system_stm32l4xx.c File Reference

This file provides the CMSIS Cortex-M4 system initialization and clock configuration. Originally provided by ST. More...

#include "stm32l4xx.h"

Go to the source code of this file.

Macros
#define	HSE_VALUE   8000000U
#define	MSI_VALUE   4000000U
#define	HSI_VALUE   16000000U

Functions
void	SystemInit (void)
	Initialize the system before calling the main() function.
void	SystemCoreClockUpdate (void)
	Update the SystemCoreClock variable according to the clock register values. More...

Variables
uint32_t	SystemCoreClock = 4000000U
	Define to enable user-defined vector table address setting. More...
const uint8_t	AHBPrescTable [16]
const uint8_t	APBPrescTable [8] = {0U, 0U, 0U, 0U, 1U, 2U, 3U, 4U}
const uint32_t	MSIRangeTable [12]

Detailed Description

This file provides the CMSIS Cortex-M4 system initialization and clock configuration. Originally provided by ST.

STM32 Bootloader

Author

Akos Pasztor

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

• SystemInit(): This function is called at startup just after reset and before jumping to the main program. This call is made inside the startup_stm32l4xx.s file.
• SystemCoreClock variable: Contains the core clock (HCLK), it can be used by the 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 MSI (4 MHz) is used as system clock source. Then SystemInit() function is called from the startup_stm32l4xx.s" file to configure the system clock before to jumping to the main program.

This file configures the system clock as follows:

Parameter	Value
System Clock source	MSI
SYSCLK (Hz)	4000000
HCLK (Hz)	4000000
AHB Prescaler	1
APB1 Prescaler	1
APB2 Prescaler	1
PLL_M	1
PLL_N	8
PLL_P	7
PLL_Q	2
PLL_R	2
PLLSAI1_P	NA
PLLSAI1_Q	NA
PLLSAI1_R	NA
PLLSAI2_P	NA
PLLSAI2_Q	NA
PLLSAI2_R	NA
Require 48MHz for USB OTG FS, SDIO and RNG	Disabled

Copyright

(c) 2026 Akos Pasztor. https://akospasztor.com This software is licensed under terms that can be found in the LICENSE file in the root directory of this software component.

Definition in file system_stm32l4xx.c.