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 127   <div class="headertitle"><div class="title">Thread Watchdogs<div class="ingroups"><a class="el" href="group__CMSIS__RTOS.html">CMSIS-RTOS API v2</a> &raquo; <a class="el" href="group__CMSIS__RTOS__ProcessIsolation.html">Process Isolation</a></div></div></div>
 128 </div><!--header-->
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 130 <p>CMSIS-RTOS defines <b>Thread Watchdogs</b> that allow to control timing constraints for thread execution (<a href="https://en.wikipedia.org/wiki/Temporal_isolation" target="_blank"><b>temporal isolation</b></a>).</p>
 131 <p>Each thread has an independent watchdog timer that is started with the function <a class="el" href="group__CMSIS__RTOS__ThreadMgmt.html#ga8f4455b06afb95c1915f15266818a8c6">osThreadFeedWatchdog(uint32_t ticks)</a>. The <span class="XML-Token">ticks</span> value specifies the timeout before it expires. Within this time interval the function <a class="el" href="group__CMSIS__RTOS__ThreadMgmt.html#ga8f4455b06afb95c1915f15266818a8c6">osThreadFeedWatchdog</a> must be called again within the thread to restart the watchdog timer.</p>
 132 <p>If the thread watchdog is not restarted during the specified amount of ticks the Watchdog Alarm callback <a class="el" href="group__CMSIS__RTOS__ThreadMgmt.html#ga5a02770aaf65c7a3c7562c109884176a">osWatchdogAlarm_Handler(osThreadId_t thread_id)</a> is triggered and can be used to recover the system or proceed to the system shutdown.</p>
 133 <p>Figure below explains the concept with an example:</p>
 134 <div class="image">
 135 <img src="thread_watchdogs.png" alt=""/>
 136 <div class="caption">
 137 Example use of Thread Watchdogs</div></div>
 138 <p><a class="el" href="group__rtos__process__isolation__faults.html">Fault Handling</a> provides more details on the available possibilities for system recovery. </p><dl class="section note"><dt>Note</dt><dd>If the application suspends a thread from scheduling by calling <a class="el" href="group__CMSIS__RTOS__ThreadMgmt.html#gaa9de419d0152bf77e9bbcd1f369fb990">osThreadSuspend</a> or <a class="el" href="group__CMSIS__RTOS__ThreadMgmt.html#gadadb56627094dbb07f6aeddf7d713fd9">osThreadSuspendClass</a>, the thread watchdog still continues to run, and it is expected to expire and trigger <a class="el" href="group__CMSIS__RTOS__ThreadMgmt.html#ga5a02770aaf65c7a3c7562c109884176a">osWatchdogAlarm_Handler</a> because the thread will not be serviced as expected. </dd>
 139 <dd>
 140 Hence it may be necessary to differentiate handling of thread watchdogs that expired unexpectedly from the thread watchdog alarms of intentionally suspended threads.</dd></dl>
 141 <h1><a class="anchor" id="rtos_process_isolation_thread_wdt_refs"></a>
 142 Function references</h1>
 143 <p>Summary of functions that implement thread watchdog functionality</p>
 144 <ul>
 145 <li><a class="el" href="group__CMSIS__RTOS__ThreadMgmt.html#ga8f4455b06afb95c1915f15266818a8c6">osThreadFeedWatchdog</a> :  Feed watchdog of the current running thread.  </li>
 146 <li><a class="el" href="group__CMSIS__RTOS__ThreadMgmt.html#ga5a02770aaf65c7a3c7562c109884176a">osWatchdogAlarm_Handler</a> :  Handler for expired thread watchdogs.   </li>
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