uart.c

#include "uart4.h"
void uart4_config()
{RCC->MP_AHB4ENSETR |= (0X1 << 6);//ＧRCC->MP_AHB4ENSETR |= (0X1 << 1);//BRCC->MP_APB1ENSETR |= (0X1 << 16);//UART4
//管脚复用GPIOG->MODER  &= (~(0X3 << 22));GPIOG->MODER |= (0X2 << 22);GPIOB->MODER &= (~(0X3 << 4));GPIOB->MODER |= (0X2 << 4);GPIOG->AFRH &= (~(0XF << 12));//UART4_TXGPIOG->AFRH |= (0X6 << 12);GPIOB->AFRL &= (~(0XF << 8));//UART4_RXGPIOB->AFRL |= (0X8 << 8);//USART设置USART4->CR1 &= (~(0X1));//使能禁用USART4->CR1 &= (~(0X1 << 28));//设置数据位USART4->CR1 &= (~(0X1 << 12));USART4->CR1 &= (~(0x1 << 15));//设置过采样倍数USART4->CR1 &= (~(0x1 << 10));//设置无奇偶校验位USART4->CR1 |= (0X1 << 3);//发送器使能位USART4->CR1 |= (0X1 << 2);//接收器使能位USART4->CR2 &= (~(0X1 << 12));USART4->BRR = (0X22B);USART4->PRESC &= (~(0XF));//设置不分频USART4->CR1 |= (0X1 << 0);//串口工作使能位}void putchar(char dat)
{while (!(USART4->ISR & (0X1 << 7)));USART4->TDR = dat;while (!(USART4->ISR & (0X1 << 6)));}char getchar()
{while (!(USART4->ISR & (0X1 << 5)));return USART4->RDR;}void puts(char *a)
{int i=0;while (a[i] != '\0'){putchar(a[i]);i++;}putchar('\n');putchar('\r');
}char * gets(char *b)
{int i=0;for(;(b[i]=getchar()) != '\r';i++){putchar(b[i]);}putchar('\r');putchar('\n');b[i]='\0';//  for (int i = 0; i < 128; i++)// {//     b[i] = getchar(); // 将接收到的字符放入str中//     putchar(b[i]); // 将接收到的字符串发送回串口调试助手//     if (b[i] == '\r') // 如果接收到了换行符//     {//         putchar('\n'); // 将接收到的字符串发送回串口调试助手//         b[i+1] = '\0';//         break;//     }return b;
}

uart.h

#ifndef  __UART4_H__
#define __UART4_H__
#include  "stm32mp1xx_gpio.h" 
#include  "stm32mp1xx_rcc.h" 
#include  "stm32mp1xx_uart.h" void uart4_config();
void putchar(char dat);
char getchar();
char * gets(char *b);
void puts(char *a);#endif

main.c

#include "uart4.h"int main()
{char dat[128];while(1){gets(dat);puts(dat);}return 0;}