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    <p>They are <strong>NOT</strong> the same thing. They are used for different purposes!<br> While both types of semaphores have a full/empty state and use the same API, their usage is very different. </p> <p><strong>Mutual Exclusion Semaphores</strong><br> Mutual Exclusion semaphores are used to protect shared resources (data structure, file, etc..). </p> <p>A Mutex semaphore is "owned" by the task that takes it. If Task B attempts to semGive a mutex currently held by Task A, Task B's call will return an error and fail.</p> <p>Mutexes always use the following sequence: </p> <pre> - SemTake - Critical Section - SemGive</pre> <p>Here is a simple example:</p> <pre> Thread A Thread B Take Mutex access data ... Take Mutex &lt;== Will block ... Give Mutex access data &lt;== Unblocks ... Give Mutex </pre> <p><strong>Binary Semaphore</strong><br> Binary Semaphore address a totally different question: </p> <ul> <li>Task B is pended waiting for something to happen (a sensor being tripped for example).</li> <li>Sensor Trips and an Interrupt Service Routine runs. It needs to notify a task of the trip.</li> <li>Task B should run and take appropriate actions for the sensor trip. Then go back to waiting.</li> </ul> <pre><code> Task A Task B ... Take BinSemaphore &lt;== wait for something Do Something Noteworthy Give BinSemaphore do something &lt;== unblocks </code></pre> <p>Note that with a binary semaphore, it is OK for B to take the semaphore and A to give it.<br> Again, a binary semaphore is NOT protecting a resource from access. The act of Giving and Taking a semaphore are fundamentally decoupled.<br> It typically makes little sense for the same task to so a give and a take on the same binary semaphore.</p>
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    1. PODifference between binary semaphore and mutex
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    1. COIsn't a mutex better than a binary semaphore then? Since it doesn't make sense if someone releases a lock which he doesn't actually hold.
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    2. COThey have different purposes. Mutex is for exclusive access to a resource. A Binary semaphore should be used for Synchronization (i.e. "Hey Someone! This occurred!"). The Binary "giver" simply notifies whoever the "taker" that what they were waiting for happened.
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    3. CO@Pacerier You are confusing the purpose. A mutex is intended protect a critical region. You are correct it doesn't make sense to use a Binary Semaphore. I'll update the answer to explain the purpose of each.
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