stem32学习笔记---使用外部精准时钟实现滴答计时器精准延时

 

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 使用外部精准时钟

#include "rcc_driver.h"


//1.硬件初始化：72MHz
void rcc_init(void)
{
	//0.将RCC设置为缺省状态
	RCC_DeInit();
	
	//1.选择合适的时钟源：HSE
	RCC_HSEConfig(RCC_HSE_ON);
	
	//2.检测HSE是否真的启动
	if(RCC_WaitForHSEStartUp() == SUCCESS)
	{
		//AHB APB1 APB2
		RCC_HCLKConfig(RCC_SYSCLK_Div1);     //AHB
		RCC_PCLK1Config(RCC_HCLK_Div2);     //APB1
		RCC_PCLK2Config(RCC_SYSCLK_Div1);   //APB2    //RCC_HCLK_Div1
		
		//配置锁相环PLL
		RCC_PLLConfig(RCC_PLLSource_HSE_Div1, RCC_PLLMul_9);
		RCC_PLLCmd(ENABLE);
		
		//检测(等待PLL启动)
		while(RCC_GetFlagStatus(RCC_FLAG_PLLRDY) != SET);
		
		//将锁相环时钟设置为系统时钟
		RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);
		
		//等待PLL时钟已经设置为系统时钟
		while(RCC_GetSYSCLKSource() != 0x08);
	}
}
	
	

滴答计时器,实现精准延时

 

#include "systick_driver.h"


//1.硬件初始化:滴答定时器
void systick_init(void)  
{
	SysTick->CTRL &= ~(0x01 << 2);   //选择AHB/8= 9MHz
//	SysTick->CTRL &= 0xFFFFFFFB;     //选择AHB/8= 9MHz
}



//2.使用硬件:延时

//毫秒延时
void delay_ms(int nms)
{
	int temp;
		
	SysTick->LOAD = nms * 9000;  //计数值
	SysTick->VAL  = 0x00;        //清除当前值寄存器
	SysTick->CTRL |= 0x01;       //使能计数器
	
	do
	{
		temp = SysTick->CTRL;
	}while(((temp & 0x01) == 0x01) && !(temp & (0x01 << 16))); //判断计数完成(使能位，16bit(计数到0的标志位))
	 
	SysTick->CTRL &= ~0x01;	    //关闭计数器
	//SysTick->CTRL &= 0xFFFFFFFE;
	SysTick->LOAD = 0x00;       //清除计数值
	SysTick->VAL  = 0x00;       //清除当前值寄存器
}


//毫秒延时
void delay_us(int nus)
{
	int temp;
	
	SysTick->LOAD = nus * 9;  //计数值
	SysTick->VAL  = 0x00;        //清除当前值寄存器
	SysTick->CTRL |= 0x01;       //使能计数器

	
	do
	{
		temp = SysTick->CTRL;
	}while(((temp & 0x01) == 0x01) && !(temp & (0x01 << 16))); //判断计数完成(使能位，16bit(计数到0的标志位))
	 
	SysTick->CTRL &= ~0x01;	    //关闭计数器
	//SysTick->CTRL &= 0xFFFFFFFE;
	SysTick->LOAD = 0x00;       //清除计数值
	SysTick->VAL  = 0x00;       //清除当前值寄存器
}

#include "stm32f10x.h"
#include "led_driver.h"
#include "rcc_driver.h"
#include "systick_driver.h"


void flow_lamp(void)
{
	//红灯亮
	led_control(LED_ALL,LED_OFF);
	led_control(LED_RED,LED_ON);
	delay_ms(1000);
	
	//绿灯亮
	led_control(LED_ALL,LED_OFF);   
	led_control(LED_GREEN,LED_ON);
	delay_ms(1000);
	
	//蓝灯亮
	led_control(LED_ALL,LED_OFF);
	led_control(LED_BLUE,LED_ON);
	delay_ms(1000);
}





int main(void)
{
	rcc_init();
	systick_init();
	led_init();

	while (1)
	{
		flow_lamp();
	}

}