[嵌入式]stm32流水灯点亮

前言

实现流水灯点亮

一、点亮一个灯

首先先实现点亮一个灯

int main(void)
{		
	//打开GPIOB的时钟
	*(unsigned int *)0x40021018 = ( 1 << 3 );
	
	//设置GPIOB的0口为推挽输出模式
	*(unsigned int *)0x40010C00 &= ~( 0x0f<< (4*0));
	*(unsigned int *)0x40010C00 |= (1<<4*0);
		
	//设置0GPIOB的0口输出0
	*(unsigned int *)0x40010C0C &= ~(1 << 0);
	while (1);
}

void SystemInit(void)
{
	//函数体为空，目的是为了骗过编译器不报错
	return;
}

二、实现一个灯的闪烁点亮

int main(void)
{	
	//打开GPIOB的时钟
	*(unsigned int *)0x40021018 = ( 1 << 3 );
	
	//设置GPIOB的0口为推挽输出模式
	*(unsigned int *)0x40010C00 &= ~( 0x0f<< (4*0));
	*(unsigned int *)0x40010C00 |= (1<<4*0);
	
	while (1)
	{
		//设置0GPIOB的0口输出1
		*(unsigned int *)0x40010C0C |= (1 << 0);
		delay(1000);		//设置0GPIOB的0口输出0
		*(unsigned int *)0x40010C0C &= ~(1 << 0);
		delay(1000);
	}
}

//延时函数，不加volatile不能成功
void delay(volatile unsigned int time)
{
     unsigned int i, j;
     for (i = 0; i < time; i++)
			for (j = 0; j < time; j++)
				;
}

void SystemInit(void)
{
	//函数体为空，目的是为了骗过编译器不报错
	return;
}

特别说明：

在写延时函数的时候，一定要用volatile，不使用的话根本起不到延时的作用。

三、使用寄存器编程实现三个灯的闪烁点亮

首先根据参考手册自己编写一个简易的stm32f10x.h头文件

//用来存放STM32寄存器映射的代码

//外设 perirhral
#define PERIPH_BASE				((unsigned int)0x40000000)

#define APB1PERIPH_BASE		(PERIPH_BASE)
#define APB2PERIPH_BASE		(PERIPH_BASE + 0X10000)
#define AHBPERIPH_BASE		(PERIPH_BASE + 0X20000)

#define RCC_BASE		(AHBPERIPH_BASE + 0x1000)
#define GPIOB_BASE	(APB2PERIPH_BASE + 0xC00)

#define RCC_APB2ENR		*(unsigned int *)(RCC_BASE + 0x18)

#define GPIOB_CRL			*(unsigned int *)((GPIOB_BASE + 0x00))
#define GPIOB_CRH			*(unsigned int *)((GPIOB_BASE + 0x04))
#define GPIOB_ODR			*(unsigned int *)((GPIOB_BASE + 0x0C))
#define GPIOB_BSRR			*(unsigned int *)((GPIOB_BASE + 0x10))
#define GPIOB_BRR			*(unsigned int *)((GPIOB_BASE + 0x14))

1.使用输出数据寄存器来实现

#include "stm32f10x.h"

void delay(volatile unsigned int time);

int main(void)
{	
	//打开时钟
	RCC_APB2ENR |= (1 << 3);
	
	//设置GPIOB的PB0，PB1，PB5为推挽输出模式，速度最大为10MHZ
	GPIOB_CRL &= ~(0x0e << (4*0) );
	GPIOB_CRL |= ( 1 << (4*0) );
	
	GPIOB_CRL &= ~(0x0e << (4*1) );
	GPIOB_CRL |= ( 1 << (4*1) );
	
	GPIOB_CRL &= ~(0x0e << (4*5) );
	GPIOB_CRL |= ( 1 << (4*5) );
	
	//输出
	while (1)
	{
		GPIOB_ODR &= ~(1 << 0);	//G亮
		delay(1000);
		GPIOB_ODR |= (1 << 0);	//G灭
		delay(1000);
		
		GPIOB_ODR &= ~(1 << 1);	//B亮
		delay(1000);
		GPIOB_ODR |= (1 << 1);	//B灭
		delay(1000);

		GPIOB_ODR &= ~(1 << 5);	//R亮
		delay(1000);	
		GPIOB_ODR |= (1 << 5);	//R灭
		delay(1000);		
	}
}

//延时函数，不加volatile不能成功
void delay(volatile unsigned int time)
{
     unsigned int i, j;
     for (i = 0; i < time; i++)
			for (j = 0; j < time; j++)
				;
}

void SystemInit(void)
{
	//函数体为空，目的是为了骗过编译器不报错
	return;
}

2.使用端口位设置/清除寄存器来实现

#include "stm32f10x.h"

void delay(volatile unsigned int time);

int main(void)
{	
	//打开时钟
	RCC_APB2ENR |= (1 << 3);
	
	//设置GPIOB的PB0，PB1，PB5为推挽输出模式，速度最大为10MHZ
	GPIOB_CRL &= ~(0x0e << (4*0) );
	GPIOB_CRL |= ( 1 << (4*0) );
	
	GPIOB_CRL &= ~(0x0e << (4*1) );
	GPIOB_CRL |= ( 1 << (4*1) );
	
	GPIOB_CRL &= ~(0x0e << (4*5) );
	GPIOB_CRL |= ( 1 << (4*5) );	
	
	GPIOB_ODR = 0xFFFF;
	
	//输出
	while (1)
	{
		GPIOB_BSRR |= (1 << 16);		//G亮
		delay(1000);
		GPIOB_BSRR &= ~(1 << (16+0));
		GPIOB_BSRR |= (1 << 0);			//G灭
		delay(1000);
		GPIOB_BSRR &= ~(1 << 0);	
		
		GPIOB_BSRR |= (1 << (16+1));	//B亮
		delay(1000);
		GPIOB_BSRR &= ~(1 << (16+1));
		GPIOB_BSRR |= (1 << 1);				//B灭
		delay(1000);
		GPIOB_BSRR &= ~(1 << 1);

		GPIOB_BSRR |= (1 << (16+5));	//R亮
		delay(1000);
		GPIOB_BSRR &= ~(1 << (16+5));
		GPIOB_BSRR |= (1 << 5);				//R灭
		delay(1000);
		GPIOB_BSRR &= ~(1 << 5);			
	}
}

//延时函数，不加volatile不能成功
void delay(volatile unsigned int time)
{
     unsigned int i, j;
     for (i = 0; i < time; i++)
			for (j = 0; j < time; j++)
				;
}

void SystemInit(void)
{
	//函数体为空，目的是为了骗过编译器不报错
	return;
}

注意：对GPIOB_BSRR的第16位的置1置0操作，不能放在前后语句来执行，否则可能因为过快，还未给GPIOB的0引脚置0就已经取消置0了。其他位的操作也是一样。

总结

注意：在设置为推挽输出模式的时候，先把四位中的前三位置为0是必不可少的，因为可能因为种种原因，它的前三位并不全为0，故仅仅执行将最后一位置为1可能达不到效果。