void systick_delay_us(u32 nus)
{
u32 temp;
SysTick_CLKSourceConfig(SysTick_CLKSource_HCLK); //select system clock
SysTick->LOAD=nus*(SystemCoreClock/1000000); //time relode
SysTick->VAL=0x00; //clear timer value
SysTick->CTRL|=SysTick_CTRL_ENABLE_Msk ; //Start countdown
do
{
temp=SysTick->CTRL;
}
while(temp&0x01&&!(temp&(1<<16)));//wait for the time reach
SysTick->CTRL&=~SysTick_CTRL_ENABLE_Msk; //close the count
SysTick->VAL =0X00; //clear timer value
}
/**
* @brief us delay program function.
* @param nus: the setting us value.
* note: The system clock should be an integer multiple of 1M .
* It is ensure accuracy .
*/
void systick_delay_ms(u16 nms)
{
u32 temp;
SysTick_CLKSourceConfig(SysTick_CLKSource_HCLK); //select system clock
SysTick->LOAD=(u32)nms*((SystemCoreClock/1000000)*1000);//time relode(SysTick->LOAD is 24bit)
SysTick->VAL =0x00; //clear timer value
SysTick->CTRL|=SysTick_CTRL_ENABLE_Msk ; //Start countdown
do
{
temp=SysTick->CTRL;
}
while(temp&0x01&&!(temp&(1<<16)));//wait for the time reach
SysTick->CTRL&=~SysTick_CTRL_ENABLE_Msk; //close the count
SysTick->VAL =0X00; //clear timer value
}
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