Define CMSIS RTOS2 APIs for your Platform#

This section explains how to define a CMSIS-RTOS2 API function using FreeRTOS library as an example. This guide focuses to explain the CMSIS-RTOS2 API implementation only for those CMSIS-RTOS2 API functions that are used in the SDK v3.x.

For EFR32xG24 (hereafter referred to as EFR32) project, the CMSIS-FreeRTOS implementation is present in cmsis_os2.c file present at path: <application project>/gecko_sdk/util/third_party/freertos/cmsis/Source

For STM32 project, the CMSIS-FreeRTOS implementation is present in cmsis_os2.c file present at path: \<STM32 project\>/Middlewares/FreeRTOS

Note: For getting the description, parameters and return values of each function, refer here.

FreeRTOS Preprocessor Macros#

Define the following preprocessor macros if using FreeRTOS.

• SL_CATALOG_FREERTOS_KERNEL_PRESENT

• configNUM_USER_THREAD_LOCAL_STORAGE_POINTERS=0

• configNUM_SDK_THREAD_LOCAL_STORAGE_POINTERS=2

• configUSE_POSIX_ERRNO =1

In the FreeRTOS.h file present at \<STM32 project\>/Middlewares/Third_Party/FreeRTOS/Source/include, define the following macro as shown below:

#define configNUM_THREAD_LOCAL_STORAGE_POINTERS (configNUM_USER_THREAD_LOCAL_STORAGE_POINTERS \
                                                 + configNUM_SDK_THREAD_LOCAL_STORAGE_POINTERS) 

Sample FreeRTOS API Implementations#

The following sections contain sample FreeRTOS implementations of CMSIS RTOS2 APIs.

• Kernel Management Functions

• Thread Management Functions

• Generic Wait functions

• Event Flags Management Functions

• Mutex Management Functions

• Semaphore Management Functions

The following functions are described in these sections. These are listed here in alphabetical order:

osDelay | osEventFlagsClear | osEventFlagsDelete | osEventFlagsNew | osEventFlagsSet | osEventFlagsWait | osKernelGetTickCount | osKernelInitialize | osKernelStart | osMutexAcquire | osMutexDelete | osMutexNew | osMutexRelease | osSemaphoreAcquire | osSemaphoreDelete | osSemaphoreNew | osSemaphoreRelease | osThreadNew

Kernel Management Functions#

The following functions are covered in this section. These are mentioned in the sequence in which occur in the flow of an application: osKernelInitialize | osKernelStart | osKernelGetTickCount

osKernelInitialize#

The following example is a FreeRTOS implementation.

osStatus_t osKernelInitialize (void) {
  osStatus_t stat;

  if (IS_IRQ()) {
    stat = osErrorISR;
  }
  else {
    if (KernelState == osKernelInactive) {
      #if defined(USE_TRACE_EVENT_RECORDER)
        EvrFreeRTOSSetup(0U);
      #endif
      #if defined(USE_FreeRTOS_HEAP_5) && (HEAP_5_REGION_SETUP == 1)
        vPortDefineHeapRegions (configHEAP_5_REGIONS);
      #endif
      KernelState = osKernelReady;
      stat = osOK;
    } else {
      stat = osError;
    }
  }

  return (stat);
}

osKernelStart#

The following example is a FreeRTOS implementation.

osStatus_t sl_kernel_start(void) {
  osStatus_t stat;

  if (IS_IRQ()) {
    stat = osErrorISR;
  }
  else {
    if (KernelState == osKernelReady) {
      /* Ensure SVC priority is at the reset value */
      SVC_Setup();
      /* Change state to enable IRQ masking check */
      KernelState = osKernelRunning;
      /* Start the kernel scheduler */
      vTaskStartScheduler();
      stat = osOK;
    } else {
      stat = osError;
    }
  }

  return (stat);
}

osKernelGetTickCount#

uint32_t osKernelGetTickCount (void) {
  TickType_t ticks;

  if (IS_IRQ()) {
    ticks = xTaskGetTickCountFromISR();
  } else {
    ticks = xTaskGetTickCount();
  }

  return (ticks);
}

Thread Management Functions#

osThreadNew#

osThreadId_t osThreadNew (osThreadFunc_t func, void *argument, const osThreadAttr_t *attr) {
  const char *name;
  uint32_t stack;
  TaskHandle_t hTask;
  UBaseType_t prio;
  int32_t mem;

  hTask = NULL;

  if (!IS_IRQ() && (func != NULL)) {
    stack = configMINIMAL_STACK_SIZE;
    prio  = (UBaseType_t)osPriorityNormal;

    name = NULL;
    mem  = -1;

    if (attr != NULL) {
      if (attr->name != NULL) {
        name = attr->name;
      }
      if (attr->priority != osPriorityNone) {
        prio = (UBaseType_t)attr->priority;
      }

      if ((prio < osPriorityIdle) || (prio > osPriorityISR) || ((attr->attr_bits & osThreadJoina-ble) == osThreadJoinable)) {
        return (NULL);
      }

      if (attr->stack_size > 0U) {
        /* In FreeRTOS stack is not in bytes, but in sizeof(StackType_t) which is 4 on ARM ports.       */
        /* Stack size should be therefore 4 byte aligned in order to avoid division caused side effects */
        stack = attr->stack_size / sizeof(StackType_t);
      }

      if ((attr->cb_mem    != NULL) && (attr->cb_size    >= sizeof(StaticTask_t)) &&
          (attr->stack_mem != NULL) && (attr->stack_size >  0U)) {
        mem = 1;
      }
      else {
        if ((attr->cb_mem == NULL) && (attr->cb_size == 0U) && (attr->stack_mem == NULL)) {
          mem = 0;
        }
      }
    }
    else {
      mem = 0;
    }

    if (mem == 1) {
      #if (configSUPPORT_STATIC_ALLOCATION == 1)
        hTask = xTaskCreateStatic ((TaskFunction_t)func, name, stack, argument, prio, (Stack-Type_t  *)attr->stack_mem,
                                                                                      (StaticTask_t *)attr->cb_mem);
      #endif
    }
    else {
      if (mem == 0) {
        #if (configSUPPORT_DYNAMIC_ALLOCATION == 1)
          if (xTaskCreate ((TaskFunction_t)func, name, (uint16_t)stack, argument, prio, &hTask) != pdPASS) {
            hTask = NULL;
          }
        #endif
      }
    }
  }

  return ((osThreadId_t)hTask);
}

Generic Wait functions#

osDelay#

osStatus_t osDelay (uint32_t ticks) {
  osStatus_t stat;

  if (IS_IRQ()) {
    stat = osErrorISR;
  }
  else {
    stat = osOK;

    if (ticks != 0U) {
      vTaskDelay(ticks);
    }
  }

  return (stat);
}

Event Flags Management Functions#

The following functions are covered in this section. These are mentioned in the sequence in which occur in the flow of an application: osEventFlagsNew | osEventFlagsSet | osEventFlagsClear | osEventFlagsWait | osEventFlagsDelete

osEventFlagsNew#

osEventFlagsId_t osEventFlagsNew (const osEventFlagsAttr_t *attr) {
  EventGroupHandle_t hEventGroup;
  int32_t mem;

  hEventGroup = NULL;

  if (!IS_IRQ()) {
    mem = -1;

    if (attr != NULL) {
      if ((attr->cb_mem != NULL) && (attr->cb_size >= sizeof(StaticEventGroup_t))) {
        mem = 1;
      }
      else {
        if ((attr->cb_mem == NULL) && (attr->cb_size == 0U)) {
          mem = 0;
        }
      }
    }
    else {
      mem = 0;
    }

    if (mem == 1) {
      #if (configSUPPORT_STATIC_ALLOCATION == 1)
      hEventGroup = xEventGroupCreateStatic (attr->cb_mem);
      #endif
    }
    else {
      if (mem == 0) {
        #if (configSUPPORT_DYNAMIC_ALLOCATION == 1)
          hEventGroup = xEventGroupCreate();
        #endif
      }
    }
  }

  return ((osEventFlagsId_t)hEventGroup);
}

osEventFlagsSet#

uint32_t osEventFlagsSet (osEventFlagsId_t ef_id, uint32_t flags) {
  EventGroupHandle_t hEventGroup = (EventGroupHandle_t)ef_id;
  uint32_t rflags;
  BaseType_t yield;

  if ((hEventGroup == NULL) || ((flags & EVENT_FLAGS_INVALID_BITS) != 0U)) {
    rflags = (uint32_t)osErrorParameter;
  }
  else if (IS_IRQ()) {
  #if (configUSE_OS2_EVENTFLAGS_FROM_ISR == 0)
    (void)yield;
    /* Enable timers and xTimerPendFunctionCall function to support osEventFlagsSet from ISR */
    rflags = (uint32_t)osErrorResource;
  #else
    yield = pdFALSE;

    if (xEventGroupSetBitsFromISR (hEventGroup, (EventBits_t)flags, &yield) == pdFAIL) {
      rflags = (uint32_t)osErrorResource;
    } else {
      rflags = flags;
      portYIELD_FROM_ISR (yield);
    }
  #endif
  }
  else {
    rflags = xEventGroupSetBits (hEventGroup, (EventBits_t)flags);
  }

  return (rflags);
}

osEventFlagsClear#

uint32_t osEventFlagsClear (osEventFlagsId_t ef_id, uint32_t flags) {
  EventGroupHandle_t hEventGroup = (EventGroupHandle_t)ef_id;
  uint32_t rflags;

  if ((hEventGroup == NULL) || ((flags & EVENT_FLAGS_INVALID_BITS) != 0U)) {
    rflags = (uint32_t)osErrorParameter;
  }
  else if (IS_IRQ()) {
  #if (configUSE_OS2_EVENTFLAGS_FROM_ISR == 0)
    /* Enable timers and xTimerPendFunctionCall function to support osEventFlagsSet from ISR */
    rflags = (uint32_t)osErrorResource;
  #else
    rflags = xEventGroupGetBitsFromISR (hEventGroup);

    if (xEventGroupClearBitsFromISR (hEventGroup, (EventBits_t)flags) == pdFAIL) {
      rflags = (uint32_t)osErrorResource;
    }
  #endif
  }
  else {
    rflags = xEventGroupClearBits (hEventGroup, (EventBits_t)flags);
  }

  return (rflags);
}

osEventFlagsWait#

uint32_t osEventFlagsWait (osEventFlagsId_t ef_id, uint32_t flags, uint32_t options, uint32_t timeout) {
  EventGroupHandle_t hEventGroup = (EventGroupHandle_t)ef_id;
  BaseType_t wait_all;
  BaseType_t exit_clr;
  uint32_t rflags;

  if ((hEventGroup == NULL) || ((flags & EVENT_FLAGS_INVALID_BITS) != 0U)) {
    rflags = (uint32_t)osErrorParameter;
  }
  else if (IS_IRQ()) {
    rflags = (uint32_t)osErrorISR;
  }
  else {
    if (options & osFlagsWaitAll) {
      wait_all = pdTRUE;
    } else {
      wait_all = pdFAIL;
    }

    if (options & osFlagsNoClear) {
      exit_clr = pdFAIL;
    } else {
      exit_clr = pdTRUE;
    }

    rflags = xEventGroupWaitBits (hEventGroup, (EventBits_t)flags, exit_clr, wait_all, (Tick-Type_t)timeout);

    if (options & osFlagsWaitAll) {
      if ((flags & rflags) != flags) {
        if (timeout > 0U) {
          rflags = (uint32_t)osErrorTimeout;
        } else {
          rflags = (uint32_t)osErrorResource;
        }
      }
    }
    else {
      if ((flags & rflags) == 0U) {
        if (timeout > 0U) {
          rflags = (uint32_t)osErrorTimeout;
        } else {
          rflags = (uint32_t)osErrorResource;
        }
      }
    }
  }

  return (rflags);
}

osEventFlagsDelete#

osStatus_t osEventFlagsDelete (osEventFlagsId_t ef_id) {
  EventGroupHandle_t hEventGroup = (EventGroupHandle_t)ef_id;
  osStatus_t stat;

#ifndef USE_FreeRTOS_HEAP_1
  if (IS_IRQ()) {
    stat = osErrorISR;
  }
  else if (hEventGroup == NULL) {
    stat = osErrorParameter;
  }
  else {
    stat = osOK;
    vEventGroupDelete (hEventGroup);
  }
#else
  stat = osError;
#endif

  return (stat);
}

Mutex Management Functions#

The following functions are covered in this section. These are mentioned in the sequence in which occur in the flow of an application: osMutexNew | osMutexAcquire | osMutexRelease | osMutexDelete

osMutexNew#

osMutexId_t osMutexNew (const osMutexAttr_t *attr) {
  SemaphoreHandle_t hMutex;
  uint32_t type;
  uint32_t rmtx;
  int32_t  mem;
  #if (configQUEUE_REGISTRY_SIZE > 0)
  const char *name;
  #endif

  hMutex = NULL;

  if (!IS_IRQ()) {
    if (attr != NULL) {
      type = attr->attr_bits;
    } else {
      type = 0U;
    }

    if ((type & osMutexRecursive) == osMutexRecursive) {
      rmtx = 1U;
    } else {
      rmtx = 0U;
    }

    if ((type & osMutexRobust) != osMutexRobust) {
      mem = -1;

      if (attr != NULL) {
        if ((attr->cb_mem != NULL) && (attr->cb_size >= sizeof(StaticSemaphore_t))) {
          mem = 1;
        }
        else {
          if ((attr->cb_mem == NULL) && (attr->cb_size == 0U)) {
            mem = 0;
          }
        }
      }
      else {
        mem = 0;
      }

      if (mem == 1) {
        #if (configSUPPORT_STATIC_ALLOCATION == 1)
          if (rmtx != 0U) {
            #if (configUSE_RECURSIVE_MUTEXES == 1)
            hMutex = xSemaphoreCreateRecursiveMutexStatic (attr->cb_mem);
            #endif
          }
          else {
            hMutex = xSemaphoreCreateMutexStatic (attr->cb_mem);
          }
        #endif
      }
      else {
        if (mem == 0) {
          #if (configSUPPORT_DYNAMIC_ALLOCATION == 1)
            if (rmtx != 0U) {
              #if (configUSE_RECURSIVE_MUTEXES == 1)


              hMutex = xSemaphoreCreateRecursiveMutex ();
              #endif
            } else {
              hMutex = xSemaphoreCreateMutex ();
            }
          #endif
        }
      }

      #if (configQUEUE_REGISTRY_SIZE > 0)
      if (hMutex != NULL) {
        if (attr != NULL) {
          name = attr->name;
        } else {
          name = NULL;
        }
        vQueueAddToRegistry (hMutex, name);
      }
      #endif

      if ((hMutex != NULL) && (rmtx != 0U)) {
        hMutex = (SemaphoreHandle_t)((uint32_t)hMutex | 1U);
      }
    }
  }

  return ((osMutexId_t)hMutex);
}

osMutexAcquire#

osStatus_t osMutexAcquire (osMutexId_t mutex_id, uint32_t timeout) {
  SemaphoreHandle_t hMutex;
  osStatus_t stat;
  uint32_t rmtx;

  hMutex = (SemaphoreHandle_t)((uint32_t)mutex_id & ~1U);

  rmtx = (uint32_t)mutex_id & 1U;

  stat = osOK;

  if (IS_IRQ()) {
    stat = osErrorISR;
  }
  else if (hMutex == NULL) {
    stat = osErrorParameter;
  }
  else {
    if (rmtx != 0U) {
      #if (configUSE_RECURSIVE_MUTEXES == 1)
      if (xSemaphoreTakeRecursive (hMutex, timeout) != pdPASS) {
        if (timeout != 0U) {
          stat = osErrorTimeout;
        } else {
          stat = osErrorResource;
        }
      }
      #endif
    }
    else {
      if (xSemaphoreTake (hMutex, timeout) != pdPASS) {
        if (timeout != 0U) {
          stat = osErrorTimeout;
        } else {
          stat = osErrorResource;
        }
      }
    }
  }

  return (stat);
}

osMutexRelease#

osStatus_t osMutexRelease (osMutexId_t mutex_id) {
  SemaphoreHandle_t hMutex;
  osStatus_t stat;
  uint32_t rmtx;

  hMutex = (SemaphoreHandle_t)((uint32_t)mutex_id & ~1U);

  rmtx = (uint32_t)mutex_id & 1U;

  stat = osOK;

  if (IS_IRQ()) {
    stat = osErrorISR;
  }
  else if (hMutex == NULL) {
    stat = osErrorParameter;
  }
  else {
    if (rmtx != 0U) {
      #if (configUSE_RECURSIVE_MUTEXES == 1)
      if (xSemaphoreGiveRecursive (hMutex) != pdPASS) {
        stat = osErrorResource;
      }
      #endif
    }
    else {
      if (xSemaphoreGive (hMutex) != pdPASS) {
        stat = osErrorResource;
      }
    }
  }

  return (stat);
}

osMutexDelete#

osStatus_t osMutexDelete (osMutexId_t mutex_id) {
  osStatus_t stat;
#ifndef USE_FreeRTOS_HEAP_1
  SemaphoreHandle_t hMutex;

  hMutex = (SemaphoreHandle_t)((uint32_t)mutex_id & ~1U);

  if (IS_IRQ()) {
    stat = osErrorISR;
  }
  else if (hMutex == NULL) {
    stat = osErrorParameter;
  }
  else {
    #if (configQUEUE_REGISTRY_SIZE > 0)
    vQueueUnregisterQueue (hMutex);
    #endif
    stat = osOK;
    vSemaphoreDelete (hMutex);
  }
#else
  stat = osError;
#endif

  return (stat);
}

Semaphore Management Functions#

The following functions are covered in this section. These are mentioned in the sequence in which occur in the flow of an application: osSemaphoreNew | osSemaphoreAcquire | osSemaphoreRelease | osSemaphoreDelete

osSemaphoreNew#

osSemaphoreId_t osSemaphoreNew (uint32_t max_count, uint32_t initial_count, const osSemaphoreAttr_t *attr) {
  SemaphoreHandle_t hSemaphore;
  int32_t mem;
  #if (configQUEUE_REGISTRY_SIZE > 0)
  const char *name;
  #endif

  hSemaphore = NULL;

  if (!IS_IRQ() && (max_count > 0U) && (initial_count <= max_count)) {
    mem = -1;

    if (attr != NULL) {
      if ((attr->cb_mem != NULL) && (attr->cb_size >= sizeof(StaticSemaphore_t))) {
        mem = 1;
      }
      else {
        if ((attr->cb_mem == NULL) && (attr->cb_size == 0U)) {
          mem = 0;
        }
      }
    }
    else {
      mem = 0;

    }

    if (mem != -1) {
      if (max_count == 1U) {
        if (mem == 1) {
          #if (configSUPPORT_STATIC_ALLOCATION == 1)
            hSemaphore = xSemaphoreCreateBinaryStatic ((StaticSemaphore_t *)attr->cb_mem);
          #endif
        }
        else {
          #if (configSUPPORT_DYNAMIC_ALLOCATION == 1)
            hSemaphore = xSemaphoreCreateBinary();
          #endif
        }

        if ((hSemaphore != NULL) && (initial_count != 0U)) {
          if (xSemaphoreGive (hSemaphore) != pdPASS) {
            vSemaphoreDelete (hSemaphore);
            hSemaphore = NULL;
          }
        }
      }
      else {
        if (mem == 1) {
          #if (configSUPPORT_STATIC_ALLOCATION == 1)
            hSemaphore = xSemaphoreCreateCountingStatic (max_count, initial_count, (StaticSemaphore_t *)attr->cb_mem);
          #endif
        }
        else {
          #if (configSUPPORT_DYNAMIC_ALLOCATION == 1)
            hSemaphore = xSemaphoreCreateCounting (max_count, initial_count);
          #endif
        }
      }
      
      #if (configQUEUE_REGISTRY_SIZE > 0)
      if (hSemaphore != NULL) {
        if (attr != NULL) {
          name = attr->name;
        } else {
          name = NULL;
        }
        vQueueAddToRegistry (hSemaphore, name);
      }
      #endif
    }
  }

  return ((osSemaphoreId_t)hSemaphore);
}

osSemaphoreAcquire#

osStatus_t osSemaphoreAcquire (osSemaphoreId_t semaphore_id, uint32_t timeout) {
  SemaphoreHandle_t hSemaphore = (SemaphoreHandle_t)semaphore_id;
  osStatus_t stat;
  BaseType_t yield;

  stat = osOK;

  if (hSemaphore == NULL) {
    stat = osErrorParameter;
  }
  else if (IS_IRQ()) {
    if (timeout != 0U) {
      stat = osErrorParameter;
    }
    else {
      yield = pdFALSE;

      if (xSemaphoreTakeFromISR (hSemaphore, &yield) != pdPASS) {
        stat = osErrorResource;
      } else {
        portYIELD_FROM_ISR (yield);
      }
    }
  }
  else {
    if (xSemaphoreTake (hSemaphore, (TickType_t)timeout) != pdPASS) {
      if (timeout != 0U) {
        stat = osErrorTimeout;
      } else {
        stat = osErrorResource;
      }
    }
  }

  return (stat);
}

osSemaphoreRelease#

osStatus_t osSemaphoreRelease (osSemaphoreId_t semaphore_id) {
  SemaphoreHandle_t hSemaphore = (SemaphoreHandle_t)semaphore_id;
  osStatus_t stat;
  BaseType_t yield;

  stat = osOK;

  if (hSemaphore == NULL) {
    stat = osErrorParameter;
  }
  else if (IS_IRQ()) {
    yield = pdFALSE;

    if (xSemaphoreGiveFromISR (hSemaphore, &yield) != pdTRUE) {
      stat = osErrorResource;
    } else {


      portYIELD_FROM_ISR (yield);
    }
  }
  else {
    if (xSemaphoreGive (hSemaphore) != pdPASS) {
      stat = osErrorResource;
    }
  }

  return (stat);
}

osSemaphoreDelete#

osStatus_t osSemaphoreDelete (osSemaphoreId_t semaphore_id) {
  SemaphoreHandle_t hSemaphore = (SemaphoreHandle_t)semaphore_id;
  osStatus_t stat;

#ifndef USE_FreeRTOS_HEAP_1
  if (IS_IRQ()) {
    stat = osErrorISR;
  }
  else if (hSemaphore == NULL) {
    stat = osErrorParameter;
  }
  else {
    #if (configQUEUE_REGISTRY_SIZE > 0)
    vQueueUnregisterQueue (hSemaphore);
    #endif

    stat = osOK;
    vSemaphoreDelete (hSemaphore);
  }
#else
  stat = osError;
#endif

  return (stat);
}