event_groups.h
EventBits_t xEventGroupClearBits(
EventGroupHandle_t xEventGroup,
const EventBits_t uxBitsToClear );
Clear bits (flags) within an RTOS event group. This function cannot be called from an
interrupt. See xEventGroupClearBitsFromISR() for a version that can be
called from an interrupt.
The RTOS source file FreeRTOS/source/event_groups.c must be
included in the build for the xEventGroupClearBits() function to be available.
-
Parameters:
-
xEventGroup
|
The event group in which the bits are to be cleared. The
event group must have previously been created using a call to
xEventGroupCreate().
|
uxBitsToClear
|
A bitwise value that indicates the bit or bits to clear
in the event group. For example set uxBitsToClear to 0x08 to
clear just bit 3. Set uxBitsToClear to 0x09 to clear bit 3
and bit 0.
|
-
Returns:
-
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. */
}
}
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