今天介HAL库操作普通IO口，就是输入/输出。
如果用CubeMX配置io工程，打开以后可以看到如下代码：
GPIO_InitTypeDef GPIO_Initure; __HAL_RCC_GPIOB_CLK_ENABLE(); // 根据名字，这是使能B端口 GPIO_Initure.Pin=GPIO_PIN_0; // 0口 GPIO_Initure.Mode=GPIO_MODE_OUTPUT_PP; // 推挽输出 GPIO_Initure.Pull=GPIO_PULLUP; // 上拉 GPIO_Initure.Speed=GPIO_SPEED_HIGH; // 高速 HAL_GPIO_Init(GPIOB,&GPIO_Initure); // 调用初始化函数 HAL_GPIO_WritePin(GPIOB,GPIO_PIN_0,GPIO_PIN_SET); // 初始化电平
看到代码的时候，如果想深入了解一定要深入的仔细分析，看看到底是怎么调用的，操作了那些寄存器（不需要自己操作，但是要了解），用一个词来概括，抽丝剥茧。首先定义了一个 GPIO_InitTypeDef 类型的结构体，从名字可以看出是IO口初始化的类型配置，然后使能B端口，再然后配置刚才定义的结构体，把各种功能赋给各个成员变量。我们可以看一下这个结构体怎么定义的，，代码如下：
typedef struct { uint32_t Pin; /*!< Specifies the GPIO pins to be configured. This parameter can be any value of @ref GPIO_pins_define */ uint32_t Mode; /*!< Specifies the operating mode for the selected pins. This parameter can be a value of @ref GPIO_mode_define */ uint32_t Pull; /*!< Specifies the Pull-up or Pull-Down activation for the selected pins. This parameter can be a value of @ref GPIO_pull_define */ uint32_t Speed; /*!< Specifies the speed for the selected pins. This parameter can be a value of @ref GPIO_speed_define */ uint32_t Alternate; /*!< Peripheral to be connected to the selected pins. This parameter can be a value of @ref GPIO_Alternate_function_selection */ }GPIO_InitTypeDef;
这个结构体里面每一个元素都要仔细的看一下，Pin：指定配置那个脚，那参数怎么看呢？看英文注释，他说：这个参数是GPIO_pins_define的任何一个，这个又是什么呢？进去看看？会发现这不是变量，找不到他，那没办法，既注释中有他，那么我们肯定是可以找到的，那就整个工程搜索一下，还真的搜到了，如下：
/** @defgroup GPIO_pins_define GPIO pins define * @{ */ #define GPIO_PIN_0 ((uint16_t)0x0001) /* Pin 0 selected */ #define GPIO_PIN_1 ((uint16_t)0x0002) /* Pin 1 selected */ #define GPIO_PIN_2 ((uint16_t)0x0004) /* Pin 2 selected */ #define GPIO_PIN_3 ((uint16_t)0x0008) /* Pin 3 selected */ #define GPIO_PIN_4 ((uint16_t)0x0010) /* Pin 4 selected */ #define GPIO_PIN_5 ((uint16_t)0x0020) /* Pin 5 selected */ #define GPIO_PIN_6 ((uint16_t)0x0040) /* Pin 6 selected */ #define GPIO_PIN_7 ((uint16_t)0x0080) /* Pin 7 selected */ #define GPIO_PIN_8 ((uint16_t)0x0100) /* Pin 8 selected */ #define GPIO_PIN_9 ((uint16_t)0x0200) /* Pin 9 selected */ #define GPIO_PIN_10 ((uint16_t)0x0400) /* Pin 10 selected */ #define GPIO_PIN_11 ((uint16_t)0x0800) /* Pin 11 selected */ #define GPIO_PIN_12 ((uint16_t)0x1000) /* Pin 12 selected */ #define GPIO_PIN_13 ((uint16_t)0x2000) /* Pin 13 selected */ #define GPIO_PIN_14 ((uint16_t)0x4000) /* Pin 14 selected */ #define GPIO_PIN_15 ((uint16_t)0x8000) /* Pin 15 selected */ #define GPIO_PIN_All ((uint16_t)0xFFFF) /* All pins selected */ #define GPIO_PIN_MASK ((uint32_t)0x0000FFFF) /* PIN mask for assert test */
其实意思就是，结构体中的Pin变量可以是这些宏定义中的任何一个，从命名来说也就是0-15哪些脚。继续看，Mode：指定那个脚的模式，这个参数可以是 GPIO_mode_define 中的任何一个，找到他看看，如下：
/** @defgroup GPIO_mode_define GPIO mode define * @brief GPIO Configuration Mode * Elements values convention: 0xX0yz00YZ * - X : GPIO mode or EXTI Mode * - y : External IT or Event trigger detection * - z : IO configuration on External IT or Event * - Y : Output type (Push Pull or Open Drain) * - Z : IO Direction mode (Input, Output, Alternate or Analog) * @{ */ #define GPIO_MODE_INPUT ((uint32_t)0x00000000) /*!< Input Floating Mode */ #define GPIO_MODE_OUTPUT_PP ((uint32_t)0x00000001) /*!< Output Push Pull Mode */ #define GPIO_MODE_OUTPUT_OD ((uint32_t)0x00000011) /*!< Output Open Drain Mode */ #define GPIO_MODE_AF_PP ((uint32_t)0x00000002) /*!< Alternate Function Push Pull Mode */ #define GPIO_MODE_AF_OD ((uint32_t)0x00000012) /*!< Alternate Function Open Drain Mode */ #define GPIO_MODE_ANALOG ((uint32_t)0x00000003) /*!< Analog Mode */ #define GPIO_MODE_IT_RISING ((uint32_t)0x10110000) /*!< External Interrupt Mode with Rising edge trigger detection */ #define GPIO_MODE_IT_FALLING ((uint32_t)0x10210000) /*!< External Interrupt Mode with Falling edge trigger detection */ #define GPIO_MODE_IT_RISING_FALLING ((uint32_t)0x10310000) /*!< External Interrupt Mode with Rising/Falling edge trigger detection */ #define GPIO_MODE_EVT_RISING ((uint32_t)0x10120000) /*!< External Event Mode with Rising edge trigger detection */ #define GPIO_MODE_EVT_FALLING ((uint32_t)0x10220000) /*!< External Event Mode with Falling edge trigger detection */ #define GPIO_MODE_EVT_RISING_FALLING ((uint32_t)0x10320000) /*!< External Event Mode with Rising/Falling edge trigger detection */
上面就是IO口的各种功能配置，依次是：输入、推挽输出、开漏输出等等。同理，可以可以找到Pull、Speed等可以赋什么值。到此这个结构体就“充满”了，配置好了，我们的告诉系统啊，好接下来调用 HAL_GPIO_Init(GPIOB,&GPIO_Initure); 就是把刚才配制好的结构体扔到这个叫做IO口初始化的函数中。这个函数有两个参数，第一个是B就是那个端口，第二个是我们配置的结构体，其实就是：B端口的0号脚，这样的功能。这个函数太长了，说关键的部分，该函数会把我们的引脚的功能逐个抽离出来，然后配置相应的寄存器，就实现了这个脚的配置，代码如下：
void HAL_GPIO_Init(GPIO_TypeDef *GPIOx, GPIO_InitTypeDef *GPIO_Init) { uint32_t position; uint32_t ioposition = 0x00; uint32_t iocurrent = 0x00; uint32_t temp = 0x00; /* Check the parameters 这里是检查我们的配置的参数是否正确 */ assert_param(IS_GPIO_ALL_INSTANCE(GPIOx)); assert_param(IS_GPIO_PIN(GPIO_Init->Pin)); assert_param(IS_GPIO_MODE(GPIO_Init->Mode)); assert_param(IS_GPIO_PULL(GPIO_Init->Pull)); /* Configure the port pins */ for(position = 0; position < GPIO_NUMBER; position++) { /* Get the IO position */ ioposition = ((uint32_t)0x01) << position; /* Get the current IO position */ iocurrent = (uint32_t)(GPIO_Init->Pin) & ioposition; if(iocurrent == ioposition) { /*--------------------- GPIO Mode Configuration ------------------------*/ /* In case of Alternate function mode selection */ if((GPIO_Init->Mode == GPIO_MODE_AF_PP) || (GPIO_Init->Mode == GPIO_MODE_AF_OD)) { /* Check the Alternate function parameter */ assert_param(IS_GPIO_AF(GPIO_Init->Alternate)); /* Configure Alternate function mapped with the current IO */ temp = GPIOx->AFR[position >> 3]; temp &= ~((uint32_t)0xF << ((uint32_t)(position & (uint32_t)0x07) * 4)) ; temp |= ((uint32_t)(GPIO_Init->Alternate) << (((uint32_t)position & (uint32_t)0x07) * 4)); GPIOx->AFR[position >> 3] = temp; } /* Configure IO Direction mode (Input, Output, Alternate or Analog) */ temp = GPIOx->MODER; temp &= ~(GPIO_MODER_MODER0 << (position * 2)); temp |= ((GPIO_Init->Mode & GPIO_MODE) << (position * 2)); GPIOx->MODER = temp; /* In case of Output or Alternate function mode selection */ if((GPIO_Init->Mode == GPIO_MODE_OUTPUT_PP) || (GPIO_Init->Mode == GPIO_MODE_AF_PP) || (GPIO_Init->Mode == GPIO_MODE_OUTPUT_OD) || (GPIO_Init->Mode == GPIO_MODE_AF_OD)) { /* Check the Speed parameter */ assert_param(IS_GPIO_SPEED(GPIO_Init->Speed)); /* Configure the IO Speed */ temp = GPIOx->OSPEEDR; temp &= ~(GPIO_OSPEEDER_OSPEEDR0 << (position * 2)); temp |= (GPIO_Init->Speed << (position * 2)); GPIOx->OSPEEDR = temp; /* Configure the IO Output Type */ temp = GPIOx->OTYPER; temp &= ~(GPIO_OTYPER_OT_0 << position) ; temp |= (((GPIO_Init->Mode & GPIO_OUTPUT_TYPE) >> 4) << position); GPIOx->OTYPER = temp; } /* Activate the Pull-up or Pull down resistor for the current IO */ temp = GPIOx->PUPDR; temp &= ~(GPIO_PUPDR_PUPDR0 << (position * 2)); temp |= ((GPIO_Init->Pull) << (position * 2)); GPIOx->PUPDR = temp; /*--------------------- EXTI Mode Configuration ------------------------*/ /* Configure the External Interrupt or event for the current IO */ if((GPIO_Init->Mode & EXTI_MODE) == EXTI_MODE) { /* Enable SYSCFG Clock */ __HAL_RCC_SYSCFG_CLK_ENABLE(); temp = SYSCFG->EXTICR[position >> 2]; temp &= ~(((uint32_t)0x0F) << (4 * (position & 0x03))); temp |= ((uint32_t)(GPIO_GET_INDEX(GPIOx)) << (4 * (position & 0x03))); SYSCFG->EXTICR[position >> 2] = temp; /* Clear EXTI line configuration */ temp = EXTI->IMR; temp &= ~((uint32_t)iocurrent); if((GPIO_Init->Mode & GPIO_MODE_IT) == GPIO_MODE_IT) { temp |= iocurrent; } EXTI->IMR = temp; temp = EXTI->EMR; temp &= ~((uint32_t)iocurrent); if((GPIO_Init->Mode & GPIO_MODE_EVT) == GPIO_MODE_EVT) { temp |= iocurrent; } EXTI->EMR = temp; /* Clear Rising Falling edge configuration */ temp = EXTI->RTSR; temp &= ~((uint32_t)iocurrent); if((GPIO_Init->Mode & RISING_EDGE) == RISING_EDGE) { temp |= iocurrent; } EXTI->RTSR = temp; temp = EXTI->FTSR; temp &= ~((uint32_t)iocurrent); if((GPIO_Init->Mode & FALLING_EDGE) == FALLING_EDGE) { temp |= iocurrent; } EXTI->FTSR = temp; } } } }
回过头来，再看一下开启GPIOB时钟，__HAL_RCC_GPIOB_CLK_ENABLE(); 他是一个很大的宏，把和这个宏有关的都贴上一起分析：
#define __HAL_RCC_GPIOB_CLK_ENABLE() do { \ __IO uint32_t tmpreg = 0x00; \ SET_BIT(RCC->AHB1ENR, RCC_AHB1ENR_GPIOBEN);\ /* Delay after an RCC peripheral clock enabling */ \ tmpreg = READ_BIT(RCC->AHB1ENR, RCC_AHB1ENR_GPIOBEN);\ UNUSED(tmpreg); \ } while(0) #define SET_BIT(REG, BIT) ((REG) |= (BIT)) #define RCC_AHB1ENR_GPIOBEN ((uint32_t)0x00000002) #define READ_BIT(REG, BIT) ((REG) & (BIT)) #define UNUSED(x) ((void)(x)) // 避免警告——百度
这个宏，简单一点看，把当作一个函数看一下，执行一次do里面的，把寄存器 AHB1ENR 1位置1，就是使能GPIOB。
总结一下IO是使用，想配置一个脚作为普通口用，就要定义一个配置结构体，初始化这个脚所在的口的时钟，然后“填满”它，在把他扔到初始化函数中，到此，就配置好了一个普通的IO口作为输入输出。
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