/* 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 group 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 group 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 group 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. */
}
}
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