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在之前分享的资料中有一份PDF文件http://share.eepw.com.cn/share/download/id/381630 在这个文档里有Systick的介绍。

上图中STK_CSR寄存器主要是设置时钟源，是否产生异常请求，是否使能计数。

第二个寄存器是存放计数器减到0时重载的数值。第三个寄存器是计数器当前值

uint32_t ui_opt_us;
uint32_t ui_opt_ms;

void delay_init()
{
	HAL_SYSTICK_CLKSourceConfig(SYSTICK_CLKSOURCE_HCLK_DIV8);
	ui_opt_us = HAL_RCC_GetHCLKFreq() / 8000000;
	ui_opt_ms = ui_opt_us * 1000;
}

void delay_us(uint32_t xus)
{
	uint32_t ui_tmp = 0x00;
	SysTick->LOAD = xus * ui_opt_us;
	SysTick->VAL = 0x00;
	SysTick->CTRL = 0x01;
	
	do
	{
		ui_tmp = SysTick->CTRL;
	}while((ui_tmp & 0x01) && (!(ui_tmp & (1 << 16))));
	
	SysTick->CTRL = 0x00;
	SysTick->VAL = 0x00;
	
}

void delay_ms(uint32_t xms)
{
	uint32_t ui_tmp = 0x00;
	SysTick->LOAD = xms * ui_opt_ms;
	SysTick->VAL = 0x00;
	SysTick->CTRL = 0x01;
	
	do
	{
		ui_tmp = SysTick->CTRL;
	}while((ui_tmp & 0x01) && (!(ui_tmp & (1 << 16))));
	
	SysTick->CTRL = 0x00;
	SysTick->VAL = 0x00;
	
}

	delay_init();
  while (1)
  {
		printf("-->%d\n\r",ui_time_count);
		delay_ms(1000);
		ui_time_count++;
  }