STM32CubeF7/Projects/STM32F767ZI-Nucleo/Examples_LL/RCC/RCC_OutputSystemClockOnMCO

/**
  @page RCC_OutputSystemClockOnMCO RCC example
  
  @verbatim
  ******************************************************************************
  * @file    Examples_LL/RCC/RCC_OutputSystemClockOnMCO/readme.txt 
  * @author  MCD Application Team
  * @brief   Description of the RCC example.
  ******************************************************************************
  * @attention
  *
  * Copyright (c) 2016 STMicroelectronics.
  * All rights reserved.
  *
  * This software is licensed under terms that can be found in the LICENSE file
  * in the root directory of this software component.
  * If no LICENSE file comes with this software, it is provided AS-IS.
  *
  ******************************************************************************
  @endverbatim

@par Example Description

This example describes how to configure MCO pins (PA8 and PC9) to output the system clock.

At start-up, USER button and MCO pin are configured. The program configures SYSCLK
to the max frequency using the PLL with HSE as clock source.

The signal on PA8 and PC9 can be monitored with an oscilloscope
to check the different MCO configuration set at each button press.
Different configuration will be observed
 - HSI frequency with frequency value around @16MHz.
 - PLLCLK frequency value divided by 4, hence around @54MHz.
 - SYSCLK frequency value divided by 2, hence around @108MHz.
 - HSE frequency value divided by 2, hence around @4MHz.

When user press User push-button, a LED1 toggle is done to indicate a change in MCO config.

@par Keywords

System, RCC, PLL, HSI, PLLCLK, SYSCLK, HSE, Clock, Oscillator

@Note If the user code size exceeds the DTCM-RAM size or starts from internal cacheable memories (SRAM1 and SRAM2),that is shared between several processors,
      then it is highly recommended to enable the CPU cache and maintain its coherence at application level.
      The address and the size of cacheable buffers (shared between CPU and other masters)  must be properly updated to be aligned to cache line size (32 bytes).

@Note It is recommended to enable the cache and maintain its coherence, but depending on the use case
      It is also possible to configure the MPU as "Write through", to guarantee the write access coherence.
      In that case, the MPU must be configured as Cacheable/Bufferable/Not Shareable.
      Even though the user must manage the cache coherence for read accesses.
      Please refer to the AN4838 “Managing memory protection unit (MPU) in STM32 MCUs”
      Please refer to the AN4839 “Level 1 cache on STM32F7 Series”

@par Directory contents 

  - RCC/RCC_OutputSystemClockOnMCO/Inc/stm32f7xx_it.h          Interrupt handlers header file
  - RCC/RCC_OutputSystemClockOnMCO/Inc/main.h                  Header for main.c module
  - RCC/RCC_OutputSystemClockOnMCO/Inc/stm32_assert.h          Template file to include assert_failed function
  - RCC/RCC_OutputSystemClockOnMCO/Src/stm32f7xx_it.c          Interrupt handlers
  - RCC/RCC_OutputSystemClockOnMCO/Src/main.c                  Main program
  - RCC/RCC_OutputSystemClockOnMCO/Src/system_stm32f7xx.c      STM32F7xx system source file


@par Hardware and Software environment

  - This example runs on STM32F767xx devices.

  - This example has been tested with NUCLEO-F767ZI board and can be
    easily tailored to any other supported device and development board.

  - NUCLEO-F767ZI Set-up
    - Connect the MCO pin to an oscilloscope to monitor the different waveforms:
      - PA.08: connected to pin 23 of CN12 connector for Nucleo-144 (MB1137)
      - PC.09: connected to pin 1 of CN12 connector for Nucleo-144 (MB1137)

@par How to use it ?

In order to make the program work, you must do the following :
 - Open your preferred toolchain
 - Rebuild all files and load your image into target memory
 - Run the example


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