STM32学习之路-外部中断(2)

OK,继续上篇的内容. 配置好外部中断源以后, 就得使能外部中断线了.

为了方便看再借下这个图：



对外部中断的使能其实就是配置上面这些寄存器.即使能哪EXIT线,选择上面模式,是中断还是事件,选择下降沿还是上升沿.

具体怎么写寄存器这就不研究了, = = 太麻烦了.. 直接用STM32的库就行了,来看看它的代码吧

这是EXTI结构体的初始化函数,

void EXTI_StructInit(EXTI_InitTypeDef* EXTI_InitStruct)
{
EXTI_InitStruct->EXTI_Line = EXTI_LINENONE;
EXTI_InitStruct->EXTI_Mode = EXTI_Mode_Interrupt; //中断模式
EXTI_InitStruct->EXTI_Trigger = EXTI_Trigger_Falling; //下降沿触发
EXTI_InitStruct->EXTI_LineCmd = DISABLE;
}#define EXTI_LINENONE    ((uint32_t)0x00000)  /* No interrupt selected */
从这里我们就可以知道我们要给它的结构体弄哪些东西了,例子：

EXTI_InitStructure.EXTI_Line = EXTI_Line2;
EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;
EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Falling;
EXTI_InitStructure.EXTI_LineCmd = ENABLE;
EXTI_Init(&EXTI_InitStructure);

看看EXTI_Init（）
void EXTI_Init(EXTI_InitTypeDef* EXTI_InitStruct)
{
uint32_t tmp = 0;

/* Check the parameters */
assert_param(IS_EXTI_MODE(EXTI_InitStruct->EXTI_Mode));
assert_param(IS_EXTI_TRIGGER(EXTI_InitStruct->EXTI_Trigger));
assert_param(IS_EXTI_LINE(EXTI_InitStruct->EXTI_Line));
assert_param(IS_FUNCTIONAL_STATE(EXTI_InitStruct->EXTI_LineCmd));

tmp = (uint32_t)EXTI_BASE;

if (EXTI_InitStruct->EXTI_LineCmd != DISABLE)
{
/* Clear EXTI line configuration */
EXTI->IMR &= ~EXTI_InitStruct->EXTI_Line;
EXTI->EMR &= ~EXTI_InitStruct->EXTI_Line;

tmp += EXTI_InitStruct->EXTI_Mode;

*(__IO uint32_t *) tmp |= EXTI_InitStruct->EXTI_Line;

/* Clear Rising Falling edge configuration */
EXTI->RTSR &= ~EXTI_InitStruct->EXTI_Line;
EXTI->FTSR &= ~EXTI_InitStruct->EXTI_Line;

/* Select the trigger for the selected external interrupts */
if (EXTI_InitStruct->EXTI_Trigger == EXTI_Trigger_Rising_Falling)
{
/* Rising Falling edge */
EXTI->RTSR |= EXTI_InitStruct->EXTI_Line;
EXTI->FTSR |= EXTI_InitStruct->EXTI_Line;
}
else
{
tmp = (uint32_t)EXTI_BASE;
tmp += EXTI_InitStruct->EXTI_Trigger;

*(__IO uint32_t *) tmp |= EXTI_InitStruct->EXTI_Line;
}
}
else
{
tmp += EXTI_InitStruct->EXTI_Mode;

/* Disable the selected external lines */
*(__IO uint32_t *) tmp &= ~EXTI_InitStruct->EXTI_Line;
}
}OK....