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 <span id="projectnumber">Version 1.03</span>
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<a href="#func-members">Functions</a> </div>
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<div class="title">Semaphores<div class="ingroups"><a class="el" href="group__CMSIS__RTOS__InterThread.html">Inter-Thread Communication and Resource Sharing</a></div></div> </div>
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<p>Access shared resources simultaneously from different threads.
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<a href="#details">More...</a></p>
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<table class="memberdecls">
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<tr class="heading"><td colspan="2"><h2 class="groupheader"><a name="define-members"></a>
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Macros</h2></td></tr>
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<tr class="memitem:ga7da4c7bfb340779c9fc7b321f5ab3e3a"><td class="memItemLeft" align="right" valign="top">#define </td><td class="memItemRight" valign="bottom"><a class="el" href="group__CMSIS__RTOS__SemaphoreMgmt.html#ga7da4c7bfb340779c9fc7b321f5ab3e3a">osFeature_Semaphore</a>   30</td></tr>
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<tr class="memdesc:ga7da4c7bfb340779c9fc7b321f5ab3e3a"><td class="mdescLeft"> </td><td class="mdescRight">maximum count for <a class="el" href="group__CMSIS__RTOS__SemaphoreMgmt.html#ga97381e8e55cd47cec390bf57c96d6edb">osSemaphoreCreate</a> function <a href="#ga7da4c7bfb340779c9fc7b321f5ab3e3a">More...</a><br/></td></tr>
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<tr class="separator:ga7da4c7bfb340779c9fc7b321f5ab3e3a"><td class="memSeparator" colspan="2"> </td></tr>
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<tr class="memitem:ga9e66fe361749071e5ab87826c43c2f1b"><td class="memItemLeft" align="right" valign="top">#define </td><td class="memItemRight" valign="bottom"><a class="el" href="group__CMSIS__RTOS__SemaphoreMgmt.html#ga9e66fe361749071e5ab87826c43c2f1b">osSemaphoreDef</a>(name)   const <a class="el" href="structosSemaphoreDef__t.html">osSemaphoreDef_t</a> os_semaphore_def_##name = { 0 }</td></tr>
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<tr class="memdesc:ga9e66fe361749071e5ab87826c43c2f1b"><td class="mdescLeft"> </td><td class="mdescRight">Define a Semaphore object. <a href="#ga9e66fe361749071e5ab87826c43c2f1b">More...</a><br/></td></tr>
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<tr class="separator:ga9e66fe361749071e5ab87826c43c2f1b"><td class="memSeparator" colspan="2"> </td></tr>
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<tr class="memitem:ga03761ee8d2c3cd4544e18364ab301dac"><td class="memItemLeft" align="right" valign="top">#define </td><td class="memItemRight" valign="bottom"><a class="el" href="group__CMSIS__RTOS__SemaphoreMgmt.html#ga03761ee8d2c3cd4544e18364ab301dac">osSemaphore</a>(name)   &os_semaphore_def_##name</td></tr>
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<tr class="memdesc:ga03761ee8d2c3cd4544e18364ab301dac"><td class="mdescLeft"> </td><td class="mdescRight">Access a Semaphore definition. <a href="#ga03761ee8d2c3cd4544e18364ab301dac">More...</a><br/></td></tr>
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<tr class="separator:ga03761ee8d2c3cd4544e18364ab301dac"><td class="memSeparator" colspan="2"> </td></tr>
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</table><table class="memberdecls">
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<tr class="heading"><td colspan="2"><h2 class="groupheader"><a name="func-members"></a>
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Functions</h2></td></tr>
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<tr class="memitem:ga97381e8e55cd47cec390bf57c96d6edb"><td class="memItemLeft" align="right" valign="top"><a class="el" href="cmsis__os_8h.html#aa8968896c84094aa973683c84fa06f84">osSemaphoreId</a> </td><td class="memItemRight" valign="bottom"><a class="el" href="group__CMSIS__RTOS__SemaphoreMgmt.html#ga97381e8e55cd47cec390bf57c96d6edb">osSemaphoreCreate</a> (const <a class="el" href="structosSemaphoreDef__t.html">osSemaphoreDef_t</a> *semaphore_def, int32_t count)</td></tr>
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<tr class="memdesc:ga97381e8e55cd47cec390bf57c96d6edb"><td class="mdescLeft"> </td><td class="mdescRight">Create and Initialize a Semaphore object used for managing resources. <a href="#ga97381e8e55cd47cec390bf57c96d6edb">More...</a><br/></td></tr>
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<tr class="separator:ga97381e8e55cd47cec390bf57c96d6edb"><td class="memSeparator" colspan="2"> </td></tr>
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<tr class="memitem:gacc15b0fc8ce1167fe43da33042e62098"><td class="memItemLeft" align="right" valign="top">int32_t </td><td class="memItemRight" valign="bottom"><a class="el" href="group__CMSIS__RTOS__SemaphoreMgmt.html#gacc15b0fc8ce1167fe43da33042e62098">osSemaphoreWait</a> (<a class="el" href="cmsis__os_8h.html#aa8968896c84094aa973683c84fa06f84">osSemaphoreId</a> semaphore_id, uint32_t millisec)</td></tr>
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<tr class="memdesc:gacc15b0fc8ce1167fe43da33042e62098"><td class="mdescLeft"> </td><td class="mdescRight">Wait until a Semaphore token becomes available. <a href="#gacc15b0fc8ce1167fe43da33042e62098">More...</a><br/></td></tr>
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<tr class="separator:gacc15b0fc8ce1167fe43da33042e62098"><td class="memSeparator" colspan="2"> </td></tr>
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<tr class="memitem:gab108914997c49e14d8ff1ae0d1988ca0"><td class="memItemLeft" align="right" valign="top"><a class="el" href="group__CMSIS__RTOS__Status.html#gae2e091fefc4c767117727bd5aba4d99e">osStatus</a> </td><td class="memItemRight" valign="bottom"><a class="el" href="group__CMSIS__RTOS__SemaphoreMgmt.html#gab108914997c49e14d8ff1ae0d1988ca0">osSemaphoreRelease</a> (<a class="el" href="cmsis__os_8h.html#aa8968896c84094aa973683c84fa06f84">osSemaphoreId</a> semaphore_id)</td></tr>
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<tr class="memdesc:gab108914997c49e14d8ff1ae0d1988ca0"><td class="mdescLeft"> </td><td class="mdescRight">Release a Semaphore token. <a href="#gab108914997c49e14d8ff1ae0d1988ca0">More...</a><br/></td></tr>
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<tr class="separator:gab108914997c49e14d8ff1ae0d1988ca0"><td class="memSeparator" colspan="2"> </td></tr>
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<tr class="memitem:gabae2801ac2c096f6e8c69a264908f595"><td class="memItemLeft" align="right" valign="top"><a class="el" href="group__CMSIS__RTOS__Status.html#gae2e091fefc4c767117727bd5aba4d99e">osStatus</a> </td><td class="memItemRight" valign="bottom"><a class="el" href="group__CMSIS__RTOS__SemaphoreMgmt.html#gabae2801ac2c096f6e8c69a264908f595">osSemaphoreDelete</a> (<a class="el" href="cmsis__os_8h.html#aa8968896c84094aa973683c84fa06f84">osSemaphoreId</a> semaphore_id)</td></tr>
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<tr class="memdesc:gabae2801ac2c096f6e8c69a264908f595"><td class="mdescLeft"> </td><td class="mdescRight">Delete a Semaphore that was created by <a class="el" href="group__CMSIS__RTOS__SemaphoreMgmt.html#ga97381e8e55cd47cec390bf57c96d6edb">osSemaphoreCreate</a>. <a href="#gabae2801ac2c096f6e8c69a264908f595">More...</a><br/></td></tr>
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<tr class="separator:gabae2801ac2c096f6e8c69a264908f595"><td class="memSeparator" colspan="2"> </td></tr>
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</table>
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<a name="details" id="details"></a><h2 class="groupheader">Description</h2>
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<p>Semaphores are used to manage and protect access to shared resources. Semaphores are very similar to <a class="el" href="group__CMSIS__RTOS__MutexMgmt.html">Mutexes</a>. Whereas a Mutex permits just one thread to access a shared resource at a time, a semaphore can be used to permit a fixed number of threads to access a pool of shared resources. Using semaphores, access to a group of identical peripherals can be managed (for example multiple DMA channels).</p>
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<div class="image">
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<img src="Semaphore.png" alt="Semaphore.png"/>
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<div class="caption">
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CMSIS-RTOS Semaphore</div></div>
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<p> A semaphore object should be initialized to the maximum number of available tokens. This number of available resources is specified as parameter of the <a class="el" href="group__CMSIS__RTOS__SemaphoreMgmt.html#ga97381e8e55cd47cec390bf57c96d6edb">osSemaphoreCreate</a> function. Each time a semaphore token is obtained with <a class="el" href="group__CMSIS__RTOS__SemaphoreMgmt.html#gacc15b0fc8ce1167fe43da33042e62098">osSemaphoreWait</a>, the semaphore count is decremented. When the semaphore count is 0, no semaphore token can be obtained. The thread that tries to obtain the semaphore token needs to wait until the next token is free. Semaphores are released with <a class="el" href="group__CMSIS__RTOS__SemaphoreMgmt.html#gab108914997c49e14d8ff1ae0d1988ca0">osSemaphoreRelease</a> incrementing the semaphore count.</p>
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<dl class="section note"><dt>Note</dt><dd>Semaphore tokens can be acquired from threads and released from threads and ISRs.</dd></dl>
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<h2>Working with Semaphores </h2>
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<p>Follow these steps to create and use a semaphore:</p>
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<ol type="1">
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<li>Declare the semaphore container and initialize the semaphore: <div class="fragment"><div class="line"><a class="code" href="group__CMSIS__RTOS__SemaphoreMgmt.html#ga9e66fe361749071e5ab87826c43c2f1b">osSemaphoreDef</a> (my_semaphore); <span class="comment">// Declare semaphore</span></div>
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<div class="line"><a class="code" href="cmsis__os_8h.html#aa8968896c84094aa973683c84fa06f84">osSemaphoreId</a> (my_semaphore_id); <span class="comment">// Semaphore ID</span></div>
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</div><!-- fragment --></li>
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<li>Initialize the semaphore container with a number of tokens within a thread: <div class="fragment"><div class="line">my_semaphore_id = <a class="code" href="group__CMSIS__RTOS__SemaphoreMgmt.html#ga97381e8e55cd47cec390bf57c96d6edb">osSemaphoreCreate</a>(<a class="code" href="group__CMSIS__RTOS__SemaphoreMgmt.html#ga03761ee8d2c3cd4544e18364ab301dac">osSemaphore</a>(my_semaphore), 4); <span class="comment">// Create semaphore with 4 tokens</span></div>
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</div><!-- fragment --> <b>Important:</b> semaphore tokens can be created and destroyed as threads run. This means that can initialize a semaphore with zero tokens and then use one thread to add/create tokens to the semaphore while a second thread removes them. In this way you can distinguish between producer and consumer threads.</li>
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<li>Acquire a token from the semaphore container: <div class="fragment"><div class="line"><a class="code" href="group__CMSIS__RTOS__SemaphoreMgmt.html#gacc15b0fc8ce1167fe43da33042e62098">osSemaphoreWait</a>(my_semaphore_id, <a class="code" href="cmsis__os_8h.html#a9eb9a7a797a42e4b55eb171ecc609ddb">osWaitForever</a>);</div>
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</div><!-- fragment --></li>
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<li>When finished using the semaphore resource, send the token back to the semaphore container: <div class="fragment"><div class="line"><a class="code" href="group__CMSIS__RTOS__SemaphoreMgmt.html#gab108914997c49e14d8ff1ae0d1988ca0">osSemaphoreRelease</a>(my_semaphore_id);</div>
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</div><!-- fragment --></li>
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</ol>
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<h2>Semaphore Use Cases </h2>
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<p>Due to their flexibility, semaphores cover a wide range of synchronizing applications. At the same time, they are perhaps the most challenging RTOS object to understand. The following explains a use case for semaphores, taken from the book <a href="http://www.greenteapress.com/semaphores/" target="_blank">The Little Book Of Semaphores</a> by Allen B. Downey which is available for free download.</p>
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<p><b>Non-binary Semaphore (Multiplex)</b></p>
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<p>A multiplex limits the number of threads that can access a critical section of code. For example, this could be a function accessing DMA resources which can only support a limited number of calls.</p>
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<p>To allow multiple threads to run the function, initialize a semaphore to the maximum number of threads that can be allowed. The number of tokens in the semaphore represents the number of additional threads that may enter. If this number is zero, then the next thread trying to access the function will have to wait until one of the other threads exits and releases its token. When all threads have exited the token number is back to n. Ths following example shows the code for one of the threads that might access the resource:</p>
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<div class="fragment"><div class="line"><a class="code" href="group__CMSIS__RTOS__SemaphoreMgmt.html#ga9e66fe361749071e5ab87826c43c2f1b">osSemaphoreDef</a>(multiplex);</div>
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<div class="line"><a class="code" href="cmsis__os_8h.html#aa8968896c84094aa973683c84fa06f84">osSemaphoreId</a> (multiplex_id);</div>
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<div class="line"> </div>
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<div class="line"><span class="keywordtype">void</span> thread_n (<span class="keywordtype">void</span>)</div>
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<div class="line"> {</div>
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<div class="line"> multiplex_id = <a class="code" href="group__CMSIS__RTOS__SemaphoreMgmt.html#ga97381e8e55cd47cec390bf57c96d6edb">osSemaphoreCreate</a>(<a class="code" href="group__CMSIS__RTOS__SemaphoreMgmt.html#ga03761ee8d2c3cd4544e18364ab301dac">osSemaphore</a>(multiplex), 3);</div>
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<div class="line"> <span class="keywordflow">while</span>(1)</div>
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<div class="line"> {</div>
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<div class="line"> <a class="code" href="group__CMSIS__RTOS__SemaphoreMgmt.html#gacc15b0fc8ce1167fe43da33042e62098">osSemaphoreWait</a>(multiplex_id, <a class="code" href="cmsis__os_8h.html#a9eb9a7a797a42e4b55eb171ecc609ddb">osWaitForever</a>);</div>
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<div class="line"> <span class="comment">// do something</span></div>
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<div class="line"> <a class="code" href="group__CMSIS__RTOS__SemaphoreMgmt.html#gab108914997c49e14d8ff1ae0d1988ca0">osSemaphoreRelease</a>(multiplex_id);</div>
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<div class="line"> }</div>
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<div class="line"> }</div>
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</div><!-- fragment --> <h2 class="groupheader">Macro Definition Documentation</h2>
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<a class="anchor" id="ga7da4c7bfb340779c9fc7b321f5ab3e3a"></a>
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<div class="memitem">
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<td class="memname">#define osFeature_Semaphore   30</td>
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</div><div class="memdoc">
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<p>A CMSIS-RTOS implementation may support semaphores. The value <a class="el" href="group__CMSIS__RTOS__SemaphoreMgmt.html#ga7da4c7bfb340779c9fc7b321f5ab3e3a">osFeature_Semaphore</a> indicates the maximum index count for a semaphore.</p>
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<p><a class="el" href="rtxImplementation.html">CMSIS-RTOS RTX</a> Setting: <b>osFeature_Semaphore</b> is 65535 </p>
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<a class="anchor" id="ga03761ee8d2c3cd4544e18364ab301dac"></a>
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<td class="memname">#define osSemaphore</td>
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<td>(</td>
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<td class="paramtype"> </td>
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<td class="paramname">name</td><td>)</td>
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<td>   &os_semaphore_def_##name</td>
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<p>Access to semaphore object for the functions <a class="el" href="group__CMSIS__RTOS__SemaphoreMgmt.html#ga97381e8e55cd47cec390bf57c96d6edb">osSemaphoreCreate</a>.</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">name</td><td>name of the semaphore object. </td></tr>
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</table>
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</dd>
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</dl>
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<dl class="section note"><dt>Note</dt><dd>CAN BE CHANGED: The parameter to <b>osSemaphore</b> shall be consistent but the macro body is implementation specific in every CMSIS-RTOS. </dd></dl>
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<td class="memname">#define osSemaphoreDef</td>
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<td>(</td>
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<td class="paramtype"> </td>
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<td class="paramname">name</td><td>)</td>
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<td>   const <a class="el" href="structosSemaphoreDef__t.html">osSemaphoreDef_t</a> os_semaphore_def_##name = { 0 }</td>
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</div><div class="memdoc">
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<p>Define a semaphore object that is referenced by <a class="el" href="group__CMSIS__RTOS__SemaphoreMgmt.html#ga03761ee8d2c3cd4544e18364ab301dac">osSemaphore</a>.</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">name</td><td>name of the semaphore object. </td></tr>
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</table>
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</dd>
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</dl>
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<dl class="section note"><dt>Note</dt><dd>CAN BE CHANGED: The parameter to <b>osSemaphoreDef</b> shall be consistent but the macro body is implementation specific in every CMSIS-RTOS. </dd></dl>
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</div>
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</div>
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<h2 class="groupheader">Function Documentation</h2>
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<a class="anchor" id="ga97381e8e55cd47cec390bf57c96d6edb"></a>
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<td class="memname"><a class="el" href="cmsis__os_8h.html#aa8968896c84094aa973683c84fa06f84">osSemaphoreId</a> osSemaphoreCreate </td>
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<td>(</td>
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<td class="paramtype">const <a class="el" href="structosSemaphoreDef__t.html">osSemaphoreDef_t</a> * </td>
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<td class="paramname"><em>semaphore_def</em>, </td>
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</tr>
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<tr>
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<td class="paramkey"></td>
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<td></td>
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<td class="paramtype">int32_t </td>
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<td class="paramname"><em>count</em> </td>
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</tr>
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<tr>
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<td></td>
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<td>)</td>
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<td></td><td></td>
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</tr>
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</table>
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</div><div class="memdoc">
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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="paramdir">[in]</td><td class="paramname">semaphore_def</td><td>semaphore definition referenced with <a class="el" href="group__CMSIS__RTOS__SemaphoreMgmt.html#ga03761ee8d2c3cd4544e18364ab301dac">osSemaphore</a>. </td></tr>
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<tr><td class="paramdir">[in]</td><td class="paramname">count</td><td>number of available resources. </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>semaphore ID for reference by other functions or NULL in case of error. </dd></dl>
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<dl class="section note"><dt>Note</dt><dd>MUST REMAIN UNCHANGED: <b>osSemaphoreCreate</b> shall be consistent in every CMSIS-RTOS.</dd></dl>
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<p>Create and initialize a Semaphore object that is used to manage access to shared resources. The parameter <em>count</em> specifies the number of available resources. The <em>count</em> value 1 creates a binary semaphore.</p>
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<dl class="section note"><dt>Note</dt><dd>Cannot be called from <a class="el" href="functionOverview.html#CMSIS_RTOS_ISR_Calls">Interrupt Service Routines</a>.</dd></dl>
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<p><b>Code Example</b> </p>
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<div class="fragment"><div class="line"><span class="preprocessor">#include "<a class="code" href="cmsis__os_8h.html">cmsis_os.h</a>"</span></div>
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<div class="line"> </div>
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<div class="line"><a class="code" href="cmsis__os_8h.html#adfeb153a84a81309e2d958268197617f">osThreadId</a> tid_thread1; <span class="comment">// ID for thread 1</span></div>
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<div class="line"><a class="code" href="cmsis__os_8h.html#adfeb153a84a81309e2d958268197617f">osThreadId</a> tid_thread2; <span class="comment">// ID for thread 2</span></div>
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<div class="line"> </div>
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<div class="line"><a class="code" href="cmsis__os_8h.html#aa8968896c84094aa973683c84fa06f84">osSemaphoreId</a> semaphore; <span class="comment">// Semaphore ID</span></div>
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<div class="line"><a class="code" href="group__CMSIS__RTOS__SemaphoreMgmt.html#ga9e66fe361749071e5ab87826c43c2f1b">osSemaphoreDef</a>(semaphore); <span class="comment">// Semaphore definition</span></div>
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<div class="line"> </div>
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<div class="line"><span class="comment">//</span></div>
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<div class="line"><span class="comment">// Thread 1 - High Priority - Active every 3ms</span></div>
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<div class="line"><span class="comment">//</span></div>
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<div class="line"><span class="keywordtype">void</span> thread1 (<span class="keywordtype">void</span> <span class="keyword">const</span> *argument) {</div>
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<div class="line"> int32_t value;</div>
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<div class="line"></div>
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<div class="line"> <span class="keywordflow">while</span> (1) {</div>
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<div class="line"> <a class="code" href="group__CMSIS__RTOS__Wait.html#ga02e19d5e723bfb06ba9324d625162255">osDelay</a>(3); <span class="comment">// Pass control to other tasks for 3ms</span></div>
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<div class="line"> val = <a class="code" href="group__CMSIS__RTOS__SemaphoreMgmt.html#gacc15b0fc8ce1167fe43da33042e62098">osSemaphoreWait</a> (semaphore, 1); <span class="comment">// Wait 1ms for the free semaphore</span></div>
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<div class="line"> <span class="keywordflow">if</span> (val > 0) {</div>
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<div class="line"> <span class="comment">// If there was no time-out the semaphore was acquired</span></div>
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<div class="line"> : <span class="comment">// OK, the interface is free now, use it.</span></div>
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<div class="line"> <a class="code" href="group__CMSIS__RTOS__SemaphoreMgmt.html#gab108914997c49e14d8ff1ae0d1988ca0">osSemaphoreRelease</a> (semaphore); <span class="comment">// Return a token back to a semaphore</span></div>
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<div class="line"> }</div>
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<div class="line"> }</div>
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<div class="line">}</div>
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<div class="line"> </div>
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<div class="line"><span class="comment">//</span></div>
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<div class="line"><span class="comment">// Thread 2 - Normal Priority - looks for a free semaphore and uses</span></div>
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<div class="line"><span class="comment">// the resource whenever it is available</span></div>
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<div class="line"><span class="comment">//</span></div>
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<div class="line"><span class="keywordtype">void</span> thread2 (<span class="keywordtype">void</span> <span class="keyword">const</span> *argument) {</div>
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<div class="line"> <span class="keywordflow">while</span> (1) {</div>
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<div class="line"> <a class="code" href="group__CMSIS__RTOS__SemaphoreMgmt.html#gacc15b0fc8ce1167fe43da33042e62098">osSemaphoreWait</a> (semaphore, <a class="code" href="cmsis__os_8h.html#a9eb9a7a797a42e4b55eb171ecc609ddb">osWaitForever</a>); <span class="comment">// Wait indefinitely for a free semaphore</span></div>
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<div class="line"> <span class="comment">// OK, the interface is free now, use it.</span></div>
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<div class="line"> :</div>
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<div class="line"> <a class="code" href="group__CMSIS__RTOS__SemaphoreMgmt.html#gab108914997c49e14d8ff1ae0d1988ca0">osSemaphoreRelease</a> (semaphore); <span class="comment">// Return a token back to a semaphore.</span></div>
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<div class="line"> }</div>
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<div class="line">}</div>
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<div class="line"> </div>
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<div class="line"><span class="comment">// Thread definitions </span></div>
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<div class="line"><a class="code" href="group__CMSIS__RTOS__ThreadMgmt.html#gaee93d929beb350f16e5cc7fa602e229f">osThreadDef</a>(thread1, <a class="code" href="cmsis__os_8h.html#ga7f2b42f1983b9107775ec2a1c69a849aa914433934143a9ba767e59577c56e6c2">osPriorityHigh</a>, 1, 0);</div>
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<div class="line"><a class="code" href="group__CMSIS__RTOS__ThreadMgmt.html#gaee93d929beb350f16e5cc7fa602e229f">osThreadDef</a>(thread2, <a class="code" href="cmsis__os_8h.html#ga7f2b42f1983b9107775ec2a1c69a849aa45a2895ad30c79fb97de18cac7cc19f1">osPriorityNormal</a>, 1, 0);</div>
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<div class="line"> </div>
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<div class="line"><span class="keywordtype">void</span> StartApplication (<span class="keywordtype">void</span>) {</div>
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<div class="line"> semaphore = <a class="code" href="group__CMSIS__RTOS__SemaphoreMgmt.html#ga97381e8e55cd47cec390bf57c96d6edb">osSemaphoreCreate</a>(<a class="code" href="group__CMSIS__RTOS__SemaphoreMgmt.html#ga03761ee8d2c3cd4544e18364ab301dac">osSemaphore</a>(semaphore), 1);</div>
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<div class="line"></div>
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<div class="line"> tid_thread1 = <a class="code" href="group__CMSIS__RTOS__ThreadMgmt.html#gac59b5713cb083702dce759c73fd90dff">osThreadCreate</a>(<a class="code" href="group__CMSIS__RTOS__ThreadMgmt.html#gaf0c7c6b5e09f8be198312144b5c9e453">osThread</a>(thread1), NULL);</div>
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<div class="line"> tid_thread2 = <a class="code" href="group__CMSIS__RTOS__ThreadMgmt.html#gac59b5713cb083702dce759c73fd90dff">osThreadCreate</a>(<a class="code" href="group__CMSIS__RTOS__ThreadMgmt.html#gaf0c7c6b5e09f8be198312144b5c9e453">osThread</a>(thread2), NULL);</div>
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<div class="line"> :</div>
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<div class="line">}</div>
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</div><!-- fragment -->
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</div>
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<a class="anchor" id="gabae2801ac2c096f6e8c69a264908f595"></a>
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<td class="memname"><a class="el" href="group__CMSIS__RTOS__Status.html#gae2e091fefc4c767117727bd5aba4d99e">osStatus</a> osSemaphoreDelete </td>
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<td>(</td>
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<td class="paramtype"><a class="el" href="cmsis__os_8h.html#aa8968896c84094aa973683c84fa06f84">osSemaphoreId</a> </td>
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<td class="paramname"><em>semaphore_id</em></td><td>)</td>
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<td></td>
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</div><div class="memdoc">
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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="paramdir">[in]</td><td class="paramname">semaphore_id</td><td>semaphore object referenced with <a class="el" href="group__CMSIS__RTOS__SemaphoreMgmt.html#ga97381e8e55cd47cec390bf57c96d6edb">osSemaphoreCreate</a>. </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>status code that indicates the execution status of the function. </dd></dl>
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<dl class="section note"><dt>Note</dt><dd>MUST REMAIN UNCHANGED: <b>osSemaphoreDelete</b> shall be consistent in every CMSIS-RTOS.</dd></dl>
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<p>Delete a Semaphore object. The function releases internal memory obtained for Semaphore handling. After this call the <em>semaphore_id</em> is no longer valid and cannot be used. The Semaphore may be created again using the function <a class="el" href="group__CMSIS__RTOS__SemaphoreMgmt.html#ga97381e8e55cd47cec390bf57c96d6edb">osSemaphoreCreate</a>.</p>
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<p><b><a class="el" href="group__CMSIS__RTOS__Status.html">Status and Error Codes</a></b><br/>
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</p>
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<ul>
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<li><em>osOK:</em> the semaphore object has been deleted.</li>
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<li><em>osErrorISR:</em> <a class="el" href="group__CMSIS__RTOS__SemaphoreMgmt.html#gabae2801ac2c096f6e8c69a264908f595">osSemaphoreDelete</a> cannot be called from interrupt service routines.</li>
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<li><em>osErrorResource:</em> the semaphore object could not be deleted.</li>
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<li><em>osErrorParameter:</em> the parameter <em>semaphore_id</em> is incorrect.</li>
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</ul>
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<dl class="section note"><dt>Note</dt><dd>Cannot be called from <a class="el" href="functionOverview.html#CMSIS_RTOS_ISR_Calls">Interrupt Service Routines</a>. </dd></dl>
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<a class="anchor" id="gab108914997c49e14d8ff1ae0d1988ca0"></a>
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<td class="memname"><a class="el" href="group__CMSIS__RTOS__Status.html#gae2e091fefc4c767117727bd5aba4d99e">osStatus</a> osSemaphoreRelease </td>
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<td>(</td>
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<td class="paramtype"><a class="el" href="cmsis__os_8h.html#aa8968896c84094aa973683c84fa06f84">osSemaphoreId</a> </td>
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<td class="paramname"><em>semaphore_id</em></td><td>)</td>
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<td></td>
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</div><div class="memdoc">
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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="paramdir">[in]</td><td class="paramname">semaphore_id</td><td>semaphore object referenced with <a class="el" href="group__CMSIS__RTOS__SemaphoreMgmt.html#ga97381e8e55cd47cec390bf57c96d6edb">osSemaphoreCreate</a>. </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>status code that indicates the execution status of the function. </dd></dl>
|
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<dl class="section note"><dt>Note</dt><dd>MUST REMAIN UNCHANGED: <b>osSemaphoreRelease</b> shall be consistent in every CMSIS-RTOS.</dd></dl>
|
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<p>Release a Semaphore token. This increments the count of available semaphore tokens.</p>
|
|
<dl class="section note"><dt>Note</dt><dd><a class="el" href="functionOverview.html#CMSIS_RTOS_ISR_Calls">Interrupt Service Routines</a> can call this function.</dd></dl>
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<p><b><a class="el" href="group__CMSIS__RTOS__Status.html">Status and Error Codes</a></b><br/>
|
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</p>
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<ul>
|
|
<li><em>osOK:</em> the semaphore has been released.</li>
|
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<li><em>osErrorResource:</em> all tokens have already been released.</li>
|
|
<li><em>osErrorParameter:</em> the parameter <em>semaphore_id</em> is incorrect. </li>
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</ul>
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<a class="anchor" id="gacc15b0fc8ce1167fe43da33042e62098"></a>
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<td class="memname">int32_t osSemaphoreWait </td>
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<td>(</td>
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<td class="paramtype"><a class="el" href="cmsis__os_8h.html#aa8968896c84094aa973683c84fa06f84">osSemaphoreId</a> </td>
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<td class="paramname"><em>semaphore_id</em>, </td>
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<tr>
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<td class="paramkey"></td>
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<td></td>
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<td class="paramtype">uint32_t </td>
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<td class="paramname"><em>millisec</em> </td>
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</tr>
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<tr>
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<td></td>
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<td>)</td>
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<td></td><td></td>
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</div><div class="memdoc">
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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="paramdir">[in]</td><td class="paramname">semaphore_id</td><td>semaphore object referenced with <a class="el" href="group__CMSIS__RTOS__SemaphoreMgmt.html#ga97381e8e55cd47cec390bf57c96d6edb">osSemaphoreCreate</a>. </td></tr>
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<tr><td class="paramdir">[in]</td><td class="paramname">millisec</td><td><a class="el" href="functionOverview.html#CMSIS_RTOS_TimeOutValue">Timout Value</a> or 0 in case of no time-out. </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>number of available tokens, or -1 in case of incorrect parameters. </dd></dl>
|
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<dl class="section note"><dt>Note</dt><dd>MUST REMAIN UNCHANGED: <b>osSemaphoreWait</b> shall be consistent in every CMSIS-RTOS.</dd></dl>
|
|
<p>Wait until a Semaphore token becomes available. When no Semaphore token is available, the function waits for the time specified with the parameter <em>millisec</em>.</p>
|
|
<p>The argument <em>millisec</em> specifies how long the system waits for a Semaphore token to become available. While the system waits the thread that is calling this function is put into the state <b>WAITING</b>. The <em>millisec</em> timeout can have the following values:</p>
|
|
<ul>
|
|
<li>when <em>millisec</em> is 0, the function returns instantly.</li>
|
|
<li>when <em>millisec</em> is set to <b>osWaitForever</b> the function will wait for an infinite time until the Semaphore token becomes available.</li>
|
|
<li>all other values specify a time in millisecond for a timeout.</li>
|
|
</ul>
|
|
<p>The return value indicates the number of available tokens (the semaphore count value). If 0 is returned, then no semaphore was available.</p>
|
|
<dl class="section note"><dt>Note</dt><dd>Cannot be called from <a class="el" href="functionOverview.html#CMSIS_RTOS_ISR_Calls">Interrupt Service Routines</a>. </dd></dl>
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</div>
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