时钟模块（使用HAL库）"/>
【STM32】RCC时钟模块（使用HAL库）
.5/Libraries/STM32F10x_StdPeriph_Driver/inc/stm32f10x_rcc.h
STM32最新固件库v3.5/Libraries/CMSIS/CM3/DeviceSupport/ST/STM32F10x/system_stm32f10x.c · 林何/STM32F103C8 - 码云 - 开源中国 (gitee)
1.宏定义
1.宏定义的位置
如果这个宏定义只能在.c文件中使用，则应该在.c文件中定义
如果这个宏定义既可以在.c或者.h文件中使用，则应该在.h中定义
2.位带：RCC_OFFSET
因为我们STM32是32位的寄存器，所以如果我们只想要操作寄存器其中的一位，所以我们可以使用位移操作
/* ------------ RCC registers bit address in the alias region ----------- */
/*RCC_OFFSET:等价于RCC的基地址和外设寄存器之差
*/
/*!< PERIPH_BAS--》 Peripheral base address in the alias region */#define RCC_OFFSET (RCC_BASE - PERIPH_BASE)3.第一个寄存器：CR
1.HSION
/* --- CR Register ---*//* Alias word address of HSION bit */
//这个寄存器相对于基地址的位置
#define CR_OFFSET (RCC_OFFSET + 0x00)
//操作HSION这一位相对于整个CR寄存器的偏移量
#define HSION_BitNumber 0x00
//CR寄存器中的HSION中的位带
//PERIPH_BB_BASE：位带访问区的基地址
#define CR_HSION_BB (PERIPH_BB_BASE + (CR_OFFSET * 32) + (HSION_BitNumber * 4))
如果想要对其进行设置，就直接给CR_HSION_BB赋值
2.PLLON
/* Alias word address of PLLON bit */
#define PLLON_BitNumber 0x18
#define CR_PLLON_BB (PERIPH_BB_BASE + (CR_OFFSET * 32) + (PLLON_BitNumber * 4))4.RCC registers bit mask
Reset：进行位与置0
Set：进行位或置1
/* ---------------------- RCC registers bit mask ------------------------ *//* CR register bit mask */
#define CR_HSEBYP_Reset ((uint32_t)0xFFFBFFFF)
#define CR_HSEBYP_Set ((uint32_t)0x00040000)
#define CR_HSEON_Reset ((uint32_t)0xFFFEFFFF)
#define CR_HSEON_Set ((uint32_t)0x00010000)
#define CR_HSITRIM_Mask ((uint32_t)0xFFFFFF07)
2.全局变量
定义了预分配处理器
1.static
c语言中static关键字用法详解_static在c语言中的用法-CSDN博客
2.volatile
这个变量跟某一个寄存器的值进行绑定，寄存器里面有一个值是硬件可以改动的值
C语言丨深入理解volatile关键字-腾讯云开发者社区-腾讯云 (tencent)
3.uint
uint8：表示unsigned short
uint16：表示unsigned char
uint32：表示unsigned int
static __I uint8_t APBAHBPrescTable[16] = {0, 0, 0, 0, 1, 2, 3, 4, 1, 2, 3, 4, 6, 7, 8, 9};
static __I uint8_t ADCPrescTable[4] = {2, 4, 6, 8};3.函数
1.RCC_DeInit
/*** @brief Resets the RCC clock configuration to the default reset state.* @param None* @retval None*/
void RCC_DeInit(void)
{/* Set HSION bit */
//将CR这个位写为1RCC->CR |= (uint32_t)0x00000001;/* Reset SW, HPRE, PPRE1, PPRE2, ADCPRE and MCO bits */
#ifndef STM32F10X_CLRCC->CFGR &= (uint32_t)0xF8FF0000;
#else//非CL的芯片使用RCC->CFGR &= (uint32_t)0xF0FF0000;
#endif /* STM32F10X_CL */ /* Reset HSEON, CSSON and PLLON bits */
//HSEON, CSSON and PLLON：将这几位置0RCC->CR &= (uint32_t)0xFEF6FFFF;/* Reset HSEBYP bit */RCC->CR &= (uint32_t)0xFFFBFFFF;/* Reset PLLSRC, PLLXTPRE, PLLMUL and USBPRE/OTGFSPRE bits */RCC->CFGR &= (uint32_t)0xFF80FFFF;#ifdef STM32F10X_CL/* Reset PLL2ON and PLL3ON bits */RCC->CR &= (uint32_t)0xEBFFFFFF;/* Disable all interrupts and clear pending bits */RCC->CIR = 0x00FF0000;/* Reset CFGR2 register */RCC->CFGR2 = 0x00000000;
#elif defined (STM32F10X_LD_VL) || defined (STM32F10X_MD_VL) || defined (STM32F10X_HD_VL)/* Disable all interrupts and clear pending bits */RCC->CIR = 0x009F0000;/* Reset CFGR2 register */RCC->CFGR2 = 0x00000000;
#else/* Disable all interrupts and clear pending bits */RCC->CIR = 0x009F0000;
#endif /* STM32F10X_CL */}2.RCC_HSEConfig
可以关闭时钟，所以平时我们不操纵它
这个HSEConfig实际效果：控制CPU是使用
外部晶振+内部振动电路 VS 外部时钟
1.assert：断言
assert机制是c语言用来判断一个东西是对的还是错的，如果是对的直接忽略过去，如果是错的就以某一种方式告诉我们（warrning error）让我们去修改。
/* Exported macro ------------------------------------------------------------*/
#ifdef USE_FULL_ASSERT
/*** @brief The assert_param macro is used for function's parameters check.* @param expr: If expr is false, it calls assert_failed function which reports * the name of the source file and the source line number of the call * that failed. If expr is true, it returns no value.* @retval None*/#define assert_param(expr) ((expr) ? (void)0 : assert_failed((uint8_t *)__FILE__, __LINE__))
/* Exported functions ------------------------------------------------------- */void assert_failed(uint8_t* file, uint32_t line);
#else#define assert_param(expr) ((void)0)
#endif /* USE_FULL_ASSERT */这个函数要用户自己去实现
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 *///用户用自己的方法去报错一个断言错误//用户可以用#error灯方法来在编译时报错（前提是断言表达式必须在预处理时就能有结果）//更常见的方式是用户在运行时报错，用printf打印调试信息//while (1){}
}2.判断用户输入的参数是否正确
3.代码理解
/*** @brief Configures the External High Speed oscillator (HSE).* @note HSE can not be stopped if it is used directly or through the PLL as system clock.* @param RCC_HSE: specifies the new state of the HSE.* This parameter can be one of the following values:* @arg RCC_HSE_OFF: HSE oscillator OFF* @arg RCC_HSE_ON: HSE oscillator ON* @arg RCC_HSE_Bypass: HSE oscillator bypassed with external clock* @retval None*/
void RCC_HSEConfig(uint32_t RCC_HSE)
{/* Check the parameters */assert_param(IS_RCC_HSE(RCC_HSE));/* Reset HSEON and HSEBYP bits before configuring the HSE ------------------*//* Reset HSEON bit */RCC->CR &= CR_HSEON_Reset;/* Reset HSEBYP bit */RCC->CR &= CR_HSEBYP_Reset;/* Configure HSE (RCC_HSE_OFF is already covered by the code section above) */switch(RCC_HSE){case RCC_HSE_ON:/* Set HSEON bit */RCC->CR |= CR_HSEON_Set;break;case RCC_HSE_Bypass:/* Set HSEBYP and HSEON bits */RCC->CR |= CR_HSEBYP_Set | CR_HSEON_Set;break;default://RCC_HSE_OFFbreak;}
}3.RCC_WaitForHSEStartUp（等待HSE）
1.ErrorStatus
判断是否成功
一般：0：表示失败
1：表示成功
2.计数值加上volatile
因为这个变量是我们来进行判断是否超时的局部变量，所以每当我们调用这个函数的时候，应该将这个计数值清0，所以这里才使用
3.代码理解
/*** @brief Waits for HSE start-up.* @param None* @retval An ErrorStatus enumuration value:* - SUCCESS: HSE oscillator is stable and ready to use* - ERROR: HSE oscillator not yet ready*/
ErrorStatus RCC_WaitForHSEStartUp(void)
{__IO uint32_t StartUpCounter = 0;ErrorStatus status = ERROR;FlagStatus HSEStatus = RESET;/* Wait till HSE is ready and if Time out is reached exit */do{//读取寄存器的值HSEStatus = RCC_GetFlagStatus(RCC_FLAG_HSERDY);StartUpCounter++; //读取是否超时的} while((StartUpCounter != HSE_STARTUP_TIMEOUT) && (HSEStatus == RESET));//这里判断是防止超时if (RCC_GetFlagStatus(RCC_FLAG_HSERDY) != RESET){status = SUCCESS;}else{//超时status = ERROR;} return (status);
}4.RCC_GetFlagStatus（获取bit位状态）
1）确定这个RCC-FLAG在哪一个寄存器上
2）确定这个RCC_FLAG在寄存器是哪一个位上
1.返回值进行状态判断
2.输入参数
3.IS_RCC_FLAG
4.判断当前是在哪一个寄存器中
右移5位是想要判断第5位是1还是2还是3，然后进行判断是哪一个寄存器
/* Get the RCC register index *///将输入的标志位右移5位tmp = RCC_FLAG >> 5;//判断要访问哪一个寄存器if (tmp == 1) /* The flag to check is in CR register */{statusreg = RCC->CR;}else if (tmp == 2) /* The flag to check is in BDCR register */{statusreg = RCC->BDCR;}else /* The flag to check is in CSR register */{statusreg = RCC->CSR;}5.判断在寄存器的哪一个位上
/* Get the flag position *//**FLAG_Mask：0x1f*/tmp = RCC_FLAG & FLAG_Mask;if ((statusreg & ((uint32_t)1 << tmp)) != (uint32_t)RESET){bitstatus = SET;}else{bitstatus = RESET;}6.代码理解
/*** @brief Checks whether the specified RCC flag is set or not.* @param RCC_FLAG: specifies the flag to check.* * For @b STM32_Connectivity_line_devices, this parameter can be one of the* following values:* @arg RCC_FLAG_HSIRDY: HSI oscillator clock ready* @arg RCC_FLAG_HSERDY: HSE oscillator clock ready* @arg RCC_FLAG_PLLRDY: PLL clock ready* @arg RCC_FLAG_PLL2RDY: PLL2 clock ready * @arg RCC_FLAG_PLL3RDY: PLL3 clock ready * @arg RCC_FLAG_LSERDY: LSE oscillator clock ready* @arg RCC_FLAG_LSIRDY: LSI oscillator clock ready* @arg RCC_FLAG_PINRST: Pin reset* @arg RCC_FLAG_PORRST: POR/PDR reset* @arg RCC_FLAG_SFTRST: Software reset* @arg RCC_FLAG_IWDGRST: Independent Watchdog reset* @arg RCC_FLAG_WWDGRST: Window Watchdog reset* @arg RCC_FLAG_LPWRRST: Low Power reset* * For @b other_STM32_devices, this parameter can be one of the following values: * @arg RCC_FLAG_HSIRDY: HSI oscillator clock ready* @arg RCC_FLAG_HSERDY: HSE oscillator clock ready* @arg RCC_FLAG_PLLRDY: PLL clock ready* @arg RCC_FLAG_LSERDY: LSE oscillator clock ready* @arg RCC_FLAG_LSIRDY: LSI oscillator clock ready* @arg RCC_FLAG_PINRST: Pin reset* @arg RCC_FLAG_PORRST: POR/PDR reset* @arg RCC_FLAG_SFTRST: Software reset* @arg RCC_FLAG_IWDGRST: Independent Watchdog reset* @arg RCC_FLAG_WWDGRST: Window Watchdog reset* @arg RCC_FLAG_LPWRRST: Low Power reset* * @retval The new state of RCC_FLAG (SET or RESET).*/
FlagStatus RCC_GetFlagStatus(uint8_t RCC_FLAG)
{uint32_t tmp = 0;uint32_t statusreg = 0;FlagStatus bitstatus = RESET;/* Check the parameters */assert_param(IS_RCC_FLAG(RCC_FLAG));/* Get the RCC register index *///将输入的标志位右移5位tmp = RCC_FLAG >> 5;//判断要访问哪一个寄存器if (tmp == 1) /* The flag to check is in CR register */{statusreg = RCC->CR;}else if (tmp == 2) /* The flag to check is in BDCR register */{statusreg = RCC->BDCR;}else /* The flag to check is in CSR register */{statusreg = RCC->CSR;}/* Get the flag position *//**FLAG_Mask：0x1f：1 1111*///这里我们可以得出应该将“1”移动几个bit//比如我们此时选中的RCC_FLAG=RCC->CR的HSERDY（此位对应bit17）//则此时tmp=11 0001 & 1 1111=1 0001（对应十进制17） tmp = RCC_FLAG & FLAG_Mask;//RESET表示置位：表示数值“0”if ((statusreg & ((uint32_t)1 << tmp)) != (uint32_t)RESET){//此时进入，表示该位已经被设置为1bitstatus = SET;}else{bitstatus = RESET;}/* Return the flag status */return bitstatus;
}5.RCC_HSICmd（设置内部晶振状态）
发送命令的
/*** @brief Enables or disables the Internal High Speed oscillator (HSI).* @note HSI can not be stopped if it is used directly or through the PLL as system clock.* @param NewState: new state of the HSI. This parameter can be: ENABLE or DISABLE.* @retval None*/
void RCC_HSICmd(FunctionalState NewState)
{/* Check the parameters */assert_param(IS_FUNCTIONAL_STATE(NewState));*(__IO uint32_t *) CR_HSION_BB = (uint32_t)NewState;
}这里使用解引用的方式，因为我们这里只需要操纵一位
6.RCC_PLLConfig（设置时钟频率）
在使用这个PLL之前一定一定是没有使用PLL，才可以调用这个函数
配置PLL的时钟源倍频
1.参数：时钟倍频
2.参数：时钟PLL倍频系数
3.代码理解
/*** @brief Configures the PLL clock source and multiplication factor.* @note This function must be used only when the PLL is disabled.* @param RCC_PLLSource: specifies the PLL entry clock source.* For @b STM32_Connectivity_line_devices or @b STM32_Value_line_devices, * this parameter can be one of the following values:* @arg RCC_PLLSource_HSI_Div2: HSI oscillator clock divided by 2 selected as PLL clock entry* @arg RCC_PLLSource_PREDIV1: PREDIV1 clock selected as PLL clock entry* For @b other_STM32_devices, this parameter can be one of the following values:* @arg RCC_PLLSource_HSI_Div2: HSI oscillator clock divided by 2 selected as PLL clock entry* @arg RCC_PLLSource_HSE_Div1: HSE oscillator clock selected as PLL clock entry* @arg RCC_PLLSource_HSE_Div2: HSE oscillator clock divided by 2 selected as PLL clock entry * @param RCC_PLLMul: specifies the PLL multiplication factor.* For @b STM32_Connectivity_line_devices, this parameter can be RCC_PLLMul_x where x:{[4,9], 6_5}* For @b other_STM32_devices, this parameter can be RCC_PLLMul_x where x:[2,16] * @retval None*/
void RCC_PLLConfig(uint32_t RCC_PLLSource, uint32_t RCC_PLLMul)
{uint32_t tmpreg = 0;/* Check the parameters */assert_param(IS_RCC_PLL_SOURCE(RCC_PLLSource));assert_param(IS_RCC_PLL_MUL(RCC_PLLMul));tmpreg = RCC->CFGR;//我们要操纵的2个参数都在CFGR/* Clear PLLSRC, PLLXTPRE and PLLMUL[3:0] bits */tmpreg &= CFGR_PLL_Mask;//清零/* Set the PLL configuration bits */tmpreg |= RCC_PLLSource | RCC_PLLMul;//置1/* Store the new value */RCC->CFGR = tmpreg;
}7.RCC_PREDIV1Config（与F1无关，此处不看）
7.RCC_AHBPeriphClockCmd（外设时钟复位）
外设复位
/*** @brief Enables or disables the AHB peripheral clock.* @param RCC_AHBPeriph: specifies the AHB peripheral to gates its clock.* * For @b STM32_Connectivity_line_devices, this parameter can be any combination* of the following values: * @arg RCC_AHBPeriph_DMA1* @arg RCC_AHBPeriph_DMA2* @arg RCC_AHBPeriph_SRAM* @arg RCC_AHBPeriph_FLITF* @arg RCC_AHBPeriph_CRC* @arg RCC_AHBPeriph_OTG_FS * @arg RCC_AHBPeriph_ETH_MAC * @arg RCC_AHBPeriph_ETH_MAC_Tx* @arg RCC_AHBPeriph_ETH_MAC_Rx* * For @b other_STM32_devices, this parameter can be any combination of the * following values: * @arg RCC_AHBPeriph_DMA1* @arg RCC_AHBPeriph_DMA2* @arg RCC_AHBPeriph_SRAM* @arg RCC_AHBPeriph_FLITF* @arg RCC_AHBPeriph_CRC* @arg RCC_AHBPeriph_FSMC* @arg RCC_AHBPeriph_SDIO* * @note SRAM and FLITF clock can be disabled only during sleep mode.* @param NewState: new state of the specified peripheral clock.* This parameter can be: ENABLE or DISABLE.* @retval None*/
void RCC_AHBPeriphClockCmd(uint32_t RCC_AHBPeriph, FunctionalState NewState)
{/* Check the parameters */assert_param(IS_RCC_AHB_PERIPH(RCC_AHBPeriph));assert_param(IS_FUNCTIONAL_STATE(NewState));if (NewState != DISABLE){RCC->AHBENR |= RCC_AHBPeriph;}else{RCC->AHBENR &= ~RCC_AHBPeriph;}
}
8.RCC_HCLKConfig（AHB频率）
配置AHB clock
/*** @brief Configures the AHB clock (HCLK).* @param RCC_SYSCLK: defines the AHB clock divider. This clock is derived from * the system clock (SYSCLK).* This parameter can be one of the following values:* @arg RCC_SYSCLK_Div1: AHB clock = SYSCLK* @arg RCC_SYSCLK_Div2: AHB clock = SYSCLK/2* @arg RCC_SYSCLK_Div4: AHB clock = SYSCLK/4* @arg RCC_SYSCLK_Div8: AHB clock = SYSCLK/8* @arg RCC_SYSCLK_Div16: AHB clock = SYSCLK/16* @arg RCC_SYSCLK_Div64: AHB clock = SYSCLK/64* @arg RCC_SYSCLK_Div128: AHB clock = SYSCLK/128* @arg RCC_SYSCLK_Div256: AHB clock = SYSCLK/256* @arg RCC_SYSCLK_Div512: AHB clock = SYSCLK/512* @retval None*/
void RCC_HCLKConfig(uint32_t RCC_SYSCLK)
{uint32_t tmpreg = 0;/* Check the parameters *///判断要进行多少的分频assert_param(IS_RCC_HCLK(RCC_SYSCLK));//选择要进行操纵的寄存器tmpreg = RCC->CFGR;/* Clear HPRE[3:0] bits *//**CFGR_HPRE_Reset_Mask：0xFFFFFF0F==》0000 1111*///表示将CFGR的bit4-bit7位置0tmpreg &= CFGR_HPRE_Reset_Mask;/* Set HPRE[3:0] bits according to RCC_SYSCLK value *///表示将CFGR的bit4-bit7位置1tmpreg |= RCC_SYSCLK;/* Store the new value */RCC->CFGR = tmpreg;
}9.RCC_PCLK1Config（APB1频率）/RCC_PCLK2Config（APB2频率）
/*** @brief Configures the Low Speed APB clock (PCLK1).* @param RCC_HCLK: defines the APB1 clock divider. This clock is derived from * the AHB clock (HCLK).* This parameter can be one of the following values:* @arg RCC_HCLK_Div1: APB1 clock = HCLK* @arg RCC_HCLK_Div2: APB1 clock = HCLK/2* @arg RCC_HCLK_Div4: APB1 clock = HCLK/4* @arg RCC_HCLK_Div8: APB1 clock = HCLK/8* @arg RCC_HCLK_Div16: APB1 clock = HCLK/16* @retval None*/
void RCC_PCLK1Config(uint32_t RCC_HCLK)
{uint32_t tmpreg = 0;/* Check the parameters */assert_param(IS_RCC_PCLK(RCC_HCLK));tmpreg = RCC->CFGR;/* Clear PPRE1[2:0] bits */tmpreg &= CFGR_PPRE1_Reset_Mask;/* Set PPRE1[2:0] bits according to RCC_HCLK value */tmpreg |= RCC_HCLK;/* Store the new value */RCC->CFGR = tmpreg;
}/*** @brief Configures the High Speed APB clock (PCLK2).* @param RCC_HCLK: defines the APB2 clock divider. This clock is derived from * the AHB clock (HCLK).* This parameter can be one of the following values:* @arg RCC_HCLK_Div1: APB2 clock = HCLK* @arg RCC_HCLK_Div2: APB2 clock = HCLK/2* @arg RCC_HCLK_Div4: APB2 clock = HCLK/4* @arg RCC_HCLK_Div8: APB2 clock = HCLK/8* @arg RCC_HCLK_Div16: APB2 clock = HCLK/16* @retval None*/
void RCC_PCLK2Config(uint32_t RCC_HCLK)
{uint32_t tmpreg = 0;/* Check the parameters */assert_param(IS_RCC_PCLK(RCC_HCLK));tmpreg = RCC->CFGR;/* Clear PPRE2[2:0] bits */tmpreg &= CFGR_PPRE2_Reset_Mask;/* Set PPRE2[2:0] bits according to RCC_HCLK value */tmpreg |= RCC_HCLK << 3;/* Store the new value */RCC->CFGR = tmpreg;
}10.RCC_SYSCLKConfig（选择使用哪一个作为系统时钟HSI/HSE/SYS）
/*** @brief Configures the system clock (SYSCLK).* @param RCC_SYSCLKSource: specifies the clock source used as system clock.* This parameter can be one of the following values:* @arg RCC_SYSCLKSource_HSI: HSI selected as system clock* @arg RCC_SYSCLKSource_HSE: HSE selected as system clock* @arg RCC_SYSCLKSource_PLLCLK: PLL selected as system clock* @retval None*/
void RCC_SYSCLKConfig(uint32_t RCC_SYSCLKSource)
{uint32_t tmpreg = 0;/* Check the parameters *///判断用户输入的参数是否正确assert_param(IS_RCC_SYSCLK_SOURCE(RCC_SYSCLKSource));tmpreg = RCC->CFGR;/* Clear SW[1:0] bits */tmpreg &= CFGR_SW_Mask;//置0/* Set SW[1:0] bits according to RCC_SYSCLKSource value */tmpreg |= RCC_SYSCLKSource;//置1/* Store the new value */RCC->CFGR = tmpreg;
}11.RCC_APB2PeriphResetCmd(外设的重新复位)
/*** @brief Forces or releases High Speed APB (APB2) peripheral reset.* @param RCC_APB2Periph: specifies the APB2 peripheral to reset.* This parameter can be any combination of the following values:* @arg RCC_APB2Periph_AFIO, RCC_APB2Periph_GPIOA, RCC_APB2Periph_GPIOB,* RCC_APB2Periph_GPIOC, RCC_APB2Periph_GPIOD, RCC_APB2Periph_GPIOE,* RCC_APB2Periph_GPIOF, RCC_APB2Periph_GPIOG, RCC_APB2Periph_ADC1,* RCC_APB2Periph_ADC2, RCC_APB2Periph_TIM1, RCC_APB2Periph_SPI1,* RCC_APB2Periph_TIM8, RCC_APB2Periph_USART1, RCC_APB2Periph_ADC3,* RCC_APB2Periph_TIM15, RCC_APB2Periph_TIM16, RCC_APB2Periph_TIM17,* RCC_APB2Periph_TIM9, RCC_APB2Periph_TIM10, RCC_APB2Periph_TIM11 * @param NewState: new state of the specified peripheral reset.* This parameter can be: ENABLE or DISABLE.* @retval None*/
void RCC_APB2PeriphResetCmd(uint32_t RCC_APB2Periph, FunctionalState NewState)
{/* Check the parameters */assert_param(IS_RCC_APB2_PERIPH(RCC_APB2Periph));assert_param(IS_FUNCTIONAL_STATE(NewState));if (NewState != DISABLE){RCC->APB2RSTR |= RCC_APB2Periph;}else{RCC->APB2RSTR &= ~RCC_APB2Periph;}
}4.注意点：
1.进制问题
我们在寄存器中的偏移量都是以十进制进行设置的，如果想要将其定义在宏定义中，记得将其转换为十六进制
2.位段计算
5.使用库重写时钟设置函数
1.原始函数
#include "clock.h"
#include "gpio.h"void Set_SysClockTo72M(void){//检测外部晶振是否准备好unsigned int Rcc_CR_HSE_Ready=0;//等待开启PLL开启成功unsigned int Rcc_CR_PLL_Ready=0;//判断切换成PLL是否成功unsigned int RCC_CF_SWS_PLL=0;unsigned int faultTime=0;//判断等待是否超时//一、复位RCC_CR寄存器rRCC_CR = 0x00000083;//二、开启外部时钟（外部晶振）//第一步：先置0【将bit16清零】rRCC_CR &= ~(1<<16);//关闭HSEON//第二步：在置1rRCC_CR |= (1<<16);//打开HSEON，让HSE开始工作//三、检测外部时钟开启是否成功do{//检测HSEREAY（bit17）是否为1，1表示准备好Rcc_CR_HSE_Ready=rRCC_CR&(1<<17);//取出bit17faultTime++;}while((faultTime<0x0fffffff) && (Rcc_CR_HSE_Ready==0));//跳出do-while 1）要么超时2）要么准好了//判断是超时还是准备好//注意点：不能直接使用“Rcc_CR_HSE_Ready”因为rRCC_CR是需要读一次寄存器//但是读出的结果可能还未改变，所以一定不能直接使用if((rRCC_CR&(1<<17))!=0)//rRCC_CR&(1<<17)==1{//这里HSE就ready，下面再去配置PLL并且等待他ready//设置FlashrFLASH_ACR |= 0x10;rFLASH_ACR &= (~0x03);rFLASH_ACR |= (0x02);//四、对其进行预分频//HPRE【AHB】:对应bit4-bit7：不分频（000）//PPRE1【APB1】:对应bit8-bit10:进行二分频（100)//PPRE2【APB2】:对应bit11-bit13:不分频（000）//AHB和APB2未分频，APB1被2分频//所以最终：AHB和APB2都是72MHZ，APB1是36MHZ//第一步:先置0rRCC_CFGR &=(~((0x0f<<4) | (0x07<<8) | (0x07<<11)));//等价于:rRCC_CFGR=(~(0x3ff<<4));//第二步：置1rRCC_CFGR |=((0x0<<4) | (0x04<<8) | (0x0<<11));//五、设置SHE为输入时钟，同时HSE不分频//选择HSE作为PLL输入并且HSE不分频//设置为输入时钟:bit16//设置为不分频：bit17//第一步:先置0rRCC_CFGR &=(~((1<<16) | (1<<17)));//第二步：置1,bit16rRCC_CFGR |= ((1<<16) | (0<<17));//六、设置PLL倍频系数//9分频：0111：0x07rRCC_CFGR &=(~(0x0f<<18));//清零bit18-bit21rRCC_CFGR |= (0x07<<18);//设置为9倍频//七、打开PLL开关rRCC_CR |= (1<<24);//八、等待开启PLL开启成功//因为前面已经使用到，被累加了，使用这里要重新置0faultTime=0;do{led_init();Rcc_CR_PLL_Ready=rRCC_CR & (1<<25);//检测第25位是否为1faultTime++;}while((faultTime<0x0fffffff) && (Rcc_CR_PLL_Ready==0));if((rRCC_CR & (1<<25)) == (1<<25)){//到这里说明PLL已经稳定，可以用了，下面可以切换成外部时钟了//九、切换成PLLrRCC_CFGR &=(~(0x03)<<0);rRCC_CFGR |=(0x02<<0);//十、判断切换成PLL是否成功//因为前面已经使用到，被累加了，使用这里要重新置0faultTime=0;do{RCC_CF_SWS_PLL=rRCC_CFGR & (0x03<<2);//读出bit2-bit3faultTime++;led_init();//0x02<<2:表示此时转换成PLL}while ((faultTime<0x0FFFFFFF) && (RCC_CF_SWS_PLL!=(0x02<<2)));//十一、此时PLL转换成功if((rRCC_CFGR & (0x03<<2))==(0x02<<2)){//到这里我们的时钟整个就设置好了，可以结束了}else{//到这里说明PLL输出作为PLL失败while(1);}}else{//到这里说明PLL启动时出错了，PLL不能稳定工作while(1);}}else{//超时，或者未准备好，此时HSE不可以使用while(1);}}2.自己封装一个RCC_WaitForPLLStartUp
此处我们参考【RCC_WaitForHSEStartUp】这个函数来自己写
由源文件中没有定义【PLL_STARTUP_TIMEOUT】所以我们要自定义
#define PLL_STARTUP_TIMEOUT ((uint16_t)0x0500000)//本函数作用：等待PLL倍频后输出稳定
//返回值：SUCCESS说明未超时，ERROR超时
ErrorStatus RCC_WaitForPLLStartUp(void)
{__IO uint32_t StartUpCounter = 0;ErrorStatus status = ERROR;FlagStatus PLLStatus = RESET;/* Wait till HSE is ready and if Time out is reached exit */do{//读取寄存器的值PLLStatus = RCC_GetFlagStatus(RCC_FLAG_PLLRDY);StartUpCounter++; //读取是否超时的} while((StartUpCounter != PLL_STARTUP_TIMEOUT) && (PLLStatus == RESET));//这里判断是防止超时if (RCC_GetFlagStatus(RCC_FLAG_PLLRDY) != RESET){status = SUCCESS;}else{//超时status = ERROR;} return (status);
}3.完整使用库函数的clock
//这个函数里面包含了全部外设头文件
#include "stm32f10x.h"
//等价于
//#include"stm32f10x_conf.h"#define PLL_STARTUP_TIMEOUT ((uint16_t)0x0500000)//本函数作用：等待PLL倍频后输出稳定
//返回值：SUCCESS说明未超时，ERROR超时
ErrorStatus RCC_WaitForPLLStartUp(void)
{__IO uint32_t StartUpCounter = 0;ErrorStatus status = ERROR;FlagStatus PLLStatus = RESET;/* Wait till HSE is ready and if Time out is reached exit */do{//读取寄存器的值PLLStatus = RCC_GetFlagStatus(RCC_FLAG_PLLRDY);StartUpCounter++; //读取是否超时的} while((StartUpCounter != PLL_STARTUP_TIMEOUT) && (PLLStatus == RESET));//这里判断是防止超时if (RCC_GetFlagStatus(RCC_FLAG_PLLRDY) != RESET){status = SUCCESS;}else{//超时status = ERROR;} return (status);
}void Set_SysClockTo72M(void){//接收判断回来的HSE是否已经稳定ErrorStatus sta=ERROR;//faultTime：用来判断是否超时unsigned int faultTime=0;unsigned int RCC_CF_SWS_PLL=0;//一、先关闭HSEON然后在打开HSEONRCC_HSEConfig(RCC_HSE_ON);/*rRCC_CR = 0x00000083;rRCC_CR &= ~(1<<16);//关闭HSEONrRCC_CR |= (1<<16);//打开HSEON，让HSE开始工作*///二、等到HSE稳定sta=RCC_WaitForHSEStartUp();/*do{//检测HSEREAY（bit17）是否为1，1表示准备好Rcc_CR_HSE_Ready=rRCC_CR&(1<<17);//取出bit17faultTime++;}while((faultTime<0x0fffffff) && (Rcc_CR_HSE_Ready==0));//跳出do-while 1）要么超时2）要么准好了*///三、判断是HSE稳定了还是超时了if(sta==SUCCESS)//if((rRCC_CR&(1<<17))!=0)//rRCC_CR&(1<<17)==1{//这里HSE就ready，下面再去配置PLL并且等待他ready//四、设置FlashFLASH->ACR |= 0x10;FLASH->ACR &= (~0x03);FLASH->ACR |= (0x02);/*rFLASH_ACR |= 0x10;rFLASH_ACR &= (~0x03);rFLASH_ACR |= (0x02);*///AHB和APB2未分频，APB1被2分频//所以最终：AHB和APB2都是72MHZ，APB1是36MHZ//五、配置相关的倍频信息//配置HCLK为SYSCLK/1RCC_HCLKConfig(RCC_SYSCLK_Div1);//配置PCLK1为JCLK的2分频RCC_PCLK1Config(RCC_HCLK_Div2);//配置PCLK2为JCLK的1分频RCC_PCLK2Config(RCC_HCLK_Div1);/*rRCC_CFGR &=(~((0x0f<<4) | (0x07<<8) | (0x07<<11)));//等价于:rRCC_CFGR=(~(0x3ff<<4));rRCC_CFGR |=((0x0<<4) | (0x04<<8) | (0x0<<11));*///六、设置HSE/1为PLL时钟源，PLL倍频系数为9RCC_PLLConfig(RCC_PLLSource_HSE_Div1,RCC_PLLMul_9);/*//设置SHE为输入时钟，同时HSE不分频rRCC_CFGR &=(~((1<<16) | (1<<17)));rRCC_CFGR |= ((1<<16) | (0<<17));//设置PLL倍频系数//9分频：0111：0x07rRCC_CFGR &=(~(0x0f<<18));//清零bit18-bit21rRCC_CFGR |= (0x07<<18);//设置为9倍频*///七、打开PLL开关RCC_PLLCmd(ENABLE);//rRCC_CR |= (1<<24);//因为HAL库中没有等到PLL的函数//此处我们参考【RCC_WaitForHSEStartUp】这个函数来自己写//八、等待开启PLL开启成功sta=RCC_WaitForPLLStartUp();/*//因为前面已经使用到，被累加了，使用这里要重新置0faultTime=0;do{led_init();Rcc_CR_PLL_Ready=rRCC_CR & (1<<25);//检测第25位是否为1faultTime++;}while((faultTime<0x0fffffff) && (Rcc_CR_PLL_Ready==0));*///九、判断PLL稳定还是超时//if((rRCC_CR & (1<<25)) == (1<<25)){if(sta==SUCCESS){//到这里说明PLL已经稳定，可以用了，下面可以切换成外部时钟了//九、切换成PLLRCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);/*rRCC_CFGR &=(~(0x03)<<0);rRCC_CFGR |=(0x02<<0);*/ //十、判断切换成PLL是否成功//因为前面已经使用到，被累加了，使用这里要重新置0faultTime=0;do{RCC_CF_SWS_PLL=RCC->CFGR & (0x03<<2);//读出bit2-bit3faultTime++;//0x02<<2:表示此时转换成PLL}while ((faultTime<0x0FFFFFFF) && (RCC_CF_SWS_PLL!=(0x02<<2)));//十一、此时PLL转换成功if((RCC->CFGR & (0x03<<2))==(0x02<<2)){//到这里我们的时钟整个就设置好了，可以结束了}else{//到这里说明PLL输出作为PLL失败while(1);}}else{//到这里说明PLL启动时出错了，PLL不能稳定工作while(1);}}else{//超时，或者未准备好，此时HSE不可以使用while(1);}}6.SystmInit注意点：
我们在“startup_stm32f10x_md.s”文件中可以看到在执行main函数之前会先执行一个“SystemInit”函数
所以如果我们想要使用自己的设置72MHZ频率的函数，则应该将SystemInit注释调。
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