本帖最后由 LSA9281 于 2020-7-30 23:08 编辑
HAL_NVIC_SetPriority(USART1_IRQn,3,3);
转到------>
void HAL_NVIC_SetPriority(IRQn_Type IRQn, uint32_t PreemptPriority, uint32_t SubPriority)
{
uint32_t prioritygroup;
/* Check the parameters */
assert_param(IS_NVIC_SUB_PRIORITY(SubPriority));
assert_param(IS_NVIC_PREEMPTION_PRIORITY(PreemptPriority));
prioritygroup = NVIC_GetPriorityGrouping();
NVIC_SetPriority(IRQn, NVIC_EncodePriority(prioritygroup, PreemptPriority, SubPriority));
}
其中调用__STATIC_INLINE uint32_t NVIC_EncodePriority (uint32_t PriorityGroup, uint32_t PreemptPriority, uint32_t SubPriority)
{
uint32_t PriorityGroupTmp = (PriorityGroup & (uint32_t)0x07UL); /* only values 0..7 are used */
uint32_t PreemptPriorityBits;
uint32_t SubPriorityBits;
PreemptPriorityBits = ((7UL - PriorityGroupTmp) > (uint32_t)(__NVIC_PRIO_BITS)) ? (uint32_t)(__NVIC_PRIO_BITS) : (uint32_t)(7UL - PriorityGroupTmp);
SubPriorityBits = ((PriorityGroupTmp + (uint32_t)(__NVIC_PRIO_BITS)) < (uint32_t)7UL) ? (uint32_t)0UL : (uint32_t)((PriorityGroupTmp - 7UL) + (uint32_t)(__NVIC_PRIO_BITS));
return (
((PreemptPriority & (uint32_t)((1UL << (PreemptPriorityBits)) - 1UL)) << SubPriorityBits) |
((SubPriority & (uint32_t)((1UL << (SubPriorityBits )) - 1UL)))
);
}
对 NVIC_EncodePriority (uint32_t PriorityGroup, uint32_t PreemptPriority, uint32_t SubPriority)函数解释如下
/**
\brief Encode Priority
\details Encodes the priority for an interrupt with the given priority group,
preemptive priority value, and subpriority value.
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 Used priority group.
\param [in] PreemptPriority Preemptive priority value (starting from 0).
\param [in] SubPriority Subpriority value (starting from 0).
\return Encoded priority. Value can be used in the function \ref NVIC_SetPriority().
*/
翻译为
brief编码优先级
\details用给定的优先级组对中断的优先级进行编码，
抢占优先级值和子优先级值。
如果优先级分组与可用
优先级位（优先级位）冲突（conflict） ，设置可能的最小优先级组。
\param[in]PriorityGroup已使用优先级组。
\param[in]PreemptPriority抢占优先级值（从0开始）。
\param[in]次优先级次优先级值（从0开始）。
\返回编码优先级。值可在函数\ref NVIC_SetPriority（）中使用。
*/
总结：先 prioritygroup = NVIC_GetPriorityGrouping();读取一个优先级分组，但如果后来发现优先级分组与可用
优先级位（优先级位）冲突，设置可能的最小优先级组。
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