ARM 用串口来实现灯的点亮

main.c

#include "uart4.h"

//封装延时函数

void delay(int ms)

{

    int i,j;

    for(i=0;i<ms;i++)

    {

        for(j=0;j<2000;j++)

        {}

    }

}



int main()

{

    led_init();

	uart4_init();

    //char buf[128];

    char *str;

   

    //char i;

    while(1)

    {

       /*i=getchar();

        putchar(i+1);

        putchar('\n');

        putchar('\r');*/

        str=gets();

        puts(str);



        if(strcmp(str,"led1_on"))

        {

            GPIOE->ODR |= (0X1<<10);  

        }

        else if(strcmp(str,"led1_off"))

        {

            GPIOE->ODR &= ~(0X1<<10);

        }

        else if(strcmp(str,"led2_on"))

        {

            GPIOE->ODR |= (0X1<<8);

        }

        else if(strcmp(str,"led2_off"))

        {

            GPIOE->ODR &= ~(0X1<<8);

        }

        else if(strcmp(str,"led3_on"))

        {

            GPIOF->ODR |= (0X1<<10);

        }

        else if(strcmp(str,"led3_off"))

        {

            GPIOF->ODR &= ~(0X1<<10);

        }

    }

    return 0;

	

}

src/uart4.c

#include "uart4.h"

char buf[128]={0};
//led数据初始化
void led_init()
{
    //设置GPIOE/GPIOF时钟使能
    RCC->MP_AHB4ENSETR |=(0X3<<4);
    //设置PE10/PE8/PF10为输出模式
    //PE10
    GPIOE->MODER &=(~(0X3<<20));
    GPIOE->MODER |=(0X1<<20);
    //PE8
    GPIOE->MODER &=(~(0X3<<16));
    GPIOE->MODER |=(0X1<<16);
    //PF10
    GPIOF->MODER &=(~(0X3<<20));
    GPIOF->MODER |=(0X1<<20);
    //设置PE10/PE8/PF10为推完输出
    //PE10
    GPIOE->OTYPER &=(~(0X1<<10));
    //PE8
    GPIOE->OTYPER &=(~(0X1<<8));
    //PF10
    GPIOF->OTYPER &=(~(0X1<<10));
    //设置PE10/PE8/PF10为输出速度为低速
    //PE10
    GPIOE->OSPEEDR &=(~(0X3<<20));
    //PE8
    GPIOE->OSPEEDR &=(~(0X3<<16));
    //PF10
    GPIOF->OSPEEDR &=(~(0X3<<20));
    //设置PE10/PE8/PF10为无上拉无下拉
    GPIOE->PUPDR &=(~(0X3<<20));
    //PE8
    GPIOE->PUPDR &=(~(0X3<<20));
    //PE10
    GPIOE->PUPDR &=(~(0X3<<20));
}

void uart4_init()
{
    //使能GPIOB GPIOG UART4外设时钟
    RCC->MP_AHB4ENSETR |= (0x1<<1);
    RCC->MP_AHB4ENSETR |= (0x1<<6);
    RCC->MP_APB1ENSETR |= (0x1<<16);
    //设置PB2和PG11管脚复用
    //PB2
    GPIOB->MODER &= (~(0X3<<4));
    GPIOB->MODER |=(0X2<<4);
    GPIOB->AFRL &=(~(0xf<<8));
    GPIOB->AFRL |=(0x8<<8);
    //PG11
    GPIOG->MODER &= (~(0X3<<22));
    GPIOG->MODER |=(0X2<<22);
    GPIOG->AFRL &=(~(0xf<<12));
    GPIOG->AFRL |=(0x6<<12);
    //设置串口不使能UE=O
    USART4->CR1 &= (~(0X1));
    //设置8位数据位
    USART4->CR1 &=(~(0X1<<12));
    USART4->CR1 &= (~(0X1<<28));
    //设置没有奇偶校验位
    USART4->CR1 &=(~(0X1<<10));
    //设置1位停止位
    USART4->CR2 &= (~(0X3<<12));
    //设置16倍过采样
    USART4-> CR1 &= (~(0X1<<15));
    //设置时钟不分频
    USART4->PRESC &=(~0xf);
    //设置波特率为115200
    USART4->BRR=0X22B;
    //使能发送器
    USART4->CR1 |=(0X1<<3);
    //使能接收器
    USART4->CR1 |=(0X1<<2);
    //使能uart4
    USART4->CR1 |= (0X1);
}

//发送一个字符
void putchar(char a)
{
    //先判断发送数据寄存器是否为空
    //不为空阻塞等待
    while(!(USART4->ISR &(0X1<<7)));
    //为空向发送数据寄存器写入a的数据
    USART4->TDR =a;
    //写入完成需要判断发送是否完成，不完成阻塞等待，完成了则函数结束
    while(!(USART4->ISR &(0X1<<6)));
}

//接收一个字符
char getchar()
{
    char a;
    //先判断接收数据寄存器种有没有准备好的数据
    //如果数据没有准备好则阻塞等到
    while(!(USART4->ISR &(0X1<<5)));
    //如果数据准备好了则读取
    a=USART4->RDR;
    //读取完毕将读取到的数据返回
    return a;
}

//发送字符串
void puts(char *s)
{
    while(*s)
    {
        putchar(*s);
        s++;
    }
    putchar('\n');
    putchar('\r');
}
//接收字符串
char *gets()
{
    unsigned int i;
    for(i=0;i<50;i++)
    {
        buf[i]=getchar();
        putchar(buf[i]);
        if((buf[i])=='\r')
            break;
    }
    buf[i]='\0';
    putchar('\n');
    putchar('\r');

    return buf;
}

//比较两个字符串函数
int strcmp(char *dest, char *src)
{
    if(*dest == *src)
        return 0;
    while(*dest && *src)
    {
        if(*dest != *src)
        {
            return *dest - *src;
        }
        dest++;
        src++;
    }
    return 0;
}

src/uart4.h

#ifndef __UART4_H__
#define __UART4_H__
#include "stm32mp1xx_uart.h"
#include "stm32mp1xx_rcc.h"
#include "stm32mp1xx_gpio.h"
void led_init();
void uart4_init();
void putchar(char a);
char getchar();
void puts(char *s);
char *gets();
int strcmp(char *dest, char *src);

#endif