system_stm32g4xx.c File Reference

CMSIS Cortex-M4 Device Peripheral Access Layer System Source File. More...

#include "stm32g4xx.h"

Macros
#define	HSE_VALUE   24000000U
#define	HSI_VALUE   16000000U

Functions
void	SystemInit (void)
	Setup the microcontroller system.
void	SystemCoreClockUpdate (void)
	Update SystemCoreClock variable according to Clock Register Values. The SystemCoreClock variable contains the core clock (HCLK), it can be used by the user application to setup the SysTick timer or configure other parameters.

Variables
uint32_t	SystemCoreClock = HSI_VALUE
const uint8_t	AHBPrescTable [16] = {0U, 0U, 0U, 0U, 0U, 0U, 0U, 0U, 1U, 2U, 3U, 4U, 6U, 7U, 8U, 9U}
const uint8_t	APBPrescTable [8] = {0U, 0U, 0U, 0U, 1U, 2U, 3U, 4U}

Detailed Description

CMSIS Cortex-M4 Device Peripheral Access Layer System Source File.

Author

MCD Application Team

This file provides two functions and one global variable to be called from user application:

• SystemInit(): This function is called at startup just after reset and before branch to main program. This call is made inside the "startup_stm32g4xx.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.

After each device reset the HSI (16 MHz) is used as system clock source. Then SystemInit() function is called, in "startup_stm32g4xx.s" file, to configure the system clock before to branch to main program.

This file configures the system clock as follows:

---

System Clock source | HSI

SYSCLK(Hz) | 16000000

HCLK(Hz) | 16000000

AHB Prescaler | 1

APB1 Prescaler | 1

APB2 Prescaler | 1

PLL_M | 1

PLL_N | 16

PLL_P | 7

PLL_Q | 2

PLL_R | 2

Require 48MHz for RNG | Disabled

=============================================================================

Attention

Copyright (c) 2019 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.