stm32毫秒ms延时，HAL_Delay（）

STM32的HAL库确实提供了毫秒级的延时函数，即HAL_Delay()函数。这个函数使用SysTick定时器来实现延时，并且可以配置为微秒级的延时。

//stm32l4xx_hal.c
/**
  * @brief This function provides minimum 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(uint32_t Delay)
{
  uint32_t tickstart = HAL_GetTick();
  uint32_t wait = Delay;

  /* Add a period to guaranty minimum wait */
  if (wait < HAL_MAX_DELAY)
  {
    wait += (uint32_t)uwTickFreq;
  }

  while ((HAL_GetTick() - tickstart) < wait)
  {
  }
}
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