FreeRTOS: osDelay vs HAL_delay

Question

While creating FreeRTOS application project with STM32CubeMx, there are two ways you can use to introduce delay, namely osDelay and HAL_Delay.

What's the difference among them and which one should be preferred?

osDelay Code:

/*********************** Generic Wait Functions *******************************/
/**
* @brief   Wait for Timeout (Time Delay)
* @param   millisec      time delay value
* @retval  status code that indicates the execution status of the function.
*/
osStatus osDelay (uint32_t millisec)
{
#if INCLUDE_vTaskDelay
  TickType_t ticks = millisec / portTICK_PERIOD_MS;

  vTaskDelay(ticks ? ticks : 1);          /* Minimum delay = 1 tick */

  return osOK;
#else
  (void) millisec;

  return osErrorResource;
#endif
}

HAL_Delay Code:

/**
* @brief This function provides accurate delay (in milliseconds) based 
*        on variable incremented.
* @note In the default implementation , SysTick timer is the source of time base.
*       It is used to generate interrupts at regular time intervals where uwTick
*       is incremented.
* @note ThiS function is declared as __weak to be overwritten in case of other
*       implementations in user file.
* @param Delay: specifies the delay time length, in milliseconds.
* @retval None
*/
__weak void HAL_Delay(__IO uint32_t Delay)
{
  uint32_t tickstart = 0;
  tickstart = HAL_GetTick();
  while((HAL_GetTick() - tickstart) < Delay)
  {
  }
}

Answer 1

HAL_Delay is NOT a FreeRTOS functions and _osDelay is a function built around FreeRTOS function. (acc @Clifford: ) They both are entirely different function by different developers for different purposes.

osDelay is part of CMSIS Library and uses vTaskDelay() internally to introduce delay with the difference that input argument of osDelay is delay time in milliseconds while the input argument of _vTaskDelay() is number of Ticks to be delayed. (acc. @Bence Kaulics:) Using this function, OS will be notified about the delay and OS will change the status of task to blocked for that particular time period.

HAL_Delay is part of the hardware abstraction layer for our processor. It basically uses polling to introduce delay. (acc. @Bence Kaulics:) Using this function, OS won't be notified about the delay. Also if you do not use OS, then HAL_Delay is the default and only blocking delay to use provided by the HAL library. (acc. @Clifford: ) This is part of HAL Library and can be used without FreeRTOS (or when FreeRTOS is not running)

To introduce Delay using FreeRTOS functions, you can use vTaskDelay() or vTaskDelayUntil() after the scheduler has started.

(acc. @Clifford: )
Always Favour FreeRTOS API functino if you want your applicatino to be deterministic.
CubeMX is a collection of parts from multiple sources.