ARMday6作业

news2024/12/27 13:38:25

1，串口字符串收发现象实现图

2.串口控制灯亮灭

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 strcmp(char *a1,char *a2)
{
  int i=0;
  while(a1[i]==a2[i])
  {
    if(a1[i]=='\0')
     {
        break;
     } 
      i++;
  }
  int sub=a1[i]-a2[i];
   return sub;
}

int main()
{
    //led初始化
    uart4_init();
    all_led_init();
    char buf[32];
    // char i;
    while(1)
    {
        // i=getchar();
        // putchar(i+1);
        // //最终的现象：键盘输入a，串口工具显示b 
        gets(buf);
       if(strcmp(buf,"L1T")==0)
       {
          LED1_ON();
       }
       if(strcmp(buf,"L1F")==0)
       {
          LED1_OFF();
       }

       if(strcmp(buf,"L2T")==0)
       {
          LED2_ON();
       }
       if(strcmp(buf,"L2F")==0)
       {
          LED2_OFF();
       }

       if(strcmp(buf,"L3T")==0)
       {
          LED3_ON();
       }
       if(strcmp(buf,"L3F")==0)
       {
          LED3_OFF();
       }
    }
    return 0;
}

usart4.h

#ifndef __UART4_H__
#define __UART4_H__

#include "led.h"
#include "stm32mp1xx_uart.h"
#include "stm32mp1xx_rcc.h"
#include "stm32mp1xx_gpio.h"

void uart4_init();
void putchar(char a);
char getchar();
void gets(char *s);
void puts(char *s);
int strcmp(char *a1,char *a2);
#endif

usart4.c

#include "uart4.h"


void uart4_init()
{
    //使能GPIOB GPIOG UART4外设时钟
    RCC->MP_AHB4ENSETR |= (0x1<<1);//GPIOB
    RCC->MP_AHB4ENSETR |= (0x1<<6);//GPIOG
    RCC->MP_APB1ENSETR |= (0X1<<16);//UART4
    //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); 
    GPIOB->AFRH &= (~(0XF<<12));
    GPIOB->AFRH |= (0x6<<12);
    //设置串口不使能 UE=0
    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<<0);
    
}

//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;//写入数据
    //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中有没有准备好的数据
    //如果数据没有准备好则阻塞等待
    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');// '\n'切换到下一行
    putchar('\r');//'\n'回车键，切换到行头

}

//接收字符串函数
void gets(char *s)
{
    while(1)
    {
        *s=getchar();
        putchar(*s);
        if((*s)=='\r')
            break;
        s++;
    }
    *s='\0';
    putchar('\n');//换行
}

实现现象