ARMday6作业

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);//GPIOBRCC->MP_AHB4ENSETR |= (0x1<<6);//GPIOGRCC->MP_APB1ENSETR |= (0X1<<16);//UART4//设置PB2和PG11管脚复用//PB2GPIOB->MODER &= (~(0x3<<4));GPIOB->MODER |=(0x2<<4); GPIOB->AFRL &= (~(0XF<<8));GPIOB->AFRL |= (0x8<<8);//PG11GPIOG->MODER &= (~(0x3<<22));GPIOG->MODER |=(0x2<<22); GPIOB->AFRH &= (~(0XF<<12));GPIOB->AFRH |= (0x6<<12);//设置串口不使能 UE=0USART4->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115200USART4->BRR=0X22B;//使能发送器USART4->CR1 |= (0x1<<3);//使能接收器USART4->CR1 |= (0x1<<2);//使能uart4USART4->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