CMSIS-RTOS API V2

CMSIS-RTOS C API v2

Overview of all CMSIS-RTOS C API v2 functions that are implemented in the cmsis_os2.h header file.

Common Design Concepts

All RTOS objects share a common design concept. The overall life-cycle of an object can be summarized

as created -> in use -> destroyed.

Create Objects

An object is created by calling its osXxxNew function. The new function returns an identifier that can be

used to operate with the new object. The actual state of an object is typically stored in an object specific

control block. The memory layout (and size needed) for the control block is implementation specific. One

• attr_bits to control object-specific options,

• cb_mem to provide memory for the control block manually, and

• cb_size to quantify the memory size provided for the control block.

The name attribute is only used for object identification, e.g. using RTOS-aware debugging. The attached

string is not used for any other purposes internally.

The cb_mem and cb_size attributes can be used to provide memory for the control block manually instead

of relying on the implementation internal memory allocation. One has to assure that the amount of

memory pointed to by cb_mem is sufficient for the objects control block structure. If the size given as

cb_size is not sufficient the osXxxNew function returns with an error, i.e. returning

NULL. Furthermore

to the object to work with as the first xxx_id parameter.

The access function can be assumed to apply some sort of sanity checking on the id parameter. So that it

is assured one cannot accidentally call an access function with a NULL object reference. Furthermore the

concrete object type is verified, i.e. one cannot call access functions of one object type with a reference to

another object type.

All further parameter checks applied are either object and action specific or may even be implementation

specific. Thus one should always check action function return values for osErrorParameter to assure the

provided arguments were accepted.

As a rule of thumb only non-blocking access function can be used from

Interrupt Service Routines