/* * FreeRTOS Kernel V10.3.1 * Copyright (C) 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved. * * Permission is hereby granted, free of charge, to any person obtaining a copy of * this software and associated documentation files (the "Software"), to deal in * the Software without restriction, including without limitation the rights to * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of * the Software, and to permit persons to whom the Software is furnished to do so, * subject to the following conditions: * * The above copyright notice and this permission notice shall be included in all * copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. * * http://www.FreeRTOS.org * http://aws.amazon.com/freertos * * 1 tab == 4 spaces! */ #ifndef EVENT_GROUPS_H #define EVENT_GROUPS_H #ifndef INC_FREERTOS_H #error "include FreeRTOS.h" must appear in source files before "include event_groups.h" #endif /* FreeRTOS includes. */ #include "timers.h" #ifdef __cplusplus extern "C" { #endif /** * An event group is a collection of bits to which an application can assign a * meaning. For example, an application may create an event group to convey * the status of various CAN bus related events in which bit 0 might mean "A CAN * message has been received and is ready for processing", bit 1 might mean "The * application has queued a message that is ready for sending onto the CAN * network", and bit 2 might mean "It is time to send a SYNC message onto the * CAN network" etc. A task can then test the bit values to see which events * are active, and optionally enter the Blocked state to wait for a specified * bit or a group of specified bits to be active. To continue the CAN bus * example, a CAN controlling task can enter the Blocked state (and therefore * not consume any processing time) until either bit 0, bit 1 or bit 2 are * active, at which time the bit that was actually active would inform the task * which action it had to take (process a received message, send a message, or * send a SYNC). * * The event groups implementation contains intelligence to avoid race * conditions that would otherwise occur were an application to use a simple * variable for the same purpose. This is particularly important with respect * to when a bit within an event group is to be cleared, and when bits have to * be set and then tested atomically - as is the case where event groups are * used to create a synchronisation point between multiple tasks (a * 'rendezvous'). * * \defgroup EventGroup */ /** * event_groups.h * * Type by which event groups are referenced. For example, a call to * xEventGroupCreate() returns an EventGroupHandle_t variable that can then * be used as a parameter to other event group functions. * * \defgroup EventGroupHandle_t EventGroupHandle_t * \ingroup EventGroup */ struct EventGroupDef_t; typedef struct EventGroupDef_t * EventGroupHandle_t; /* * The type that holds event bits always matches TickType_t - therefore the * number of bits it holds is set by configUSE_16_BIT_TICKS (16 bits if set to 1, * 32 bits if set to 0. * * \defgroup EventBits_t EventBits_t * \ingroup EventGroup */ typedef TickType_t EventBits_t; /** * event_groups.h *
 EventGroupHandle_t xEventGroupCreate( void );
 
* * Create a new event group. * * Internally, within the FreeRTOS implementation, event groups use a [small] * block of memory, in which the event group's structure is stored. If an event * groups is created using xEventGropuCreate() then the required memory is * automatically dynamically allocated inside the xEventGroupCreate() function. * (see http://www.freertos.org/a00111.html). If an event group is created * using xEventGropuCreateStatic() then the application writer must instead * provide the memory that will get used by the event group. * xEventGroupCreateStatic() therefore allows an event group to be created * without using any dynamic memory allocation. * * Although event groups are not related to ticks, for internal implementation * reasons the number of bits available for use in an event group is dependent * on the configUSE_16_BIT_TICKS setting in FreeRTOSConfig.h. If * configUSE_16_BIT_TICKS is 1 then each event group contains 8 usable bits (bit * 0 to bit 7). If configUSE_16_BIT_TICKS is set to 0 then each event group has * 24 usable bits (bit 0 to bit 23). The EventBits_t type is used to store * event bits within an event group. * * @return If the event group was created then a handle to the event group is * returned. If there was insufficient FreeRTOS heap available to create the * event group then NULL is returned. See http://www.freertos.org/a00111.html * * Example usage:
	// Declare a variable to hold the created event group.
	EventGroupHandle_t xCreatedEventGroup;

	// Attempt to create the event group.
	xCreatedEventGroup = xEventGroupCreate();

	// Was the event group created successfully?
	if( xCreatedEventGroup == NULL )
	{
		// The event group was not created because there was insufficient
		// FreeRTOS heap available.
	}
	else
	{
		// The event group was created.
	}
   
* \defgroup xEventGroupCreate xEventGroupCreate * \ingroup EventGroup */ #if( configSUPPORT_DYNAMIC_ALLOCATION == 1 ) EventGroupHandle_t xEventGroupCreate( void ) PRIVILEGED_FUNCTION; #endif /** * event_groups.h *
 EventGroupHandle_t xEventGroupCreateStatic( EventGroupHandle_t * pxEventGroupBuffer );
 
* * Create a new event group. * * Internally, within the FreeRTOS implementation, event groups use a [small] * block of memory, in which the event group's structure is stored. If an event * groups is created using xEventGropuCreate() then the required memory is * automatically dynamically allocated inside the xEventGroupCreate() function. * (see http://www.freertos.org/a00111.html). If an event group is created * using xEventGropuCreateStatic() then the application writer must instead * provide the memory that will get used by the event group. * xEventGroupCreateStatic() therefore allows an event group to be created * without using any dynamic memory allocation. * * Although event groups are not related to ticks, for internal implementation * reasons the number of bits available for use in an event group is dependent * on the configUSE_16_BIT_TICKS setting in FreeRTOSConfig.h. If * configUSE_16_BIT_TICKS is 1 then each event group contains 8 usable bits (bit * 0 to bit 7). If configUSE_16_BIT_TICKS is set to 0 then each event group has * 24 usable bits (bit 0 to bit 23). The EventBits_t type is used to store * event bits within an event group. * * @param pxEventGroupBuffer pxEventGroupBuffer must point to a variable of type * StaticEventGroup_t, which will be then be used to hold the event group's data * structures, removing the need for the memory to be allocated dynamically. * * @return If the event group was created then a handle to the event group is * returned. If pxEventGroupBuffer was NULL then NULL is returned. * * Example usage:
	// StaticEventGroup_t is a publicly accessible structure that has the same
	// size and alignment requirements as the real event group structure.  It is
	// provided as a mechanism for applications to know the size of the event
	// group (which is dependent on the architecture and configuration file
	// settings) without breaking the strict data hiding policy by exposing the
	// real event group internals.  This StaticEventGroup_t variable is passed
	// into the xSemaphoreCreateEventGroupStatic() function and is used to store
	// the event group's data structures
	StaticEventGroup_t xEventGroupBuffer;

	// Create the event group without dynamically allocating any memory.
	xEventGroup = xEventGroupCreateStatic( &xEventGroupBuffer );
   
*/ #if( configSUPPORT_STATIC_ALLOCATION == 1 ) EventGroupHandle_t xEventGroupCreateStatic( StaticEventGroup_t *pxEventGroupBuffer ) PRIVILEGED_FUNCTION; #endif /** * event_groups.h *
	EventBits_t xEventGroupWaitBits( 	EventGroupHandle_t xEventGroup,
										const EventBits_t uxBitsToWaitFor,
										const BaseType_t xClearOnExit,
										const BaseType_t xWaitForAllBits,
										const TickType_t xTicksToWait );
 
* * [Potentially] block to wait for one or more bits to be set within a * previously created event group. * * This function cannot be called from an interrupt. * * @param xEventGroup The event group in which the bits are being tested. The * event group must have previously been created using a call to * xEventGroupCreate(). * * @param uxBitsToWaitFor A bitwise value that indicates the bit or bits to test * inside the event group. For example, to wait for bit 0 and/or bit 2 set * uxBitsToWaitFor to 0x05. To wait for bits 0 and/or bit 1 and/or bit 2 set * uxBitsToWaitFor to 0x07. Etc. * * @param xClearOnExit If xClearOnExit is set to pdTRUE then any bits within * uxBitsToWaitFor that are set within the event group will be cleared before * xEventGroupWaitBits() returns if the wait condition was met (if the function * returns for a reason other than a timeout). If xClearOnExit is set to * pdFALSE then the bits set in the event group are not altered when the call to * xEventGroupWaitBits() returns. * * @param xWaitForAllBits If xWaitForAllBits is set to pdTRUE then * xEventGroupWaitBits() will return when either all the bits in uxBitsToWaitFor * are set or the specified block time expires. If xWaitForAllBits is set to * pdFALSE then xEventGroupWaitBits() will return when any one of the bits set * in uxBitsToWaitFor is set or the specified block time expires. The block * time is specified by the xTicksToWait parameter. * * @param xTicksToWait The maximum amount of time (specified in 'ticks') to wait * for one/all (depending on the xWaitForAllBits value) of the bits specified by * uxBitsToWaitFor to become set. * * @return The value of the event group at the time either the bits being waited * for became set, or the block time expired. Test the return value to know * which bits were set. If xEventGroupWaitBits() returned because its timeout * expired then not all the bits being waited for will be set. If * xEventGroupWaitBits() returned because the bits it was waiting for were set * then the returned value is the event group value before any bits were * automatically cleared in the case that xClearOnExit parameter was set to * pdTRUE. * * Example usage:
   #define BIT_0	( 1 << 0 )
   #define BIT_4	( 1 << 4 )

   void aFunction( EventGroupHandle_t xEventGroup )
   {
   EventBits_t uxBits;
   const TickType_t xTicksToWait = 100 / portTICK_PERIOD_MS;

		// Wait a maximum of 100ms for either bit 0 or bit 4 to be set within
		// the event group.  Clear the bits before exiting.
		uxBits = xEventGroupWaitBits(
					xEventGroup,	// The event group being tested.
					BIT_0 | BIT_4,	// The bits within the event group to wait for.
					pdTRUE,			// BIT_0 and BIT_4 should be cleared before returning.
					pdFALSE,		// Don't wait for both bits, either bit will do.
					xTicksToWait );	// Wait a maximum of 100ms for either bit to be set.

		if( ( uxBits & ( BIT_0 | BIT_4 ) ) == ( BIT_0 | BIT_4 ) )
		{
			// xEventGroupWaitBits() returned because both bits were set.
		}
		else if( ( uxBits & BIT_0 ) != 0 )
		{
			// xEventGroupWaitBits() returned because just BIT_0 was set.
		}
		else if( ( uxBits & BIT_4 ) != 0 )
		{
			// xEventGroupWaitBits() returned because just BIT_4 was set.
		}
		else
		{
			// xEventGroupWaitBits() returned because xTicksToWait ticks passed
			// without either BIT_0 or BIT_4 becoming set.
		}
   }
   
* \defgroup xEventGroupWaitBits xEventGroupWaitBits * \ingroup EventGroup */ EventBits_t xEventGroupWaitBits( EventGroupHandle_t xEventGroup, const EventBits_t uxBitsToWaitFor, const BaseType_t xClearOnExit, const BaseType_t xWaitForAllBits, TickType_t xTicksToWait ) PRIVILEGED_FUNCTION; /** * event_groups.h *
	EventBits_t xEventGroupClearBits( EventGroupHandle_t xEventGroup, const EventBits_t uxBitsToClear );
 
* * Clear bits within an event group. This function cannot be called from an * interrupt. * * @param xEventGroup The event group in which the bits are to be cleared. * * @param uxBitsToClear A bitwise value that indicates the bit or bits to clear * in the event group. For example, to clear bit 3 only, set uxBitsToClear to * 0x08. To clear bit 3 and bit 0 set uxBitsToClear to 0x09. * * @return The value of the event group before the specified bits were cleared. * * Example usage:
   #define BIT_0	( 1 << 0 )
   #define BIT_4	( 1 << 4 )

   void aFunction( EventGroupHandle_t xEventGroup )
   {
   EventBits_t uxBits;

		// Clear bit 0 and bit 4 in xEventGroup.
		uxBits = xEventGroupClearBits(
								xEventGroup,	// The event group being updated.
								BIT_0 | BIT_4 );// The bits being cleared.

		if( ( uxBits & ( BIT_0 | BIT_4 ) ) == ( BIT_0 | BIT_4 ) )
		{
			// Both bit 0 and bit 4 were set before xEventGroupClearBits() was
			// called.  Both will now be clear (not set).
		}
		else if( ( uxBits & BIT_0 ) != 0 )
		{
			// Bit 0 was set before xEventGroupClearBits() was called.  It will
			// now be clear.
		}
		else if( ( uxBits & BIT_4 ) != 0 )
		{
			// Bit 4 was set before xEventGroupClearBits() was called.  It will
			// now be clear.
		}
		else
		{
			// Neither bit 0 nor bit 4 were set in the first place.
		}
   }
   
* \defgroup xEventGroupClearBits xEventGroupClearBits * \ingroup EventGroup */ EventBits_t xEventGroupClearBits( EventGroupHandle_t xEventGroup, const EventBits_t uxBitsToClear ) PRIVILEGED_FUNCTION; /** * event_groups.h *
	BaseType_t xEventGroupClearBitsFromISR( EventGroupHandle_t xEventGroup, const EventBits_t uxBitsToSet );
 
* * A version of xEventGroupClearBits() that can be called from an interrupt. * * Setting bits in an event group is not a deterministic operation because there * are an unknown number of tasks that may be waiting for the bit or bits being * set. FreeRTOS does not allow nondeterministic operations to be performed * while interrupts are disabled, so protects event groups that are accessed * from tasks by suspending the scheduler rather than disabling interrupts. As * a result event groups cannot be accessed directly from an interrupt service * routine. Therefore xEventGroupClearBitsFromISR() sends a message to the * timer task to have the clear operation performed in the context of the timer * task. * * @param xEventGroup The event group in which the bits are to be cleared. * * @param uxBitsToClear A bitwise value that indicates the bit or bits to clear. * For example, to clear bit 3 only, set uxBitsToClear to 0x08. To clear bit 3 * and bit 0 set uxBitsToClear to 0x09. * * @return If the request to execute the function was posted successfully then * pdPASS is returned, otherwise pdFALSE is returned. pdFALSE will be returned * if the timer service queue was full. * * Example usage:
   #define BIT_0	( 1 << 0 )
   #define BIT_4	( 1 << 4 )

   // An event group which it is assumed has already been created by a call to
   // xEventGroupCreate().
   EventGroupHandle_t xEventGroup;

   void anInterruptHandler( void )
   {
		// Clear bit 0 and bit 4 in xEventGroup.
		xResult = xEventGroupClearBitsFromISR(
							xEventGroup,	 // The event group being updated.
							BIT_0 | BIT_4 ); // The bits being set.

		if( xResult == pdPASS )
		{
			// The message was posted successfully.
		}
  }
   
* \defgroup xEventGroupClearBitsFromISR xEventGroupClearBitsFromISR * \ingroup EventGroup */ #if( configUSE_TRACE_FACILITY == 1 ) BaseType_t xEventGroupClearBitsFromISR( EventGroupHandle_t xEventGroup, const EventBits_t uxBitsToClear ) PRIVILEGED_FUNCTION; #else #define xEventGroupClearBitsFromISR( xEventGroup, uxBitsToClear ) xTimerPendFunctionCallFromISR( vEventGroupClearBitsCallback, ( void * ) xEventGroup, ( uint32_t ) uxBitsToClear, NULL ) #endif /** * event_groups.h *
	EventBits_t xEventGroupSetBits( EventGroupHandle_t xEventGroup, const EventBits_t uxBitsToSet );
 
* * Set bits within an event group. * This function cannot be called from an interrupt. xEventGroupSetBitsFromISR() * is a version that can be called from an interrupt. * * Setting bits in an event group will automatically unblock tasks that are * blocked waiting for the bits. * * @param xEventGroup The event group in which the bits are to be set. * * @param uxBitsToSet A bitwise value that indicates the bit or bits to set. * For example, to set bit 3 only, set uxBitsToSet to 0x08. To set bit 3 * and bit 0 set uxBitsToSet to 0x09. * * @return The value of the event group at the time the call to * xEventGroupSetBits() returns. There are two reasons why the returned value * might have the bits specified by the uxBitsToSet parameter cleared. First, * if setting a bit results in a task that was waiting for the bit leaving the * blocked state then it is possible the bit will be cleared automatically * (see the xClearBitOnExit parameter of xEventGroupWaitBits()). Second, any * unblocked (or otherwise Ready state) task that has a priority above that of * the task that called xEventGroupSetBits() will execute and may change the * event group value before the call to xEventGroupSetBits() returns. * * Example usage:
   #define BIT_0	( 1 << 0 )
   #define BIT_4	( 1 << 4 )

   void aFunction( EventGroupHandle_t xEventGroup )
   {
   EventBits_t uxBits;

		// Set bit 0 and bit 4 in xEventGroup.
		uxBits = xEventGroupSetBits(
							xEventGroup,	// The event group being updated.
							BIT_0 | BIT_4 );// The bits being set.

		if( ( uxBits & ( BIT_0 | BIT_4 ) ) == ( BIT_0 | BIT_4 ) )
		{
			// Both bit 0 and bit 4 remained set when the function returned.
		}
		else if( ( uxBits & BIT_0 ) != 0 )
		{
			// Bit 0 remained set when the function returned, but bit 4 was
			// cleared.  It might be that bit 4 was cleared automatically as a
			// task that was waiting for bit 4 was removed from the Blocked
			// state.
		}
		else if( ( uxBits & BIT_4 ) != 0 )
		{
			// Bit 4 remained set when the function returned, but bit 0 was
			// cleared.  It might be that bit 0 was cleared automatically as a
			// task that was waiting for bit 0 was removed from the Blocked
			// state.
		}
		else
		{
			// Neither bit 0 nor bit 4 remained set.  It might be that a task
			// was waiting for both of the bits to be set, and the bits were
			// cleared as the task left the Blocked state.
		}
   }
   
* \defgroup xEventGroupSetBits xEventGroupSetBits * \ingroup EventGroup */ EventBits_t xEventGroupSetBits( EventGroupHandle_t xEventGroup, const EventBits_t uxBitsToSet ) PRIVILEGED_FUNCTION; /** * event_groups.h *
	BaseType_t xEventGroupSetBitsFromISR( EventGroupHandle_t xEventGroup, const EventBits_t uxBitsToSet, BaseType_t *pxHigherPriorityTaskWoken );
 
* * A version of xEventGroupSetBits() that can be called from an interrupt. * * Setting bits in an event group is not a deterministic operation because there * are an unknown number of tasks that may be waiting for the bit or bits being * set. FreeRTOS does not allow nondeterministic operations to be performed in * interrupts or from critical sections. Therefore xEventGroupSetBitsFromISR() * sends a message to the timer task to have the set operation performed in the * context of the timer task - where a scheduler lock is used in place of a * critical section. * * @param xEventGroup The event group in which the bits are to be set. * * @param uxBitsToSet A bitwise value that indicates the bit or bits to set. * For example, to set bit 3 only, set uxBitsToSet to 0x08. To set bit 3 * and bit 0 set uxBitsToSet to 0x09. * * @param pxHigherPriorityTaskWoken As mentioned above, calling this function * will result in a message being sent to the timer daemon task. If the * priority of the timer daemon task is higher than the priority of the * currently running task (the task the interrupt interrupted) then * *pxHigherPriorityTaskWoken will be set to pdTRUE by * xEventGroupSetBitsFromISR(), indicating that a context switch should be * requested before the interrupt exits. For that reason * *pxHigherPriorityTaskWoken must be initialised to pdFALSE. See the * example code below. * * @return If the request to execute the function was posted successfully then * pdPASS is returned, otherwise pdFALSE is returned. pdFALSE will be returned * if the timer service queue was full. * * Example usage:
   #define BIT_0	( 1 << 0 )
   #define BIT_4	( 1 << 4 )

   // An event group which it is assumed has already been created by a call to
   // xEventGroupCreate().
   EventGroupHandle_t xEventGroup;

   void anInterruptHandler( void )
   {
   BaseType_t xHigherPriorityTaskWoken, xResult;

		// xHigherPriorityTaskWoken must be initialised to pdFALSE.
		xHigherPriorityTaskWoken = pdFALSE;

		// Set bit 0 and bit 4 in xEventGroup.
		xResult = xEventGroupSetBitsFromISR(
							xEventGroup,	// The event group being updated.
							BIT_0 | BIT_4   // The bits being set.
							&xHigherPriorityTaskWoken );

		// Was the message posted successfully?
		if( xResult == pdPASS )
		{
			// If xHigherPriorityTaskWoken is now set to pdTRUE then a context
			// switch should be requested.  The macro used is port specific and
			// will be either portYIELD_FROM_ISR() or portEND_SWITCHING_ISR() -
			// refer to the documentation page for the port being used.
			portYIELD_FROM_ISR( xHigherPriorityTaskWoken );
		}
  }
   
* \defgroup xEventGroupSetBitsFromISR xEventGroupSetBitsFromISR * \ingroup EventGroup */ #if( configUSE_TRACE_FACILITY == 1 ) BaseType_t xEventGroupSetBitsFromISR( EventGroupHandle_t xEventGroup, const EventBits_t uxBitsToSet, BaseType_t *pxHigherPriorityTaskWoken ) PRIVILEGED_FUNCTION; #else #define xEventGroupSetBitsFromISR( xEventGroup, uxBitsToSet, pxHigherPriorityTaskWoken ) xTimerPendFunctionCallFromISR( vEventGroupSetBitsCallback, ( void * ) xEventGroup, ( uint32_t ) uxBitsToSet, pxHigherPriorityTaskWoken ) #endif /** * event_groups.h *
	EventBits_t xEventGroupSync(	EventGroupHandle_t xEventGroup,
									const EventBits_t uxBitsToSet,
									const EventBits_t uxBitsToWaitFor,
									TickType_t xTicksToWait );
 
* * Atomically set bits within an event group, then wait for a combination of * bits to be set within the same event group. This functionality is typically * used to synchronise multiple tasks, where each task has to wait for the other * tasks to reach a synchronisation point before proceeding. * * This function cannot be used from an interrupt. * * The function will return before its block time expires if the bits specified * by the uxBitsToWait parameter are set, or become set within that time. In * this case all the bits specified by uxBitsToWait will be automatically * cleared before the function returns. * * @param xEventGroup The event group in which the bits are being tested. The * event group must have previously been created using a call to * xEventGroupCreate(). * * @param uxBitsToSet The bits to set in the event group before determining * if, and possibly waiting for, all the bits specified by the uxBitsToWait * parameter are set. * * @param uxBitsToWaitFor A bitwise value that indicates the bit or bits to test * inside the event group. For example, to wait for bit 0 and bit 2 set * uxBitsToWaitFor to 0x05. To wait for bits 0 and bit 1 and bit 2 set * uxBitsToWaitFor to 0x07. Etc. * * @param xTicksToWait The maximum amount of time (specified in 'ticks') to wait * for all of the bits specified by uxBitsToWaitFor to become set. * * @return The value of the event group at the time either the bits being waited * for became set, or the block time expired. Test the return value to know * which bits were set. If xEventGroupSync() returned because its timeout * expired then not all the bits being waited for will be set. If * xEventGroupSync() returned because all the bits it was waiting for were * set then the returned value is the event group value before any bits were * automatically cleared. * * Example usage:
 // Bits used by the three tasks.
 #define TASK_0_BIT		( 1 << 0 )
 #define TASK_1_BIT		( 1 << 1 )
 #define TASK_2_BIT		( 1 << 2 )

 #define ALL_SYNC_BITS ( TASK_0_BIT | TASK_1_BIT | TASK_2_BIT )

 // Use an event group to synchronise three tasks.  It is assumed this event
 // group has already been created elsewhere.
 EventGroupHandle_t xEventBits;

 void vTask0( void *pvParameters )
 {
 EventBits_t uxReturn;
 TickType_t xTicksToWait = 100 / portTICK_PERIOD_MS;

	 for( ;; )
	 {
		// Perform task functionality here.

		// Set bit 0 in the event flag to note this task has reached the
		// sync point.  The other two tasks will set the other two bits defined
		// by ALL_SYNC_BITS.  All three tasks have reached the synchronisation
		// point when all the ALL_SYNC_BITS are set.  Wait a maximum of 100ms
		// for this to happen.
		uxReturn = xEventGroupSync( xEventBits, TASK_0_BIT, ALL_SYNC_BITS, xTicksToWait );

		if( ( uxReturn & ALL_SYNC_BITS ) == ALL_SYNC_BITS )
		{
			// All three tasks reached the synchronisation point before the call
			// to xEventGroupSync() timed out.
		}
	}
 }

 void vTask1( void *pvParameters )
 {
	 for( ;; )
	 {
		// Perform task functionality here.

		// Set bit 1 in the event flag to note this task has reached the
		// synchronisation point.  The other two tasks will set the other two
		// bits defined by ALL_SYNC_BITS.  All three tasks have reached the
		// synchronisation point when all the ALL_SYNC_BITS are set.  Wait
		// indefinitely for this to happen.
		xEventGroupSync( xEventBits, TASK_1_BIT, ALL_SYNC_BITS, portMAX_DELAY );

		// xEventGroupSync() was called with an indefinite block time, so
		// this task will only reach here if the syncrhonisation was made by all
		// three tasks, so there is no need to test the return value.
	 }
 }

 void vTask2( void *pvParameters )
 {
	 for( ;; )
	 {
		// Perform task functionality here.

		// Set bit 2 in the event flag to note this task has reached the
		// synchronisation point.  The other two tasks will set the other two
		// bits defined by ALL_SYNC_BITS.  All three tasks have reached the
		// synchronisation point when all the ALL_SYNC_BITS are set.  Wait
		// indefinitely for this to happen.
		xEventGroupSync( xEventBits, TASK_2_BIT, ALL_SYNC_BITS, portMAX_DELAY );

		// xEventGroupSync() was called with an indefinite block time, so
		// this task will only reach here if the syncrhonisation was made by all
		// three tasks, so there is no need to test the return value.
	}
 }

 
* \defgroup xEventGroupSync xEventGroupSync * \ingroup EventGroup */ EventBits_t xEventGroupSync( EventGroupHandle_t xEventGroup, const EventBits_t uxBitsToSet, const EventBits_t uxBitsToWaitFor, TickType_t xTicksToWait ) PRIVILEGED_FUNCTION; /** * event_groups.h *
	EventBits_t xEventGroupGetBits( EventGroupHandle_t xEventGroup );
 
* * Returns the current value of the bits in an event group. This function * cannot be used from an interrupt. * * @param xEventGroup The event group being queried. * * @return The event group bits at the time xEventGroupGetBits() was called. * * \defgroup xEventGroupGetBits xEventGroupGetBits * \ingroup EventGroup */ #define xEventGroupGetBits( xEventGroup ) xEventGroupClearBits( xEventGroup, 0 ) /** * event_groups.h *
	EventBits_t xEventGroupGetBitsFromISR( EventGroupHandle_t xEventGroup );
 
* * A version of xEventGroupGetBits() that can be called from an ISR. * * @param xEventGroup The event group being queried. * * @return The event group bits at the time xEventGroupGetBitsFromISR() was called. * * \defgroup xEventGroupGetBitsFromISR xEventGroupGetBitsFromISR * \ingroup EventGroup */ EventBits_t xEventGroupGetBitsFromISR( EventGroupHandle_t xEventGroup ) PRIVILEGED_FUNCTION; /** * event_groups.h *
	void xEventGroupDelete( EventGroupHandle_t xEventGroup );
 
* * Delete an event group that was previously created by a call to * xEventGroupCreate(). Tasks that are blocked on the event group will be * unblocked and obtain 0 as the event group's value. * * @param xEventGroup The event group being deleted. */ void vEventGroupDelete( EventGroupHandle_t xEventGroup ) PRIVILEGED_FUNCTION; /* For internal use only. */ void vEventGroupSetBitsCallback( void *pvEventGroup, const uint32_t ulBitsToSet ) PRIVILEGED_FUNCTION; void vEventGroupClearBitsCallback( void *pvEventGroup, const uint32_t ulBitsToClear ) PRIVILEGED_FUNCTION; #if (configUSE_TRACE_FACILITY == 1) UBaseType_t uxEventGroupGetNumber( void* xEventGroup ) PRIVILEGED_FUNCTION; void vEventGroupSetNumber( void* xEventGroup, UBaseType_t uxEventGroupNumber ) PRIVILEGED_FUNCTION; #endif #ifdef __cplusplus } #endif #endif /* EVENT_GROUPS_H */