NVIC_SetPriorityGrouping 与NVIC_PriorityGroupConfig函数的区别

只看该作者 · 2013-9-10 17:54

本帖最后由 lanseshuijing 于 2013-9-10 18:04 编辑

所用单片机 arm m4
其中一个函数NVIC_SetPriorityGrouping 中断优先级分组分为8组此函数在core_cm4.h文件中代码如下
Set Priority Grouping

  This function sets the priority grouping field using the required unlock sequence.
  The parameter PriorityGroup is assigned to the field SCB->AIRCR [10:8] PRIGROUP field.
  Only values from 0..7 are used.
  In case of a conflict between priority grouping and available
  priority bits (__NVIC_PRIO_BITS) the smallest possible priority group is set.

\param [in]    PriorityGroup  Priority grouping field
*/
static __INLINE void NVIC_SetPriorityGrouping(uint32_t PriorityGroup)
{
  uint32_t reg_value;
  uint32_t PriorityGroupTmp = (PriorityGroup & (uint32_t)0x07);            /* only values 0..7 are used       */

  reg_value  =  SCB->AIRCR;                                                  /* read old register configuration */
  reg_value &= ~(SCB_AIRCR_VECTKEY_Msk | SCB_AIRCR_PRIGROUP_Msk);          /* clear bits to change             */
  reg_value  =  (reg_value                               |
            ((uint32_t)0x5FA << SCB_AIRCR_VECTKEY_Pos) |
            (PriorityGroupTmp << 8));                                  /* Insert write key and priorty group */
  SCB->AIRCR =  reg_value;
}
另外一个函数NVIC_PriorityGroupConfig分组分成5组在 misc.c文件中
代码如下
@brief  Configures the priority grouping: pre-emption priority and subpriority.
  * @param  NVIC_PriorityGroup: specifies the priority grouping bits length.
  * This parameter can be one of the following values:
  *    @arg NVIC_PriorityGroup_0: 0 bits for pre-emption priority
  *                               4 bits for subpriority
  *    @arg NVIC_PriorityGroup_1: 1 bits for pre-emption priority
  *                               3 bits for subpriority
  *    @arg NVIC_PriorityGroup_2: 2 bits for pre-emption priority
  *                               2 bits for subpriority
  *    @arg NVIC_PriorityGroup_3: 3 bits for pre-emption priority
  *                               1 bits for subpriority
  *    @arg NVIC_PriorityGroup_4: 4 bits for pre-emption priority
  *                               0 bits for subpriority
  * @NOTE When the NVIC_PriorityGroup_0 is selected, IRQ pre-emption is no more possible.
  *       The pending IRQ priority will be managed only by the subpriority.
  * @retval None
  */
void NVIC_PriorityGroupConfig(uint32_t NVIC_PriorityGroup)
{
  /* Check the parameters */
  assert_param(IS_NVIC_PRIORITY_GROUP(NVIC_PriorityGroup));

/* Set the PRIGROUP[10:8] bits according to NVIC_PriorityGroup value */
  SCB->AIRCR = AIRCR_VECTKEY_MASK | NVIC_PriorityGroup;
}
为什么有这么两组分组方式？同样都是对SCB->AIRCR 操作啊？谁能帮忙解释一下

只看该作者 · 2013-9-10 18:36

不是很了解帮你顶一个呼唤一下香主吧

只看该作者 · 2013-12-4 10:34

In case of a conflict between priority grouping and available priority bits (__NVIC_PRIO_BITS) the smallest possible priority group is set.

我觉得这句话说明了两个函数的区别，NVIC_SetPriorityGrouping()的参数可以是0..7，但是函数会根据芯片本身的“可用优先级位”来进行设置，例如只支持0..4个分组，如果设置为5.6.7的话，就会设置成0组。不知道我的理解对不对。。