DELAY

Functions
__STATIC_INLINE void	LL_InitTick (uint32_t HCLKFrequency, uint32_t Ticks)
	This function configures the Cortex-M SysTick source of the time base. More...
void	LL_Init1msTick (uint32_t HCLKFrequency)
	This function configures the Cortex-M SysTick source to have 1ms time base. More...
void	LL_mDelay (uint32_t Delay)
	This function provides accurate delay (in milliseconds) based on SysTick counter flag. More...

Detailed Description

Function Documentation

LL_Init1msTick()

void LL_Init1msTick

(

uint32_t

HCLKFrequency

)

This function configures the Cortex-M SysTick source to have 1ms time base.

Note

When a RTOS is used, it is recommended to avoid changing the Systick configuration by calling this function, for a delay use rather osDelay RTOS service.

Parameters

HCLKFrequency

HCLK frequency in Hz

Note

HCLK frequency can be calculated thanks to RCC helper macro or function LL_RCC_GetSystemClocksFreq

Return values

None

Definition at line 170 of file stm32l4xx_ll_utils.c.

{
  /* Use frequency provided in argument */
  LL_InitTick(HCLKFrequency, 1000U);
}

LL_InitTick()

__STATIC_INLINE void LL_InitTick	(	uint32_t	HCLKFrequency,
		uint32_t	Ticks
	)

This function configures the Cortex-M SysTick source of the time base.

Parameters

HCLKFrequency

HCLK frequency in Hz (can be calculated thanks to RCC helper macro)

Note

When a RTOS is used, it is recommended to avoid changing the SysTick configuration by calling this function, for a delay use rather osDelay RTOS service.

Parameters

Ticks

Number of ticks

Return values

None

Definition at line 279 of file stm32l4xx_ll_utils.h.

{
  /* Configure the SysTick to have interrupt in 1ms time base */
  SysTick->LOAD  = (uint32_t)((HCLKFrequency / Ticks) - 1UL);  /* set reload register */
  SysTick->VAL   = 0UL;                                       /* Load the SysTick Counter Value */
  SysTick->CTRL  = SysTick_CTRL_CLKSOURCE_Msk |
                   SysTick_CTRL_ENABLE_Msk;                   /* Enable the Systick Timer */
}

LL_mDelay()

void LL_mDelay

(

uint32_t

Delay

)

This function provides accurate delay (in milliseconds) based on SysTick counter flag.

Note

When a RTOS is used, it is recommended to avoid using blocking delay and use rather osDelay service.

To respect 1ms timebase, user should call LL_Init1msTick function which will configure Systick to 1ms

Parameters

Delay

specifies the delay time length, in milliseconds.

Return values

None

Definition at line 186 of file stm32l4xx_ll_utils.c.

{
  __IO uint32_t  tmp = SysTick->CTRL;  /* Clear the COUNTFLAG first */
  uint32_t tmpDelay = Delay;

  /* Add this code to indicate that local variable is not used */
  ((void)tmp);

  /* Add a period to guaranty minimum wait */
  if(tmpDelay < LL_MAX_DELAY)
  {
    tmpDelay++;
  }

  while (tmpDelay != 0U)
  {
    if((SysTick->CTRL & SysTick_CTRL_COUNTFLAG_Msk) != 0U)
    {
      tmpDelay--;
    }
  }
}