实验串口实现发送字符/字符串

头文件

#ifndef __UART4_H__
#define __UART4_H__

#include "stm32mp1xx_gpio.h"
#include "stm32mp1xx_rcc.h"
#include "stm32mp1xx_uart.h"

//串口初始化
void uart_init();

//发送一个字符
void uart_put_char(const char str);

//发送一个字符串
void uart_put_string(const char *str);

//接收一个字符
char uart_get_char();

//接收一个字符串
char* uart_get_string();

#endif

源文件

#include "uart4.h"

//串口初始化
void uart_init()
{
     /*********RCC章节初始化************/
    RCC->MP_AHB4ENSETR |= (0x1 << 1);
    RCC->MP_AHB4ENSETR |= (0x1 << 6);
    RCC->MP_APB1ENSETR |= (0x1 << 16);
     /*********GPIO章节初始化************/
    GPIOB->MODER &= ~(0x3 << 4);
    GPIOB->MODER |= (0x1 << 5);

    GPIOB->AFRL &=~(0Xf<<8);
    GPIOB->AFRL |=(0X8<<8);

    GPIOG->MODER &= ~(0x3 << 22);
    GPIOG->MODER |= (0x2 << 22);

    GPIOG->AFRH &=~(0Xf<<12);
    GPIOG->AFRH |= (0X6<<12);

     /*********UART4章节初始化************/
    if(USART4->CR1 & (0x1 << 0))
    {
        //将UE设置为禁止
        USART4->CR1 &= (~(0x1 << 0));
    }

    USART4->CR1 &= ~(0x1<<12);
    USART4->CR1 &= ~(0x1<<28);
    USART4->CR1 &= ~(0x1<<15);
    USART4->CR1 &= ~(0x1<<10);

    USART4->CR1 &= ~(0x1<<3);
    USART4->CR1 |= (0x1<<3);

    USART4->CR1 &= ~(0x1<<2);
    USART4->CR1 |= (0x1<<2);

    USART4->CR1 &= ~(0x1<<0);
    USART4->CR1 |= (0x1<<0);

    USART4->CR2 &= ~(0x3<<12);

    USART4->PRESC &= ~(0xf<<0);

    USART4->BRR = 0x22B;


}

//发送一个字符
void uart_put_char(const char str)
{
    //1.判断发送数据寄存器是否为空,为空，才可以发送下一个字节
    //ISR[7]  
    //读0:发送数据寄存器满，需要等待
    //读1:发送数据寄存器空，才可以发送下一个字节数据
    while(!(USART4->ISR & (0x1 << 7)));

    //2.将要发送的字符，写到发送数据寄存器中
    USART4->TDR = str;

    //3.判断发送数据是否完成 ISR[6]
    while(!(USART4->ISR & (0x1 << 6)));
}

//发送一个字符串
void uart_put_string(const char* str)
{
    //判断是否为'\0',一个字符一个字符发送
    for(int i=0;(*(str+i))!='\0';i++)
    {
        //1.判断发送数据寄存器是否为空,为空，才可以发送下一个字节
        //ISR[7]  
        //读0:发送数据寄存器满，需要等待
        //读1:发送数据寄存器空，才可以发送下一个字节数据
        while(!(USART4->ISR & (0x1 << 7)));

        //2.将要发送的字符，写到发送数据寄存器中
        USART4->TDR = *(str+i);

        //3.判断发送数据是否完成 ISR[6]
        while(!(USART4->ISR & (0x1 << 6)));

    }
}

//接收一个字符
char uart_get_char()
{
    char ch;
    //1.判断接收数据寄存器是否有数据可读 ISR[5]
    while(!(USART4->ISR & (0x1 << 5)));
    
    //2.将接收到的数据读出来
    ch = USART4->RDR;
    return ch;
}

char buffer[50] = {0};
//接收一个字符串
char* uart_get_string()
{
    int i=0;
    uart_put_char('\n');
    uart_put_char('\r');
    //1.循环进行接收
    for(i=0; i<49; i++)
    {
        while(!(USART4->ISR & (0x1 << 5)));
        if(USART4->RDR == '\r')
        {
            uart_put_char('\n');
            uart_put_char('\r');
            buffer[i] = '\0';
            break;
        }
        buffer[i]=(char)(USART4->RDR);
        uart_put_char(buffer[i]);
    }
    //3.字符串补'\0'
    if(i == 49)
    {
        uart_put_char('\n');
        uart_put_char('\r');
        buffer[49]='\0';
    }
    return buffer;
}

mian.c

#include "uart4.h"
extern void printf(const char *fmt, ...);
void delay_ms(int ms)
{
    int i,j;
    for(i = 0; i < ms;i++)
        for (j = 0; j < 1800; j++);
}


int main()
{
    printf("gogogo\n");
    //串口初始化
    uart_init();
    //实现串口数据收发

    while(1)
    {
        uart_put_char(uart_get_char()+1);
        //uart_put_string(uart_get_string());
    }
    return 0;
} 

字符串：