STM32设置SysTick中断抢占优先级.doc

STM32设置SysTick中断抢占优先级最近使用STM32时希望将systick的中断优先级降低，但是CMSIS里给出的例子都是类似 NVIC_InitStructure.NVIC_IRQChannel = TIM1_UP_IRQn; NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0; NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; NVIC_Init(&NVIC_InitStructure);还是没有配置systick。后来阅读CM3的技术参考手册，讲解了NVIC的配置。中断分为内核中断和芯片的中断，配置的寄存器位置不同。芯片的中断配置在NVIC的IP内，内核的中断配置在SCB内。可以直接调用core_cm3.h里的函数static _INLINE void NVIC_SetPriority(IRQn_Type IRQn, uint32_t priority) if(IRQn SHP(uint32_t)(IRQn) & 0xF)-4 = (priority IP(uint32_t)(IRQn) = (priority AIRCR = AIRCR_VECTKEY_MASK | NVIC_PriorityGroup;或static _INLINE void NVIC_SetPriorityGrouping(uint32_t PriorityGroup) uint32_t reg_value; uint32_t PriorityGroupTmp = (PriorityGroup & 0x07); /* only values 0.7 are used */ reg_value = SCB-AIRCR; /* read old register configuration */ reg_value &= (SCB_AIRCR_VECTKEY_Msk | SCB_AIRCR_PRIGROUP_Msk); /* clear bits to change */ reg_value = (reg_value | (0x5FA SCB_AIRCR_VECTKEY_Pos) | (PriorityGroupTmp AIRCR = reg_value;参数范围为07，具体如下随后配置各个中断的优先级，对于外设的中断可以使用固件库的程序，比较直观。如最前面所给出的例子，但是根据其实现，是不能够用来配置内核中断的，例如 NVIC_InitStructure.NVIC_IRQChannel = SysTick_IRQn; NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0; NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;NVIC_Init(&NVIC_InitStructure);这是错误的，因为内部使用IRQn寻址，而SysTick_IRQn为-1. 所以对于Sysick使用core_cm3.h的函数NVIC_SetPriority(SysTick_IRQn, 4);这时不能显式的看出抢先式优先级与子优先级，写入的优先级需要根据优先级组的配置来选择。NVIC_SetPriority(SysTick_IRQn, n);n=0x000x03 设置Systick为抢占优先级0n=0x040x07 设置Systick为抢占优先级1n=0x080x0B 设置Systick为抢占优先级2n=0x0C0x0F 设置Systick为抢占优先级3 NVIC_SetPriority函数指定中断优先级的寄存器位（STM32只用4位来表示优先级）的数据，例如中断优先