral | |
* within the device, by first setting up a clock generator from a master clock | |
* source, and then linking the generator to the desired channel. This clock | |
* can then be used to clock a module within the device. | |
* | |
* \section asfdoc_samd20_system_gclk_basic_use_case_setup Setup | |
* | |
* \subsection asfdoc_samd20_system_gclk_basic_use_case_setup_prereq Prerequisites | |
* There are no special setup requirements for this use-case. | |
* | |
* \subsection asfdoc_samd20_system_gclk_basic_use_case_setup_code Code | |
* Copy-paste the following setup code to your user application: | |
* \snippet qs_gclk_basic.c setup | |
* | |
* Add to user application initialization (typically the start of \c main()): | |
* \snippet qs_gclk_basic.c setup_init | |
* | |
* \subsection asfdoc_samd20_system_gclk_basic_use_case_setup_flow Workflow | |
* -# Create a GCLK generator configuration struct, which can be filled out to | |
* adjust the configuration of a single clock generator. | |
* \snippet qs_gclk_basic.c setup_1 | |
* -# Initialize the generator 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_gclk_basic.c setup_2 | |
* -# Adjust the configuration struct to request that the master clock source | |
* channel 0 be used as the source of the generator, and set the generator | |
* output prescaler to divide the input clock by a factor of 128. | |
* \snippet qs_gclk_basic.c setup_3 | |
* -# Configure the generator using the configuration structure. | |
* \note The existing configuration struct may be re-used, as long as any | |
* values that have been altered from the default settings are taken | |
* into account by the user application. | |
* | |
* \snippet qs_gclk_basic.c setup_4 | |
* -# Enable the generator once it has been properly configured, to begin clock | |
* generation. | |
* \snippet qs_gclk_basic.c setup_5 | |
* | |
* -# Create a GCLK channel configuration struct, which can be filled out to | |
* adjust the configuration of a single generic clock channel. | |
* \snippet qs_gclk_basic.c setup_6 | |
* -# Initialize the channel 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_gclk_basic.c setup_7 | |
* -# Adjust the configuration struct to request that the previously configured | |
* and enabled clock generator be used as the clock source for the channel. | |
* \snippet qs_gclk_basic.c setup_8 | |
* -# Configure the channel using the configuration structure. | |
* \note The existing configuration struct may be re-used, as long as any | |
* values that have been altered from the default settings are taken | |
* into account by the user application. | |
* | |
* \snippet qs_gclk_basic.c setup_9 | |
* -# Enable the channel once it has been properly configured, to output the | |
* clock to the channel's peripheral module consumers. | |
* \snippet qs_gclk_basic.c setup_10 | |
* | |
* \section asfdoc_samd20_system_gclk_basic_use_case_main Use Case | |
* | |
* \subsection asfdoc_samd20_system_gclk_basic_use_case_code Code | |
* Copy-paste the following code to your user application: | |
* \snippet qs_gclk_basic.c main | |
* | |
* \subsection asfdoc_samd20_system_gclk_basic_use_case_flow Workflow | |
* -# As the clock is generated asynchronously to the system core, no special | |
* extra application code is required. | |
*/ |