进入main后第一步是
Reset of all peripherals, Initializes the Flash interface and the Systick.
HAL_StatusTypeDef HAL_Init(void)
{
/* Configure Flash prefetch, Instruction cache, Data cache */
#if (INSTRUCTION_CACHE_ENABLE != 0U)
__HAL_FLASH_INSTRUCTION_CACHE_ENABLE();
#endif /* INSTRUCTION_CACHE_ENABLE */
#if (DATA_CACHE_ENABLE != 0U)
__HAL_FLASH_DATA_CACHE_ENABLE();
#endif /* DATA_CACHE_ENABLE */
#if (PREFETCH_ENABLE != 0U)
__HAL_FLASH_PREFETCH_BUFFER_ENABLE();
#endif /* PREFETCH_ENABLE */
/* Set Interrupt Group Priority */
HAL_NVIC_SetPriorityGrouping(NVIC_PRIORITYGROUP_4);
/* Use systick as time base source and configure 1ms tick (default clock after Reset is HSI) */
HAL_InitTick(TICK_INT_PRIORITY);
/* Init the low level hardware */
HAL_MspInit();
/* Return function status */
return HAL_OK;
}
#define PREFETCH_ENABLE 1U
#define INSTRUCTION_CACHE_ENABLE 1U
#define DATA_CACHE_ENABLE 1U预取使能、指令缓存使能、数据缓存使能。
#define __HAL_FLASH_INSTRUCTION_CACHE_ENABLE() (FLASH->ACR |= FLASH_ACR_ICEN)
#define __HAL_FLASH_DATA_CACHE_ENABLE() (FLASH->ACR |= FLASH_ACR_DCEN)
#define __HAL_FLASH_PREFETCH_BUFFER_ENABLE() (FLASH->ACR |= FLASH_ACR_PRFTEN)优先级：
/** @defgroup CORTEX_Preemption_Priority_Group CORTEX Preemption Priority Group
* @{
*/
#define NVIC_PRIORITYGROUP_0 0x00000007U /*!< 0 bits for pre-emption priority
4 bits for subpriority */
#define NVIC_PRIORITYGROUP_1 0x00000006U /*!< 1 bits for pre-emption priority
3 bits for subpriority */
#define NVIC_PRIORITYGROUP_2 0x00000005U /*!< 2 bits for pre-emption priority
2 bits for subpriority */
#define NVIC_PRIORITYGROUP_3 0x00000004U /*!< 3 bits for pre-emption priority
1 bits for subpriority */
#define NVIC_PRIORITYGROUP_4 0x00000003U /*!< 4 bits for pre-emption priority
0 bits for subpriority */NVIC_PRIORITYGROUP_4是4 位优先级全部用于抢占优先级（Pre-emption Priority），子优先级（Subpriority）为 0 位。
具体特性如下：
抢占优先级：可设置 0~15 共 16 个级别，数值越小优先级越高。
子优先级：无区分能力，所有中断在同一抢占级别下视为同等响应优先级。
中断嵌套：仅当抢占优先级不同时发生嵌套；若抢占优先级相同，则按自然向量表顺序或响应顺序处理，无法通过子优先级区分。
此配置适用于需要最大化中断嵌套层级、对响应顺序要求不精细的场景。
void HAL_NVIC_SetPriorityGrouping(uint32_t PriorityGroup)
{
/* Check the parameters */
assert_param(IS_NVIC_PRIORITY_GROUP(PriorityGroup));
/* Set the PRIGROUP[10:8] bits according to the PriorityGroup parameter value */
NVIC_SetPriorityGrouping(PriorityGroup);
}
#define NVIC_SetPriorityGrouping __NVIC_SetPriorityGrouping
__STATIC_INLINE void __NVIC_SetPriorityGrouping(uint32_t PriorityGroup)
{
uint32_t reg_value;
uint32_t PriorityGroupTmp = (PriorityGroup & (uint32_t)0x07UL); /* only values 0..7 are used */
reg_value = SCB->AIRCR; /* read old register configuration */
reg_value &= ~((uint32_t)(SCB_AIRCR_VECTKEY_Msk | SCB_AIRCR_PRIGROUP_Msk)); /* clear bits to change */
reg_value = (reg_value |
((uint32_t)0x5FAUL << SCB_AIRCR_VECTKEY_Pos) |
(PriorityGroupTmp << SCB_AIRCR_PRIGROUP_Pos) ); /* Insert write key and priority group */
SCB->AIRCR = reg_value;
}滴答时钟配置
#define TICK_INT_PRIORITY ((uint32_t)4U) /*!< tick interrupt priority */
/* Use systick as time base source and configure 1ms tick (default clock after Reset is HSI) */
HAL_InitTick(TICK_INT_PRIORITY);
__weak HAL_StatusTypeDef HAL_InitTick(uint32_t TickPriority)
{
/* Configure the SysTick to have interrupt in 1ms time basis*/
if (HAL_SYSTICK_Config(SystemCoreClock / (1000U / uwTickFreq)) > 0U)
{
return HAL_ERROR;
}
/* Configure the SysTick IRQ priority */
if (TickPriority < (1UL << __NVIC_PRIO_BITS))
{
HAL_NVIC_SetPriority(SysTick_IRQn, TickPriority, 0U);
uwTickPrio = TickPriority;
}
else
{
return HAL_ERROR;
}
/* Return function status */
return HAL_OK;
}关于时基源（Time Base）和HAL_Delay() 函数使用限制的标准注释，核心含义是：默认由 SysTick 提供 1ms 时基中断；若在中断服务程序（ISR）中调用 HAL_Delay()，必须确保 SysTick 中断优先级高于该 ISR，否则会导致死锁；相关函数为 __weak 定义，允许用户重写以实现自定义时基。
Init the low level hardware 初始化底层硬件
void HAL_MspInit(void)
{
__HAL_RCC_SYSCFG_CLK_ENABLE();
__HAL_RCC_PWR_CLK_ENABLE();
HAL_NVIC_SetPriorityGrouping(NVIC_PRIORITYGROUP_3);
}
#define __HAL_RCC_SYSCFG_CLK_ENABLE() do { \
__IO uint32_t tmpreg = 0x00U; \
SET_BIT(RCC->APB2ENR, RCC_APB2ENR_SYSCFGEN);\
/* Delay after an RCC peripheral clock enabling */ \
tmpreg = READ_BIT(RCC->APB2ENR, RCC_APB2ENR_SYSCFGEN);\
UNUSED(tmpreg); \
} while(0U)
#define __HAL_RCC_PWR_CLK_ENABLE() do { \
__IO uint32_t tmpreg = 0x00U; \
SET_BIT(RCC->APB1ENR, RCC_APB1ENR_PWREN);\
/* Delay after an RCC peripheral clock enabling */ \
tmpreg = READ_BIT(RCC->APB1ENR, RCC_APB1ENR_PWREN);\
UNUSED(tmpreg); \
} while(0U)中断优先级分组（Priority Group）在整个系统中只能配置一次，多次调用 NVIC_PriorityGroupConfig 会以最后一次配置为准，之前的配置会被覆盖。
读寄存器可以看到SCB->AIRCR的变化
开始SCB->AIRCR=0xFA050000，
执行HAL_NVIC_SetPriorityGrouping(NVIC_PRIORITYGROUP_4);后
SCB->AIRCR=0xFA050300，
执行HAL_MspInit();后
SCB->AIRCR=0xFA050400。
配置系统时钟：SystemClock_Config();
void SystemClock_Config(void)
{
RCC_OscInitTypeDef RCC_OscInitStruct = {0};
RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
/** Configure the main internal regulator output voltage
*/
__HAL_RCC_PWR_CLK_ENABLE();
__HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);
/** Initializes the RCC Oscillators according to the specified parameters
* in the RCC_OscInitTypeDef structure.
*/
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
RCC_OscInitStruct.HSEState = RCC_HSE_ON;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
RCC_OscInitStruct.PLL.PLLM = 4;
RCC_OscInitStruct.PLL.PLLN = 168;
RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
RCC_OscInitStruct.PLL.PLLQ = 4;
if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
{
Error_Handler();
}
/** Initializes the CPU, AHB and APB buses clocks
*/
RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
|RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV4;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV2;
if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_5) != HAL_OK)
{
Error_Handler();
}
/** Enables the Clock Security System
*/
HAL_RCC_EnableCSS();
}使能
#define __HAL_RCC_PWR_CLK_ENABLE() do { \
__IO uint32_t tmpreg = 0x00U; \
SET_BIT(RCC->APB1ENR, RCC_APB1ENR_PWREN);\
/* Delay after an RCC peripheral clock enabling */ \
tmpreg = READ_BIT(RCC->APB1ENR, RCC_APB1ENR_PWREN);\
UNUSED(tmpreg); \
} while(0U)配置内部主调节器输出电压
#define PWR_CR_VOS_Pos (14U)
#define PWR_CR_VOS_Msk (0x1UL << PWR_CR_VOS_Pos) /*!< 0x00004000 */
#define PWR_CR_VOS PWR_CR_VOS_Msk /*!< VOS bit (Regulator voltage scaling output selection) */
#define PWR_REGULATOR_VOLTAGE_SCALE1 PWR_CR_VOS /* Scale 1 mode(default value at reset): the maximum value of fHCLK = 168 MHz. */
#define PWR_REGULATOR_VOLTAGE_SCALE2 0x00000000U /* Scale 2 mode: the maximum value of fHCLK = 144 MHz. */
#define __HAL_PWR_VOLTAGESCALING_CONFIG(__REGULATOR__) do { \
__IO uint32_t tmpreg = 0x00U; \
MODIFY_REG(PWR->CR, PWR_CR_VOS, (__REGULATOR__)); \
/* Delay after an RCC peripheral clock enabling */ \
tmpreg = READ_BIT(PWR->CR, PWR_CR_VOS); \
UNUSED(tmpreg); \
} while(0U)配置微控制器的时钟源和 PLL（锁相环）参数，以初始化系统时钟树
typedef struct
{
uint32_t OscillatorType; /*!< The oscillators to be configured.
This parameter can be a value of @ref RCC_Oscillator_Type */
uint32_t HSEState; /*!< The new state of the HSE.
This parameter can be a value of @ref RCC_HSE_Config */
uint32_t LSEState; /*!< The new state of the LSE.
This parameter can be a value of @ref RCC_LSE_Config */
uint32_t HSIState; /*!< The new state of the HSI.
This parameter can be a value of @ref RCC_HSI_Config */
uint32_t HSICalibrationValue; /*!< The HSI calibration trimming value (default is RCC_HSICALIBRATION_DEFAULT).
This parameter must be a number between Min_Data = 0x00 and Max_Data = 0x1F */
uint32_t LSIState; /*!< The new state of the LSI.
This parameter can be a value of @ref RCC_LSI_Config */
RCC_PLLInitTypeDef PLL; /*!< PLL structure parameters */
}RCC_OscInitTypeDef;
RCC_OscInitTypeDef RCC_OscInitStruct = {0};
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
RCC_OscInitStruct.HSEState = RCC_HSE_ON;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
RCC_OscInitStruct.PLL.PLLM = 4;
RCC_OscInitStruct.PLL.PLLN = 168;
RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
RCC_OscInitStruct.PLL.PLLQ = 4;
if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
{
Error_Handler();
}外部高速时钟
__weak HAL_StatusTypeDef HAL_RCC_OscConfig(RCC_OscInitTypeDef *RCC_OscInitStruct)
{
uint32_t tickstart, pll_config;
/* Check Null pointer */
if(RCC_OscInitStruct == NULL)
{
return HAL_ERROR;
}
/* Check the parameters */
assert_param(IS_RCC_OSCILLATORTYPE(RCC_OscInitStruct->OscillatorType));
/*------------------------------- HSE Configuration ------------------------*/
if(((RCC_OscInitStruct->OscillatorType) & RCC_OSCILLATORTYPE_HSE) == RCC_OSCILLATORTYPE_HSE)
{
/* Check the parameters */
assert_param(IS_RCC_HSE(RCC_OscInitStruct->HSEState));
/* When the HSE is used as system clock or clock source for PLL in these cases HSE will not disabled */
if((__HAL_RCC_GET_SYSCLK_SOURCE() == RCC_CFGR_SWS_HSE) ||\
((__HAL_RCC_GET_SYSCLK_SOURCE() == RCC_CFGR_SWS_PLL) && ((RCC->PLLCFGR & RCC_PLLCFGR_PLLSRC) == RCC_PLLCFGR_PLLSRC_HSE)))
{
if((__HAL_RCC_GET_FLAG(RCC_FLAG_HSERDY) != RESET) && (RCC_OscInitStruct->HSEState == RCC_HSE_OFF))
{
return HAL_ERROR;
}
}
else
{
/* Set the new HSE configuration ---------------------------------------*/
__HAL_RCC_HSE_CONFIG(RCC_OscInitStruct->HSEState);
/* Check the HSE State */
if((RCC_OscInitStruct->HSEState) != RCC_HSE_OFF)
{
/* Get Start Tick */
tickstart = HAL_GetTick();
/* Wait till HSE is ready */
while(__HAL_RCC_GET_FLAG(RCC_FLAG_HSERDY) == RESET)
{
if((HAL_GetTick() - tickstart ) > HSE_TIMEOUT_VALUE)
{
return HAL_TIMEOUT;
}
}
}
else
{
/* Get Start Tick */
tickstart = HAL_GetTick();
/* Wait till HSE is bypassed or disabled */
while(__HAL_RCC_GET_FLAG(RCC_FLAG_HSERDY) != RESET)
{
if((HAL_GetTick() - tickstart ) > HSE_TIMEOUT_VALUE)
{
return HAL_TIMEOUT;
}
}
}
}
}
/*----------------------------- HSI Configuration --------------------------*/
if(((RCC_OscInitStruct->OscillatorType) & RCC_OSCILLATORTYPE_HSI) == RCC_OSCILLATORTYPE_HSI)
{
/* Check the parameters */
assert_param(IS_RCC_HSI(RCC_OscInitStruct->HSIState));
assert_param(IS_RCC_CALIBRATION_VALUE(RCC_OscInitStruct->HSICalibrationValue));
/* Check if HSI is used as system clock or as PLL source when PLL is selected as system clock */
if((__HAL_RCC_GET_SYSCLK_SOURCE() == RCC_CFGR_SWS_HSI) ||\
((__HAL_RCC_GET_SYSCLK_SOURCE() == RCC_CFGR_SWS_PLL) && ((RCC->PLLCFGR & RCC_PLLCFGR_PLLSRC) == RCC_PLLCFGR_PLLSRC_HSI)))
{
/* When HSI is used as system clock it will not disabled */
if((__HAL_RCC_GET_FLAG(RCC_FLAG_HSIRDY) != RESET) && (RCC_OscInitStruct->HSIState != RCC_HSI_ON))
{
return HAL_ERROR;
}
/* Otherwise, just the calibration is allowed */
else
{
/* Adjusts the Internal High Speed oscillator (HSI) calibration value.*/
__HAL_RCC_HSI_CALIBRATIONVALUE_ADJUST(RCC_OscInitStruct->HSICalibrationValue);
}
}
else
{
/* Check the HSI State */
if((RCC_OscInitStruct->HSIState)!= RCC_HSI_OFF)
{
/* Enable the Internal High Speed oscillator (HSI). */
__HAL_RCC_HSI_ENABLE();
/* Get Start Tick*/
tickstart = HAL_GetTick();
/* Wait till HSI is ready */
while(__HAL_RCC_GET_FLAG(RCC_FLAG_HSIRDY) == RESET)
{
if((HAL_GetTick() - tickstart ) > HSI_TIMEOUT_VALUE)
{
return HAL_TIMEOUT;
}
}
/* Adjusts the Internal High Speed oscillator (HSI) calibration value. */
__HAL_RCC_HSI_CALIBRATIONVALUE_ADJUST(RCC_OscInitStruct->HSICalibrationValue);
}
else
{
/* Disable the Internal High Speed oscillator (HSI). */
__HAL_RCC_HSI_DISABLE();
/* Get Start Tick*/
tickstart = HAL_GetTick();
/* Wait till HSI is ready */
while(__HAL_RCC_GET_FLAG(RCC_FLAG_HSIRDY) != RESET)
{
if((HAL_GetTick() - tickstart ) > HSI_TIMEOUT_VALUE)
{
return HAL_TIMEOUT;
}
}
}
}
}
/*------------------------------ LSI Configuration -------------------------*/
if(((RCC_OscInitStruct->OscillatorType) & RCC_OSCILLATORTYPE_LSI) == RCC_OSCILLATORTYPE_LSI)
{
/* Check the parameters */
assert_param(IS_RCC_LSI(RCC_OscInitStruct->LSIState));
/* Check the LSI State */
if((RCC_OscInitStruct->LSIState)!= RCC_LSI_OFF)
{
/* Enable the Internal Low Speed oscillator (LSI). */
__HAL_RCC_LSI_ENABLE();
/* Get Start Tick*/
tickstart = HAL_GetTick();
/* Wait till LSI is ready */
while(__HAL_RCC_GET_FLAG(RCC_FLAG_LSIRDY) == RESET)
{
if((HAL_GetTick() - tickstart ) > LSI_TIMEOUT_VALUE)
{
return HAL_TIMEOUT;
}
}
}
else
{
/* Disable the Internal Low Speed oscillator (LSI). */
__HAL_RCC_LSI_DISABLE();
/* Get Start Tick */
tickstart = HAL_GetTick();
/* Wait till LSI is ready */
while(__HAL_RCC_GET_FLAG(RCC_FLAG_LSIRDY) != RESET)
{
if((HAL_GetTick() - tickstart ) > LSI_TIMEOUT_VALUE)
{
return HAL_TIMEOUT;
}
}
}
}
/*------------------------------ LSE Configuration -------------------------*/
if(((RCC_OscInitStruct->OscillatorType) & RCC_OSCILLATORTYPE_LSE) == RCC_OSCILLATORTYPE_LSE)
{
FlagStatus pwrclkchanged = RESET;
/* Check the parameters */
assert_param(IS_RCC_LSE(RCC_OscInitStruct->LSEState));
/* Update LSE configuration in Backup Domain control register */
/* Requires to enable write access to Backup Domain of necessary */
if(__HAL_RCC_PWR_IS_CLK_DISABLED())
{
__HAL_RCC_PWR_CLK_ENABLE();
pwrclkchanged = SET;
}
if(HAL_IS_BIT_CLR(PWR->CR, PWR_CR_DBP))
{
/* Enable write access to Backup domain */
SET_BIT(PWR->CR, PWR_CR_DBP);
/* Wait for Backup domain Write protection disable */
tickstart = HAL_GetTick();
while(HAL_IS_BIT_CLR(PWR->CR, PWR_CR_DBP))
{
if((HAL_GetTick() - tickstart) > RCC_DBP_TIMEOUT_VALUE)
{
return HAL_TIMEOUT;
}
}
}
/* Set the new LSE configuration -----------------------------------------*/
__HAL_RCC_LSE_CONFIG(RCC_OscInitStruct->LSEState);
/* Check the LSE State */
if((RCC_OscInitStruct->LSEState) != RCC_LSE_OFF)
{
/* Get Start Tick*/
tickstart = HAL_GetTick();
/* Wait till LSE is ready */
while(__HAL_RCC_GET_FLAG(RCC_FLAG_LSERDY) == RESET)
{
if((HAL_GetTick() - tickstart ) > RCC_LSE_TIMEOUT_VALUE)
{
return HAL_TIMEOUT;
}
}
}
else
{
/* Get Start Tick */
tickstart = HAL_GetTick();
/* Wait till LSE is ready */
while(__HAL_RCC_GET_FLAG(RCC_FLAG_LSERDY) != RESET)
{
if((HAL_GetTick() - tickstart ) > RCC_LSE_TIMEOUT_VALUE)
{
return HAL_TIMEOUT;
}
}
}
/* Restore clock configuration if changed */
if(pwrclkchanged == SET)
{
__HAL_RCC_PWR_CLK_DISABLE();
}
}
/*-------------------------------- PLL Configuration -----------------------*/
/* Check the parameters */
assert_param(IS_RCC_PLL(RCC_OscInitStruct->PLL.PLLState));
if ((RCC_OscInitStruct->PLL.PLLState) != RCC_PLL_NONE)
{
/* Check if the PLL is used as system clock or not */
if(__HAL_RCC_GET_SYSCLK_SOURCE() != RCC_CFGR_SWS_PLL)
{
if((RCC_OscInitStruct->PLL.PLLState) == RCC_PLL_ON)
{
/* Check the parameters */
assert_param(IS_RCC_PLLSOURCE(RCC_OscInitStruct->PLL.PLLSource));
assert_param(IS_RCC_PLLM_VALUE(RCC_OscInitStruct->PLL.PLLM));
assert_param(IS_RCC_PLLN_VALUE(RCC_OscInitStruct->PLL.PLLN));
assert_param(IS_RCC_PLLP_VALUE(RCC_OscInitStruct->PLL.PLLP));
assert_param(IS_RCC_PLLQ_VALUE(RCC_OscInitStruct->PLL.PLLQ));
/* Disable the main PLL. */
__HAL_RCC_PLL_DISABLE();
/* Get Start Tick */
tickstart = HAL_GetTick();
/* Wait till PLL is ready */
while(__HAL_RCC_GET_FLAG(RCC_FLAG_PLLRDY) != RESET)
{
if((HAL_GetTick() - tickstart ) > PLL_TIMEOUT_VALUE)
{
return HAL_TIMEOUT;
}
}
/* Configure the main PLL clock source, multiplication and division factors. */
WRITE_REG(RCC->PLLCFGR, (RCC_OscInitStruct->PLL.PLLSource | \
RCC_OscInitStruct->PLL.PLLM | \
(RCC_OscInitStruct->PLL.PLLN << RCC_PLLCFGR_PLLN_Pos) | \
(((RCC_OscInitStruct->PLL.PLLP >> 1U) - 1U) << RCC_PLLCFGR_PLLP_Pos) | \
(RCC_OscInitStruct->PLL.PLLQ << RCC_PLLCFGR_PLLQ_Pos)));
/* Enable the main PLL. */
__HAL_RCC_PLL_ENABLE();
/* Get Start Tick */
tickstart = HAL_GetTick();
/* Wait till PLL is ready */
while(__HAL_RCC_GET_FLAG(RCC_FLAG_PLLRDY) == RESET)
{
if((HAL_GetTick() - tickstart ) > PLL_TIMEOUT_VALUE)
{
return HAL_TIMEOUT;
}
}
}
else
{
/* Disable the main PLL. */
__HAL_RCC_PLL_DISABLE();
/* Get Start Tick */
tickstart = HAL_GetTick();
/* Wait till PLL is ready */
while(__HAL_RCC_GET_FLAG(RCC_FLAG_PLLRDY) != RESET)
{
if((HAL_GetTick() - tickstart ) > PLL_TIMEOUT_VALUE)
{
return HAL_TIMEOUT;
}
}
}
}
else
{
/* Check if there is a request to disable the PLL used as System clock source */
if((RCC_OscInitStruct->PLL.PLLState) == RCC_PLL_OFF)
{
return HAL_ERROR;
}
else
{
/* Do not return HAL_ERROR if request repeats the current configuration */
pll_config = RCC->PLLCFGR;
if((READ_BIT(pll_config, RCC_PLLCFGR_PLLSRC) != RCC_OscInitStruct->PLL.PLLSource) ||
(READ_BIT(pll_config, RCC_PLLCFGR_PLLM) != RCC_OscInitStruct->PLL.PLLM) ||
(READ_BIT(pll_config, RCC_PLLCFGR_PLLN) != RCC_OscInitStruct->PLL.PLLN) ||
(READ_BIT(pll_config, RCC_PLLCFGR_PLLP) != RCC_OscInitStruct->PLL.PLLP) ||
(READ_BIT(pll_config, RCC_PLLCFGR_PLLQ) != RCC_OscInitStruct->PLL.PLLQ))
{
return HAL_ERROR;
}
}
}
}
return HAL_OK;
}Initializes the CPU, AHB and APB buses clocks
typedef struct
{
uint32_t ClockType; /*!< The clock to be configured.
This parameter can be a value of @ref RCC_System_Clock_Type */
uint32_t SYSCLKSource; /*!< The clock source (SYSCLKS) used as system clock.
This parameter can be a value of @ref RCC_System_Clock_Source */
uint32_t AHBCLKDivider; /*!< The AHB clock (HCLK) divider. This clock is derived from the system clock (SYSCLK).
This parameter can be a value of @ref RCC_AHB_Clock_Source */
uint32_t APB1CLKDivider; /*!< The APB1 clock (PCLK1) divider. This clock is derived from the AHB clock (HCLK).
This parameter can be a value of @ref RCC_APB1_APB2_Clock_Source */
uint32_t APB2CLKDivider; /*!< The APB2 clock (PCLK2) divider. This clock is derived from the AHB clock (HCLK).
This parameter can be a value of @ref RCC_APB1_APB2_Clock_Source */
}RCC_ClkInitTypeDef;
RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
|RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV4;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV2;
HAL_StatusTypeDef HAL_RCC_ClockConfig(RCC_ClkInitTypeDef *RCC_ClkInitStruct, uint32_t FLatency)
{
uint32_t tickstart;
/* Check Null pointer */
if(RCC_ClkInitStruct == NULL)
{
return HAL_ERROR;
}
/* Check the parameters */
assert_param(IS_RCC_CLOCKTYPE(RCC_ClkInitStruct->ClockType));
assert_param(IS_FLASH_LATENCY(FLatency));
/* To correctly read data from FLASH memory, the number of wait states (LATENCY)
must be correctly programmed according to the frequency of the CPU clock
(HCLK) and the supply voltage of the device. */
/* Increasing the number of wait states because of higher CPU frequency */
if(FLatency > __HAL_FLASH_GET_LATENCY())
{
/* Program the new number of wait states to the LATENCY bits in the FLASH_ACR register */
__HAL_FLASH_SET_LATENCY(FLatency);
/* Check that the new number of wait states is taken into account to access the Flash
memory by reading the FLASH_ACR register */
if(__HAL_FLASH_GET_LATENCY() != FLatency)
{
return HAL_ERROR;
}
}
/*-------------------------- HCLK Configuration --------------------------*/
if(((RCC_ClkInitStruct->ClockType) & RCC_CLOCKTYPE_HCLK) == RCC_CLOCKTYPE_HCLK)
{
/* Set the highest APBx dividers in order to ensure that we do not go through
a non-spec phase whatever we decrease or increase HCLK. */
if(((RCC_ClkInitStruct->ClockType) & RCC_CLOCKTYPE_PCLK1) == RCC_CLOCKTYPE_PCLK1)
{
MODIFY_REG(RCC->CFGR, RCC_CFGR_PPRE1, RCC_HCLK_DIV16);
}
if(((RCC_ClkInitStruct->ClockType) & RCC_CLOCKTYPE_PCLK2) == RCC_CLOCKTYPE_PCLK2)
{
MODIFY_REG(RCC->CFGR, RCC_CFGR_PPRE2, (RCC_HCLK_DIV16 << 3));
}
assert_param(IS_RCC_HCLK(RCC_ClkInitStruct->AHBCLKDivider));
MODIFY_REG(RCC->CFGR, RCC_CFGR_HPRE, RCC_ClkInitStruct->AHBCLKDivider);
}
/*------------------------- SYSCLK Configuration ---------------------------*/
if(((RCC_ClkInitStruct->ClockType) & RCC_CLOCKTYPE_SYSCLK) == RCC_CLOCKTYPE_SYSCLK)
{
assert_param(IS_RCC_SYSCLKSOURCE(RCC_ClkInitStruct->SYSCLKSource));
/* HSE is selected as System Clock Source */
if(RCC_ClkInitStruct->SYSCLKSource == RCC_SYSCLKSOURCE_HSE)
{
/* Check the HSE ready flag */
if(__HAL_RCC_GET_FLAG(RCC_FLAG_HSERDY) == RESET)
{
return HAL_ERROR;
}
}
/* PLL is selected as System Clock Source */
else if((RCC_ClkInitStruct->SYSCLKSource == RCC_SYSCLKSOURCE_PLLCLK) ||
(RCC_ClkInitStruct->SYSCLKSource == RCC_SYSCLKSOURCE_PLLRCLK))
{
/* Check the PLL ready flag */
if(__HAL_RCC_GET_FLAG(RCC_FLAG_PLLRDY) == RESET)
{
return HAL_ERROR;
}
}
/* HSI is selected as System Clock Source */
else
{
/* Check the HSI ready flag */
if(__HAL_RCC_GET_FLAG(RCC_FLAG_HSIRDY) == RESET)
{
return HAL_ERROR;
}
}
__HAL_RCC_SYSCLK_CONFIG(RCC_ClkInitStruct->SYSCLKSource);
/* Get Start Tick */
tickstart = HAL_GetTick();
while (__HAL_RCC_GET_SYSCLK_SOURCE() != (RCC_ClkInitStruct->SYSCLKSource << RCC_CFGR_SWS_Pos))
{
if ((HAL_GetTick() - tickstart) > CLOCKSWITCH_TIMEOUT_VALUE)
{
return HAL_TIMEOUT;
}
}
}
/* Decreasing the number of wait states because of lower CPU frequency */
if(FLatency < __HAL_FLASH_GET_LATENCY())
{
/* Program the new number of wait states to the LATENCY bits in the FLASH_ACR register */
__HAL_FLASH_SET_LATENCY(FLatency);
/* Check that the new number of wait states is taken into account to access the Flash
memory by reading the FLASH_ACR register */
if(__HAL_FLASH_GET_LATENCY() != FLatency)
{
return HAL_ERROR;
}
}
/*-------------------------- PCLK1 Configuration ---------------------------*/
if(((RCC_ClkInitStruct->ClockType) & RCC_CLOCKTYPE_PCLK1) == RCC_CLOCKTYPE_PCLK1)
{
assert_param(IS_RCC_PCLK(RCC_ClkInitStruct->APB1CLKDivider));
MODIFY_REG(RCC->CFGR, RCC_CFGR_PPRE1, RCC_ClkInitStruct->APB1CLKDivider);
}
/*-------------------------- PCLK2 Configuration ---------------------------*/
if(((RCC_ClkInitStruct->ClockType) & RCC_CLOCKTYPE_PCLK2) == RCC_CLOCKTYPE_PCLK2)
{
assert_param(IS_RCC_PCLK(RCC_ClkInitStruct->APB2CLKDivider));
MODIFY_REG(RCC->CFGR, RCC_CFGR_PPRE2, ((RCC_ClkInitStruct->APB2CLKDivider) << 3U));
}
/* Update the SystemCoreClock global variable */
SystemCoreClock = HAL_RCC_GetSysClockFreq() >> AHBPrescTable[(RCC->CFGR & RCC_CFGR_HPRE)>> RCC_CFGR_HPRE_Pos];
/* Configure the source of time base considering new system clocks settings */
HAL_InitTick (uwTickPrio);
return HAL_OK;
}启用时钟安全系统（Clock Security System, CSS）
void HAL_RCC_EnableCSS(void)
{
*(__IO uint32_t *) RCC_CR_CSSON_BB = (uint32_t)ENABLE;
}
If a failure is detected on the HSE oscillator clock, this oscillator is automatically disabled and an interrupt is generated to inform the software about the failure (Clock Security System Interrupt, CSSI),allowing the MCU to perform rescue operations. The CSSI is linked to the Cortex-M4 NMI (Non-Maskable Interrupt) exception vector.
触发NMI中断。