GD32如何配置中断优先级分组以及中断优先级

使用GD32 MCU的过程中，大家可能会有以下疑问：中断优先级如何配置和使用？

本文将会为大家解析中断优先级分组以及中断优先级的配置使用：

中断优先级分组配置

一个GD32 MCU系统需要大家明确系统中使用的中断优先级分组，避免中断优先级配置越界导致一些不符合预期的中断现象。

中断优先级分组可采用以下函数接口，其中有4个bit可用于中断优先级分组，如果全用于抢占优先级，则可以配置0-15的优先级，如果2位用于抢占，2位用于次优先级，则抢占优先级可以配置0-3，此优先级可以配置0-3。

C
/*!
    \brief      set the priority group
    \param[in]  nvic_prigroup: the NVIC priority group
      \arg        NVIC_PRIGROUP_PRE0_SUB4:0 bits for pre-emption priority 4 bits for subpriority
      \arg        NVIC_PRIGROUP_PRE1_SUB3:1 bits for pre-emption priority 3 bits for subpriority
      \arg        NVIC_PRIGROUP_PRE2_SUB2:2 bits for pre-emption priority 2 bits for subpriority
      \arg        NVIC_PRIGROUP_PRE3_SUB1:3 bits for pre-emption priority 1 bits for subpriority
      \arg        NVIC_PRIGROUP_PRE4_SUB0:4 bits for pre-emption priority 0 bits for subpriority
    \param[out] none
    \retval     none
*/
void nvic_priority_group_set(uint32_t nvic_prigroup)
{
    /* set the priority group value */
    SCB->AIRCR = NVIC_AIRCR_VECTKEY_MASK | nvic_prigroup;
}

注意：如果中断优先级配置为2位抢占和2位此优先级的话，抢占优先级配置为4（二进制为100b），优先级配置越界，实际配置进去的优先级为0，最高优先级，因而明确中断优先级分组非常重要。

中断优先级配置

中断优先级配置采用以下函数。

C
/*!
    \brief      enable NVIC request
    \param[in]  nvic_irq: the NVIC interrupt request, detailed in IRQn_Type
    \param[in]  nvic_irq_pre_priority: the pre-emption priority needed to set
    \param[in]  nvic_irq_sub_priority: the subpriority needed to set
    \param[out] none
    \retval     none
*/
void nvic_irq_enable(uint8_t nvic_irq, uint8_t nvic_irq_pre_priority, 
                     uint8_t nvic_irq_sub_priority)
{
    uint32_t temp_priority = 0x00U, temp_pre = 0x00U, temp_sub = 0x00U;
    /* use the priority group value to get the temp_pre and the temp_sub */
    if(((SCB->AIRCR) & (uint32_t)0x700U)==NVIC_PRIGROUP_PRE0_SUB4){
        temp_pre=0U;
        temp_sub=0x4U;
    }else if(((SCB->AIRCR) & (uint32_t)0x700U)==NVIC_PRIGROUP_PRE1_SUB3){
        temp_pre=1U;
        temp_sub=0x3U;
    }else if(((SCB->AIRCR) & (uint32_t)0x700U)==NVIC_PRIGROUP_PRE2_SUB2){
        temp_pre=2U;
        temp_sub=0x2U;
    }else if(((SCB->AIRCR) & (uint32_t)0x700U)==NVIC_PRIGROUP_PRE3_SUB1){
        temp_pre=3U;
        temp_sub=0x1U;
    }else if(((SCB->AIRCR) & (uint32_t)0x700U)==NVIC_PRIGROUP_PRE4_SUB0){
        temp_pre=4U;
        temp_sub=0x0U;
    }else{
        nvic_priority_group_set(NVIC_PRIGROUP_PRE2_SUB2);
        temp_pre=2U;
        temp_sub=0x2U;
    }
    /* get the temp_priority to fill the NVIC->IP register */
    temp_priority = (uint32_t)nvic_irq_pre_priority << (0x4U - temp_pre);
    temp_priority |= nvic_irq_sub_priority &(0x0FU >> (0x4U - temp_sub));
    temp_priority = temp_priority << 0x04U;
    NVIC->IP[nvic_irq] = (uint8_t)temp_priority;
    /* enable the selected IRQ */
    NVIC->ISER[nvic_irq >> 0x05U] = (uint32_t)0x01U << (nvic_irq & (uint8_t)0x1FU);
}

nvic_irq为中断号，中断号可以通过gd32f30x.h获取，如下图所示，nvic_irq_pre_priority为抢占优先级配置，nvic_irq_sub_priority为此优先级配置，注意优先级配置要根据优先级分组进行配置，不要越界哦。