FreeRTOS移植以及任务

FreeRTOS移植
1.在sys.h中需要把SYSTEM_SUPPORT_OS 改为 1，支持我们使用 FreeRTOS

//0,不支持 os
//1,支持 os
#define SYSTEM_SUPPORT_OS 1 //定义系统文件夹是否支持 OS

2.出现报错
…\SYSTEM\usart\usart.c(6): error: #5: cannot open source input file “includes.h”: No such file or directory
即需要修改usart.c 文件：

```c
默认是添加的 UCOS 中的 includes.h 头文件，修改以后如下：
//如果使用 os,则包括下面的头文件即可.
#if SYSTEM_SUPPORT_OS
#include "FreeRTOS.h" //os 使用
#endif
``

3.delay.c函数需要大改

FreeRTOS 的系统时钟是由滴答定时器提供的，需要根据FreeRTOS的系统节拍来初始化滴答定时器，delay_init()就是来完成这个功能的。
FreeRTOS 的系统时钟节拍由宏 configTICK_RATE_HZ 来设置，这个值我们可以自由设置，但是一旦设置好以后我们就要根据这个值来初始化滴答定时器，其实就是设置滴答定时器的中断周期。在基础例程中滴答定时器的时钟频率设置的是 AHB 的 1/8，这里为了兼容 FreeRTOS 将滴答定时器的时钟频率改为了 AHB，也就是 72MHz！这一点一定要注意！
完整delay.c文件

#include "delay.h"
// 	 
//如果需要使用OS,则包括下面的头文件即可.
#if SYSTEM_SUPPORT_OS
#include "FreeRTOS.h"					//ucos 使用	  
#include "task.h"  //文件在FreeRTOS\include
#endifstatic u8  fac_us=0;							//us延时倍乘数			   
static u16 fac_ms=0;							//ms延时倍乘数,在ucos下,代表每个节拍的ms数extern void xPortSysTickHandler(void);//systick中断服务函数,使用ucos时用到
void SysTick_Handler(void){if(xTaskGetSchedulerState()!=taskSCHEDULER_NOT_STARTED){xPortSysTickHandler();}}//初始化延迟函数
//SYSTICK的时钟固定为AHB时钟，基础例程里面SYSTICK时钟频率为AHB/8
//这里为了兼容FreeRTOS，所以将SYSTICK的时钟频率改为AHB的频率！
//SYSCLK:系统时钟频率
void delay_init()
{u32 reload;SysTick_CLKSourceConfig(SysTick_CLKSource_HCLK);//选择外部时钟  HCLKfac_us=SystemCoreClock/1000000;				//不论是否使用OS,fac_us都需要使用reload=SystemCoreClock/1000000;				//每秒钟的计数次数 单位为M  reload*=1000000/configTICK_RATE_HZ;			//根据configTICK_RATE_HZ设定溢出时间//reload为24位寄存器,最大值:16777216,在72M下,约合0.233s左右	fac_ms=1000/configTICK_RATE_HZ;				//代表OS可以延时的最少单位	   SysTick->CTRL|=SysTick_CTRL_TICKINT_Msk;   	//开启SYSTICK中断SysTick->LOAD=reload; 						//每1/configTICK_RATE_HZ秒中断一次	SysTick->CTRL|=SysTick_CTRL_ENABLE_Msk;   	//开启SYSTICK    
}//延时nus
//nus:要延时的us数.	
//nus:0~204522252(最大值即2^32/fac_us@fac_us=168)	    								   
void delay_us(u32 nus)
{		u32 ticks;u32 told,tnow,tcnt=0;u32 reload=SysTick->LOAD;				//LOAD的值	    	 ticks=nus*fac_us; 						//需要的节拍数 told=SysTick->VAL;        				//刚进入时的计数器值while(1){tnow=SysTick->VAL;	if(tnow!=told){	    if(tnow<told)tcnt+=told-tnow;	//这里注意一下SYSTICK是一个递减的计数器就可以了.else tcnt+=reload-tnow+told;	    told=tnow;if(tcnt>=ticks)break;			//时间超过/等于要延迟的时间,则退出.}  };										    
}  
//延时nms
//nms:要延时的ms数
//nms:0~65535
void delay_ms(u32 nms)
{	if(xTaskGetSchedulerState()!=taskSCHEDULER_NOT_STARTED)//系统已经运行{		if(nms>=fac_ms)						//延时的时间大于OS的最少时间周期 { vTaskDelay(nms/fac_ms);	 		//FreeRTOS延时}nms%=fac_ms;						//OS已经无法提供这么小的延时了,采用普通方式延时    }delay_us((u32)(nms*1000));				//普通方式延时
}## FreeRTOS任务//延时nms,不会引起任务调度
//nms:要延时的ms数
void delay_xms(u32 nms)
{u32 i;for(i=0;i<nms;i++) delay_us(1000);
}

任务句柄： * TaskHandle_t

struct tskTaskControlBlock; /* The old naming convention is used to prevent breaking kernel aware debuggers. */
typedef struct tskTaskControlBlock * TaskHandle_t;

最终要溯源到 tskTaskControlBlock， tskTaskControlBlock是一个任务句柄结构体，在tasks.c文件中

ypedef struct tskTaskControlBlock       /* The old naming convention is used to prevent breaking kernel aware debuggers. */
{volatile StackType_t * pxTopOfStack; /*< Points to the location of the last item placed on the tasks stack.  THIS MUST BE THE FIRST MEMBER OF THE TCB STRUCT. */#if ( portUSING_MPU_WRAPPERS == 1 )xMPU_SETTINGS xMPUSettings; /*< The MPU settings are defined as part of the port layer.  THIS MUST BE THE SECOND MEMBER OF THE TCB STRUCT. */#endifListItem_t xStateListItem;                  /*< The list that the state list item of a task is reference from denotes the state of that task (Ready, Blocked, Suspended ). */ListItem_t xEventListItem;                  /*< Used to reference a task from an event list. */UBaseType_t uxPriority;                     /*< The priority of the task.  0 is the lowest priority. */StackType_t * pxStack;                      /*< Points to the start of the stack. */char pcTaskName[ configMAX_TASK_NAME_LEN ]; /*< Descriptive name given to the task when created.  Facilitates debugging only. */ /*lint !e971 Unqualified char types are allowed for strings and single characters only. */#if ( ( portSTACK_GROWTH > 0 ) || ( configRECORD_STACK_HIGH_ADDRESS == 1 ) )StackType_t * pxEndOfStack; /*< Points to the highest valid address for the stack. */#endif#if ( portCRITICAL_NESTING_IN_TCB == 1 )UBaseType_t uxCriticalNesting; /*< Holds the critical section nesting depth for ports that do not maintain their own count in the port layer. */#endif#if ( configUSE_TRACE_FACILITY == 1 )UBaseType_t uxTCBNumber;  /*< Stores a number that increments each time a TCB is created.  It allows debuggers to determine when a task has been deleted and then recreated. */UBaseType_t uxTaskNumber; /*< Stores a number specifically for use by third party trace code. */#endif#if ( configUSE_MUTEXES == 1 )UBaseType_t uxBasePriority; /*< The priority last assigned to the task - used by the priority inheritance mechanism. */UBaseType_t uxMutexesHeld;#endif#if ( configUSE_APPLICATION_TASK_TAG == 1 )TaskHookFunction_t pxTaskTag;#endif#if ( configNUM_THREAD_LOCAL_STORAGE_POINTERS > 0 )void * pvThreadLocalStoragePointers[ configNUM_THREAD_LOCAL_STORAGE_POINTERS ];#endif#if ( configGENERATE_RUN_TIME_STATS == 1 )configRUN_TIME_COUNTER_TYPE ulRunTimeCounter; /*< Stores the amount of time the task has spent in the Running state. */#endif#if ( configUSE_NEWLIB_REENTRANT == 1 )/* Allocate a Newlib reent structure that is specific to this task.* Note Newlib support has been included by popular demand, but is not* used by the FreeRTOS maintainers themselves.  FreeRTOS is not* responsible for resulting newlib operation.  User must be familiar with* newlib and must provide system-wide implementations of the necessary* stubs. Be warned that (at the time of writing) the current newlib design* implements a system-wide malloc() that must be provided with locks.** See the third party link http://www.nadler.com/embedded/newlibAndFreeRTOS.html* for additional information. */struct  _reent xNewLib_reent;#endif#if ( configUSE_TASK_NOTIFICATIONS == 1 )volatile uint32_t ulNotifiedValue[ configTASK_NOTIFICATION_ARRAY_ENTRIES ];volatile uint8_t ucNotifyState[ configTASK_NOTIFICATION_ARRAY_ENTRIES ];#endif/* See the comments in FreeRTOS.h with the definition of* tskSTATIC_AND_DYNAMIC_ALLOCATION_POSSIBLE. */#if ( tskSTATIC_AND_DYNAMIC_ALLOCATION_POSSIBLE != 0 ) /*lint !e731 !e9029 Macro has been consolidated for readability reasons. */uint8_t ucStaticallyAllocated;                     /*< Set to pdTRUE if the task is a statically allocated to ensure no attempt is made to free the memory. */#endif#if ( INCLUDE_xTaskAbortDelay == 1 )uint8_t ucDelayAborted;#endif#if ( configUSE_POSIX_ERRNO == 1 )int iTaskErrno;#endif
} tskTCB;

xTaskCreate()函数的参数：

BaseType_t xTaskCreate( TaskFunction_t pxTaskCode,const char * const pcName, /*lint !e971 Unqualified char types are allowed for strings and single characters only. */const configSTACK_DEPTH_TYPE usStackDepth,void * const pvParameters,UBaseType_t uxPriority,TaskHandle_t * const pxCreatedTask )