【经验分享】STM32F103固件库源码解析——RCC_APB2PeriphClockCmd

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STMCU小助手发布时间：2022-5-2 09:13

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文章简介:	STM32F103固件库源码解析——RCC_APB2PeriphClockCmd

RCC_APB2PeriphClockCmd函数用来开启或关闭APB2外设时钟，

该函数总览如下，

/**" q$ \! r, {% Q# m' i. J
* @brief Enables or disables the High Speed APB (APB2) peripheral clock.
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* @param RCC_APB2Periph: specifies the APB2 peripheral to gates its clock.
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* This parameter can be any combination of the following values:
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* @arg RCC_APB2Periph_AFIO, RCC_APB2Periph_GPIOA, RCC_APB2Periph_GPIOB,
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* RCC_APB2Periph_GPIOC, RCC_APB2Periph_GPIOD, RCC_APB2Periph_GPIOE,( ] s2 O+ A7 P, G
* RCC_APB2Periph_GPIOF, RCC_APB2Periph_GPIOG, RCC_APB2Periph_ADC1,
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* RCC_APB2Periph_ADC2, RCC_APB2Periph_TIM1, RCC_APB2Periph_SPI1,
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* RCC_APB2Periph_TIM8, RCC_APB2Periph_USART1, RCC_APB2Periph_ADC3,
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* RCC_APB2Periph_TIM15, RCC_APB2Periph_TIM16, RCC_APB2Periph_TIM17,9 C% k2 S; B! v: N8 ^' q! V' F
* RCC_APB2Periph_TIM9, RCC_APB2Periph_TIM10, RCC_APB2Periph_TIM11
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* @param NewState: new state of the specified peripheral clock.
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* This parameter can be: ENABLE or DISABLE.+ l8 ^9 ]% r5 z7 E" ^4 z
* @retval None
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*/
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void RCC_APB2PeriphClockCmd(uint32_t RCC_APB2Periph, FunctionalState NewState)
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{
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/* Check the parameters */4 s& b3 {& }# H0 e- l
assert_param(IS_RCC_APB2_PERIPH(RCC_APB2Periph));
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assert_param(IS_FUNCTIONAL_STATE(NewState));8 [; e+ v# M: o) g
if (NewState != DISABLE)
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RCC->APB2ENR |= RCC_APB2Periph;* K) b0 u3 t2 ]6 k: ?9 [( ?6 @! S3 g
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RCC->APB2ENR &= ~RCC_APB2Periph;
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}
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}

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如下，FunctionalState是枚举类型，DISABLE 值为0，ENABLE 值为1，使用该参数判断是否要开相应的时钟。

typedef enum {DISABLE = 0, ENABLE = !DISABLE} FunctionalState;

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在stm32f10x_rcc.h中，有APB2_peripheral的宏定义。

/** @defgroup APB2_peripheral - n1 e4 l+ n/ a; a" j6 ^
* @{
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*/
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#define RCC_APB2Periph_AFIO ((uint32_t)0x00000001)
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#define RCC_APB2Periph_GPIOA ((uint32_t)0x00000004)
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#define RCC_APB2Periph_GPIOB ((uint32_t)0x00000008)( v7 G6 Y7 \! p/ Y% g; } ^: |5 q
#define RCC_APB2Periph_GPIOC ((uint32_t)0x00000010)2 \+ F6 o/ p# { n6 J6 W* Y# a0 [
#define RCC_APB2Periph_GPIOD ((uint32_t)0x00000020)
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#define RCC_APB2Periph_GPIOE ((uint32_t)0x00000040)& T4 t5 m7 g4 d" o' S! R
#define RCC_APB2Periph_GPIOF ((uint32_t)0x00000080)7 J# g ^# j# h1 @5 H
#define RCC_APB2Periph_GPIOG ((uint32_t)0x00000100)
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#define RCC_APB2Periph_ADC1 ((uint32_t)0x00000200)9 f. Q( l3 H' x% C+ l
#define RCC_APB2Periph_ADC2 ((uint32_t)0x00000400)
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#define RCC_APB2Periph_TIM1 ((uint32_t)0x00000800)1 c G0 D. }- ~! E0 Q2 U
#define RCC_APB2Periph_SPI1 ((uint32_t)0x00001000)3 P. ]; y) Y6 ], N+ s8 t/ m
#define RCC_APB2Periph_TIM8 ((uint32_t)0x00002000)
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#define RCC_APB2Periph_USART1 ((uint32_t)0x00004000)' D: V' s3 e$ U9 C5 |& R
#define RCC_APB2Periph_ADC3 ((uint32_t)0x00008000)' E, }8 i4 e. h1 i, a8 R, t
#define RCC_APB2Periph_TIM15 ((uint32_t)0x00010000)$ N4 U2 c4 o8 R: U1 k. q$ E
#define RCC_APB2Periph_TIM16 ((uint32_t)0x00020000)
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#define RCC_APB2Periph_TIM17 ((uint32_t)0x00040000)$ ^1 b1 v& I+ n
#define RCC_APB2Periph_TIM9 ((uint32_t)0x00080000); P" R/ I+ Y* u) m6 {: o3 v
#define RCC_APB2Periph_TIM10 ((uint32_t)0x00100000)0 V) n9 I+ H: M% P8 d0 R7 T J' N- W
#define RCC_APB2Periph_TIM11 ((uint32_t)0x00200000)
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#define IS_RCC_APB2_PERIPH(PERIPH) ((((PERIPH) & 0xFFC00002) == 0x00) && ((PERIPH) != 0x00))

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APB2 外设时钟使能寄存器(RCC_APB2ENR)如下，可见APB2_peripheral的宏定义正好对应了寄存器RCC_APB2ENR的对应位。

IS_RCC_APB2_PERIPH(PERIPH)宏定义实现了输入判断，当输入参数不符合RCC_APB2Periph的数据格式时，返回0。

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if (NewState != DISABLE)
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RCC->APB2ENR |= RCC_APB2Periph;: l, \0 w# k: `1 [
}
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else
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RCC->APB2ENR &= ~RCC_APB2Periph;
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}

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这段代码是开启对应APB2外设时钟的主要实现语句。

如下，RCC是指向RCC_TypeDef结构体类型的指针，RCC_BASE就是RCC寄存器的映射地址，也就是RCC指针的值。

#define RCC ((RCC_TypeDef *) RCC_BASE)

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RCC_TypeDef结构体的定义如下，

/** % l) w# U- S* d( t2 N5 j
* @brief Reset and Clock Control
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typedef struct
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__IO uint32_t CR;" O U; t8 O; l. s) E5 F
__IO uint32_t CFGR;0 W& J. k5 r( [' v0 J, H) w1 t
__IO uint32_t CIR;- V, _' y! T9 h; x) t- a Y
__IO uint32_t APB2RSTR;
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__IO uint32_t APB1RSTR;# M" ?' |, `8 P. C1 T7 j& r
__IO uint32_t AHBENR;
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__IO uint32_t APB2ENR;
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__IO uint32_t APB1ENR;
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__IO uint32_t BDCR;
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__IO uint32_t CSR;
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#ifdef STM32F10X_CL : U$ B) v: _0 \; ?+ l5 p, a m8 R
__IO uint32_t AHBRSTR;; z. W' c3 G" T/ q: Y. f7 Z/ U
__IO uint32_t CFGR2;
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#endif /* STM32F10X_CL */
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#if defined (STM32F10X_LD_VL) || defined (STM32F10X_MD_VL) || defined (STM32F10X_HD_VL)
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uint32_t RESERVED0;
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__IO uint32_t CFGR2;5 ^5 b" G* ]9 R" Q: U W7 z
#endif /* STM32F10X_LD_VL || STM32F10X_MD_VL || STM32F10X_HD_VL */ & [- Z4 |0 _) J' Y2 Y
} RCC_TypeDef;