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Jessy J
Jessy J
Associate III
May 14, 2018
Question

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  • May 14, 2018
  • 35 replies
  • 4287 views

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    35 replies

    Tesla DeLorean
    Tesla DeLorean
    Guru
    May 14, 2018
    Posted on May 14, 2018 at 23:53

    How is this related to this thread?

    Check that you have a working SysTick interrupt, and that it is incrementing the HAL Tick properly.

    If you are calling this delay in an interrupt you'll need to ensure the SysTick preempts everything else.

    There should be a whole collection of Free RTOS examples, perhaps review how they work and are structured, and apply that to your code.

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    Jessy J
    Jessy JAuthor
    Associate III
    May 15, 2018
    Posted on May 15, 2018 at 12:10

    Thank ou Clive One for your reply 

    ensure the SysTick preempts everything else. please ?? I am blocked

    Tesla DeLorean
    Tesla DeLorean
    Guru
    May 15, 2018
    Posted on May 15, 2018 at 13:30

    Review the NVIC preemption and sub-priority settings, and the group settings that determine the bits assigned to each. System Handler priorities managed in the SCB

    Read up on the functionality of the processor

    https://www.amazon.com/Definitive-Guide-Cortex%C2%AE-M3-Cortex%C2%AE-M4-Processors/dp/0124080820

     
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    Jessy J
    Jessy JAuthor
    Associate III
    May 15, 2018
    Posted on May 15, 2018 at 15:39

    Is the systick good when using FreeRTOS or shall I change it to timer ? I saw in some forums saying systick is not good performing when it comes to rtos is that true please ? Shall i continue using systick or not ? 

    Tesla DeLorean
    Tesla DeLorean
    Guru
    May 15, 2018
    Posted on May 15, 2018 at 16:49

    It is as usable as any other interrupt.

    I don't like software interrupt based counters for the kinds of applications the ST HAL uses them for.

    If you use SysTick, and you use the tick count it generates, and you use that count in other interrupt routines, then you are going to have to ensure that SysTick preempts ALL other interrupt sources and routines.

    I don't particularly like the HAL implementation.

    When your call-back routines are called you are running in interrupt context, you should do what you need quickly and leave, or queue more complex processing for a deferred thread or worker task.

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    Jessy J
    Jessy JAuthor
    Associate III
    May 15, 2018
    Posted on May 15, 2018 at 16:59

    I changed the systick functions in which will be usuable by FreeRTOS  like this ..systick and HAL_GetTick are declared weak so I changed it like this

    /**

    * dummy function to avoid the standard initialization code

    */

    HAL_StatusTypeDef HAL_InitTick(uint32_t TickPriority)

    {

    return HAL_OK;

    }

    /**

    * @brief Get the value of the Kernel SysTick timer

    * @param None

    * @retval None

    * @note MUST REMAIN UNCHANGED: \b osKernelSysTick shall be consistent in every CMSIS-RTOS.

    */

    uint32_t HAL_GetTick(void)

    {

    return osKernelSysTick();

    }

    /**

    * @brief This function handles System tick timer.

    */

    void SysTick_Handler(void)

    {

    /* USER CODE BEGIN SysTick_IRQn 0 */

    if (xTaskGetSchedulerState() != taskSCHEDULER_NOT_STARTED)

    {

    osSystickHandler();

    }

    /* USER CODE END SysTick_IRQn 0 */

    /* USER CODE BEGIN SysTick_IRQn 1 */

    /* USER CODE END SysTick_IRQn 1 */

    }

    void HAL_Delay ( volatile uint32_t millis)

    {

    /* remplace la fonction de délai de blocage de la bibliothèque HAL avec l'équivalent de la reconnaissance de threads FreeRTOS */

    /*(mappage HAL_Delay () à vTaskDelay () résout le problème du blocage d'une fonction dans un timeout)*/

    osDelay (millis);

    }

     I am not sure if I am doing well or not 

    what do you think ? 

    Jessy J
    Jessy JAuthor
    Associate III
    May 15, 2018
    Posted on May 15, 2018 at 17:00

    and how 

    ensure that SysTick preempts ALL other interrupt sources and routine ?? is there something in the code I use it to ensure this please ??? 

    A
    Artur IWANICKI
    ST Employee
    May 16, 2018
    Posted on May 16, 2018 at 08:19

    Hello,

    I would recommend to you to keep SysTick as a time base for FreeRTOS. In this case it will have lowest possible priority (0xF in STM32) and the same like PendSV.

    Both of them are specified in FreeRTOSConfig.h file as 'configLIBRARY_LOWEST_INTERRUPT_PRIORITY'.

    If you are using HAL libraries you would need a timer to generate all delay functions and timeouts. For this I would suggest to use either TIM6 or TIM7. Both are 16 bit without any input/output channels, so you would not loose any input/output timer channels. If you are using STM32CubeMX for code generation this timer assignment can be done within SYS peripheral section -> Timebase. This timer (used by HAL) will have highest possible priority (0).

    Concerning rest of the interrupts you need to specify which interrupts will execute functions of FreeRTOS. For those interrupts you should set priority specified by configLIBRARY_MAX_SYSCALL_INTERRUPT_PRIORITY (by default in STM32CubeMX it is set to 5). Rest of the interrupts should have higher priority (lower number).

    In such a model your hardware and its interrupts which will not use OS functions will not be interrupted/blocked by OS as operating system in most of its functions is using critical sections which are blocking interrupts to the level of configLIBRARY_MAX_SYSCALL_INTERRUPT_PRIORITY.

    I hope it clarifies the topic a bit.

    Best Regards,

    Artur

    Jessy J
    Jessy JAuthor
    Associate III
    May 16, 2018
    Posted on May 16, 2018 at 09:03

    Hello, 

    Thank you so much 

    Artur for your reply . 

    in reeRTOSConfig.h I have this 

    #define configLIBRARY_LOWEST_INTERRUPT_PRIORITY 15

    #define configLIBRARY_MAX_SYSCALL_INTERRUPT_PRIORITY 5

    #define configMAX_SYSCALL_INTERRUPT_PRIORITY ( configLIBRARY_MAX_SYSCALL_INTERRUPT_PRIORITY << (8 - configPRIO_BITS) )

    #define configPRIO_BITS __NVIC_PRIO_BITS with 

    __NVIC_PRIO_BITS 4 

    the interruption priorities is correct right ?? 

     the functino HAL_Delay and HAL_GetDelay are weak functon so I thought to rewrite them with using the freeRTOS functinos like this : 

    uint32_t HAL_GetTick(void)

    {

    return osKernelSysTick();

    }

    /**

    * @brief This function handles System tick timer.

    */

    void SysTick_Handler(void)

    {

    /* USER CODE BEGIN SysTick_IRQn 0 */

    if (xTaskGetSchedulerState() != taskSCHEDULER_NOT_STARTED)

    {

    osSystickHandler();

    }

    /* USER CODE END SysTick_IRQn 0 */

    }

    void HAL_Delay ( volatile uint32_t millis)

    {

    /* remplace la fonction de délai de blocage de la bibliothèque HAL avec l'équivalent de la reconnaissance de threads FreeRTOS */

    /*(mappage HAL_Delay () à vTaskDelay () résout le problème du blocage d'une fonction dans un timeout)*/

    osDelay (millis);

    }

    When I debug it blocks in portmacro.h of FreeRTOS  in this function 

    portFORCE_INLINE static void vPortRaiseBASEPRI( void )

    {

    uint32_t ulNewBASEPRI;

    __asm volatile

    (

    ' mov %0, %1 \n' \

    ' msr basepri, %0 \n' \

    ' isb \n' \

    ' dsb \n' \

    :'=r' (ulNewBASEPRI) : 'i' ( configMAX_SYSCALL_INTERRUPT_PRIORITY )

    );

    }

    If I am not wrong the vPortRaiseBASEPRI function is related to the priorities right ?? 

    How can  solve this please ? 

    Thank you so much in advance 

    Best regards

    A
    Artur IWANICKI
    ST Employee
    May 16, 2018
    Posted on May 16, 2018 at 10:04

    Hello,

    Your NVIC configuration looks correct. 

    BASEPRI is the name of the core registers which is used to block interrupt on the desired level (always vs preemption priorities). As you see in above code you are configuring BASEPRI with configMAX_SYSCALL_INTERRUPT_PRIORITY (5 in your case). 

    I see you are using os functions within HAL functions . 

    I would separate those two worlds. Please select different timer (SYS->Timebase) for HAL libraries and leave SysTick for OS. It will help you with proper interrupt management.

    If you will use Systick for HAL and OS you will face the situation that your SysTick interrupt (having lowest possible priority) will be stucked as it will be blocked by most of the OS functions at entrance to critical section (operations on BASEPRI).

    Best Regards,

    Artur

    Jessy J
    Jessy JAuthor
    Associate III
    May 16, 2018
    Posted on May 16, 2018 at 10:11

    Hello, 

    I wanted to configure the interruptino using Systick and then change it to timer but it is not correct right ?? 

    If no , which Timer shall I use in SYS PLEASE ?? 

    Can You tell me more about timers and how to use it ? I am a debutant about timers 

    Jessy J
    Jessy JAuthor
    Associate III
    May 16, 2018
    Posted on May 16, 2018 at 10:24

    I changed it to tTIM6 .when I debug it blocks in the BASEPRI function I do not know why yet 

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