main.c

#include "uart4.h"#include "led.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(){//初始化串口uart4_init();all_led_init();char buf[32];while(1){gets(buf);if( buf[0] == 'A'){LED1_ON();}else if(buf[0] == 'B'){LED2_ON;}else if(buf[0] == 'C'){LED3_ON;}else if(buf[0] == 'D'){LED1_OFF;}else if(buf[0] == 'E'){LED2_OFF;}else if(buf[0] == 'F'){LED3_OFF;}puts(buf);}return 0;}

uart4.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');
}

uart4.h

#ifndef __UART4_H__
#define __UART4_H__
#include "stm32mp1xx_uart.h"
#include "stm32mp1xx_gpio.h"
#include "stm32mp1xx_rcc.h"void uart4_init();
void putchar(char a);
char getchar();
void puts(char *s);
void gets(char *s);#endif

led.c

#include "led.h"void all_led_init()//led灯的初始化
{//GPIOE/GPIOF时钟使能RCC  |= (0x3<<4);//PE10设置为输出GPIOE_MODER &= (~(0X3<<20));GPIOE_MODER |= (0X1<<20);//PF10设置为输出GPIOF_MODER &= (~(0X3<<20));GPIOF_MODER |= (0X1<<20);//PE8设置为输出GPIOE_MODER &= (~(0X3<<16));GPIOE_MODER |= (0X1<<16);//PE10设置为推挽输出GPIOE_OTYPER &= (~(0X1<<10));//PF10设置为推挽输出GPIOF_OTYPER &= (~(0X1<<10));//PE8设置为推挽输出GPIOE_OTYPER &= (~(0X1<<8));//PE10设置为低速输出GPIOE_OSPEEDR &= (~(0X3<<20));//PF10设置为低速输出GPIOF_OSPEEDR &= (~(0X3<<20));//PE8设置为低速输出GPIOE_OSPEEDR &= (~(0X3<<16));//PE10无上拉下拉电阻GPIOE_OPUPDR &= (~(0X3<<20));//PF10无上拉下拉电阻GPIOF_OPUPDR &= (~(0X3<<20));//PE8无上拉下拉电阻GPIOE_OPUPDR &= (~(0X3<<16));//三盏灯默认输出低电平GPIOE_ODR &= (~(0X1<<10));GPIOF_ODR &= (~(0X1<<10));GPIOE_ODR &= (~(0X1<<8));
}//led1亮
void LED1_ON()
{GPIOE_ODR |= (0X1<<10);
}
//led2亮
void LED2_ON()
{GPIOF_ODR |= (0X1<<10);
}
//led1亮
void LED3_ON()
{GPIOE_ODR |= (0X1<<8);
}//LED1灭
void LED1_OFF()
{GPIOE_ODR &= (~(0X1<<10));
}
//LED2灭
void LED2_OFF()
{GPIOF_ODR &= (~(0X1<<10));
}
//LED3灭
void LED3_OFF()
{GPIOE_ODR &= (~(0X1<<8));
}

led.h

#ifndef __LED_H__
#define __LED_H__
#define RCC (*(unsigned int *)0X50000A28)
#define GPIOE_MODER (*(unsigned int *)0X50006000)
#define GPIOF_MODER (*(unsigned int *)0X50007000)
#define GPIOE_OTYPER (*(unsigned int *)0X50006004)
#define GPIOE_OSPEEDR (*(unsigned int *)0X50006008)
#define GPIOE_OPUPDR (*(unsigned int *)0X5000600C)
#define GPIOE_ODR (*(unsigned int *)0X50006014)
#define GPIOF_OTYPER (*(unsigned int *)0X50007004)
#define GPIOF_OSPEEDR (*(unsigned int *)0X50007008)
#define GPIOF_OPUPDR (*(unsigned int *)0X5000700C)
#define GPIOF_ODR (*(unsigned int *)0X50007014)
void all_led_init();
void LED1_ON();
void LED2_ON();
void LED3_ON();
void LED1_OFF();
void LED2_OFF();
void LED3_OFF();#endif