【STM32】GPIO功能复用

其他 2020-09-08 11:01:03 阅读次数: 0

00. 目录

文章目录

01. GPIO复用概述

STM32F4 有很多的内置外设，这些外设的外部引脚都是与 GPIO 复用的。也就是说，一个 GPIO如果可以复用为内置外设的功能引脚，那么当这个 GPIO 作为内置外设使用的时候，就叫做复用。

STM32F4 系列微控制器 IO 引脚通过一个复用器连接到内置外设或模块。该复用器一次只允许一个外设的复用功能（AF）连接到对应的 IO 口。这样可以确保共用同一个 IO 引脚的外设之间不会发生冲突。

每个 IO 引脚都有一个复用器，该复用器采用 16 路复用功能输入（AF0 到 AF15），可通过GPIOx_AFRL(针对引脚 0-7)和 GPIOx_AFRH（针对引脚 8-15）寄存器对这些输入进行配置，每四位控制一路复用

1）完成复位后，所有 IO 都会连接到系统的复用功能 0（AF0）。
2）外设的复用功能映射到 AF1 到 AF13。
3）Cortex-M4 EVENTOUT 映射到 AF15。
在这里插入图片描述

02. 寄存器描述

探索者 STM32F407 开发板的原理图上 PC11 的原理图如图 所示：
在这里插入图片描述

PC11 可以作为 SPI3_MISO/U3_RX/U4_RX/SDIO_D3/DCMI_D4/I2S3ext_SD等复用功能输出，这么多复用功能，如果这些外设都开启了，那么对 STM32F1 来说，那就可能乱套了，外设之间可互相干扰，但是 STM32F4，由于有复用功能选择功能，可以让 PC11 仅连接到某个特定的外设，因此不存在互相干扰的情况。

GPIO 复用功能低位寄存器 (GPIOx_AFRL) (x = A…I)
GPIO alternate function low register
偏移地址：0x20
复位值：0x0000 0000
在这里插入图片描述

GPIO 复用功能高位寄存器 (GPIOx_AFRH) (x = A…I)
GPIO alternate function high register
偏移地址：0x24
复位值：0x0000 0000
在这里插入图片描述

在微控制器完成复位后，所有 IO 口都会连接到系统复用功能 0（AF0）。这里大家需要注意，对于系统复用功能 AF0，我们将 IO 口连接到 AF0 之后，还要根据所用功能进行配置：

  1. JTAG/SWD:在器件复位之后，会将这些功能引脚指定为专用引脚。也就是说，这些引脚在复位后默认就是 JTAG/SWD 功能。如果我们要作为 GPIO 来使用，就需要对对应的 IO口复用器进行配置。

  2. RTC_REFIN:此引脚在系统复位之后要使用的话要配置为浮空输入模式。

  3. MCO1 和 MCO2：这些引脚在系统复位之后要使用的话要配置为复用功能模式。

03. 类型

复用功能相关宏

/** 
  * @brief   AF 0 selection  
  */ 
#define GPIO_AF_RTC_50Hz      ((uint8_t)0x00)  /* RTC_50Hz Alternate Function mapping */
#define GPIO_AF_MCO           ((uint8_t)0x00)  /* MCO (MCO1 and MCO2) Alternate Function mapping */
#define GPIO_AF_TAMPER        ((uint8_t)0x00)  /* TAMPER (TAMPER_1 and TAMPER_2) Alternate Function mapping */
#define GPIO_AF_SWJ           ((uint8_t)0x00)  /* SWJ (SWD and JTAG) Alternate Function mapping */
#define GPIO_AF_TRACE         ((uint8_t)0x00)  /* TRACE Alternate Function mapping */
#if defined(STM32F446xx)
#define GPIO_AF0_TIM2         ((uint8_t)0x00)  /* TIM2 Alternate Function mapping */
#endif /* STM32F446xx */

/** 
  * @brief   AF 1 selection  
  */ 
#define GPIO_AF_TIM1          ((uint8_t)0x01)  /* TIM1 Alternate Function mapping */
#define GPIO_AF_TIM2          ((uint8_t)0x01)  /* TIM2 Alternate Function mapping */
#if defined(STM32F410xx) || defined(STM32F413_423xx)
#define GPIO_AF_LPTIM         ((uint8_t)0x01)  /* LPTIM Alternate Function mapping */
#endif /* STM32F410xx || STM32F413_423xx */
/** 
  * @brief   AF 2 selection  
  */ 
#define GPIO_AF_TIM3          ((uint8_t)0x02)  /* TIM3 Alternate Function mapping */
#define GPIO_AF_TIM4          ((uint8_t)0x02)  /* TIM4 Alternate Function mapping */
#define GPIO_AF_TIM5          ((uint8_t)0x02)  /* TIM5 Alternate Function mapping */

/** 
  * @brief   AF 3 selection  
  */ 
#define GPIO_AF_TIM8          ((uint8_t)0x03)  /* TIM8 Alternate Function mapping */
#define GPIO_AF_TIM9          ((uint8_t)0x03)  /* TIM9 Alternate Function mapping */
#define GPIO_AF_TIM10         ((uint8_t)0x03)  /* TIM10 Alternate Function mapping */
#define GPIO_AF_TIM11         ((uint8_t)0x03)  /* TIM11 Alternate Function mapping */
#if defined(STM32F446xx)
#define GPIO_AF3_CEC          ((uint8_t)0x03)  /* CEC Alternate Function mapping */
#endif /* STM32F446xx */
#if defined(STM32F413_423xx)
#define GPIO_AF3_DFSDM2       ((uint8_t)0x03)  /* DFSDM2 Alternate Function mapping */
#endif /* STM32F413_423xx */
/** 
  * @brief   AF 4 selection  
  */ 
#define GPIO_AF_I2C1          ((uint8_t)0x04)  /* I2C1 Alternate Function mapping */
#define GPIO_AF_I2C2          ((uint8_t)0x04)  /* I2C2 Alternate Function mapping */
#define GPIO_AF_I2C3          ((uint8_t)0x04)  /* I2C3 Alternate Function mapping */
#if defined(STM32F446xx)
#define GPIO_AF4_CEC          ((uint8_t)0x04)  /* CEC Alternate Function mapping */
#endif /* STM32F446xx */
#if defined(STM32F410xx) || defined(STM32F412xG) || defined(STM32F413_423xx) || defined(STM32F446xx)
#define GPIO_AF_FMPI2C        ((uint8_t)0x04)  /* FMPI2C Alternate Function mapping */
#endif /* STM32F410xx || STM32F446xx */

/** 
  * @brief   AF 5 selection  
  */ 
#define GPIO_AF_SPI1          ((uint8_t)0x05)  /* SPI1/I2S1 Alternate Function mapping */
#define GPIO_AF_SPI2          ((uint8_t)0x05)  /* SPI2/I2S2 Alternate Function mapping */
#define GPIO_AF5_SPI3         ((uint8_t)0x05)  /* SPI3/I2S3 Alternate Function mapping (Only for STM32F411xE and STM32F413_423xx Devices) */
#define GPIO_AF_SPI4          ((uint8_t)0x05)  /* SPI4/I2S4 Alternate Function mapping */
#define GPIO_AF_SPI5          ((uint8_t)0x05)  /* SPI5 Alternate Function mapping      */
#define GPIO_AF_SPI6          ((uint8_t)0x05)  /* SPI6 Alternate Function mapping      */

/** 
  * @brief   AF 6 selection  
  */ 
#define GPIO_AF_SPI3          ((uint8_t)0x06)  /* SPI3/I2S3 Alternate Function mapping */
#define GPIO_AF6_SPI1         ((uint8_t)0x06)  /* SPI1 Alternate Function mapping (Only for STM32F410xx Devices) */
#define GPIO_AF6_SPI2         ((uint8_t)0x06)  /* SPI2 Alternate Function mapping (Only for STM32F410xx/STM32F411xE Devices) */
#define GPIO_AF6_SPI4         ((uint8_t)0x06)  /* SPI4 Alternate Function mapping (Only for STM32F411xE Devices) */
#define GPIO_AF6_SPI5         ((uint8_t)0x06)  /* SPI5 Alternate Function mapping (Only for STM32F410xx/STM32F411xE Devices) */
#define GPIO_AF_SAI1          ((uint8_t)0x06)  /* SAI1 Alternate Function mapping      */
#define GPIO_AF_I2S2ext       ((uint8_t)0x06)  /* I2S2ext_SD Alternate Function mapping (only for STM32F412xG and STM32F413_423xx Devices) */
#if defined(STM32F412xG) || defined(STM32F413_423xx)
#define GPIO_AF6_DFSDM1       ((uint8_t)0x06)  /* DFSDM1 Alternate Function mapping */
#endif /* STM32F412xG || STM32F413_423xx */
#if defined(STM32F413_423xx)
#define GPIO_AF6_DFSDM2       ((uint8_t)0x06)  /* DFSDM2 Alternate Function mapping */
#endif /* STM32F413_423xx */

/** 
  * @brief   AF 7 selection  
  */ 
#define GPIO_AF_USART1         ((uint8_t)0x07)  /* USART1 Alternate Function mapping  */
#define GPIO_AF_USART2         ((uint8_t)0x07)  /* USART2 Alternate Function mapping  */
#define GPIO_AF_USART3         ((uint8_t)0x07)  /* USART3 Alternate Function mapping  */
#define GPIO_AF7_SPI3          ((uint8_t)0x07)  /* SPI3/I2S3ext Alternate Function mapping */
#if defined(STM32F413_423xx)
#define GPIO_AF7_DFSDM2        ((uint8_t)0x07)  /* DFSDM2 Alternate Function mapping     */
#define GPIO_AF7_SAI1          ((uint8_t)0x07)  /* SAI1 Alternate Function mapping       */
#endif /* STM32F413_423xx */

/** 
  * @brief   AF 7 selection Legacy 
  */ 
#define GPIO_AF_I2S3ext   GPIO_AF7_SPI3

/** 
  * @brief   AF 8 selection  
  */ 
#define GPIO_AF_UART4         ((uint8_t)0x08)  /* UART4 Alternate Function mapping  */
#define GPIO_AF_UART5         ((uint8_t)0x08)  /* UART5 Alternate Function mapping  */
#define GPIO_AF_USART6        ((uint8_t)0x08)  /* USART6 Alternate Function mapping */
#define GPIO_AF_UART7         ((uint8_t)0x08)  /* UART7 Alternate Function mapping  */
#define GPIO_AF_UART8         ((uint8_t)0x08)  /* UART8 Alternate Function mapping  */
#if defined(STM32F412xG) || defined(STM32F413_423xx)
#define GPIO_AF8_USART3        ((uint8_t)0x08)  /* USART3 Alternate Function mapping */
#define GPIO_AF8_DFSDM1        ((uint8_t)0x08)  /* DFSDM Alternate Function mapping  */
#define GPIO_AF8_CAN1          ((uint8_t)0x08)  /* CAN1 Alternate Function mapping   */
#endif /* STM32F412xG || STM32F413_423xx */
#if defined(STM32F446xx)
#define GPIO_AF8_SAI2          ((uint8_t)0x08)  /* SAI2 Alternate Function mapping */
#define GPIO_AF_SPDIF         ((uint8_t)0x08)   /* SPDIF Alternate Function mapping */
#endif /* STM32F446xx */

/** 
  * @brief   AF 9 selection 
  */ 
#define GPIO_AF_CAN1          ((uint8_t)0x09)  /* CAN1 Alternate Function mapping  */
#define GPIO_AF_CAN2          ((uint8_t)0x09)  /* CAN2 Alternate Function mapping  */
#define GPIO_AF_TIM12         ((uint8_t)0x09)  /* TIM12 Alternate Function mapping */
#define GPIO_AF_TIM13         ((uint8_t)0x09)  /* TIM13 Alternate Function mapping */
#define GPIO_AF_TIM14         ((uint8_t)0x09)  /* TIM14 Alternate Function mapping */
#define GPIO_AF9_I2C2         ((uint8_t)0x09)  /* I2C2 Alternate Function mapping (Only for STM32F401xx/STM32F410xx/STM32F411xE/STM32F412xG/STM32F413_423xx Devices) */
#define GPIO_AF9_I2C3         ((uint8_t)0x09)  /* I2C3 Alternate Function mapping (Only for STM32F401xx/STM32F411xE/STM32F412xG and STM32F413_423xx Devices) */
#if defined(STM32F446xx)
#define GPIO_AF9_SAI2         ((uint8_t)0x09)  /* SAI2 Alternate Function mapping */
#endif /* STM32F446xx */
#define GPIO_AF9_LTDC         ((uint8_t)0x09)  /* LTDC Alternate Function mapping */
#if defined(STM32F412xG) || defined(STM32F413_423xx) || defined(STM32F446xx) || defined(STM32F469_479xx)
#define GPIO_AF9_QUADSPI      ((uint8_t)0x09)  /* QuadSPI Alternate Function mapping */
#endif /* STM32F412xG || STM32F413_423xx || STM32F446xx || STM32F469_479xx */
#if defined(STM32F410xx) || defined(STM32F412xG) || defined(STM32F413_423xx)
#define GPIO_AF9_FMPI2C       ((uint8_t)0x09)  /* FMPI2C Alternate Function mapping (Only for STM32F410xx Devices) */
#endif /* STM32F410xx || STM32F412xG || STM32F413_423xx */

/** 
  * @brief   AF 10 selection  
  */ 
#define GPIO_AF_OTG_FS         ((uint8_t)0xA)  /* OTG_FS Alternate Function mapping */
#define GPIO_AF_OTG_HS         ((uint8_t)0xA)  /* OTG_HS Alternate Function mapping */
#if defined(STM32F446xx)
#define GPIO_AF10_SAI2         ((uint8_t)0x0A)  /* SAI2 Alternate Function mapping */
#endif /* STM32F446xx */
#if defined(STM32F412xG) || defined(STM32F413_423xx) || defined(STM32F446xx) || defined(STM32F469_479xx)
#define GPIO_AF10_QUADSPI      ((uint8_t)0x0A)  /* QuadSPI Alternate Function mapping */
#endif /* STM32F412xG || STM32F413_423xx || STM32F446xx || STM32F469_479xx */
#if defined(STM32F412xG) || defined(STM32F413_423xx)
#define GPIO_AF10_FMC           ((uint8_t)0xA)  /* FMC Alternate Function mapping    */
#define GPIO_AF10_DFSDM1         ((uint8_t)0xA) /* DFSDM Alternate Function mapping  */
#endif /* STM32F412xG || STM32F413_423xx */
#if defined(STM32F413_423xx)
#define GPIO_AF10_DFSDM2        ((uint8_t)0x0A)  /* DFSDM2 Alternate Function mapping */
#define GPIO_AF10_SAI1          ((uint8_t)0x0A)  /* SAI1 Alternate Function mapping   */
#endif /* STM32F413_423xx */
/** 
  * @brief   AF 11 selection  
  */ 
#define GPIO_AF_ETH             ((uint8_t)0x0B)  /* ETHERNET Alternate Function mapping */
#if defined(STM32F413_423xx)
#define GPIO_AF11_UART4         ((uint8_t)0x0B)  /* UART4 Alternate Function mapping  */
#define GPIO_AF11_UART5         ((uint8_t)0x0B)  /* UART5 Alternate Function mapping  */
#define GPIO_AF11_UART9         ((uint8_t)0x0B)  /* UART9 Alternate Function mapping  */
#define GPIO_AF11_UART10        ((uint8_t)0x0B)  /* UART10 Alternate Function mapping */
#define GPIO_AF11_CAN3          ((uint8_t)0x0B)  /* CAN3 Alternate Function mapping   */
#endif /* STM32F413_423xx */

/** 
  * @brief   AF 12 selection  
  */ 
#if defined(STM32F40_41xxx) || defined(STM32F412xG) || defined(STM32F413_423xx)
#define GPIO_AF_FSMC             ((uint8_t)0xC)  /* FSMC Alternate Function mapping                     */
#endif /* STM32F40_41xxx || STM32F412xG || STM32F413_423xx */

#if defined(STM32F427_437xx) || defined(STM32F429_439xx) || defined(STM32F446xx) || defined(STM32F469_479xx)
#define GPIO_AF_FMC              ((uint8_t)0xC)  /* FMC Alternate Function mapping                      */
#endif /* STM32F427_437xx || STM32F429_439xx || STM32F446xx || STM32F469_479xx */

#define GPIO_AF_OTG_HS_FS        ((uint8_t)0xC)  /* OTG HS configured in FS, Alternate Function mapping */
#define GPIO_AF_SDIO             ((uint8_t)0xC)  /* SDIO Alternate Function mapping                     */

/** 
  * @brief   AF 13 selection  
  */ 
#define GPIO_AF_DCMI          ((uint8_t)0x0D)  /* DCMI Alternate Function mapping */
#if defined(STM32F469_479xx)
#define GPIO_AF_DSI           ((uint8_t)0x0D)  /* DSI Alternate Function mapping */
#endif /* STM32F469_479xx */
/** 
  * @brief   AF 14 selection  
  */
#define GPIO_AF_LTDC          ((uint8_t)0x0E)  /* LCD-TFT Alternate Function mapping */
#if defined(STM32F413_423xx)
#define GPIO_AF14_RNG         ((uint8_t)0x0E)  /* RNG Alternate Function mapping  */
#endif /* STM32F413_423xx */

/** 
  * @brief   AF 15 selection  
  */ 
#define GPIO_AF_EVENTOUT      ((uint8_t)0x0F)  /* EVENTOUT Alternate Function mapping */

#define IS_GPIO_AF(AF)   (((AF) == GPIO_AF_RTC_50Hz)  || ((AF) == GPIO_AF_TIM14)     || \
                          ((AF) == GPIO_AF_MCO)       || ((AF) == GPIO_AF_TAMPER)    || \
                          ((AF) == GPIO_AF_SWJ)       || ((AF) == GPIO_AF_TRACE)     || \
                          ((AF) == GPIO_AF_TIM1)      || ((AF) == GPIO_AF_TIM2)      || \
                          ((AF) == GPIO_AF_TIM3)      || ((AF) == GPIO_AF_TIM4)      || \
                          ((AF) == GPIO_AF_TIM5)      || ((AF) == GPIO_AF_TIM8)      || \
                          ((AF) == GPIO_AF_I2C1)      || ((AF) == GPIO_AF_I2C2)      || \
                          ((AF) == GPIO_AF_I2C3)      || ((AF) == GPIO_AF_SPI1)      || \
                          ((AF) == GPIO_AF_SPI2)      || ((AF) == GPIO_AF_TIM13)     || \
                          ((AF) == GPIO_AF_SPI3)      || ((AF) == GPIO_AF_TIM14)     || \
                          ((AF) == GPIO_AF_USART1)    || ((AF) == GPIO_AF_USART2)    || \
                          ((AF) == GPIO_AF_USART3)    || ((AF) == GPIO_AF_UART4)     || \
                          ((AF) == GPIO_AF_UART5)     || ((AF) == GPIO_AF_USART6)    || \
                          ((AF) == GPIO_AF_CAN1)      || ((AF) == GPIO_AF_CAN2)      || \
                          ((AF) == GPIO_AF_OTG_FS)    || ((AF) == GPIO_AF_OTG_HS)    || \
                          ((AF) == GPIO_AF_ETH)       || ((AF) == GPIO_AF_OTG_HS_FS) || \
                          ((AF) == GPIO_AF_SDIO)      || ((AF) == GPIO_AF_DCMI)      || \
                          ((AF) == GPIO_AF_EVENTOUT)  || ((AF) == GPIO_AF_FSMC))
#endif /* STM32F40_41xxx */

04. 函数

GPIO复用功能函数

/* GPIO Alternate functions configuration function ****************************/
void GPIO_PinAFConfig(GPIO_TypeDef* GPIOx, uint16_t GPIO_PinSource, uint8_t GPIO_AF);

05. 参考示例

串口配置

/*GPIOA9 与 GPIOA10 初始化*/
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9 | GPIO_Pin_10;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;// 复用功能
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;//速度 50MHz
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP; //推挽复用输出
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP; //上拉
GPIO_Init(GPIOA,&GPIO_InitStructure); //初始化 PA9，PA10

/*PA9 连接 AF7，复用为 USART1_TX */
GPIO_PinAFConfig(GPIOA,GPIO_PinSource9,GPIO_AF_USART1);
/* PA10 连接 AF7,复用为 USART1_RX*/
GPIO_PinAFConfig(GPIOA,GPIO_PinSource10,GPIO_AF_USART1);

06. 附录

6.1 【STM32】STM32系列教程汇总

网址：【STM32】STM32系列教程汇总

07. 声明

该教程参考了正点原子的《STM32 F4 开发指南》

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