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<div class="title">xSemaphoreCreateBinaryStatic</div> </div>
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<p>semphr. h </p><pre>SemaphoreHandle_t xSemaphoreCreateBinaryStatic( StaticSemaphore_t *pxSemaphoreBuffer )</pre><p>Creates a new binary semaphore instance, and returns a handle by which the new semaphore can be referenced.</p>
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<p>NOTE: In many usage scenarios it is faster and more memory efficient to use a direct to task notification in place of a binary semaphore! <a href="http://www.freertos.org/RTOS-task-notifications.html">http://www.freertos.org/RTOS-task-notifications.html</a></p>
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<p>Internally, within the FreeRTOS implementation, binary semaphores use a block of memory, in which the semaphore structure is stored. If a binary semaphore is created using xSemaphoreCreateBinary() then the required memory is automatically dynamically allocated inside the xSemaphoreCreateBinary() function. (see <a href="http://www.freertos.org/a00111.html">http://www.freertos.org/a00111.html</a>). If a binary semaphore is created using xSemaphoreCreateBinaryStatic() then the application writer must provide the memory. xSemaphoreCreateBinaryStatic() therefore allows a binary semaphore to be created without using any dynamic memory allocation.</p>
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<p>This type of semaphore can be used for pure synchronisation between tasks or between an interrupt and a task. The semaphore need not be given back once obtained, so one task/interrupt can continuously 'give' the semaphore while another continuously 'takes' the semaphore. For this reason this type of semaphore does not use a priority inheritance mechanism. For an alternative that does use priority inheritance see xSemaphoreCreateMutex().</p>
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<dl class="params"><dt>Parameters</dt><dd>
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<table class="params">
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<tr><td class="paramname">pxSemaphoreBuffer</td><td>Must point to a variable of type StaticSemaphore_t, which will then be used to hold the semaphore's data structure, removing the need for the memory to be allocated dynamically.</td></tr>
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</table>
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</dd>
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</dl>
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<dl class="section return"><dt>Returns</dt><dd>If the semaphore is created then a handle to the created semaphore is returned. If pxSemaphoreBuffer is NULL then NULL is returned.</dd></dl>
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<p>Example usage: </p><pre>
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SemaphoreHandle_t xSemaphore = NULL;
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StaticSemaphore_t xSemaphoreBuffer;</pre><pre>void vATask( void * pvParameters )
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{
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// Semaphore cannot be used before a call to xSemaphoreCreateBinary().
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// The semaphore's data structures will be placed in the xSemaphoreBuffer
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// variable, the address of which is passed into the function. The
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// function's parameter is not NULL, so the function will not attempt any
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// dynamic memory allocation, and therefore the function will not return
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// return NULL.
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xSemaphore = xSemaphoreCreateBinary( &xSemaphoreBuffer );</pre><pre> // Rest of task code goes here.
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}
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