本文將會(huì)為大家解析中斷優(yōu)先級(jí)分組以及中斷優(yōu)先級(jí)的配置使用：
中斷優(yōu)先級(jí)分組配置
一個(gè)GD32 MCU系統(tǒng)需要大家明確系統(tǒng)中使用的中斷優(yōu)先級(jí)分組，避免中斷優(yōu)先級(jí)配置越界導(dǎo)致一些不符合預(yù)期的中斷現(xiàn)象。
中斷優(yōu)先級(jí)分組可采用以下函數(shù)接口，其中有4個(gè)bit可用于中斷優(yōu)先級(jí)分組，如果全用于搶占優(yōu)先級(jí)，則可以配置0-15的優(yōu)先級(jí)，如果2位用于搶占，2位用于次優(yōu)先級(jí)，則搶占優(yōu)先級(jí)可以配置0-3，此優(yōu)先級(jí)可以配置0-3。
/*!
\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：如果中斷優(yōu)先級(jí)配置為2位搶占和2位此優(yōu)先級(jí)的話，搶占優(yōu)先級(jí)配置為4（二進(jìn)制為100b），優(yōu)先級(jí)配置越界，實(shí)際配置進(jìn)去的優(yōu)先級(jí)為0，最高優(yōu)先級(jí)，因而明確中斷優(yōu)先級(jí)分組非常重要。
中斷優(yōu)先級(jí)配置
中斷優(yōu)先級(jí)配置采用以下函數(shù)。
/*!
\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為中斷號(hào)，中斷號(hào)可以通過gd32f30x.h獲取，如下圖所示，nvic_irq_pre_priority為搶占優(yōu)先級(jí)配置，nvic_irq_sub_priority為此優(yōu)先級(jí)配置，注意優(yōu)先級(jí)配置要根據(jù)優(yōu)先級(jí)分組進(jìn)行配置，不要越界哦。
