库函数位屏蔽

1532512486 · 发表于 2016-6-2 23:03:44

本帖最后由 1532512486 于 2016-6-2 23:07 编辑

GPIO_Initstructure.GPIO_Pin=GPIO_Pin_0;会不会影响之前GPIO_Initstructure.GPIO_Pin的值，库函数开发都不考虑位屏蔽吗？？
是不是应该写成 GPIO_Initstructure.GPIO_Pin|=GPIO_Pin_0？？？

zmingwang · 发表于 2016-6-2 23:03:45

这位同学,你都有这种疑问了,为什么不跟到GPIO_Init()这个函数中去看一眼呢
[mw_shl_code=c,true]void GPIO_Init(GPIO_TypeDef* GPIOx, GPIO_InitTypeDef* GPIO_InitStruct)
{
  uint32_t pinpos = 0x00, pos = 0x00 , currentpin = 0x00;

  /* Check the parameters */
  assert_param(IS_GPIO_ALL_PERIPH(GPIOx));
  assert_param(IS_GPIO_PIN(GPIO_InitStruct->GPIO_Pin));
  assert_param(IS_GPIO_MODE(GPIO_InitStruct->GPIO_Mode));
  assert_param(IS_GPIO_PUPD(GPIO_InitStruct->GPIO_PuPd));

  /* -------------------------Configure the port pins---------------- */
  /*-- GPIO Mode Configuration --*/
  for (pinpos = 0x00; pinpos < 0x10; pinpos++)
  {
pos = ((uint32_t)0x01) << pinpos;
/* Get the port pins position */
currentpin = (GPIO_InitStruct->GPIO_Pin) & pos;

if (currentpin == pos)
{
   GPIOx->MODER  &= ~(GPIO_MODER_MODER0 << (pinpos * 2));
   GPIOx->MODER |= (((uint32_t)GPIO_InitStruct->GPIO_Mode) << (pinpos * 2));

   if ((GPIO_InitStruct->GPIO_Mode == GPIO_Mode_OUT) || (GPIO_InitStruct->GPIO_Mode == GPIO_Mode_AF))
   {
      /* Check Speed mode parameters */
      assert_param(IS_GPIO_SPEED(GPIO_InitStruct->GPIO_Speed));

      /* Speed mode configuration */
      GPIOx->OSPEEDR &= ~(GPIO_OSPEEDER_OSPEEDR0 << (pinpos * 2));
      GPIOx->OSPEEDR |= ((uint32_t)(GPIO_InitStruct->GPIO_Speed) << (pinpos * 2));

      /* Check Output mode parameters */
      assert_param(IS_GPIO_OTYPE(GPIO_InitStruct->GPIO_OType));

      /* Output mode configuration*/
      GPIOx->OTYPER  &= ~((GPIO_OTYPER_OT_0) << ((uint16_t)pinpos)) ;
      GPIOx->OTYPER |= (uint16_t)(((uint16_t)GPIO_InitStruct->GPIO_OType) << ((uint16_t)pinpos));
   }

   /* Pull-up Pull down resistor configuration*/
   GPIOx->PUPDR &= ~(GPIO_PUPDR_PUPDR0 << ((uint16_t)pinpos * 2));
   GPIOx->PUPDR |= (((uint32_t)GPIO_InitStruct->GPIO_PuPd) << (pinpos * 2));
}
  }
}
[/mw_shl_code]
注意看第13行有个运行16次的for循环,增量是pinpos,17行取了当前pin的掩码,19行判断是不是配置了当前pin,只有配置了的pin才进行功能设置.
也就是说,GPIO_Init这个函数,只会初始化你在GPIO_Pin中配置了的引脚,不会影响其他引脚.