转自:https://blog.csdn.net/xukai871105/article/details/53516857
前言
本文将说明在FreeRTOS嵌入式操作系统中,如何设置STM32 Cortex M3和M4系列MCU的中断优先级。
总结
- 【1】STM32L1系列,STM32F1系列,STM32F4系列,设置NVIC时需要使用NVIC_PriorityGroup_4。
- 【2】抢占优先级的要比“MAX”更大,而比“LOWEST”更小。例如 configLIBRARY_MAX_SYSCALL_INTERRUPT_PRIORITY=5 , configLIBRARY_LOWEST_INTERRUPT_PRIORITY=15 ,那么NVIC抢占优先级设置的具体值应该比MAX=5更大(包括等于),比LOWEST=15更小(包括等于),也就是说5,6,7,8,9,10,11,12,13,14,15肯定是合法值。
- 【3】FreeRTOS中,数值越大优先级越高,这种优先级可以成为逻辑优先级。Cortex M3/M4中断中,数值越大优先级越低,这种优先级成为中断优先级。两者相反,所以才会出现比"MAX"更大而比“LOWEST”更小的情况。
示意代码
【FreeRTOSConfig.h】
/* Use the system definition, if there is one */ #ifdef __NVIC_PRIO_BITS #define configPRIO_BITS __NVIC_PRIO_BITS #else #define configPRIO_BITS 4 /* 15 priority levels */ #endif #define configLIBRARY_LOWEST_INTERRUPT_PRIORITY 15 #define configLIBRARY_MAX_SYSCALL_INTERRUPT_PRIORITY 5 /* The lowest priority. */ #define configKERNEL_INTERRUPT_PRIORITY ( configLIBRARY_LOWEST_INTERRUPT_PRIORITY << (8 - configPRIO_BITS) ) /* Priority 5, or 95 as only the top four bits are implemented. */ /* !!!! configMAX_SYSCALL_INTERRUPT_PRIORITY must not be set to zero !!!! See http://www.FreeRTOS.org/RTOS-Cortex-M3-M4.html. */ #define configMAX_SYSCALL_INTERRUPT_PRIORITY ( configLIBRARY_MAX_SYSCALL_INTERRUPT_PRIORITY << (8 - configPRIO_BITS) )
【NVIC设置】
【示例A】
NVIC_InitTypeDef NVIC_InitStructure; NVIC_PriorityGroupConfig(NVIC_PriorityGroup_4); NVIC_InitStructure.NVIC_IRQChannel = XXXX_IRQn; NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = configLIBRARY_LOWEST_INTERRUPT_PRIORITY; NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; NVIC_Init(&NVIC_InitStructure);
【示例A】
NVIC_InitTypeDef NVIC_InitStructure; NVIC_PriorityGroupConfig(NVIC_PriorityGroup_4); NVIC_InitStructure.NVIC_IRQChannel = XXXX_IRQn; NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = configLIBRARY_LOWEST_INTERRUPT_PRIORITY-1; NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; NVIC_Init(&NVIC_InitStructure);
原文地址:https://www.cnblogs.com/aaronLinux/p/11108140.html
时间: 2024-10-12 12:55:16