STM32中SYSTEM文件夹

F1:
delay_init()函数
void delay_init(uint16_t sysclk)
{
	SysTick->CTRL=0;
	
	HAL_SYSTICK_CLKSourceConfig(SYSTICK_CLKSOURCE_HCLK_DIV8);
	g_fac_us=sysclk/8;//set Crossover factor as 8
}

delay_us()函数：
void delay_us(uint32_t nus)
{
	uint32_t temp;
	SysTick->LOAD=nus*g_fac_us;//load time
	SysTick->VAL=0x00;//clear counter
	SysTick->CTRL|=1<<0;//start count back
	do
	{
	temp=SysTick->CTRL;
	}while((temp&0x01)&&!(temp&(1<<16)));

	SysTick->CTRL&=~(1<<0);//closeSYSTICK
	SysTick->VAL=0X00;//clear counter
}

delay_ms()函数：
void delay_ms(uint16_t nms)
{
	uint32_t repeat =nms/1000;
	
	uint32_t remain=nms%1000;
	
	while(repeat)
	{
		delay_us(1000*1000);
		repeat--;

	}
	if(remain)
	{
	delay_us(remain*1000);
	} 

}