Page Comparison

Compile-time configuration allows users to determine which features to enable and those features that are not needed. With compile-time configuration, the code and data sizes of µC/OS-III (i.e., its footprint) can be reduced by enabling only the desired functionality.

...

When set to DEF_ENABLED, this option specifies that application-defined hooks can be called from µC/OS-III’s hooks. This allows the application code to extend the functionality of µC/OS-III. Specifically:

Application hook functions could be declared as shown in the code below.

It’s also up to a user to set the value of the pointers so that they point to the appropriate functions as shown below. The pointers do not have to be set in main() but, you can set them after calling OSInit().

Note that not every hook function need to be defined, only the ones the user wants to place in the application code.

Also, if you don't intend to extend µC/OS-III’s hook through these application hooks, you can set OS_CFG_APP_HOOKS_EN to DEF_DISABLED to save RAM (i.e., the pointers).

OS_CFG_ARG_CHK_EN

OS_CFG_ARG_CHK_EN determines whether the user wants most of µC/OS-III functions to perform argument checking. When set to DEF_ENABLED, µC/OS-III ensures that pointers passed to functions are non-NULL, that arguments passed are within allowable range, that options are valid, and more. When set to DEF_DISABLED, those arguments are not checked and the amount of code space and processing time required by µC/OS-III is reduced. You would set OS_CFG_ARG_CHK_EN to DEF_DISABLED if you are certain that the arguments will always be correct.

µC/OS-III performs argument checking in close to 50 functions. Therefore, you can save a few hundred bytes of code space by disabling this check. However, you should always enable argument checking until you are certain the code can be trusted.

OS_CFG_CALLED_FROM_ISR_CHK_EN

OS_CFG_CALLED_FROM_ISR_CHK_EN determines whether most of µC/OS-III functions are to confirm that the function is not called from an ISR. In other words, most of the functions from µC/OS-III should be called by task-level code except “post” type functions (which can also be called from ISRs). By setting this DEF_ENABLED, µC/OS-III is told to make sure that functions that are only supposed to be called by tasks are not called by ISRs. It’s highly recommended to set this to DEF_ENABLED until you are absolutely sure that the code is behaving correctly and that task-level functions are always called from tasks. You can set this to DEF_DISABLED to save code space and, of course, processing time.

µC/OS-III performs this check in approximately 50 functions. Therefore, you can save a few hundred bytes of code space by disabling this check.

OS_CFG_DBG_EN

When set to DEF_ENABLED, this configuration adds ROM constants located in os_dbg.c to help support kernel aware debuggers. Specifically, a number of named ROM variables can be queried by a debugger to find out about compiled-in options. For example, a debugger can find out the size of a OS_TCB, µC/OS-III’s version number, the size of an event flag group (OS_FLAG_GRP), and much more.

OS_CFG_DYN_TICK_EN

When set to DEF_ENABLED, µC/OS-III will use a dynamic ticking mechanism instead of the traditional continuous tick. This allows µC/OS-III to sleep until a task needs to be awakened, instead of waking up every 1/OS_CFG_TICK_RATE_HZ seconds to find no that no tasks need to be awakened. This can be used to save power since the scheduler is run only when strictly necessary.

Note that the use of this feature requires a proper Board Support Package (BSP) that implements the API described in bsp_os.c, bsp_os_a.asm and bsp_os.h.

OS_CFG_INVALID_OS_CALLS_CHK_EN

...

void  App_OS_TaskCreateHook (OS_TCB *p_tcb)
{
    /* Your code here */
}
 
 
void  App_OS_TaskDelHook (OS_TCB *p_tcb)
{
    /* Your code here */
}
 
 
void  App_OS_TaskReturnHook (OS_TCB *p_tcb)
{
    /* Your code here */
}
 
 
void  App_OS_IdleTaskHook (void)
{
    /* Your code here */
}
 
 
void  App_OS_StatTaskHook (void)
{
    /* Your code here */
}
 
 
void  App_OS_TaskSwHook (void)
{
    /* Your code here */
}
 
 
void  App_OS_TimeTickHook (void)
{
    /* Your code here */
}

It’s also up to a user to set the value of the pointers so that they point to the appropriate functions as shown below. The pointers do not have to be set in main() but, you can set them after calling OSInit().

void  main (void)
{
     OS_ERR  err;
 
 
     OSInit(&err);
     :
     :
     OS_AppTaskCreateHookPtr = (OS_APP_HOOK_TCB )App_OS_TaskCreateHook;
     OS_AppTaskDelHookPtr    = (OS_APP_HOOK_TCB )App_OS_TaskDelHook;
     OS_AppTaskReturnHookPtr = (OS_APP_HOOK_TCB )App_OS_TaskReturnHook;
     OS_AppIdleTaskHookPtr   = (OS_APP_HOOK_VOID)App_OS_IdleTaskHook;
     OS_AppStatTaskHookPtr   = (OS_APP_HOOK_VOID)App_OS_StatTaskHook;
     OS_AppTaskSwHookPtr     = (OS_APP_HOOK_VOID)App_OS_TaskSwHook;
     OS_AppTimeTickHookPtr   = (OS_APP_HOOK_VOID)App_OS_TimeTickHook;
     :
     :
     OSStart(&err);
}

Note that not every hook function need to be defined, only the ones the user wants to place in the application code.

Also, if you don't intend to extend µC/OS-III’s hook through these application hooks, you can set OS_CFG_APP_HOOKS_EN to DEF_DISABLED  to save RAM (i.e., the pointers).

OS_CFG_ARG_CHK_EN

OS_CFG_ARG_CHK_EN determines whether the user wants most of µC/OS-III functions to perform argument checking. When set to DEF_ENABLED, µC/OS-III ensures that pointers passed to functions are non-NULL, that arguments passed are within allowable range, that options are valid, and more. When set to DEF_DISABLED, those arguments are not checked and the amount of code space and processing time required by µC/OS-III is reduced. You would set OS_CFG_ARG_CHK_EN to DEF_DISABLED if you are certain that the arguments will always be correct.

µC/OS-III performs argument checking in close to 50 functions. Therefore, you can save a few hundred bytes of code space by disabling this check. However, you should always enable argument checking until you are certain the code can be trusted.

OS_CFG_CALLED_FROM_ISR_CHK_EN

OS_CFG_CALLED_FROM_ISR_CHK_EN determines whether most of µC/OS-III functions are to confirm that the function is not called from an ISR. In other words, most of the functions from µC/OS-III should be called by task-level code except “post” type functions (which can also be called from ISRs). By setting this DEF_ENABLED, µC/OS-III is told to make sure that functions that are only supposed to be called by tasks are not called by ISRs. It’s highly recommended to set this to  DEF_ENABLED  until you are absolutely sure that the code is behaving correctly and that task-level functions are always called from tasks. You can set this to  DEF_DISABLED  to save code space and, of course, processing time.

µC/OS-III performs this check in more than 40 approximately 50 functions. Therefore, you can save a few hundred bytes of code space by disabling this check.

OS_CFG_

...

DBG_EN

Warning, this feature is DEPRECATED and will be removed in a future release of µC/OS-III.

When set to DEF_ENABLED, OS_CFG_ISR_POST_DEFERRED_EN reduces interrupt latency since interrupts are not disabled during most critical sections of code within µC/OS-III. Instead, the scheduler is locked during the processing of these critical sections. The advantage of setting this to DEF_ENABLED is that interrupt latency is lower, however, ISR to task response is slightly higher. It is recommended to set OS_CFG_ISR_POST_DEFERRED_EN to DEF_ENABLED when enabling the following services, since setting this to DEF_DISABLED would potentially make interrupt latency unacceptably high:

The compromise to make is:

OS_CFG_ISR_POST_DEFERRED_EN set to DEF_ENABLED

Short interrupt latency, longer ISR-to-task response.

OS_CFG_ISR_POST_DEFERRED_EN set to DEF_DISABLED

...

When set to DEF_ENABLED, this configuration adds ROM constants located in os_dbg.c to help support kernel aware debuggers. Specifically, a number of named ROM variables can be queried by a debugger to find out about compiled-in options. For example, a debugger can find out the size of a OS_TCB, µC/OS-III’s version number, the size of an event flag group (OS_FLAG_GRP), and much more.

OS_CFG_DYN_TICK_EN

When set to DEF_ENABLED, µC/OS-III will use a dynamic ticking mechanism instead of the traditional continuous tick. This allows µC/OS-III to sleep until a task needs to be awakened, instead of waking up every 1/OS_CFG_TICK_RATE_HZ seconds to find no that no tasks need to be awakened. This can be used to save power since the scheduler is run only when strictly necessary.

Note that the use of this feature requires a proper Board Support Package (BSP) that implements the API described in Board Support Package.

OS_CFG_INVALID_OS_CALLS_CHK_EN

When set to DEF_ENABLED, µC/OS-III will validate the call and check that the kernel is indeed running before performing the function. You would set OS_CFG_INVALID_OS_CALLS_CHK_EN to DEF_DISABLED if you are sure that the OS functions will be called only once OSStart() has been called. 

µC/OS-III performs this check in more than 40 functions. Therefore, you can save a few hundred bytes of code space by disabling this check.

OS_CFG_OBJ_TYPE_CHK_EN

OS_CFG_OBJ_TYPE_CHK_EN determines whether most of µC/OS-III functions should check to see if the function is manipulating the proper object. In other words, if attempting to post to a semaphore, is the user in fact passing a semaphore object or another object by mistake? It is recommended to set  OS_CFG_OBJ_TYPE_CHK_EN to  to DEF_ENABLED until absolutely certain that the code is behaving correctly and the user code is always pointing to the proper objects. You would set this to DEF_DISABLED  to save code space as well as data space.

...

When OS_CFG_TS_EN is set to DEF_ENABLED, it enables it enables the timestamp facilities provided by µC/CPU. This allows the user and the kernel to measure the time between various events. For example, the time spent by a task pending on an object, the maximum interrupt disable time (if CPU_CFG_INT_DIS_MEAS_EN is set to  DEF_ENABLED), the time the scheduler is locked, etc. This option is mostly useful in profiling and performance measurement contexts. To save space and processing time, set this option to  DEF_DISABLED .

Note that to use the timestamp facilities the µC/CPU Board Support Package should implement the functions described in cpu_bsp.c and cpu_bsp.h.

OS_CFG_PEND_MULTI_EN

Warning, this feature is DEPRECATED and will be removed in a future release of µC/OS-III.

When this option is set to DEF_ENABLED, it allows the user to pend on multiple objects (message queues and semaphores only) at once.

OS_CFG_PRIO_MAX

OS_CFG_PRIO_MAX specifies the maximum number of priorities available in the application. Specifying OS_CFG_PRIO_MAX to just the number of priorities the user intends to use, reduces the amount of RAM needed by µC/OS-III.

...

OS_CFG_SCHED_LOCK_TIME_MEAS_EN

When set to DEF_ENABLED ,  OS_CFG_SCHED_LOCK_TIME_MEAS_EN allows µC allows µC/OS-III to use the timestamp facilities (provided  OS_CFG_TS_EN is also set to  DEF_ENABLED) to measure the peak amount of time that the scheduler is locked. Use this feature to profile the application, the deployed application should set this to  DEF_DISABLED .

OS_CFG_SCHED_ROUND_ROBIN_EN

Set OS_CFG_SCHED_ROUND_ROBIN_EN to DEF_ENABLED  to use the Round Robin Scheduler. This is only useful when there is multiple tasks sharing the same priority, if this is not your case, set this option to DEF_DISABLED . See Round-Robin Scheduling for more information.

...

When OS_CFG_FLAG_EN is set to DEF_ENABLED, it enables the event the event flag services and data structures. If event flags are not needed, set this to DEF_DISABLED. It reduces the amount of code and data space needed by µC/OS-III. Note than when OS_CFG_FLAG_EN is set to DEF_DISABLED , it is not necessary to enable or disable any of the other OS_CFG_FLAG_xxx options in this section.

...

When OS_CFG_MEM_EN is set to DEF_ENABLED, it enables it enables the µC/OS-III partition memory manager. If your application does not require the partitionned memory manager, set this to DEF_DISABLE to reduce µC/OS-III's code and data space usage.

...

When OS_CFG_MUTEX_EN is set to DEF_ENABLED, it enables the mutual exclusion semaphore services and data structures. If your application does not require mutexes, set this option to DEF_DISABLED to to reduce the amount of code and data space needed by µC/OS-III. When OS_CFG_MUTEX_EN is set to DEF_DISABLED, there is no need to enable or disable any of the other OS_CFG_MUTEX_XXX options in this section.

...

If your application needs to delete mutexes with  OSMutexDel ()  once they're created, set  OS_CFG_MUTEX_DEL_EN  to DEF_ENABLED, if not, set this option to DEF_DISABLED. Critical applications should not delete kernel objects once the kernel is started.

...

When OS_CFG_MUTEX_PEND_ABORT_EN is set to DEF_ENABLED, it enables the generation of the function  OSMutexPendAbort(). If your application does not require fault-aborts on mutexes, set this option to DEF_DISABLED.

...

If your application needs to delete message queues with OSQDel() once they're created, set OS_CFG_Q_DEL_EN to DEF_ENABLED, if not, set this option to DEF_DISABLED. Critical applications should not delete kernel objects once the kernel is started.

...

When OS_CFG_Q_FLUSH_EN is set to DEF_ENABLED, it allows your application to flush, or clear, a message queue with OSQFlush(). If this feature is not needed, set this option to  DEF_DISABLED .

OS_CFG_Q_PEND_ABORT_EN

When OS_CFG_Q_PEND_ABORT_EN is set to DEF_ENABLED, it enables the generation of the function OSQPendAbort(). If your application does not require fault-aborts on message queues, set this option to DEF_DISABLED.

...

If your application needs to delete semaphores with  OSSemDel ()  once they're created, set OS_CFG_SEM_DEL_EN to DEF_ENABLED, if not, set this option to DEF_DISABLED. Critical applications should not delete kernel objects once the kernel is started.

...

When OS_CFG_SEM_PEND_ABORT_EN is set to DEF_ENABLED, it enables the generation of the function  OSSemPendAbort(). If your application does not require fault-aborts on semaphores queues, set this option to DEF_DISABLED.

...

If your application needs to explicitly set the value of a semaphore with  OSSemSet()  at  at another time than it's creation, set OS_CFG_SEM_SET_EN to DEF_ENABLE, if not, set this option to DEF_DISABLED.

...

OS_CFG_STAT_TASK_EN specifies whether or not to enable µC/OS-III’s statistic task, as well as its initialization function. When set to  DEF_ENABLED , the statistic task OS_StatTask() and the statistic task initialization function are enabled. OS_StatTask() computes the CPU usage of an application, the stack usage of each task, the CPU usage of each task at run time and more.

...

OS_StatTask() computes stack usage of each task created when the option OS_CFG_STAT_TASK_STK_CHK_EN is set to  DEF_ENABLED . In this case, OS_StatTask() calls OSTaskStkChk() for each task and the result is placed in the task’s TCB. The .StkFree and .StkUsed fields of the task’s TCB represent the amount of free space (in CPU_STK elements) and amount of used space (in CPU_STK elements), respectively.

...

OS_CFG_STAT_TASK_STK_CHK_EN

When set to DEF_ENABLED, this this option allows the statistic task to call OSTaskStkChk() for each task created. Note that for this to happen, OS_CFG_STAT_TASK_EN must also be set to  DEF_ENABLED . However, you can call OSStatStkChk() from one of the tasks to obtain this information about the tasks.

...

If your application needs to dynamically change a task's priority using OSTaskChangePrio()  , set OS_CFG_TASK_CHANGE_PRIO_EN to DEF_ENABLED. If not, set this option to DEF_DISABLED. Note that the new priority has to be available and not currently in-use by a kernel task.

...

Setting OS_CFG_TASK_IDLE_EN to DEF_ENABLED allows µC/OS-III to create it's Idle Task at priority OS_CFG_PRIO_MAX-1. However, to save data space, it is possible to remove the Idle Task. To do so, set this option to  DEF_DISABLED. Doing so will move the functionality of the Idle Task within the OSSched() function. The same counters will be incremented and the same hooks will be called under the same circumstances.

OS_CFG_TASK_PROFILE_EN

To enable the performance profiling tools within µC/OS-III, set OS_CFG_TASK_PROFILE_EN to DEF_ENABLED. Doing so allows variables to be allocated in each task’s OS_TCB to hold performance data about each task. When enabled, each task will have variables to keep track of the number of times a task is switched in, the task execution time, the CPU usage percentage of the task relative to the other tasks and more. The information made available with this feature is highly useful when debugging, but requires extra RAM. To save data and code space, set this option to  DEF_DISABLED after your are certain that you application is profiled and works correctly.

OS_CFG_TASK_Q_EN

When OS_CFG_TASK_Q_EN is set to DEF_ENABLED, it  allows the generation of the OSTaskQ???() functions used to send and receive messages directly to and from tasks and ISRs. Sending messages directly to a task is more efficient than sending messages using a traditional message queue because there is no pend list associated with messages sent to a task. If your application does not require task-level message queues, set this option to DEF_DISABLED. Note that if this option is set to DEF_DISABLED , the  OS_CFG_TASK_Q_PEND_ABORT_EN configuration option is ignored.

OS_CFG_TASK_Q_PEND_ABORT_EN

...

If your application requires the ability to explicitly suspend and resume the execution of tasks, set OS_CFG_TASK_SUSPEND_EN to DEF_ENABLED. Doing so, allows the generation of the OSTaskSuspend() and OSTaskResume() functions used to suspend and resume tasks, respectively. Note that other effects are additive with the suspension. For example, if a suspended task is pending on a semaphore that becomes available, the task will not run until it's explicitly resumed with OSTaskResume(). Also, the suspension of a task can be nested. To resume a task, you must call OSTaskResume() the same number of times  OSTaskSuspend() was called. If  If your application does not require this feature, set this option to DEF_DISABLED.

...

When OS_CFG_TMR_EN is set to DEF_ENABLED, it enables the timer management services. If your application does no require programmable timers, set this option to DEF_DISABLED to reduce µC/OS-III's required code and data space. to reduce µC/OS-III's required code and data space.

OS_CFG_TMR_DEL_EN

If your application needs to delete timers with OSTmrDel()  once they're created, set OS_CFG_TMR_DEL_EN to DEF_ENABLED, if not, set this option to DEF_DISABLED. Critical applications should not delete kernel objects once the kernel is started.

Trace Options

OS_CFG_

...

TRACE_EN

If your application needs to delete timers with OSTmrDel() once they're created, set OS_CFG_TMR_DEL_EN to DEF_ENABLED, if notµC/OS-III has built-in trace points throughout the code to record all the kernel events and interrupts in real-time. These trace calls are disabled by default and enabled when this constant is set to DEF_ENABLED. If you do not require this feature, set this option to DEF_DISABLED. Critical applications should not delete kernel objects once the kernel is started.

µC/Trace Configuration

TRACE_CFG_EN

Although not specifically part of µC/OS-III, µC/Trace, a Windows-based RTOS Event Analyzer (i.e. tool) that is fully integrated in the latest version of µC/OS-III. µC/Trace functionality is enabled by setting TRACE_CFG_EN to DEF_ENABLED. You will need to have purchased the µC/Trace product in order to set TRACE_CFG_EN to DEF_ENABLED or else your compiler will complain about missing macros and functions. Consult the Micriµm website for details and availability of this highly useful tool to not only reduce the required code and data space but also to eliminate the inherent overhead.

OS_CFG_TRACE_API_ENTER_EN

When this constant is set to DEF_ENABLED the beginning of each API call in µC/OS-III will be recorded as part of the trace (it applies to SEGGER's SystemView only).

OS_CFG_TRACE_API_EXIT_EN

When this constant is set to DEF_ENABLED the end of each API call in µC/OS-III will be recorded as part of the trace (it applies to SEGGER's SystemView only).