运行STM32F105，由于外部晶振是12MHZ，所以对官方库进行修改：
首先stm32f10x.h修改晶振为#define HSE_VALUE ((uint32_t)12000000)。
想把主频设置为48MHz,system_stm32f10x.c文件修改函数
static void SetSysClockTo48(void)
{
__IO uint32_t StartUpCounter = 0, HSEStatus = 0;
/* SYSCLK, HCLK, PCLK2 and PCLK1 configuration ---------------------------*/
/* Enable HSE */
RCC->CR |= ((uint32_t)RCC_CR_HSEON);
/* Wait till HSE is ready and if Time out is reached exit */
do
{
HSEStatus = RCC->CR & RCC_CR_HSERDY;
StartUpCounter++;
} while((HSEStatus == 0) && (StartUpCounter != HSE_STARTUP_TIMEOUT));
if ((RCC->CR & RCC_CR_HSERDY) != RESET)
{
HSEStatus = (uint32_t)0x01;
}
else
{
HSEStatus = (uint32_t)0x00;
}
if (HSEStatus == (uint32_t)0x01)
{
/* Enable Prefetch Buffer */
FLASH->ACR |= FLASH_ACR_PRFTBE;
/* Flash 1 wait state */
FLASH->ACR &= (uint32_t)((uint32_t)~FLASH_ACR_LATENCY);
FLASH->ACR |= (uint32_t)FLASH_ACR_LATENCY_1;
/* HCLK = SYSCLK */
RCC->CFGR |= (uint32_t)RCC_CFGR_HPRE_DIV1;
/* PCLK2 = HCLK */
RCC->CFGR |= (uint32_t)RCC_CFGR_PPRE2_DIV1;
/* PCLK1 = HCLK */
RCC->CFGR |= (uint32_t)RCC_CFGR_PPRE1_DIV2;
#ifdef STM32F10X_CL
/* Configure PLLs ------------------------------------------------------*/
/* PLL2 configuration: PLL2CLK = (HSE / 5) * 8 = 40 MHz */
/* PREDIV1 configuration: PREDIV1CLK = PLL2 / 5 = 8 MHz */
RCC->CFGR2 &= (uint32_t)~(RCC_CFGR2_PREDIV2 | RCC_CFGR2_PLL2MUL |
RCC_CFGR2_PREDIV1 | RCC_CFGR2_PREDIV1SRC);
if (HSE_VALUE == 25000000)
{
/* Configure PLLs ------------------------------------------------------*/
/* PLL2 configuration: PLL2CLK = (HSE / 5) * 8 = 40 MHz */
/* PREDIV1 configuration: PREDIV1CLK = PLL2 / 5 = 8 MHz */
RCC->CFGR2 |= (uint32_t)(RCC_CFGR2_PREDIV2_DIV5 | RCC_CFGR2_PLL2MUL8 |
RCC_CFGR2_PREDIV1SRC_PLL2 | RCC_CFGR2_PREDIV1_DIV5);
}
else if (HSE_VALUE == 8000000)
{
/* Configure PLLs ------------------------------------------------------*/
/* PLL2 configuration: PLL2CLK = (HSE / 2) * 10 = 40 MHz */
/* PREDIV1 configuration: PREDIV1CLK = PLL2 / 5 = 8 MHz */
RCC->CFGR2 |= (uint32_t)(RCC_CFGR2_PREDIV2_DIV2 | RCC_CFGR2_PLL2MUL10 |
RCC_CFGR2_PREDIV1SRC_PLL2 | RCC_CFGR2_PREDIV1_DIV5);
}
else if (HSE_VALUE == 12000000)
{
/* Configure PLLs ------------------------------------------------------*/
/* PLL2 configuration: PLL2CLK = (HSE / 3) * 10 = 40 MHz */
/* PREDIV1 configuration: PREDIV1CLK = PLL2 / 5 = 8 MHz */
RCC->CFGR2 |= (uint32_t)(RCC_CFGR2_PREDIV2_DIV3 | RCC_CFGR2_PLL2MUL10 |
RCC_CFGR2_PREDIV1SRC_PLL2 | RCC_CFGR2_PREDIV1_DIV5);
}
else
{
/* Configure PLLs ------------------------------------------------------*/
/* PLL2 configuration: PLL2CLK = (HSE / 5) * 8 = 40 MHz */
/* PREDIV1 configuration: PREDIV1CLK = PLL2 / 5 = 8 MHz */
RCC->CFGR2 |= (uint32_t)(RCC_CFGR2_PREDIV2_DIV5 | RCC_CFGR2_PLL2MUL8 |
RCC_CFGR2_PREDIV1SRC_PLL2 | RCC_CFGR2_PREDIV1_DIV5);
}
/* Enable PLL2 */
RCC->CR |= RCC_CR_PLL2ON;
/* Wait till PLL2 is ready */
while((RCC->CR & RCC_CR_PLL2RDY) == 0)
{
}
/* PLL configuration: PLLCLK = PREDIV1 * 6 = 48 MHz */
RCC->CFGR &= (uint32_t)~(RCC_CFGR_PLLXTPRE | RCC_CFGR_PLLSRC | RCC_CFGR_PLLMULL);
RCC->CFGR |= (uint32_t)(RCC_CFGR_PLLXTPRE_PREDIV1 | RCC_CFGR_PLLSRC_PREDIV1 |
RCC_CFGR_PLLMULL6);
#else
/* PLL configuration: PLLCLK = HSE * 6 = 48 MHz */
RCC->CFGR &= (uint32_t)((uint32_t)~(RCC_CFGR_PLLSRC | RCC_CFGR_PLLXTPRE | RCC_CFGR_PLLMULL));
RCC->CFGR |= (uint32_t)(RCC_CFGR_PLLSRC_HSE | RCC_CFGR_PLLMULL6);
#endif /* STM32F10X_CL */
/* Enable PLL */
RCC->CR |= RCC_CR_PLLON;
/* Wait till PLL is ready */
while((RCC->CR & RCC_CR_PLLRDY) == 0)
{
}
/* Select PLL as system clock source */
RCC->CFGR &= (uint32_t)((uint32_t)~(RCC_CFGR_SW));
RCC->CFGR |= (uint32_t)RCC_CFGR_SW_PLL;
/* Wait till PLL is used as system clock source */
while ((RCC->CFGR & (uint32_t)RCC_CFGR_SWS) != (uint32_t)0x08)
{
}
}
else
{ /* If HSE fails to start-up, the application will have wrong clock
configuration. User can add here some code to deal with this error */
}
}
通过函数
RCC_ClocksTypeDef rcc_clk;
RCC_GetClocksFreq(&rcc_clk);
获取到时钟分频正确且MCU运行正常（如串口输出，定时器中断）
然后自己写了个函数设置分频
void Set_System(void)
{
ErrorStatus HSEStartUpStatus;
/* SYSCLK, HCLK, PCLK2 and PCLK1 configuration -----------------------------*/
/* RCC system reset(for debug purpose) */
RCC_DeInit();
/* Enable HSE */
RCC_HSEConfig(RCC_HSE_ON);
/* Wait till HSE is ready */
HSEStartUpStatus = RCC_WaitForHSEStartUp();
if (HSEStartUpStatus == SUCCESS)
{
/* Enable Prefetch Buffer */
FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable);
/* Flash 2 wait state */
FLASH_SetLatency(FLASH_Latency_2);
/* HCLK = SYSCLK */
RCC_HCLKConfig(RCC_SYSCLK_Div1);
/* PCLK2 = HCLK */
RCC_PCLK2Config(RCC_HCLK_Div1);
/* PCLK1 = HCLK/2 */
RCC_PCLK1Config(RCC_HCLK_Div2);
#ifdef STM32F10X_CL
/* Configure PLLs *********************************************************/
/* PLL2 configuration: PLL2CLK = (HSE / 3) * 10 = 40 MHz */
/* HSE_VALUE = 120000000 HZ, stm32f10x.h */
RCC_PREDIV2Config(RCC_PREDIV2_Div3);
RCC_PLL2Config(RCC_PLL2Mul_10);
/* Enable PLL2 */
RCC_PLL2Cmd(ENABLE);
/* Wait till PLL2 is ready */
while (RCC_GetFlagStatus(RCC_FLAG_PLL2RDY) == RESET)
{}
/* PLL configuration: PLLCLK = (PLL2 / 5) * 6 = 48 MHz */
RCC_PREDIV1Config(RCC_PREDIV1_Source_PLL2, RCC_PREDIV1_Div5);
RCC_PLLConfig(RCC_PLLSource_PREDIV1, RCC_PLLMul_6);
#else
/* PLLCLK = 8MHz * 9 = 72 MHz */
RCC_PLLConfig(RCC_PLLSource_HSE_Div1, RCC_PLLMul_9);
#endif
/* Enable PLL */
RCC_PLLCmd(ENABLE);
/* Wait till PLL is ready */
while (RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET)
{
}
/* Select PLL as system clock source */
RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);
/* Wait till PLL is used as system clock source */
while(RCC_GetSYSCLKSource() != 0x08)
{
}
RCC_OTGFSCLKConfig(RCC_OTGFSCLKSource_PLLVCO_Div3);
}
else
{
/* If HSE fails to start-up, the application will have wrong clock configuration.
User can add here some code to deal with this error */
/* Go to infinite loop */
while (1)
{
}
}
}
这个效果和修改官方库一样，分频正确且MCU运行正常，但是比较电流发现，修改官方库的方法比自己写的分频函数电流小了2个ma。
求教有经验的大神指点原因？ |
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