第一章 FreeRTOS移植——STM32F4xx

FreeRTOS版本 V8.2.3

1.1 移植所需文件(keil)

1)与FreeRTOS内核相关list.c queue.c tasks.c,文件位FreeRTOS\Source
2)与内存分配相关heap_1.c,heap_2.c,heap_3.c,heap_4.c，STM32选择heap_2.c。文件位于FreeRTOS\Source\portable\MemMang
3)与移植相关port.c,portmacro.h。这些代码不但和编译器有关还和平台（MCU）有关。FreeRTOS先以编译器为大类，然后再以平台（MCU）为小类。在这里选择Keil编译器，平台为ARM_CM4F(IAR中有portasm.s,keil无)该文件位于FreeRTOS\Source\portable\RVDS\ARM_CM4F。
4)除了上述内容之外，还包括FreeRTOS内核相关的头文件。该文件FreeRTOS\Source\include

1.2 FreeRTOS代码修改

无
IAR的话要修改对应处理器的启动文件中的SVC_Handle,PendSV_Handle和SysTick_Handle为vPortSVCHandler，xPortPendSVHandler和xPortSysTickHandler即将这些中断交给FreeRTOS管理。
keil中在FreeRTOSConfig.h中以#define vPortSVCHandler SVC_Handler的方式实现。

1.3 配置

#define configUSE_IDLE_HOOK             0//没有钩子函数
#define configUSE_TICK_HOOK             0//没有钩子函数
#define configCPU_CLOCK_HZ              ( ( unsigned long )168000000 )//处理器频率
#define configTICK_RATE_HZ              ( ( TickType_t ) 100 )
#define configMAX_PRIORITIES            ( 5 )
#define configMINIMAL_STACK_SIZE        ( ( unsigned short ) 130 )//idle任务用的，不改
#define configTOTAL_HEAP_SIZE           ( ( size_t ) ( 75 * 1024 ) )
#define configMAX_TASK_NAME_LEN         ( 10 )
#define configUSE_TRACE_FACILITY        0//开启TRACE功能后，RAM占用量会增大许多
#define configUSE_16_BIT_TICKS          0
#define configIDLE_SHOULD_YIELD         1
#define configUSE_MUTEXES               1
#define configQUEUE_REGISTRY_SIZE       8
#define configCHECK_FOR_STACK_OVERFLOW  0//堆栈溢出检查
#define configUSE_RECURSIVE_MUTEXES     1
#define configUSE_MALLOC_FAILED_HOOK    0
#define configUSE_APPLICATION_TASK_TAG  0
#define configUSE_COUNTING_SEMAPHORES   1
#define configGENERATE_RUN_TIME_STATS   0
/* Co-routine definitions. */
#define configUSE_CO_ROUTINES       0
#define configMAX_CO_ROUTINE_PRIORITIES ( 2 )

/* Software timer definitions. */
#define configUSE_TIMERS                1
#define configTIMER_TASK_PRIORITY       ( 2 )
#define configTIMER_QUEUE_LENGTH        10
#define configTIMER_TASK_STACK_DEPTH    ( configMINIMAL_STACK_SIZE * 2 )

/* Set the following definitions to 1 to include the API function, or zero
to exclude the API function. */
#define INCLUDE_vTaskPrioritySet        1
#define INCLUDE_uxTaskPriorityGet       1
#define INCLUDE_vTaskDelete             1
#define INCLUDE_vTaskCleanUpResources   1
#define INCLUDE_vTaskSuspend            1
#define INCLUDE_vTaskDelayUntil         1
#define INCLUDE_vTaskDelay              1

/* Cortex-M specific definitions. */
#ifdef __NVIC_PRIO_BITS
    /* __NVIC_PRIO_BITS will be specified when CMSIS is being used. */
    //STM32F4XX uses 4 Bits for the Priority Levels
        #define configPRIO_BITS             __NVIC_PRIO_BITS
#else
    #define configPRIO_BITS             4        /* 15 priority levels */
#endif

/* The lowest interrupt priority that can be used in a call to a "set priority"
function. */
#define configLIBRARY_LOWEST_INTERRUPT_PRIORITY         0xf

/* The highest interrupt priority that can be used by any interrupt service
routine that makes calls to interrupt safe FreeRTOS API functions.  DO NOT CALL
INTERRUPT SAFE FREERTOS API FUNCTIONS FROM ANY INTERRUPT THAT HAS A HIGHER
PRIORITY THAN THIS! (higher priorities are lower numeric values. */
/*中断优先级数大于(优先级低于)这个的,ISR不能调用interrupt  safe FreeRTOS API functions*/

#define configLIBRARY_MAX_SYSCALL_INTERRUPT_PRIORITY    5

/* Interrupt priorities used by the kernel port layer itself.  These are generic
to all Cortex-M ports, and do not rely on any particular library functions. */
#define configKERNEL_INTERRUPT_PRIORITY         ( configLIBRARY_LOWEST_INTERRUPT_PRIORITY << (8 - configPRIO_BITS) )
/* !!!! 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) )

/* Normal assert() semantics without relying on the provision of an assert.h
header file. */
#define configASSERT( x ) if( ( x ) == 0 ) { taskDISABLE_INTERRUPTS(); for( ;; ); } 

/* Definitions that map the FreeRTOS port interrupt handlers to their CMSIS
standard names. */
#define vPortSVCHandler SVC_Handler
#define xPortPendSVHandler PendSV_Handler
#define xPortSysTickHandler SysTick_Handler

#endif /* FREERTOS_CONFIG_H */

• #define configLIBRARY_MAX_SYSCALL_INTERRUPT_PRIORITY 5
• #define configMAX_SYSCALL_INTERRUPT_PRIORITY ( configLIBRARY_MAX_SYSCALL_INTERRUPT_PRIORITY << (8 - configPRIO_BITS) )
  优先级高于5(…3,4)的ISR不能调用interrupt safe FreeRTOS API functions，所以不会被FreeRTOS内核造成延时；不能被屏蔽(即使临界代码段)。
  优先级不高于5(5,6,7,8…)的ISR可以调用interrupt safe FreeRTOS API functions，可以屏蔽。
  移位,M4的优先级是MSB对齐的
• #define configLIBRARY_LOWEST_INTERRUPT_PRIORITY 0xf

• #define configKERNEL_INTERRUPT_PRIORITY ( configLIBRARY_LOWEST_INTERRUPT_PRIORITY << (8 - configPRIO_BITS) )
  configKERNEL_INTERRUPT_PRIORITY 应该设置成最低优先级(最低为0xf在M4中)
  设置有FreeRTOS内核使用的中断优先级，调用API函数也必须执行在这个中断上
  
  中断优先级配置例子(此图中0是最低优先级)

• 参考链接
  1、FreeRTOS配置说明–官网、上文翻译
  2、http://www.amobbs.com/thread-5476482-1-1.html
  3、http://bbs.armfly.com/read.php?tid=15063