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<div id="projectname">CMSIS-RTOS
 <span id="projectnumber">Version 1.02</span>
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<div id="projectbrief">CMSIS-RTOS API: Generic RTOS interface for Cortex-M processor-based devices.</div>
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<a href="#define-members">Macros</a> |
<a href="#func-members">Functions</a> </div>
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<div class="title">Message Queue</div> </div>
<div class="ingroups"><a class="el" href="group___c_m_s_i_s___r_t_o_s___inter_thread.html">Inter-Thread Communication and Resource Sharing</a></div></div><!--header-->
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<p>Exchange messages between threads in a FIFO-like operation.
<a href="#details">More...</a></p>
<table class="memberdecls">
<tr class="heading"><td colspan="2"><h2 class="groupheader"><a name="define-members"></a>
Macros</h2></td></tr>
<tr class="memitem:ga479a6561f859e3d4818e25708593d203"><td class="memItemLeft" align="right" valign="top">#define </td><td class="memItemRight" valign="bottom"><a class="el" href="group___c_m_s_i_s___r_t_o_s___message.html#ga479a6561f859e3d4818e25708593d203">osFeature_MessageQ</a>   1</td></tr>
<tr class="memdesc:ga479a6561f859e3d4818e25708593d203"><td class="mdescLeft"> </td><td class="mdescRight">Message Queues: 1=available, 0=not available. <a href="#ga479a6561f859e3d4818e25708593d203"></a><br/></td></tr>
<tr class="separator:ga479a6561f859e3d4818e25708593d203"><td class="memSeparator" colspan="2"> </td></tr>
<tr class="memitem:gac9a6a6276c12609793e7701afcc82326"><td class="memItemLeft" align="right" valign="top">#define </td><td class="memItemRight" valign="bottom"><a class="el" href="group___c_m_s_i_s___r_t_o_s___message.html#gac9a6a6276c12609793e7701afcc82326">osMessageQDef</a>(name, queue_sz, type)</td></tr>
<tr class="memdesc:gac9a6a6276c12609793e7701afcc82326"><td class="mdescLeft"> </td><td class="mdescRight">Create a Message Queue Definition. <a href="#gac9a6a6276c12609793e7701afcc82326"></a><br/></td></tr>
<tr class="separator:gac9a6a6276c12609793e7701afcc82326"><td class="memSeparator" colspan="2"> </td></tr>
<tr class="memitem:ga2d446a0b4bb90bf05d6f92eedeaabc97"><td class="memItemLeft" align="right" valign="top">#define </td><td class="memItemRight" valign="bottom"><a class="el" href="group___c_m_s_i_s___r_t_o_s___message.html#ga2d446a0b4bb90bf05d6f92eedeaabc97">osMessageQ</a>(name)   &os_messageQ_def_##name</td></tr>
<tr class="memdesc:ga2d446a0b4bb90bf05d6f92eedeaabc97"><td class="mdescLeft"> </td><td class="mdescRight">Access a Message Queue Definition. <a href="#ga2d446a0b4bb90bf05d6f92eedeaabc97"></a><br/></td></tr>
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<tr class="heading"><td colspan="2"><h2 class="groupheader"><a name="func-members"></a>
Functions</h2></td></tr>
<tr class="memitem:gaf3b9345cf426304d46565152bc26fb78"><td class="memItemLeft" align="right" valign="top"><a class="el" href="cmsis__os_8h.html#ad9ec70c32c6c521970636b521e12d17f">osMessageQId</a> </td><td class="memItemRight" valign="bottom"><a class="el" href="group___c_m_s_i_s___r_t_o_s___message.html#gaf3b9345cf426304d46565152bc26fb78">osMessageCreate</a> (const <a class="el" href="structos_message_q_def__t.html">osMessageQDef_t</a> *queue_def, <a class="el" href="cmsis__os_8h.html#adfeb153a84a81309e2d958268197617f">osThreadId</a> thread_id)</td></tr>
<tr class="memdesc:gaf3b9345cf426304d46565152bc26fb78"><td class="mdescLeft"> </td><td class="mdescRight">Create and Initialize a Message Queue. <a href="#gaf3b9345cf426304d46565152bc26fb78"></a><br/></td></tr>
<tr class="separator:gaf3b9345cf426304d46565152bc26fb78"><td class="memSeparator" colspan="2"> </td></tr>
<tr class="memitem:gac0dcf462fc92de8ffaba6cc004514a6d"><td class="memItemLeft" align="right" valign="top"><a class="el" href="group___c_m_s_i_s___r_t_o_s___status.html#gae2e091fefc4c767117727bd5aba4d99e">osStatus</a> </td><td class="memItemRight" valign="bottom"><a class="el" href="group___c_m_s_i_s___r_t_o_s___message.html#gac0dcf462fc92de8ffaba6cc004514a6d">osMessagePut</a> (<a class="el" href="cmsis__os_8h.html#ad9ec70c32c6c521970636b521e12d17f">osMessageQId</a> queue_id, uint32_t info, uint32_t millisec)</td></tr>
<tr class="memdesc:gac0dcf462fc92de8ffaba6cc004514a6d"><td class="mdescLeft"> </td><td class="mdescRight">Put a Message to a Queue. <a href="#gac0dcf462fc92de8ffaba6cc004514a6d"></a><br/></td></tr>
<tr class="separator:gac0dcf462fc92de8ffaba6cc004514a6d"><td class="memSeparator" colspan="2"> </td></tr>
<tr class="memitem:ga6c6892b8f2296cca6becd57ca2d7e1ae"><td class="memItemLeft" align="right" valign="top"><a class="el" href="group___c_m_s_i_s___r_t_o_s___definitions.html#structos_event">osEvent</a> </td><td class="memItemRight" valign="bottom"><a class="el" href="group___c_m_s_i_s___r_t_o_s___message.html#ga6c6892b8f2296cca6becd57ca2d7e1ae">osMessageGet</a> (<a class="el" href="cmsis__os_8h.html#ad9ec70c32c6c521970636b521e12d17f">osMessageQId</a> queue_id, uint32_t millisec)</td></tr>
<tr class="memdesc:ga6c6892b8f2296cca6becd57ca2d7e1ae"><td class="mdescLeft"> </td><td class="mdescRight">Get a Message or Wait for a Message from a Queue. <a href="#ga6c6892b8f2296cca6becd57ca2d7e1ae"></a><br/></td></tr>
<tr class="separator:ga6c6892b8f2296cca6becd57ca2d7e1ae"><td class="memSeparator" colspan="2"> </td></tr>
</table>
<a name="details" id="details"></a><h2 class="groupheader">Description</h2>
<p><b>Message</b> <b>passing</b> is another basic communication model between threads. In the message passing model, one thread sends data explicitly, while another thread receives it. The operation is more like some kind of I/O rather than a direct access to information to be shared. In CMSIS-RTOS, this mechanism is called s <b>message</b> <b>queue</b>. The data is passed from one thread to another in a FIFO-like operation. Using message queue functions, you can control, send, receive, or wait for messages. The data to be passed can be of integer or pointer type:</p>
<div class="image">
<img src="MessageQueue.png" alt="MessageQueue.png"/>
<div class="caption">
CMSIS-RTOS Message Queue</div></div>
<p> Compared to a <a class="el" href="group___c_m_s_i_s___r_t_o_s___pool_mgmt.html">Memory Pool</a>, message queues are less efficient in general, but solve a broader range of problems. Sometimes, threads do not have a common address space or the use of shared memory raises problems, such as mutual exclusion.</p>
<h2>Working with Message Queues</h2>
<p>Follow these steps to create and use a message queue:</p>
<ol type="1">
<li>Setup the message queue: <div class="fragment"><div class="line"><a class="code" href="group___c_m_s_i_s___r_t_o_s___message.html#gac9a6a6276c12609793e7701afcc82326" title="Create a Message Queue Definition.">osMessageQDef</a>(message_q, 5, uint32_t); <span class="comment">// Declare a message queue</span></div>
<div class="line"><a class="code" href="cmsis__os_8h.html#ad9ec70c32c6c521970636b521e12d17f" title="Message ID identifies the message queue (pointer to a message queue control block).">osMessageQId</a> (message_q_id); <span class="comment">// Declare an ID for the message queue</span></div>
</div><!-- fragment --></li>
<li>Then, create the message queue in a thread: <div class="fragment"><div class="line">message_q_id = <a class="code" href="group___c_m_s_i_s___r_t_o_s___message.html#gaf3b9345cf426304d46565152bc26fb78" title="Create and Initialize a Message Queue.">osMessageCreate</a>(<a class="code" href="group___c_m_s_i_s___r_t_o_s___message.html#ga2d446a0b4bb90bf05d6f92eedeaabc97" title="Access a Message Queue Definition.">osMessageQ</a>(message_q), NULL);</div>
</div><!-- fragment --></li>
<li>Fill the message queue with data: <div class="fragment"><div class="line">uint32_t data = 512;</div>
<div class="line"> </div>
<div class="line"><a class="code" href="group___c_m_s_i_s___r_t_o_s___mail.html#ga485ef6f81854ebda8ffbce4832181e02" title="Put a mail to a queue.">osMailPut</a>(message_q_id, data, <a class="code" href="cmsis__os_8h.html#a9eb9a7a797a42e4b55eb171ecc609ddb" title="Timeout value.">osWaitForever</a>);</div>
</div><!-- fragment --></li>
<li>From the receiving thread access the data using: <div class="fragment"><div class="line"><a class="code" href="group___c_m_s_i_s___r_t_o_s___definitions.html#structos_event" title="Event structure contains detailed information about an event.">osEvent</a> <span class="keyword">event</span> = <a class="code" href="group___c_m_s_i_s___r_t_o_s___message.html#ga6c6892b8f2296cca6becd57ca2d7e1ae" title="Get a Message or Wait for a Message from a Queue.">osMessageGet</a>(message_q_id, <a class="code" href="cmsis__os_8h.html#a9eb9a7a797a42e4b55eb171ecc609ddb" title="Timeout value.">osWaitForever</a>);</div>
</div><!-- fragment --> </li>
</ol>
<h2 class="groupheader">Macro Definition Documentation</h2>
<a class="anchor" id="ga479a6561f859e3d4818e25708593d203"></a>
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<td class="memname">#define osFeature_MessageQ   1</td>
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<p>A CMSIS-RTOS implementation may support message queues.</p>
<ul>
<li>When <a class="el" href="group___c_m_s_i_s___r_t_o_s___mail.html#gaceb2e0071ce160d153047f2eac1aca8e">osFeature_MailQ</a> is 1 message queues are supported.</li>
<li>When <a class="el" href="group___c_m_s_i_s___r_t_o_s___mail.html#gaceb2e0071ce160d153047f2eac1aca8e">osFeature_MailQ</a> is 0 no message queues are supported. </li>
</ul>
</div>
</div>
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<td class="memname">#define osMessageQ</td>
<td>(</td>
<td class="paramtype"> </td>
<td class="paramname">name</td><td>)</td>
<td>   &os_messageQ_def_##name</td>
</tr>
</table>
</div><div class="memdoc">
<p>Access to the message queue definition for the function <a class="el" href="group___c_m_s_i_s___r_t_o_s___message.html#gaf3b9345cf426304d46565152bc26fb78">osMessageCreate</a>.</p>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">name</td><td>name of the queue </td></tr>
</table>
</dd>
</dl>
<dl class="section note"><dt>Note</dt><dd>CAN BE CHANGED: The parameter to <b>osMessageQ</b> shall be consistent but the macro body is implementation specific in every CMSIS-RTOS. </dd></dl>
</div>
</div>
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<td class="memname">#define osMessageQDef</td>
<td>(</td>
<td class="paramtype"> </td>
<td class="paramname">name, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype"> </td>
<td class="paramname">queue_sz, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype"> </td>
<td class="paramname">type </td>
</tr>
<tr>
<td></td>
<td>)</td>
<td></td><td></td>
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<p>Define the attributes of a message queue created by the function <a class="el" href="group___c_m_s_i_s___r_t_o_s___message.html#gaf3b9345cf426304d46565152bc26fb78">osMessageCreate</a> using <a class="el" href="group___c_m_s_i_s___r_t_o_s___message.html#ga2d446a0b4bb90bf05d6f92eedeaabc97">osMessageQ</a>.</p>
<dl class="section note"><dt>Note</dt><dd>The parameter <em>thread</em> registers the receiving thread for a message and is needed for the general <a class="el" href="group___c_m_s_i_s___r_t_o_s___wait.html#ga8470c8aaedfde524a44e22e5b2328285">osWait</a> function to deliver the message.</dd></dl>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">name</td><td>name of the queue. </td></tr>
<tr><td class="paramname">queue_sz</td><td>maximum number of messages in the queue. </td></tr>
<tr><td class="paramname">type</td><td>data type of a single message element (for debugger). </td></tr>
</table>
</dd>
</dl>
<dl class="section note"><dt>Note</dt><dd>CAN BE CHANGED: The parameter to <b>osMessageQDef</b> shall be consistent but the macro body is implementation specific in every CMSIS-RTOS. </dd></dl>
</div>
</div>
<h2 class="groupheader">Function Documentation</h2>
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<td class="memname"><a class="el" href="cmsis__os_8h.html#ad9ec70c32c6c521970636b521e12d17f">osMessageQId</a> osMessageCreate </td>
<td>(</td>
<td class="paramtype">const <a class="el" href="structos_message_q_def__t.html">osMessageQDef_t</a> * </td>
<td class="paramname"><em>queue_def</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype"><a class="el" href="cmsis__os_8h.html#adfeb153a84a81309e2d958268197617f">osThreadId</a> </td>
<td class="paramname"><em>thread_id</em> </td>
</tr>
<tr>
<td></td>
<td>)</td>
<td></td><td></td>
</tr>
</table>
</div><div class="memdoc">
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramdir">[in]</td><td class="paramname">queue_def</td><td>queue definition referenced with <a class="el" href="group___c_m_s_i_s___r_t_o_s___message.html#ga2d446a0b4bb90bf05d6f92eedeaabc97">osMessageQ</a>. </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">thread_id</td><td>thread ID (obtained by <a class="el" href="group___c_m_s_i_s___r_t_o_s___thread_mgmt.html#gac59b5713cb083702dce759c73fd90dff">osThreadCreate</a> or <a class="el" href="group___c_m_s_i_s___r_t_o_s___thread_mgmt.html#gab1df2a28925862ef8f9cf4e1c995c5a7">osThreadGetId</a>) or NULL. </td></tr>
</table>
</dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>message queue ID for reference by other functions or NULL in case of error. </dd></dl>
<dl class="section note"><dt>Note</dt><dd>MUST REMAIN UNCHANGED: <b>osMessageCreate</b> shall be consistent in every CMSIS-RTOS.</dd></dl>
<p>Create and initialize a message queue.</p>
<dl class="section note"><dt>Note</dt><dd>Cannot be called from <a class="el" href="_function_overview.html#CMSIS_RTOS_ISR_Calls">Interrupt Service Routines</a>.</dd></dl>
<p><b>Code Example</b> </p>
<div class="fragment"><div class="line"><span class="preprocessor">#include "<a class="code" href="cmsis__os_8h.html">cmsis_os.h</a>"</span></div>
<div class="line"> </div>
<div class="line"><a class="code" href="cmsis__os_8h.html#adfeb153a84a81309e2d958268197617f" title="Thread ID identifies the thread (pointer to a thread control block).">osThreadId</a> tid_thread1; <span class="comment">// ID for thread 1</span></div>
<div class="line"><a class="code" href="cmsis__os_8h.html#adfeb153a84a81309e2d958268197617f" title="Thread ID identifies the thread (pointer to a thread control block).">osThreadId</a> tid_thread2; <span class="comment">// for thread 2</span></div>
<div class="line"> </div>
<div class="line"><span class="keyword">typedef</span> <span class="keyword">struct </span>{ <span class="comment">// Message object structure</span></div>
<div class="line"> <span class="keywordtype">float</span> voltage; <span class="comment">// AD result of measured voltage</span></div>
<div class="line"> <span class="keywordtype">float</span> current; <span class="comment">// AD result of measured current</span></div>
<div class="line"> <span class="keywordtype">int</span> counter; <span class="comment">// A counter value</span></div>
<div class="line">} T_MEAS;</div>
<div class="line"> </div>
<div class="line"><a class="code" href="group___c_m_s_i_s___r_t_o_s___pool_mgmt.html#ga87b471d4fe2d5dbd0040708edd52771b" title="Define a Memory Pool.">osPoolDef</a>(mpool, 16, T_MEAS); <span class="comment">// Define memory pool</span></div>
<div class="line"><a class="code" href="cmsis__os_8h.html#a08d2e20fd9bbd96220fe068d420f3686" title="Pool ID identifies the memory pool (pointer to a memory pool control block).">osPoolId</a> mpool;</div>
<div class="line"><a class="code" href="group___c_m_s_i_s___r_t_o_s___message.html#gac9a6a6276c12609793e7701afcc82326" title="Create a Message Queue Definition.">osMessageQDef</a>(MsgBox, 16, T_MEAS); <span class="comment">// Define message queue</span></div>
<div class="line"><a class="code" href="cmsis__os_8h.html#ad9ec70c32c6c521970636b521e12d17f" title="Message ID identifies the message queue (pointer to a message queue control block).">osMessageQId</a> MsgBox;</div>
<div class="line"> </div>
<div class="line"><span class="keywordtype">void</span> send_thread (<span class="keywordtype">void</span> <span class="keyword">const</span> *argument); <span class="comment">// forward reference</span></div>
<div class="line"><span class="keywordtype">void</span> recv_thread (<span class="keywordtype">void</span> <span class="keyword">const</span> *argument); <span class="comment">// forward reference</span></div>
<div class="line"> <span class="comment">// Thread definitions</span></div>
<div class="line"><a class="code" href="group___c_m_s_i_s___r_t_o_s___thread_mgmt.html#gaee93d929beb350f16e5cc7fa602e229f" title="Create a Thread Definition with function, priority, and stack requirements.">osThreadDef</a>(send_thread, <a class="code" href="group___c_m_s_i_s___r_t_o_s___thread_mgmt.html#ga7f2b42f1983b9107775ec2a1c69a849aa45a2895ad30c79fb97de18cac7cc19f1" title="priority: normal (default)">osPriorityNormal</a>, 1, 0);</div>
<div class="line"><a class="code" href="group___c_m_s_i_s___r_t_o_s___thread_mgmt.html#gaee93d929beb350f16e5cc7fa602e229f" title="Create a Thread Definition with function, priority, and stack requirements.">osThreadDef</a>(recv_thread, <a class="code" href="group___c_m_s_i_s___r_t_o_s___thread_mgmt.html#ga7f2b42f1983b9107775ec2a1c69a849aa45a2895ad30c79fb97de18cac7cc19f1" title="priority: normal (default)">osPriorityNormal</a>, 1, 2000);</div>
<div class="line"> </div>
<div class="line"><span class="comment">//</span></div>
<div class="line"><span class="comment">// Thread 1: Send thread</span></div>
<div class="line"><span class="comment">//</span></div>
<div class="line"><span class="keywordtype">void</span> send_thread (<span class="keywordtype">void</span> <span class="keyword">const</span> *argument) {</div>
<div class="line"> T_MEAS *mptr;</div>
<div class="line"> </div>
<div class="line"> mptr = <a class="code" href="group___c_m_s_i_s___r_t_o_s___pool_mgmt.html#gaa0b2994f1a866c19e0d11e6e0d44f543" title="Allocate a memory block from a memory pool.">osPoolAlloc</a>(mpool); <span class="comment">// Allocate memory for the message</span></div>
<div class="line"> mptr->voltage = 223.72; <span class="comment">// Set the message content</span></div>
<div class="line"> mptr->current = 17.54;</div>
<div class="line"> mptr->counter = 120786;</div>
<div class="line"> <a class="code" href="group___c_m_s_i_s___r_t_o_s___message.html#gac0dcf462fc92de8ffaba6cc004514a6d" title="Put a Message to a Queue.">osMessagePut</a>(MsgBox, (uint32_t)mptr, <a class="code" href="cmsis__os_8h.html#a9eb9a7a797a42e4b55eb171ecc609ddb" title="Timeout value.">osWaitForever</a>); <span class="comment">// Send Message</span></div>
<div class="line"> <a class="code" href="group___c_m_s_i_s___r_t_o_s___wait.html#ga02e19d5e723bfb06ba9324d625162255" title="Wait for Timeout (Time Delay).">osDelay</a>(100);</div>
<div class="line"> </div>
<div class="line"> mptr = <a class="code" href="group___c_m_s_i_s___r_t_o_s___pool_mgmt.html#gaa0b2994f1a866c19e0d11e6e0d44f543" title="Allocate a memory block from a memory pool.">osPoolAlloc</a>(mpool); <span class="comment">// Allocate memory for the message</span></div>
<div class="line"> mptr->voltage = 227.23; <span class="comment">// Prepare a 2nd message</span></div>
<div class="line"> mptr->current = 12.41;</div>
<div class="line"> mptr->counter = 170823;</div>
<div class="line"> <a class="code" href="group___c_m_s_i_s___r_t_o_s___message.html#gac0dcf462fc92de8ffaba6cc004514a6d" title="Put a Message to a Queue.">osMessagePut</a>(MsgBox, (uint32_t)mptr, <a class="code" href="cmsis__os_8h.html#a9eb9a7a797a42e4b55eb171ecc609ddb" title="Timeout value.">osWaitForever</a>); <span class="comment">// Send Message</span></div>
<div class="line"> <a class="code" href="group___c_m_s_i_s___r_t_o_s___thread_mgmt.html#gaf13a667493c5d629a90c13e113b99233" title="Pass control to next thread that is in state READY.">osThreadYield</a>(); <span class="comment">// Cooperative multitasking</span></div>
<div class="line"> <span class="comment">// We are done here, exit this thread</span></div>
<div class="line">}</div>
<div class="line"> </div>
<div class="line"><span class="comment">//</span></div>
<div class="line"><span class="comment">// Thread 2: Receive thread</span></div>
<div class="line"><span class="comment">//</span></div>
<div class="line"><span class="keywordtype">void</span> recv_thread (<span class="keywordtype">void</span> <span class="keyword">const</span> *argument) {</div>
<div class="line"> T_MEAS *rptr;</div>
<div class="line"> <a class="code" href="group___c_m_s_i_s___r_t_o_s___definitions.html#structos_event" title="Event structure contains detailed information about an event.">osEvent</a> evt;</div>
<div class="line"> </div>
<div class="line"> <span class="keywordflow">for</span> (;;) {</div>
<div class="line"> evt = <a class="code" href="group___c_m_s_i_s___r_t_o_s___message.html#ga6c6892b8f2296cca6becd57ca2d7e1ae" title="Get a Message or Wait for a Message from a Queue.">osMessageGet</a>(MsgBox, <a class="code" href="cmsis__os_8h.html#a9eb9a7a797a42e4b55eb171ecc609ddb" title="Timeout value.">osWaitForever</a>); <span class="comment">// wait for message</span></div>
<div class="line"> <span class="keywordflow">if</span> (evt.<a class="code" href="group___c_m_s_i_s___r_t_o_s___definitions.html#ad477a289f1f03ac45407b64268d707d3" title="status code: event or error information">status</a> == <a class="code" href="group___c_m_s_i_s___r_t_o_s___status.html#gae2e091fefc4c767117727bd5aba4d99ead604f3673359dd4ac643b16dc5a2c342" title="function completed; message event occurred.">osEventMessage</a>) {</div>
<div class="line"> rptr = evt.<a class="code" href="group___c_m_s_i_s___r_t_o_s___definitions.html#a0b9f8fd3645f01d8cb09cae82add2d7f" title="event value">value</a>.<a class="code" href="group___c_m_s_i_s___r_t_o_s___definitions.html#a117104b82864d3b23ec174af6d392709" title="message or mail as void pointer">p</a>;</div>
<div class="line"> printf (<span class="stringliteral">"\nVoltage: %.2f V\n"</span>, rptr->voltage);</div>
<div class="line"> printf (<span class="stringliteral">"Current: %.2f A\n"</span>, rptr->current);</div>
<div class="line"> printf (<span class="stringliteral">"Number of cycles: %d\n"</span>, rptr->counter);</div>
<div class="line"> <a class="code" href="group___c_m_s_i_s___r_t_o_s___pool_mgmt.html#ga4a861e9c469c9d0daf5721bf174f8e54" title="Return an allocated memory block back to a specific memory pool.">osPoolFree</a>(mpool, rptr); <span class="comment">// free memory allocated for message</span></div>
<div class="line"> }</div>
<div class="line"> }</div>
<div class="line">}</div>
<div class="line"> </div>
<div class="line"><span class="keywordtype">void</span> StartApplication (<span class="keywordtype">void</span>) {</div>
<div class="line"> mpool = <a class="code" href="group___c_m_s_i_s___r_t_o_s___pool_mgmt.html#ga34af5c4f4ab38f4138ea7f1f9ece3a1a" title="Create and Initialize a memory pool.">osPoolCreate</a>(<a class="code" href="group___c_m_s_i_s___r_t_o_s___pool_mgmt.html#ga5f0b204a82327533d420210125c90697" title="Access a Memory Pool definition.">osPool</a>(mpool)); <span class="comment">// create memory pool</span></div>
<div class="line"> MsgBox = <a class="code" href="group___c_m_s_i_s___r_t_o_s___message.html#gaf3b9345cf426304d46565152bc26fb78" title="Create and Initialize a Message Queue.">osMessageCreate</a>(<a class="code" href="group___c_m_s_i_s___r_t_o_s___message.html#ga2d446a0b4bb90bf05d6f92eedeaabc97" title="Access a Message Queue Definition.">osMessageQ</a>(MsgBox), NULL); <span class="comment">// create msg queue</span></div>
<div class="line"> </div>
<div class="line"> tid_thread1 = <a class="code" href="group___c_m_s_i_s___r_t_o_s___thread_mgmt.html#gac59b5713cb083702dce759c73fd90dff" title="Create a thread and add it to Active Threads and set it to state READY.">osThreadCreate</a>(<a class="code" href="group___c_m_s_i_s___r_t_o_s___thread_mgmt.html#gaf0c7c6b5e09f8be198312144b5c9e453" title="Access a Thread definition.">osThread</a>(send_thread), NULL);</div>
<div class="line"> tid_thread2 = <a class="code" href="group___c_m_s_i_s___r_t_o_s___thread_mgmt.html#gac59b5713cb083702dce759c73fd90dff" title="Create a thread and add it to Active Threads and set it to state READY.">osThreadCreate</a>(<a class="code" href="group___c_m_s_i_s___r_t_o_s___thread_mgmt.html#gaf0c7c6b5e09f8be198312144b5c9e453" title="Access a Thread definition.">osThread</a>(recv_thread), NULL);</div>
<div class="line"> :</div>
<div class="line">}</div>
</div><!-- fragment -->
</div>
</div>
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<td class="memname"><a class="el" href="group___c_m_s_i_s___r_t_o_s___definitions.html#structos_event">osEvent</a> osMessageGet </td>
<td>(</td>
<td class="paramtype"><a class="el" href="cmsis__os_8h.html#ad9ec70c32c6c521970636b521e12d17f">osMessageQId</a> </td>
<td class="paramname"><em>queue_id</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">uint32_t </td>
<td class="paramname"><em>millisec</em> </td>
</tr>
<tr>
<td></td>
<td>)</td>
<td></td><td></td>
</tr>
</table>
</div><div class="memdoc">
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramdir">[in]</td><td class="paramname">queue_id</td><td>message queue ID obtained with <a class="el" href="group___c_m_s_i_s___r_t_o_s___message.html#gaf3b9345cf426304d46565152bc26fb78">osMessageCreate</a>. </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">millisec</td><td><a class="el" href="_function_overview.html#CMSIS_RTOS_TimeOutValue">Timout Value</a> or 0 in case of no time-out. </td></tr>
</table>
</dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>event information that includes status code. </dd></dl>
<dl class="section note"><dt>Note</dt><dd>MUST REMAIN UNCHANGED: <b>osMessageGet</b> shall be consistent in every CMSIS-RTOS.</dd></dl>
<p>Suspend the execution of the current <b>RUNNING</b> thread until a message arrives. When a message is already in the queue, the function returns instantly with the message information.</p>
<p>The argument <em>millisec</em> specifies how long the system waits for a message 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 value 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 a message arrives.</li>
<li>all other values specify a time in millisecond for a timeout.</li>
</ul>
<dl class="section note"><dt>Note</dt><dd>The parameter <em>millisec</em> must be 0 for using this function in an ISR. </dd>
<dd>
<a class="el" href="_function_overview.html#CMSIS_RTOS_ISR_Calls">Interrupt Service Routines</a> can call this function.</dd></dl>
<p><b><a class="el" href="group___c_m_s_i_s___r_t_o_s___status.html">Status and Error Codes</a></b><br/>
</p>
<ul>
<li><em>osOK:</em> no message is available in the queue and no timeout was specified.</li>
<li><em>osEventTimeout:</em> no message has arrived during the given timeout period.</li>
<li><em>osEventMessage:</em> message received, <em>value.p</em> contains the pointer to message.</li>
<li><em>osErrorParameter:</em> a parameter is invalid or outside of a permitted range. </li>
</ul>
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<td class="memname"><a class="el" href="group___c_m_s_i_s___r_t_o_s___status.html#gae2e091fefc4c767117727bd5aba4d99e">osStatus</a> osMessagePut </td>
<td>(</td>
<td class="paramtype"><a class="el" href="cmsis__os_8h.html#ad9ec70c32c6c521970636b521e12d17f">osMessageQId</a> </td>
<td class="paramname"><em>queue_id</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">uint32_t </td>
<td class="paramname"><em>info</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">uint32_t </td>
<td class="paramname"><em>millisec</em> </td>
</tr>
<tr>
<td></td>
<td>)</td>
<td></td><td></td>
</tr>
</table>
</div><div class="memdoc">
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramdir">[in]</td><td class="paramname">queue_id</td><td>message queue ID obtained with <a class="el" href="group___c_m_s_i_s___r_t_o_s___message.html#gaf3b9345cf426304d46565152bc26fb78">osMessageCreate</a>. </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">info</td><td>message information. </td></tr>
<tr><td class="paramdir">[in]</td><td class="paramname">millisec</td><td><a class="el" href="_function_overview.html#CMSIS_RTOS_TimeOutValue">Timout Value</a> or 0 in case of no time-out. </td></tr>
</table>
</dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>status code that indicates the execution status of the function. </dd></dl>
<dl class="section note"><dt>Note</dt><dd>MUST REMAIN UNCHANGED: <b>osMessagePut</b> shall be consistent in every CMSIS-RTOS.</dd></dl>
<p>Put the message <em>info</em> in a message queue specified by <em>queue_id</em>.</p>
<p>When the message queue is full, the system retries for a specified time with <em>millisec</em>. While the system retries 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 a message queue slot becomes available.</li>
<li>all other values specify a time in millisecond for a timeout.</li>
</ul>
<dl class="section note"><dt>Note</dt><dd>The parameter <em>millisec</em> must be 0 for using this function in an ISR. </dd>
<dd>
<a class="el" href="_function_overview.html#CMSIS_RTOS_ISR_Calls">Interrupt Service Routines</a> can call this function.</dd></dl>
<p><b><a class="el" href="group___c_m_s_i_s___r_t_o_s___status.html">Status and Error Codes</a></b><br/>
</p>
<ul>
<li><em>osOK:</em> the message is put into the queue.</li>
<li><em>osErrorResource:</em> no memory in the queue was available.</li>
<li><em>osErrorTimeoutResource:</em> no memory in the queue was available during the given time limit.</li>
<li><em>osErrorParameter:</em> a parameter is invalid or outside of a permitted range. </li>
</ul>
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