【经验分享】STM32 GPIO功能复用

[复制链接]

STMCU小助手发布时间：2022-4-2 22:00

文章
文章封面:
文章简介:	STM32 GPIO功能复用

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。

$255@5}T_90{@@A]2`4J}FG4.png$

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：

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

1%$J{ZY0`HBV3I23R0FMX3X.png

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

$1C%O9MJMC5BXN{(_7@(V627.png$

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：

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。

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。

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 */

复制代码

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);

复制代码

05. 参考示例
串口配置