Posted on September 13, 2014 at 01:12
Hi,
I am trying to create a 64MHz system clock by using the 8MHz HSI clock and the PLL (PLLMUL = 16). But the firmware stops working after this line:
RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);
But it will work if I change the PLLMUL to 13 or less. The user manual says the STM32F103 system clock max frequency is 72MHz, so I don't know why the firmware fails.
Below is a simple example main.c file, the project was created by Keil uVision 5.1. Project file attached.
/* Includes ------------------------------------------------------------------*/
#include ''stm32f10x.h''
#include ''stm32f10x_gpio.h''
#include ''stm32f10x_rcc.h''
#include <
stdio.h
>
int main(void)
{
GPIO_InitTypeDef gpio_init_structure; //GPIO structure
RCC_HSICmd(ENABLE);
RCC_PLLConfig(RCC_PLLSource_HSI_Div2, RCC_PLLMul_16);
// Enable PLL
RCC_PLLCmd(ENABLE);
// Checks whether the specified RCC flag is set or not
// Wait till PLL is ready
while(RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET);
// Select PLL as system clock source
RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
/* Output clock on MCO pin ---------------------------------------------*/
gpio_init_structure.GPIO_Pin = GPIO_Pin_8;
gpio_init_structure.GPIO_Mode = GPIO_Mode_AF_PP;
gpio_init_structure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOA, &gpio_init_structure);
// RCC_MCOConfig(RCC_MCO_HSE); // Put on MCO pin the: freq. of external crystal
RCC_MCOConfig(RCC_MCO_SYSCLK); // Put on MCO pin the: System clock selected
while(1);
}
#ifdef USE_FULL_ASSERT
/**
* @brief Reports the name of the source file and the source line number
* where the assert_param error has occurred.
* @param file: pointer to the source file name
* @param line: assert_param error line source number
* @retval None
*/
void assert_failed(uint8_t* file, uint32_t line)
{
/* User can add his own implementation to report the file name and line number,
ex: printf(''Wrong parameters value: file %s on line %d\r\n'', file, line) */
/* Infinite loop */
while (1)
{
}
}
#endif
/**
* @}
*/
/**
* @}
*/
/******************* (C) COPYRIGHT 2011 STMicroelectronics *****END OF FILE****/
