HAL_SYSTICK_Config(SystemCoreClock / (1000U / uwTickFreq)

/*
以STM32F407为例子，为什么参数是这个
0. (SystemCoreClock / (1000U / uwTickFreq)): (表示systick的reload value)
1. SystemCoreClock 系统时钟 168000000: (1s可以计数这么多)
2. (1000U / uwTickFreq): (将1s分成1000份即1ms, 所以uwTickFreq毫秒后，触发systick中断)
3. (1000U / uwTickFreq): (1S将中断这么多次)
*/
HAL_SYSTICK_Config(SystemCoreClock / (1000U / uwTickFreq))

扩展

/*stm32f4xx_hal_cortex.c*/
/**
  * @brief  Initializes the System Timer and its interrupt, and starts the System Tick Timer.
  *         Counter is in free running mode to generate periodic interrupts.
  * @param  TicksNumb Specifies the ticks Number of ticks between two interrupts.
  * @retval status:  - 0  Function succeeded.
  *                  - 1  Function failed.
  */
uint32_t HAL_SYSTICK_Config(uint32_t TicksNumb)
{
   return SysTick_Config(TicksNumb);
}

/*core_cm4.h.c*/
/**
  \brief   System Tick Configuration
  \details Initializes the System Timer and its interrupt, and starts the System Tick Timer.
           Counter is in free running mode to generate periodic interrupts.
  \param [in]  ticks  Number of ticks between two interrupts.
  \return          0  Function succeeded.
  \return          1  Function failed.
  \note    When the variable <b>__Vendor_SysTickConfig</b> is set to 1, then the
           function <b>SysTick_Config</b> is not included. In this case, the file <b><i>device</i>.h</b>
           must contain a vendor-specific implementation of this function.
 */
__STATIC_INLINE uint32_t SysTick_Config(uint32_t ticks)
{
  if ((ticks - 1UL) > SysTick_LOAD_RELOAD_Msk)
  {
    return (1UL);                                                   /* Reload value impossible */
  }

  SysTick->LOAD  = (uint32_t)(ticks - 1UL);                         /* set reload register */
  NVIC_SetPriority (SysTick_IRQn, (1UL << __NVIC_PRIO_BITS) - 1UL); /* set Priority for Systick Interrupt */
  SysTick->VAL   = 0UL;                                             /* Load the SysTick Counter Value */
  SysTick->CTRL  = SysTick_CTRL_CLKSOURCE_Msk |
                   SysTick_CTRL_TICKINT_Msk   |
                   SysTick_CTRL_ENABLE_Msk;                         /* Enable SysTick IRQ and SysTick Timer */
  return (0UL);                                                     /* Function successful */
}

/**
  \brief   Set Interrupt Priority
  \details Sets the priority of a device specific interrupt or a processor exception.
           The interrupt number can be positive to specify a device specific interrupt,
           or negative to specify a processor exception.
  \param [in]      IRQn  Interrupt number.
  \param [in]  priority  Priority to set.
  \note    The priority cannot be set for every processor exception.
 */
__STATIC_INLINE void __NVIC_SetPriority(IRQn_Type IRQn, uint32_t priority)
{
  if ((int32_t)(IRQn) >= 0)
  {
    NVIC->IP[((uint32_t)IRQn)]               = (uint8_t)((priority << (8U - __NVIC_PRIO_BITS)) & (uint32_t)0xFFUL);
  }
  else
  {
    SCB->SHP[(((uint32_t)IRQn) & 0xFUL)-4UL] = (uint8_t)((priority << (8U - __NVIC_PRIO_BITS)) & (uint32_t)0xFFUL);
  }
}

对比ucosii

/*os_cpu_c.c*/
/*
*********************************************************************************************************
*                                         INITIALIZE SYS TICK
*
* Description: Initialize the SysTick using the number of counts between two ticks.
*
* Arguments  : cnts     Number of SysTick counts between two OS tick interrupts.
*
* Note(s)    : 1) This function MUST be called after OSStart() & after processor initialization.
*
*              2) Either OS_CPU_SysTickInitFreq or OS_CPU_SysTickInit() can be called.
*********************************************************************************************************
*/

void  OS_CPU_SysTickInit (INT32U  cnts)
{
    INT32U  prio;
    INT32U  basepri;


                                                                /* Set BASEPRI boundary from the configuration.         */
    basepri               = (INT32U)(CPU_CFG_KA_IPL_BOUNDARY << (8u - CPU_CFG_NVIC_PRIO_BITS));
    OS_CPU_CM_SYST_RVR    = cnts - 1u;                          /* Set Reload register.                                 */

                                                                /* Set SysTick handler prio.                            */
    prio                  =  OS_CPU_CM_SCB_SHPRI3;
    prio                 &=  0x00FFFFFFu;
    prio                 |= (basepri << 24u);
    OS_CPU_CM_SCB_SHPRI3  = prio;

                                                                /* Enable timer.                                        */
    OS_CPU_CM_SYST_CSR   |= OS_CPU_CM_SYST_CSR_CLKSOURCE |
                            OS_CPU_CM_SYST_CSR_ENABLE;
                                                                /* Enable timer interrupt.                              */
    OS_CPU_CM_SYST_CSR   |= OS_CPU_CM_SYST_CSR_TICKINT;
}