CMSIS-RTOS  Version 1.02
CMSIS-RTOS API: Generic RTOS interface for Cortex-M processor-based devices.
Function Overview

The following list provides a brief overview of all CMSIS-RTOS functions. Functions marked with $ are optional. A specific CMSIS-RTOS implementation may not provide all functions, but this is clearly indicated with osFeatureXXXX defines.

  • Mail Queue
    • osMailCreate : Define and initialize a mail queue with fix-size memory blocks.
    • osMailAlloc : Allocate a memory block.
    • osMailCAlloc : Allocate a memory block and zero-set this block.
    • osMailPut : Put a memory block into a mail queue.
    • osMailGet : Get a mail or suspend thread execution until mail arrives.
    • osMailFree : Return a memory block to the mail queue.

Timout Value

The timeout value specifies the number of timer ticks until a timeout or time delay elapses. The value is an upper bound and depends on the actual time elapsed since the last timer tick.

For a value of 1 the system waits until the next timer tick occurs. That means that the actual timeout value can be one timer tick less than the specified timeout value.

TimerValues.png
Timer Values

Calls from Interrupt Service Routines

The following CMSIS-RTOS functions can be called from threads and Interrupt Service Routines (ISR):

Functions that cannot be called from an ISR are verifying the interrupt status and return, in case they are called from an ISR context, the status code osErrorISR. In some implementations, this condition might be caught using the HARD FAULT vector.

Some CMSIS-RTOS implementations support CMSIS-RTOS function calls from multiple ISRs at the same time. If this is impossible, the CMSIS-RTOS rejects calls by nested ISR functions with the status code osErrorISRRecursive.