src/uart.c

#include"uart.h"void uart4_init()
{//设置UART4的RCc时钟使能//RCC_MP_APB1ENSETR[16]->1RCC->MP_APB1ENSETR |= (0x1<<16);//设置GPIOB和GPIOG的时钟使能//RCC_MP_AHB4ENSETR[6]->1//RCC_MP_AHB4ENSETR[1]->1RCC->MP_AHB4ENSETR |= (0x1<<1);RCC->MP_AHB4ENSETR |= (0X1<<6);//设置PG11和PB2功能复用为UART4功能//PG11//GPIOG_MODER[23:22]->10GPIOG->MODER &= (~(0X3<<22));GPIOG->MODER |= (0X2<<22);//GPIOG_AFRH[15:12]->0110    GPIOG->AFRH &= (~(0xf<<12));GPIOG->AFRH |= (0x6<<12);//PB2//GPIOB_MODER[5:4]->10//GPIOB_AFRL[11:8]->1000GPIOB->MODER &= (~(0x3<<4));GPIOB->MODER |= (0X2<<4);GPIOB->AFRL &= (~(0xF<<8));GPIOB->AFRL |= (0x8<<8);//禁用串口USART4->CR1 &=(~0x1);//设置数据8个数据位 CR1[28]->0  CR1[12]-》0USART4->CR1 &= (~(0X1<<28));USART4->CR1 &= (~(0X1<<12));//设置没有校验位CR1[10]->0USART4->CR1 &= (~(0X1<<10));//设置1个停止位CR2[13:12]->00USART4->CR2 &= (~(0x3<<12));//设置16倍采样 CR1[15]->0USART4->CR1 &= (~(0X1<<15));//设置波特率为115200 BRR=0X22BUSART4->BRR |= 0X22B;//设置1分频 PRESC[3:0]->0000USART4->PRESC &= (~(0XF));//使能发送器 CR1[3]->1USART4->CR1 |= (0X1<<3);//使能接收器 CR1[2]->1USART4->CR1 |= (0X1<<2);//使能串口 CR1[0]->1USART4->CR1 |= (0X1);}
//串口发送一个字符
void putchar(char c)
{//判断发送数据寄存器有没有数据，没有数据时可以发送while(!(USART4->ISR&(0X1<<7)));USART4->TDR=c;//将要发送的数据保存在发送寄存器中while(!(USART4->ISR&(0X1<<6)));//数据传输完成，函数结束
}
//串口接受一个字符
char getchar()
{char c;//判断是否有数据准备好while(!(USART4->ISR&(0X1<<5)));//数据传输完成，函数结束c=USART4->RDR;return c;}
//串口发送一个字符串
//串口接收一个字符串

 include/uart.h

#ifndef __UART_H__
#define __UART_H__
#include"stm32mp1xx_uart.h"
#include"stm32mp1xx_gpio.h"
#include"stm32mp1xx_rcc.h"void uart4_init();
void putchar(char c);
char getchar();
#endif

 main.c

#include "uart.h"int main()
{char c;uart4_init();//串口初始化while(1){//串口数据收发//接收一个字符c=getchar();//发送字符putchar(c+1);}return 0;
}