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Microchip AN1264 not using mutex

Posted by on June 24, 2011

I am just wondering if there is any specific reason or advantage for using binary semaphores instead of mutexes in AN1264 from Microchip. In most cases I think a mutex would be more appropriate.


RE: Microchip AN1264 not using mutex

Posted by Richard on June 24, 2011
I am not the application note author, so can only speculate. If the semaphores are used for mutual exclusion, then it might be better to use a mutex, I would agree. The only real difference between the two is that a mutex includes a basic priority inheritance mechanism, whereas binary semaphores don't.


RE: Microchip AN1264 not using mutex

Posted by Richard Damon on June 24, 2011
My guess, based on the fact that while they are using FreeRTOS as the example, they also want to be as general as possible, would be that since a Semaphore is a simpler object, and is available in more RTOSes than a mutex, it makes there example more generic. A Mutex is a Binary Semaphore with additional features to specialize it for mutual exclusion, which for FreeRTOS means adding priority inheritance.

Reading over their usage, a mutex really is the proper choice, as they are using them mutual exclusion on a resource, which is what mutexes were developed for.

RE: Microchip AN1264 not using mutex

Posted by on June 24, 2011
Thanks for the help! Portability looks like a good reason. Or maybe the application author simply used to use semaphores. As far as I know, mutexes were introduced later in FreeRTOS. Or could maybe memory usage or performance be also a reason for his choice?

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