系统可裁剪，就是对系统的功能打开和关闭,用到的功能就打开，不用的就关闭(ENABLE& DISABLE),这个文件就在os_cfg.h中。
os_cfg.h文件位于工程uC/OS-II CONFIG结构下面。
该文件中重要的几个宏定义：
1、最低优先级OS_LOWEST_PRIO
这个与配置任务优先级有关,最低优先级任务配置的最大值。
任务优先级的关系：优先级越小，数值越大；优先级越大，数值越小。
位于os_cfg.h文件第39行：
#define OS_LOWEST_PRIO 63u /* Defines the lowest priority that can be assigned ... */
2.系统每秒滴答数OS_TICKS_PER_SEC
意思：系统每秒时钟滴答多少次。它与系统延时(OSTimeDly)关系比较重要，项目中该值等于10000（100us）,
调用OSTimeDly(100)，相当于延时100个滴答时间，即10ms。
位于os_cfg.h文件第51行：
#define OS_TICKS_PER_SEC 10000u /* Set the number of ticks in one second */
3.任务堆栈大小OS_TASK_XXX_STK_SIZE
这几个宏定义在使用相应功能时有用，如果RAM资源有限，这个任务堆栈的大小最好根据任务来评估一下，
资源有限不能太大，太小程序不能正常运行。
位于os_cfg.h文件第54--57行：
/* --------------------- TASK STACK SIZE ---------------------- */
#define OS_TASK_TMR_STK_SIZE 128u /* Timer task stack size (# of OS_STK wide entries) */
#define OS_TASK_STAT_STK_SIZE 128u /* Statistics task stack size (# of OS_STK wide entries) */
#define OS_TASK_IDLE_STK_SIZE 128u /* Idle task stack size (# of OS_STK wide entries) */
4.其它内核事件开关
与系统其它资源相关的配置，正常情况下需要使用的时候开启，不用尽量关闭。一是节约资源，二是减少编译时间。
源码注解：
1.各项参数
/* ---------------------- MISCELLANEOUS ----------------------- */
#define OS_APP_HOOKS_EN 0u /* Application-defined hooks are called from the uC/OS-II hooks使能APP应用HOOK函数*/
#define OS_ARG_CHK_EN 0u /* Enable (1) or Disable (0) argument checking 参数检查 */
#define OS_CPU_HOOKS_EN 1u /* uC/OS-II hooks are found in the processor port files使能OS_CPU HOOK函数*/
#define OS_DEBUG_EN 0u /* Enable(1) debug variables 使能系统调试功能 */
#define OS_EVENT_MULTI_EN 0u /* Include code for OSEventPendMulti()使用OSEventPendMulti()函数 */
#define OS_EVENT_NAME_EN 0u /* Enable names for Sem, Mutex, Mbox and Q使能事件(Sem,Mutex,Mbox and Q)名称*/
#define OS_LOWEST_PRIO 63u /* Defines the lowest priority that can be assigned ... 定义最低优先级(值) */
/* ... MUST NEVER be higher than 254!必须小于254 */
#define OS_MAX_EVENTS 10u /* Max. number of event control blocks in your application事件控制块的最大数(应用程序中)*/
#define OS_MAX_FLAGS 5u /* Max. number of Event Flag Groups in your application事件标志组的最大数(应用程序中) */
#define OS_MAX_MEM_PART 0u /* Max. number of memory partitions 内存分区最大数 */
#define OS_MAX_QS 5u /* Max. number of queue control blocks in your application队列控制块的最大数(应用程序中)*/
#define OS_MAX_TASKS 20u /* Max. number of tasks in your application, MUST be >= 2应用程序(任务)最大数 */
/*使用OSSchedLock()和OSSchedUnLock()函数*/
#define OS_SCHED_LOCK_EN 1u /* Include code for OSSchedLock() and OSSchedUnlock() */
#define OS_TICK_STEP_EN 1u /* Enable tick stepping feature for uC/OS-View使能tickstepping */
#define OS_TICKS_PER_SEC 10000u /* Set the number of ticks in one second 每秒滴答数 */
HOOKS函数是os_cpu_c.c里面相关的函数，这里OS_CPU_HOOKS_EN被系统调用，将其定义为使能。
OS_DEBUG_EN 系统自带的调试功能，不使用就失能。
2.任务堆栈大小
/* --------------------- TASK STACK SIZE任务堆栈大小 ---------------------- */
#define OS_TASK_TMR_STK_SIZE 128u /* Timer task stack size (# of OS_STK wide entries) */
#define OS_TASK_STAT_STK_SIZE 128u /* Statistics task stack size (# of OS_STK wide entries) */
#define OS_TASK_IDLE_STK_SIZE 128u /* Idle task stack size (# of OS_STK wide entries) */
和自己建立任务时建立任务堆栈差不多的意思。
3.任务管理
/* --------------------- TASK MANAGEMENT 任务管理---------------------- */
#define OS_TASK_CHANGE_PRIO_EN 1u /* Include code for OSTaskChangePrio() 任务优先级切换 */
#define OS_TASK_CREATE_EN 1u /* Include code for OSTaskCreate() 创建任务 */
#define OS_TASK_CREATE_EXT_EN 1u /* Include code for OSTaskCreateExt()创建扩展版本任务 */
#define OS_TASK_DEL_EN 1u /* Include code for OSTaskDel() 删除任务 */
#define OS_TASK_NAME_EN 1u /* Enable task names 使用OSTaskNameGet()和OSTaskNameSet() 任务名称 */
#define OS_TASK_PROFILE_EN 1u /* Include variables in OS_TCB for profiling 包含OS_TCB性能分析 */
#define OS_TASK_QUERY_EN 1u /* Include code for OSTaskQuery()使用OSTaskQuety() 查询任务 */
#define OS_TASK_REG_TBL_SIZE 1u /* Size of task variables array (#of INT32U entries)任务数组变量大小*/
#define OS_TASK_STAT_EN 1u /* Enable (1) or Disable(0) the statistics task 使能统计任务 */
#define OS_TASK_STAT_STK_CHK_EN 1u /* Check task stacks from statistic task 使能检查任务堆栈 */
#define OS_TASK_SUSPEND_EN 1u /* Include code for OSTaskSuspend() and OSTaskResume()任务挂起、继续 */
#define OS_TASK_SW_HOOK_EN 1u /* Include code for OSTaskSwHook() 任务切换HOOK函数 */
任务管理主要针对uC/OS-ii Source结构下os_task.c文件中的源代码，os_task.c文件包含任务的建立、删除、挂起等关于任务的一些函数接口，
需要使用就打开。
4。系统其它功能
/* ----------------------- EVENT FLAGS事件标志 ------------------------ */
#define OS_FLAG_EN 1u /* Enable (1) or Disable (0) code generation for EVENT FLAGS使能事件标志所有功能 */
#define OS_FLAG_ACCEPT_EN 1u /* Include code for OSFlagAccept()获取事件状态 */
#define OS_FLAG_DEL_EN 1u /* Include code for OSFlagDel()删除事件 */
#define OS_FLAG_NAME_EN 1u /* Enable names for event flag group使用事件标志名称 */
#define OS_FLAG_QUERY_EN 1u /* Include code for OSFlagQuery()查询事件 */
#define OS_FLAG_WAIT_CLR_EN 1u /* Include code for Wait on Clear EVENT FLAGS使能事件等待清除功能 */
#define OS_FLAGS_NBITS 16u /* Size in #bits of OS_FLAGS data type (8, 16 or 32)定义事件数据类型 */
/* -------------------- MESSAGE MAILBOXES消息邮箱 --------------------- */
#define OS_MBOX_EN 1u /* Enable (1) or Disable (0) code generation for MAILBOXES */
#define OS_MBOX_ACCEPT_EN 1u /* Include code for OSMboxAccept() */
#define OS_MBOX_DEL_EN 1u /* Include code for OSMboxDel() */
#define OS_MBOX_PEND_ABORT_EN 1u /* Include code for OSMboxPendAbort() */
#define OS_MBOX_POST_EN 1u /* Include code for OSMboxPost() */
#define OS_MBOX_POST_OPT_EN 1u /* Include code for OSMboxPostOpt() */
#define OS_MBOX_QUERY_EN 1u /* Include code for OSMboxQuery() */
/* --------------------- MEMORY MANAGEMENT内存管理 -------------------- */
#define OS_MEM_EN 1u /* Enable (1) or Disable (0) code generation for MEMORY MANAGER */
#define OS_MEM_NAME_EN 1u /* Enable memory partition names */
#define OS_MEM_QUERY_EN 1u /* Include code for OSMemQuery() */
/* ---------------- MUTUAL EXCLUSION SEMAPHORES互斥信号量 --------------- */
#define OS_MUTEX_EN 1u /* Enable (1) or Disable (0) code generation for MUTEX */
#define OS_MUTEX_ACCEPT_EN 1u /* Include code for OSMutexAccept() */
#define OS_MUTEX_DEL_EN 1u /* Include code for OSMutexDel() */
#define OS_MUTEX_QUERY_EN 1u /* Include code for OSMutexQuery() */
/* ---------------------- MESSAGE QUEUES消息队列 ---------------------- */
#define OS_Q_EN 1u /* Enable (1) or Disable (0) code generation for QUEUES */
#define OS_Q_ACCEPT_EN 1u /* Include code for OSQAccept() */
#define OS_Q_DEL_EN 1u /* Include code for OSQDel() */
#define OS_Q_FLUSH_EN 1u /* Include code for OSQFlush() */
#define OS_Q_PEND_ABORT_EN 1u /* Include code for OSQPendAbort() */
#define OS_Q_POST_EN 1u /* Include code for OSQPost() */
#define OS_Q_POST_FRONT_EN 1u /* Include code for OSQPostFront() */
#define OS_Q_POST_OPT_EN 1u /* Include code for OSQPostOpt() */
#define OS_Q_QUERY_EN 1u /* Include code for OSQQuery() */
/* ------------------------ SEMAPHORES信号量 ------------------------ */
#define OS_SEM_EN 1u /* Enable (1) or Disable (0) code generation for SEMAPHORES */
#define OS_SEM_ACCEPT_EN 1u /* Include code for OSSemAccept() */
#define OS_SEM_DEL_EN 1u /* Include code for OSSemDel() */
#define OS_SEM_PEND_ABORT_EN 1u /* Include code for OSSemPendAbort() */
#define OS_SEM_QUERY_EN 1u /* Include code for OSSemQuery() */
#define OS_SEM_SET_EN 1u /* Include code for OSSemSet() */
/* --------------------- TIME MANAGEMENT时间管理 ---------------------- */
#define OS_TIME_DLY_HMSM_EN 1u /* Include code for OSTimeDlyHMSM() */
#define OS_TIME_DLY_RESUME_EN 1u /* Include code for OSTimeDlyResume() */
#define OS_TIME_GET_SET_EN 1u /* Include code for OSTimeGet() and OSTimeSet() */
#define OS_TIME_TICK_HOOK_EN 1u /* Include code for OSTimeTickHook() */
/* --------------------- TIMER MANAGEMENT定时器管理 --------------------- */
#define OS_TMR_EN 0u /* Enable (1) or Disable (0) code generation for TIMERS */
#define OS_TMR_CFG_MAX 16u /* Maximum number of timers */
#define OS_TMR_CFG_NAME_EN 1u /* Determine timer names */
#define OS_TMR_CFG_WHEEL_SIZE 8u /* Size of timer wheel (#Spokes) */
#define OS_TMR_CFG_TICKS_PER_SEC 10u /* Rate at which timer management task runs (Hz) */
uC/OS-ii操作系统可以进行多进程通信，每种功能都对应一个源代码文件。
每种功能都有使能全局的宏定义，只有使能了全局宏定义才可以使用里面的功能，每个模块也配置了选通开关。