void delay_init()
{
SysTick_CLKSourceConfig(SysTick_CLKSource_HCLK_Div8);
fac_us=SystemCoreClock/8000000;
fac_ms=(u16)fac_us*1000;
}
void BSP_Delay_us(u32 nus)
{
u32 temp;
SysTick->LOAD=nus*fac_us;
SysTick->VAL=0x00;
SysTick->CTRL|=SysTick_CTRL_ENABLE_Msk ;
do
{
temp=SysTick->CTRL;
}while((temp&0x01)&&!(temp&(1<<16)));
SysTick->CTRL&=~SysTick_CTRL_ENABLE_Msk;
SysTick->VAL =0X00;
}
主频为72M，延时us函数。
问题：这样写的中断优先级是多少，没有设置SysTick_Handler,并且没有在中断服务函数里中任何事?
假设定义里一个定时器4，优先级如下，是否会抢断systick中断。即谁的优先级高
void TIM4_NVIC_Configuration(void)
{
NVIC_InitTypeDef NVIC_InitStructure;
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_0);
NVIC_InitStructure.NVIC_IRQChannel = TIM4_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
}
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