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STM32 HAL库GPIO初始化函数分析

函数代码及其注释

HAL库的封装非常完善，在可以使用HAL_GPIO_Init函数初始化端口用于外部中断，无需自己手动修改寄存器什么的。

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void HAL_GPIO_Init(GPIO_TypeDef  *GPIOx, GPIO_InitTypeDef *GPIO_Init)
{
  uint32_t position = 0x00u; // 记录当前初始化的是第几个管脚
  uint32_t ioposition; 
  uint32_t iocurrent; 
  uint32_t temp;
  uint32_t config = 0x00u;
  __IO uint32_t *configregister; /* Store the address of CRL or CRH register based on pin number */
  uint32_t registeroffset;       /* offset used during computation of CNF and MODE bits placement inside CRL or CRH register */

  /* Check the parameters */
  assert_param(IS_GPIO_ALL_INSTANCE(GPIOx));
  assert_param(IS_GPIO_PIN(GPIO_Init->Pin));
  assert_param(IS_GPIO_MODE(GPIO_Init->Mode));

  /* Configure the port pins */
  while (((GPIO_Init->Pin) >> position) != 0x00u)
  {
    /* Get the IO position */
    /* 记录当前初始化的是哪个管脚（二进制形式，1为初始化的管脚）*/
    ioposition = (0x01uL << position);

    /* Get the current IO position */
    /* 中间变量，用于检查position指定的管脚是否被指定要初始化 */
    iocurrent = (uint32_t)(GPIO_Init->Pin) & ioposition;

    if (iocurrent == ioposition)
    {
      /* Check the Alternate function parameters */
      assert_param(IS_GPIO_AF_INSTANCE(GPIOx));

      /* Based on the required mode, filling config variable with MODEy[1:0] and CNFy[3:2] corresponding bits */
      /* 根据输入变量生成对应寄存器的值 */
      switch (GPIO_Init->Mode)
      {
        /* If we are configuring the pin in OUTPUT push-pull mode */
        /* 推挽输出配置 */
        case GPIO_MODE_OUTPUT_PP:
          /* Check the GPIO speed parameter */
          assert_param(IS_GPIO_SPEED(GPIO_Init->Speed));
          config = GPIO_Init->Speed + GPIO_CR_CNF_GP_OUTPUT_PP;
          break;

        /* If we are configuring the pin in OUTPUT open-drain mode */
        /* 开漏输出配置 */
        case GPIO_MODE_OUTPUT_OD:
          /* Check the GPIO speed parameter */
          assert_param(IS_GPIO_SPEED(GPIO_Init->Speed));
          config = GPIO_Init->Speed + GPIO_CR_CNF_GP_OUTPUT_OD;
          break;

        /* If we are configuring the pin in ALTERNATE FUNCTION push-pull mode */
        /* 特殊功能推挽输出配置 */
        case GPIO_MODE_AF_PP:
          /* Check the GPIO speed parameter */
          assert_param(IS_GPIO_SPEED(GPIO_Init->Speed));
          config = GPIO_Init->Speed + GPIO_CR_CNF_AF_OUTPUT_PP;
          break;

        /* If we are configuring the pin in ALTERNATE FUNCTION open-drain mode */
        /* 特殊功能开漏输出配置 */
        case GPIO_MODE_AF_OD:
          /* Check the GPIO speed parameter */
          assert_param(IS_GPIO_SPEED(GPIO_Init->Speed));
          config = GPIO_Init->Speed + GPIO_CR_CNF_AF_OUTPUT_OD;
          break;

        /* If we are configuring the pin in INPUT (also applicable to EVENT and IT mode) */
        /* 普通输入、中断输入和事件输入 */
        case GPIO_MODE_INPUT:
        case GPIO_MODE_IT_RISING:
        case GPIO_MODE_IT_FALLING:
        case GPIO_MODE_IT_RISING_FALLING:
        case GPIO_MODE_EVT_RISING:
        case GPIO_MODE_EVT_FALLING:
        case GPIO_MODE_EVT_RISING_FALLING:
          /* Check the GPIO pull parameter */
          assert_param(IS_GPIO_PULL(GPIO_Init->Pull));
          if (GPIO_Init->Pull == GPIO_NOPULL)
          {
            config = GPIO_CR_MODE_INPUT + GPIO_CR_CNF_INPUT_FLOATING;
          }
          else if (GPIO_Init->Pull == GPIO_PULLUP)
          {
            config = GPIO_CR_MODE_INPUT + GPIO_CR_CNF_INPUT_PU_PD;

            /* Set the corresponding ODR bit */
            GPIOx->BSRR = ioposition;
          }
          else /* GPIO_PULLDOWN */
          {
            config = GPIO_CR_MODE_INPUT + GPIO_CR_CNF_INPUT_PU_PD;

            /* Reset the corresponding ODR bit */
            GPIOx->BRR = ioposition;
          }
          break;

        /* If we are configuring the pin in INPUT analog mode */
        case GPIO_MODE_ANALOG:
          config = GPIO_CR_MODE_INPUT + GPIO_CR_CNF_ANALOG;
          break;

        /* Parameters are checked with assert_param */
        default:
          break;
      }

      /* Check if the current bit belongs to first half or last half of the pin count number
       in order to address CRH or CRL register*/
      configregister = (iocurrent < GPIO_PIN_8) ? &GPIOx->CRL     : &GPIOx->CRH;
      registeroffset = (iocurrent < GPIO_PIN_8) ? (position << 2u) : ((position - 8u) << 2u);

      /* Apply the new configuration of the pin to the register */
      MODIFY_REG((*configregister), ((GPIO_CRL_MODE0 | GPIO_CRL_CNF0) << registeroffset), (config << registeroffset));

      /*--------------------- EXTI Mode Configuration ------------------------*/
      /* 外部中断配置 */
      /* Configure the External Interrupt or event for the current IO */
      if ((GPIO_Init->Mode & EXTI_MODE) == EXTI_MODE)
      {
        /* Enable AFIO Clock */
        __HAL_RCC_AFIO_CLK_ENABLE();
        /* EXTICR 16位 总共四个，每个EXITCR分别控制四个中断，总共 4 * 4 = 16个中断
           position >> 2  ==>  position / 4 ，把 0-15 转换为 0-4 即找到对应的寄存器
        */
        temp = AFIO->EXTICR[position >> 2u]; 
        /* position & 3  ==>  position % 4 ，即找到在当前EXITCR寄存器中，position对应的是哪一个中断。
           乘4是因为左移的单位是 “中断数”，一个中断对应4位，我要左移 n个中断 意味着要左移 n * 4位。
        */
        CLEAR_BIT(temp, (0x0Fu) << (4u * (position & 0x03u)));
        SET_BIT(temp, (GPIO_GET_INDEX(GPIOx)) << (4u * (position & 0x03u)));
        AFIO->EXTICR[position >> 2u] = temp;


        /* Enable or disable the rising trigger */
        /* 设置上升沿触发 */
        if ((GPIO_Init->Mode & RISING_EDGE) == RISING_EDGE)
        {
          SET_BIT(EXTI->RTSR, iocurrent);
        }
        else
        {
          CLEAR_BIT(EXTI->RTSR, iocurrent);
        }

        /* Enable or disable the falling trigger */
        /* 设置下降沿触发 */
        if ((GPIO_Init->Mode & FALLING_EDGE) == FALLING_EDGE)
        {
          SET_BIT(EXTI->FTSR, iocurrent);
        }
        else
        {
          CLEAR_BIT(EXTI->FTSR, iocurrent);
        }

        /* Configure the event mask */
        if ((GPIO_Init->Mode & GPIO_MODE_EVT) == GPIO_MODE_EVT)
        {
          SET_BIT(EXTI->EMR, iocurrent);
        }
        else
        {
          CLEAR_BIT(EXTI->EMR, iocurrent);
        }

        /* Configure the interrupt mask */
         /* 设置中断屏蔽 为0时不允许对应中断 */
        if ((GPIO_Init->Mode & GPIO_MODE_IT) == GPIO_MODE_IT)
        {
          SET_BIT(EXTI->IMR, iocurrent);
        }
        else
        {
          CLEAR_BIT(EXTI->IMR, iocurrent);
        }
      }
    }
  // 配置下一位
	position++;
  }
}

附：各寄存器的结构

EXTICR 外部中断控制寄存器

总共有四个，结构都类似
EXTICR

EXTI_IMR 外部中断屏蔽寄存器

EXTICR

Author: LouisZ
Link: http://notes.louisz.top/2024/07/stm32-hal-gpio-init-comment/
Copyright Notice: All articles in this blog are licensed under CC BY-NC-SA 4.0 unless stating additionally.
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