GPIO相关寄存器

1. STM32的GPIO相关寄存器

GPIOx_BRR
GPIOx_BSRR
GPIOx_CRH
GPIOx_CRL
GPIOx_IDR
GPIOx_LCKR
GPIOx_ODR

1.1 输入输出方向的设置

涉及到两个32位的配置寄存器（Configuration Register），CRH，CRL。

GPIOB->CRL &= 0x0FFFFFFF;GPIOB->CRL|=0x30000000;//3<<28;//配置PB7为输出
GPIOB->CRL &= 0x0FFFFFFF;GPIOB->CRL|=0x80000000;//8<<28;//配置PB7为输入

GPIOB->CRH &= 0xFFFFFFF0;GPIOB->CRH|=3<<0; //配置PB8为输出
GPIOB->CRH &= 0xFFFFFFF0;GPIOB->CRH|=8<<0; //配置PB8为输入

    /* 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));

1.2 读取引脚高低电平值

涉及到两个32位数据寄存器（Data Register），IDR，ODR。

#define I2C_SDA_READ()  (GPIO_PORT_I2C->IDR & I2C_SDA_PIN)						// 读取SDA电平

void HAL_GPIO_TogglePin(GPIO_TypeDef *GPIOx, uint16_t GPIO_Pin)
{
  uint32_t odr = GPIOx->ODR;
  /* Set selected pins that were at low level, and reset ones that were high */
  GPIOx->BSRR = ((odr & GPIO_Pin) << GPIO_NUMBER) | (~odr & GPIO_Pin);
}

GPIO_PinState HAL_GPIO_ReadPin(GPIO_TypeDef *GPIOx, uint16_t GPIO_Pin)
{
  GPIO_PinState bitstatus;
  if ((GPIOx->IDR & GPIO_Pin) != (uint32_t)GPIO_PIN_RESET)
  {
    bitstatus = GPIO_PIN_SET;
  }
  else
  {
    bitstatus = GPIO_PIN_RESET;
  }
  return bitstatus;
}

1.3 置位和复位的设置

涉及到一个32位置位/复位寄存器（Bit Set/Reset Register），BSRR；一个32位复位寄存器（Bit Reset Register），BRR。

GPIOB->BSRR = GPIO_PIN_7;						// PB7 Set
GPIOB->BSRR = (uint32_t)GPIO_PIN_7<< 16U  		// PB7 Reset
GPIOB->BRR  = GPIO_PIN_7;                      // PB7 Reset

void HAL_GPIO_WritePin(GPIO_TypeDef *GPIOx, uint16_t GPIO_Pin, GPIO_PinState PinState)
{
  if (PinState != GPIO_PIN_RESET)
  {
    GPIOx->BSRR = GPIO_Pin;
  }
  else
  {
    GPIOx->BSRR = (uint32_t)GPIO_Pin << 16u;
  }
}

1.4 锁定IO

TTL施密特触发器有开/关,相应的一个32位锁定寄存器（GPIOx_LCKR）可以控制开关让输入数据寄存器保持当前的状态，达到一个锁定的效果，在某些应用场合很有效果。
要使用该寄存器，需要先激活“锁定”功能。

HAL_StatusTypeDef HAL_GPIO_LockPin(GPIO_TypeDef *GPIOx, uint16_t GPIO_Pin)
{
  __IO uint32_t tmp = GPIO_LCKR_LCKK;
  /* Apply lock key write sequence */
  SET_BIT(tmp, GPIO_Pin);
  /* Set LCKx bit(s): LCKK='1' + LCK[15-0] */
  GPIOx->LCKR = tmp;
  /* Reset LCKx bit(s): LCKK='0' + LCK[15-0] */
  GPIOx->LCKR = GPIO_Pin;
  /* Set LCKx bit(s): LCKK='1' + LCK[15-0] */
  GPIOx->LCKR = tmp;
  /* Read LCKK register. This read is mandatory to complete key lock sequence */
  tmp = GPIOx->LCKR;

  /* read again in order to confirm lock is active */
  if ((uint32_t)(GPIOx->LCKR & GPIO_LCKR_LCKK))
  {
    return HAL_OK;
  }
  else
  {
    return HAL_ERROR;
  }
}

2. HHD

未完待续。