在学习 At32 的过程中遇到了nvic优先级组，在此做个记录方便以后查阅。at32的固件库中 NVIC 相关的 API 在 at32f413_misc.c 文件中。

nvic_priority_group_type

nvic_priority_group_type 枚举类型，定义了5中分组类型，定义如下：

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/**
  * @brief nvic interrupt priority group
  */
typedef enum
{
  NVIC_PRIORITY_GROUP_0                  = ((uint32_t)0x7), /*!< 0 bits for preemption priority, 4 bits for subpriority */
  NVIC_PRIORITY_GROUP_1                  = ((uint32_t)0x6), /*!< 1 bits for preemption priority, 3 bits for subpriority */
  NVIC_PRIORITY_GROUP_2                  = ((uint32_t)0x5), /*!< 2 bits for preemption priority, 2 bits for subpriority */
  NVIC_PRIORITY_GROUP_3                  = ((uint32_t)0x4), /*!< 3 bits for preemption priority, 1 bits for subpriority */
  NVIC_PRIORITY_GROUP_4                  = ((uint32_t)0x3)  /*!< 4 bits for preemption priority, 0 bits for subpriority */
} nvic_priority_group_type;

配置优先级分组

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// 配置 NVIC 分组为 4 位抢占优先级，0位子优先级。
nvic_priority_group_config(NVIC_PRIORITY_GROUP_4);