Limitation of using global variable as semaphore in RTOS

[sacrpio]

ANYBODY RTOS EXPERT

DEAR FRIEND,
I WANT TO USE GLOBAL VARIABLE AS A BINARY SEMAPHORE IN ONE MY RTOS PROGRAM. I KNOW IT IS POSSIBLE, BUT I DONOT KNOW THE LIMITATION WITH THIS TYPE OF USE. WHAT ARE THE LIMITATION (EXCLUDING FACILITY OF MUTEX SEMAPHORE) HERE.

THANKS

 

[Ace-X]

ANYBODY RTOS EXPERT

Actually, "binary semaphore" and "mutex semaphore" are the same. As to implementation - it is the standard rule: you have to ensure atomic operations of test-modify for your semaphore if your system is pre-emptive. In others words, there should be no task switching during operation like "if (mutex==0) then mutex=1;".