实现串口收发字符/字符串

uart4.c

#include "uart4.h"

void hal_uart_init()
{

	//rcc初始化
	//使能CPIOB组控制器
	RCC->MP_AHB4ENSETR |= (0x1 << 1);
	//使能CPIOG组控制器
	RCC->MP_AHB4ENSETR |= (0x1 << 6);
	//使能UART4控制器
	RCC->MP_APB1ENSETR |= (0x1 << 16);

	//gpio
	GPIOG->MODER &= (~(0x3 << 4));
	GPIOG->MODER |= (0x1 << 5 );

	GPIOG->MODER &= (~(0x3 << 22));
	GPIOG->MODER |= (0x1 << 23);

	GPIOG->AFRL &= (~(0xf << 8));
	GPIOG->AFRL |= (0x1 << 11);	
	
	GPIOG->AFRH &= (~(0xf << 12));
	GPIOG->AFRH |= (0x1 << 13);
	GPIOG->AFRH |= (0x1 << 14);


	//uart
	USART4->CR1 &= (~(0x1 << 12));
	USART4->CR1 &= (~(0x1 << 28));
	USART4->CR1 &= (~(0x1 << 15));
	USART4->CR1 &= (~(0x1 << 10));
	USART4->CR1 |= (0x1 << 3);
	USART4->CR1 |= (0x1 << 2);
	USART4->CR1 |= (0x1);

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

	USART4->BRR = 0x22B;

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






}
//输出一个字符
void hal_put_char(const char str)
{
	while(!(USART4->ISR & (0x1 << 7)));
	USART4->TDR = str;

}
//输出一个字符串
void hal_put_string(const char *str)
{

	while(*str!='\0')
	{
		hal_put_char(*str);
		str++;
	}
	hal_put_char('\r');
	hal_put_char('\n');
}
//接收一个字符
char hal_get_char()
{

	while(!(USART4->ISR & (0x1 << 5)));
	return USART4->RDR;
}

char str[256]="";
//输出一个字符串
char* hal_get_string()
{
	int i=0;
	while(1)
	{
		while(!(USART4->ISR & (0x1 << 5)));
		
		if(USART4->RDR == '\r')
		{

			str[i]='\0';
			break;
		}
		str[i]=USART4->RDR;
		//键盘输入时的打印
		hal_put_char(str[i]);
		i++;
	
	}
	hal_put_char('\r');
	hal_put_char('\n');
	return str;

}

uart4.h

#ifndef __LED_H__
#define __LED_H__

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

//初始化函数
void hal_uart_init();

//发送字符
void hal_put_char(const char str);

//发送字符串
void hal_put_string(const char *string);

//接受字符
char hal_get_char();

//接受字符串
char * hal_get_string();
#endif

main.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()
{
	hal_uart_init();
	hal_put_string("put string test success");
	while(1)
	{

	//	hal_put_char(hal_get_char()+1);
	
		hal_put_string(hal_get_string());

	}
	return 0;
}