system_stm32f30x.c File Reference

CMSIS Cortex-M4 Device Peripheral Access Layer System Source File. This file contains the system clock configuration for STM32F30x devices and is customized for use with stm32f301_nucleo Kit. The STM32F30x is configured to run at 72 MHz, following the three configuration below:

• PLL_SOURCE_HSI (default) : HSI (~8MHz) used to clock the PLL, and the PLL is used as system clock source, 64 MHz is maximum frequency on PLL HSI mode.
• PLL_SOURCE_HSE : HSE (8MHz) used to clock the PLL, and the PLL is used as system clock source.
• PLL_SOURCE_HSE_BYPASS : HSE bypassed with an external clock (8MHz, coming from ST-Link) used to clock the PLL, and the PLL is used as system clock source.

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Detailed Description

CMSIS Cortex-M4 Device Peripheral Access Layer System Source File. This file contains the system clock configuration for STM32F30x devices and is customized for use with stm32f301_nucleo Kit. The STM32F30x is configured to run at 72 MHz, following the three configuration below:

• PLL_SOURCE_HSI (default) : HSI (~8MHz) used to clock the PLL, and the PLL is used as system clock source, 64 MHz is maximum frequency on PLL HSI mode.
• PLL_SOURCE_HSE : HSE (8MHz) used to clock the PLL, and the PLL is used as system clock source.
• PLL_SOURCE_HSE_BYPASS : HSE bypassed with an external clock (8MHz, coming from ST-Link) used to clock the PLL, and the PLL is used as system clock source.

Author:

MCD Application Team

Version:

V1.0.0

Date:

20-June-2014 1. This file provides two functions and one global variable to be called from user application:

• SystemInit(): Setups the system clock (System clock source, PLL Multiplier and Divider factors, AHB/APBx prescalers and Flash settings), depending on the configuration made in the clock xls tool. This function is called at startup just after reset and before branch to main program. This call is made inside the "startup_stm32f334x8.s" file.

• SystemCoreClock variable: Contains the core clock (HCLK), it can be used by the user application to setup the SysTick timer or configure other parameters.

• SystemCoreClockUpdate(): Updates the variable SystemCoreClock and must be called whenever the core clock is changed during program execution.

2. After each device reset the HSI (8 MHz) is used as system clock source. Then SystemInit() function is called, in "startup_stm32f334x8.s" file, to configure the system clock before to branch to main program.

3. If the system clock source selected by user fails to startup, the SystemInit() function will do nothing and HSI still used as system clock source. User can add some code to deal with this issue inside the SetSysClock() function.

4. The default value of HSE crystal is set to 8MHz, refer to "HSE_VALUE" define in "stm32f30x.h" file. When HSE is used as system clock source, directly or through PLL, and you are using different crystal you have to adapt the HSE value to your own configuration.

Attention:

© COPYRIGHT 2014 STMicroelectronics

Licensed under MCD-ST Liberty SW License Agreement V2, (the "License"); You may not use this file except in compliance with the License. You may obtain a copy of the License at:

http://www.st.com/software_license_agreement_liberty_v2

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

Definition in file system_stm32f30x.c.