Add CMSIS-RTOS RTX & CubeMX adapt generated files

This section explains how to add the CMSIS-RTOS RTX real-time operating system.

Setup in STM32CubeMX

In STM32CubeMX ensure that the System Tick Interrupt is set to the lowest priority (which is the highest number).

Configuration tab

• Under System open NVIC Configuration.
• Click on System tick timer and set Preemption Priority to 15 (highest possible value).
• Click OK to close the NVIC Configuration dialog.

Setup in MDK

In MDK, the steps to add the CMSIS-RTOS RTX real-time operating system to a project that is configured with STM32CubeMX are:

Step 1: Add CMSIS-RTOS RTX

• Open the Manage Run-Time Environment window and add CMSIS:RTOS (API):Keil RTX.

Step 2: Configure CMSIS-RTOS RTX parameters

• Open the configuration file RTX_Conf_CM.c from the project window, component group CMSIS.
• Optionally you may change to the Configuration Wizard tab.
• Change the following settings:
  • Main Thread stack size [bytes] 1024
  • RTOS Kernel Timer input clock frequency [Hz] set to core clock frequency
• Save the file.

Step 3: Add code for CMSIS-RTOS RTX in 'main.c'

• Open the source file main.c from the project window, source group STM32CubeMX:Common Sources and add code lines in the sections USER CODE BEGIN / USER CODE END as shown below:

:

/* USER CODE BEGIN Includes */

#include "cmsis_os.h" // ARM::CMSIS:RTOS:Keil RTX

/* USER CODE END Includes */

:

/* USER CODE BEGIN 0 */

extern uint32_t os_time;

uint32_t HAL_GetTick(void) { // Add HAL_GetTick function for STM32Cube HAL

return os_time;

}

/* USER CODE END 0 */

:

int main(void)

{

:

/* USER CODE BEGIN 1 */

osKernelInitialize (); // Initialize RTOS Kernel for setup

/* USER CODE END 1 */

:

/* USER CODE BEGIN 2 */

osKernelStart (); // Begin thread switching

/* USER CODE END 2 */

:

Step 4: Remove SysTick_Handler in stm32f7xx_it.c

• STM32CubeMX generates a SysTick_Handler that is in-compatible with CMSIS-RTOS RTX. Remove the code for the SysTick_Handler in the source file stm32f7xx_it.c as shown below.

#if 0

void SysTick_Handler(void)

{

/* USER CODE BEGIN SysTick_IRQn 0 */

/* USER CODE END SysTick_IRQn 0 */

HAL_IncTick();

HAL_SYSTICK_IRQHandler();

/* USER CODE BEGIN SysTick_IRQn 1 */

/* USER CODE END SysTick_IRQn 1 */

}

#endif

Step 5: Build Project in MDK

• Use Project - Build Target to generate the application code.

The source file generated by STM32CubeMX can be accessed in the MDK project window, source group STM32CubeMX:Common Sources. These file require the following modifications.

Changes to 'stm32fxxx_it.c'

CMSIS-Driver and CMSIS-RTOS RTX implement their own interrupt handlers.

• For using CMSIS-RTOS RTX remove the code of the SysTick_Handler.
• For using CMSIS-Driver remove the code of the related Interruption Handler.

Note

STM32CubeMX re-generates this file and it is required to remove the interrupt handlers after using Generate Code.

Changes to 'main.c'

• CMSIS-Driver initialize peripherals using dedicated functions that are called by middleware. Initialization code in 'main.c' for the related peripherals is therefore not required and may be removed.
• CMSIS-RTOS RTX requires initialization code. Refer to Add CMSIS-RTOS RTX for detailed information.