fun.c

#include "my_typ_head.h"//初始化
void uart_init()
{//1.使能GPIOB/GPIOG/UART4时钟  RCC_MP_AHB4ENSETR/RCC_MP_APB1ENSETR//设置GPIOB\GPIOG控制器时钟使能  0X50000A28(*(unsigned int *)0X50000A28) |= (0X10);(*(unsigned int *)0X50000A28) |= (0X1<<6);//设置UART4时钟使能(*(unsigned int *)0X50000A00) |= (0X1<<16);//2.设置PG11/PB2为复用功能  GPIOX_MODERGPIOG->MODER &=(~(0X3<<22));GPIOG->MODER |=(0X2<<22);GPIOB->MODER &=(~(0X3<<4));GPIOB->MODER |=(0X2<<4);//3.PG11/PB2为uart4复用功能  GPIOX_AFRL/GPIOX_AFRHGPIOB->AFRL |=(0X1000<<8);GPIOG->AFRH |=(0X0110<<12);//4.设置数据位宽为8位  USART_CR1USART4->CR1 &= (~(0X1<<28));USART4->CR1 &= (~(0X1<<12));//5.设置16倍过采样USART_CR1USART4->CR1 &=(~(0X1<<15));//6.设置无校验  USART_CR1USART4->CR1 &=(~(0X1<<10));//7.设置停止位  USART_CR2USART4->CR1 &=(~(0X3<<12));//8.设置波特率  USART_BRRUSART4->BRR |=(0X22B);//9.发送器使能  USART_CR1USART4->CR1 |=(0X1<<3);//10.接收器使能  USART_CR1USART4->CR1 |=(0X1<<2);//11.串口使能  USART_CR1USART4->CR1 |=(0X1);}char readchar()
{char c;//1.判断接收数据寄存器数据是否准备好  USART_ISR[5]while(!(USART4->ISR&(0X1<<5)));//2.如果准备好就读取  USART_RDRc=USART4->RDR;//3.返回  return c;
}void sendchar(char c)
{//1.判断发送数据寄存器是否不满USART_ISR[7]while(!(USART4->ISR&(0X1<<7)));//2.如果不满就写入  USART_TDRUSART4->TDR=c;//3.等到发送完成后函数结束  USART_ISR[6]while(!(USART4->ISR&(0X1<<6)));
}

main.c

#include "my_typ_head.h"int main(){//初始化uart_init();char c='A';while(1){//2.接收一个字节数据readchar();//3.发送一个字节数据sendchar(c);}return 0;}

head.h

#ifndef __GPIO_H__
#define __GPIO_H__
#include "/home/ubuntu/xiangmu/kaifaban_c/02-c/common/include/stm32mp1xx_gpio.h"
#include "/home/ubuntu/xiangmu/kaifaban_c/02-c/common/include/stm32mp1xx_rcc.h"
#include "/home/ubuntu/xiangmu/kaifaban_c/02-c/common/include/stm32mp1xx_uart.h"void uart_init();
char readchar();
void sendchar(char c);
#endif //__GPIO_H__