Abstract: In order to have a clear understanding of the exclusive access principle and mechanism of mutex on shared resources, based on the brief analysis of the meaning, application occasions, scheduling mechanism and key elements of mutex in real-time operating systems, the mbedOS mutex scheduling mechanism are theoretically analyzed. Takes the KL36 chip as an example the mbedOS mutex is realized and the scheduling process information of thread response mutex is output spontaneously based on the sequence diagram and printf method. And the real-time performance of mutex scheduling mechanism is analyzed. The analysis of mutex scheduling mechanism is helpful to further analyze other synchronization and communication methods of mbedOS, and can also provide reference for in-depth understanding of other real-time operating system synchronization and communication methods. 

Key words: real time operating system(RTOS), mutex, mbedOS real-time operating system, KL36chip, printf