一. RTOS的概念

// 经典单片机程序
void main()
{while (1){喂一口饭();回一个信息();}
}
------------------------------------------------------
// RTOS程序    
喂饭()
{while (1){喂一口饭();}
}回信息()
{while (1){回一个信息();}
}void main()
{create_task(喂饭);create_task(回信息);start_scheduler();while (1){sleep();}
}

二.FreeRTOS目录结构

三.从官方源码裁剪

1. 下载

2. 删减目录

3. 编译、执行

4. 添加串口打印功能

• 去掉无关的代码：LCD等

• 增加串口打印功能

  • 初始化串口

  • 实现fputc

四. 创建任务

BaseType_t xTaskCreate( TaskFunction_t pxTaskCode, // 函数指针, 任务函数const char * const pcName, // 任务的名字const configSTACK_DEPTH_TYPE usStackDepth, // 栈大小,单位为word,10表示40字节void * const pvParameters, // 调用任务函数时传入的参数UBaseType_t uxPriority, // 优先级TaskHandle_t * const pxCreatedTask // 任务句柄, 以后使用它来操作这个任务); 

1.创建第一个任务 

void Task1Function(void*param)//函数指针
{while(1){printf("1");}
}/*-----------------------------------------------------------*/int main( void )
{TaskHandle_t xHandleTask1;
#ifdef DEBUGdebug();
#endifprvSetupHardware();printf("hello,world,nimade!\r\n");xTaskCreate(Task1Function,"Task1",100,NULL,1,&xHandleTask1);//创建任务/* Start the scheduler. */vTaskStartScheduler();/* Will only get here if there was not enough heap space to create theidle task. */return 0;
}

不断的执行1 

2.创建第二个任务 

void Task1Function(void*param)
{while(1){printf("1");}
}
void Task2Function(void*param)
{while(1){printf("2");}
}
/*-----------------------------------------------------------*/int main( void )
{TaskHandle_t xHandleTask1;
#ifdef DEBUGdebug();
#endifprvSetupHardware();printf("hello,world,nimade!\r\n");xTaskCreate(Task1Function,"Task1",100,NULL,1,&xHandleTask1);xTaskCreate(Task2Function,"Task2",100,NULL,1,NULL);//这里没有加句柄/* Start the scheduler. */vTaskStartScheduler();/* Will only get here if there was not enough heap space to create theidle task. */return 0;
}

3.动态内存的使用 

        TCB_t * pxNewTCB;//任务控制块BaseType_t xReturn;

对于每一个任务都有一个TCB_t 结构体，对于这个结构体可以使用动态分配也可以静态分配。动态分配在程序里面使用 xTaskCreate()；

    TaskHandle_t xTaskCreateStatic( TaskFunction_t pxTaskCode,const char * const pcName, /*lint !e971 Unqualified char types are allowed for strings and single characters only. */const uint32_t ulStackDepth,void * const pvParameters,UBaseType_t uxPriority,StackType_t * const puxStackBuffer,StaticTask_t * const pxTaskBuffer ){

void Task1Function(void*param)
{while(1){printf("1");}
}
void Task2Function(void*param)
{while(1){printf("2");}
}
void Task4Function(void*param)
{while(1){     printf("3");}
}/*-----------------------------------------------------------*/
StackType_t xTask4Stack[100];//100*4字节
StaticTask_t xTask4TCB;StackType_t xIdleTaskStack[100];//100*4字节
StaticTask_t xIdleTaskTCB;void vApplicationGetIdleTaskMemory( StaticTask_t ** ppxIdleTaskTCBBuffer,StackType_t ** ppxIdleTaskStackBuffer,uint32_t * pulIdleTaskStackSize )
{*ppxIdleTaskTCBBuffer = &xIdleTaskTCB;*ppxIdleTaskStackBuffer = xIdleTaskStack;*pulIdleTaskStackSize = 100;
}int main( void )
{LED_Init();TaskHandle_t xHandleTask1;
#ifdef DEBUGdebug();
#endifprvSetupHardware();printf("hello,world,nimade!\r\n");xTaskCreate(Task1Function,"Task1",100,NULL,1,&xHandleTask1);xTaskCreate(Task2Function,"Task2",100,NULL,1,NULL);xTaskCreateStatic(Task4Function,"Task4",100,NULL,1,xTask4Stack,&xTask4TCB);/* Start the scheduler. */vTaskStartScheduler();/* Will only get here if there was not enough heap space to create theidle task. */return 0;
}