STM32F1xx_HAL库_V1.4.0_及例程

/** @page RCC_ClockConfig RCC Clock Config example @verbatim ******************** (C) COPYRIGHT 2016 STMicroelectronics ******************* * @file RCC/RCC_ClockConfig/readme.txt * @author MCD Application Team * @version V1.4.0 * @date 29-April-2016 * @brief Description of the RCC Clock Config example. ****************************************************************************** * * Redistribution and use in source and binary forms, with or without modification, * are permitted provided that the following conditions are met: * 1. Redistributions of source code must retain the above copyright notice, * this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright notice, * this list of conditions and the following disclaimer in the documentation * and/or other materials provided with the distribution. * 3. Neither the name of STMicroelectronics nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * ****************************************************************************** @endverbatim @par Example Description This example describes how to use the RCC HAL API to configure the system clock (SYSCLK) and modify the clock settings in run mode. In this example, after startup SYSCLK is configured to the max frequency using the PLL with HSI as clock source, the User push-button (connected to External lines 10 to 15) will be used to change the PLL source: - from HSE bypass to HSI - from HSI to HSE bypass @note In HSE bypass mode, input clock will come from the MCO from ST_LINK MCU. This frequency cannot be changed, and it is fixed at 8 MHz. To use MCO from ST_LINK you need to check the Board User Manual to know how to connect the MCO pin to the STM32 device. Each time the User push-button is pressed; External lines 10 to 15 interrupt is generated and in the ISR the PLL oscillator source is checked using __HAL_RCC_GET_PLL_OSCSOURCE() macro: - If the HSE bypass oscillator is selected as PLL source, the following steps will be followed to switch the PLL source to HSI oscillator: a- Switch the system clock source to HSE bypass to allow modification of the PLL configuration b- Enable HSI Oscillator, select it as PLL source and finally activate the PLL c- Select the PLL as system clock source and configure the HCLK, PCLK1 and PCLK2 clocks dividers d- Disable the HSE bypass oscillator (optional, if the HSE is no more needed by the application) - If the HSI oscillator is selected as PLL source, the following steps will be followed to switch the PLL source to HSE bypass oscillator: a- Switch the system clock source to HSI to allow modification of the PLL configuration b- Enable HSE bypass Oscillator, select it as PLL source and finally activate the PLL c- Select the PLL as system clock source and configure the HCLK, PCLK1 and PCLK2 clocks dividers d- Disable the HSI oscillator (optional, if the HSI is no more needed by the application) In this example the SYSCLK is outputted on the MCO1 pin(PA.08). One LED is toggled with a timing defined by the HAL_Delay() API. @note Care must be taken when using HAL_Delay(), this function provides accurate delay (in milliseconds) based on variable incremented in SysTick ISR. This implies that if HAL_Delay() is called from a peripheral ISR process, then the SysTick interrupt must have higher priority (numerically lower) than the peripheral interrupt. Otherwise the caller ISR process will be blocked. To change the SysTick interrupt priority you have to use HAL_NVIC_SetPriority() function. @note The application need to ensure that the SysTick time base is always set to 1 millisecond to have correct HAL operation. @par Directory contents - RCC/RCC_ClockConfig/Inc/stm32f1xx_hal_conf.h HAL configuration file - RCC/RCC_ClockConfig/Inc/stm32f1xx_it.h Interrupt handlers header file - RCC/RCC_ClockConfig/Inc/main.h Header for main.c module - RCC/RCC_ClockConfig/Src/stm32f1xx_it.c Interrupt handlers - RCC/RCC_ClockConfig/Src/main.c Main program - RCC/RCC_ClockConfig/Src/system_stm32f1xx.c STM32F1xx system source file @par Hardware and Software environment - This example runs on STM32F103xB devices. - This example has been tested with STM32F103RB-Nucleo board and can be easily tailored to any other supported device and development board. @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 * <h3><center>&copy; COPYRIGHT STMicroelectronics</center></h3> */