ARM day7 (串口协议)

实验一

键盘输入一个字符'a',串口工具显示'b'

uart4.h

#ifndef __UART4_H__
#define __UART4_H__

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

//初始化UART4
void hal_uart4_init();

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

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

//接收一个字符
char hal_get_char();

//接收一个字符串
char* hal_get_string();



#endif

uart4.c

#include "uart4.h"


//初始化UART4
void hal_uart4_init()
{
	/*************RCC*************/
	//1.GPIOB使能 MP_AHB4ENSETR[1] = 1
	RCC->MP_AHB4ENSETR |= (0x1 << 1);
	//2.GPIOG使能 MP_AHB4ENSETR[6] = 1
	RCC->MP_AHB4ENSETR |= (0x1 << 6);
	//3.UART4使能 MP_APB1ENSETR[16] = 1
	RCC->MP_APB1ENSETR |= (0x1 << 16);

	/************GPIO*************/
	//1.设置 FB2 引脚为复用模式 MODER[5:4] = 10
	GPIOB->MODER &= (~(0X3 << 4));
	GPIOB->MODER |= (0x2 << 4);

	//2.设置 FB2 引脚复用为 UART4_RX AFRL[11:8] = 1000
	GPIOB->AFRL &= (~(0xf << 8));
	GPIOB->AFRL |= (0x8 << 8);
	
	//1.设置 FG11 引脚为复用模式 MODER[23:22] = 10
	GPIOG->MODER &= (~(0X3 << 22));
	GPIOG->MODER |= (0X2 << 22);
		
	//2.设置 FG11 引脚复用为 UART4_TX AFRL[15:12] = 1000
	GPIOG->AFRL &= (~(0XF << 12));
	GPIOG->AFRL |= (0X6 << 12);


	/***********UART4*************/
	//0.设置串口UE = 0
	USART4->CR1 &= (~0x1); 
	
	//1.设置1位起始位，8位数据位
	USART4->CR1 &= (~(0x1 << 28));
	USART4->CR1 &= (~(0x1 << 12));
		
	//2.没有奇偶校验
	USART4->CR1 &= (~(0x1 << 10));
	
	//3.设置1位停止位
	USART4->CR2 &= (~(0x3 << 12)); 
	
	//4.设置16倍采样位
	USART4->CR1 &= (~(0x1 << 15));

	//5.设置串口不分频
	USART4->PRESC &= (~0xF);
	
	//6.设置串口波特率为115200
	USART4->BRR &= (~0xFFFF);
	USART4->BRR |= (0x22B);

	//7.设置串口发送器使能
	USART4->CR1 |= (0x1 << 3);

	//8.设置串口接收器使能
	USART4->CR1 |= (0x1 << 2);

	//9.设置串口使能
	USART4->CR1 |= 0x1;

}



//发送一个字符
void hal_put_char(const char str)
{
	//1.判断是否为空 ISR[7]
	//0为满（堵塞），1为空（发送）
	while(!(USART4->ISR & (0x1 << 7)));
	//2.将要发送内容赋值寄存器
	USART4->TDR = str;
	//3.判断一帧数据是否发送完成ISR[6]
	//0未完成，1已完成
	while(!(USART4->ISR & (0x1 << 6)));

}


//接收一个字符
char hal_get_char()
{
	//1.判断接收是否有数据ISR[5]
	
	while(!(USART4->ISR & (0x1 << 5)));

	//2.将数据读取
	return USART4->RDR;


}

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()
{

	//使能初始化
	hal_uart4_init();

	while(1)
	{
		char arr = hal_get_char();	
		hal_put_char(arr+1);
	}
	return 0;
}

实现二

键盘输入一个字符串，串口工具回显输入的字符串

uart4.h

#ifndef __UART4_H__
#define __UART4_H__

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

//初始化UART4
void hal_uart4_init();



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

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

//接收一个字符
char hal_get_char();

//接收一个字符串
char* hal_get_string();



#endif

uart4.c

#include "uart4.h"

extern void delay_ms(int ms);

//初始化UART4
void hal_uart4_init()
{
	/*************RCC*************/
	//1.GPIOB使能 MP_AHB4ENSETR[1] = 1
	RCC->MP_AHB4ENSETR |= (0x1 << 1);
	//2.GPIOG使能 MP_AHB4ENSETR[6] = 1
	RCC->MP_AHB4ENSETR |= (0x1 << 6);
	//3.UART4使能 MP_APB1ENSETR[16] = 1
	RCC->MP_APB1ENSETR |= (0x1 << 16);

	/************GPIO*************/
	//1.设置 FB2 引脚为复用模式 MODER[5:4] = 10
	GPIOB->MODER &= (~(0X3 << 4));
	GPIOB->MODER |= (0x2 << 4);

	//2.设置 FB2 引脚复用为 UART4_RX AFRL[11:8] = 1000
	GPIOB->AFRL &= (~(0xf << 8));
	GPIOB->AFRL |= (0x8 << 8);

	//1.设置 FG11 引脚为复用模式 MODER[23:22] = 10
	GPIOG->MODER &= (~(0X3 << 22));
	GPIOG->MODER |= (0X2 << 22);

	//2.设置 FG11 引脚复用为 UART4_TX AFRL[15:12] = 1000
	GPIOG->AFRL &= (~(0XF << 12));
	GPIOG->AFRL |= (0X6 << 12);

	/***********UART4*************/
	//0.设置串口UE = 0
	if(USART4->CR1 & 0x1)
	{
		delay_ms(500);
		USART4->CR1 &= (~0x1); 
	}
	//1.设置1位起始位，8位数据位
	USART4->CR1 &= (~(0x1 << 28));
	USART4->CR1 &= (~(0x1 << 12));

	//2.没有奇偶校验
	USART4->CR1 &= (~(0x1 << 10));

	//3.设置1位停止位
	USART4->CR2 &= (~(0x3 << 12)); 

	//4.设置16倍采样位
	USART4->CR1 &= (~(0x1 << 15));

	//5.设置串口不分频
	USART4->PRESC &= (~0xF);

	//6.设置串口波特率为115200
	USART4->BRR &= (~0xFFFF);
	USART4->BRR |= (0x22B);

	//7.设置串口发送器使能
	USART4->CR1 |= (0x1 << 3);

	//8.设置串口接收器使能
	USART4->CR1 |= (0x1 << 2);

	//9.设置串口使能
	USART4->CR1 |= 0x1;

}

//发送一个字符
void hal_put_char(const char str)
{
	//1.判断是否为空 ISR[7]
	//0为满（堵塞），1为空（发送）
	while(!(USART4->ISR & (0x1 << 7)));
	//2.将要发送内容赋值寄存器
	USART4->TDR = str;
	//3.判断一帧数据是否发送完成ISR[6]
	//0未完成，1已完成
	while(!(USART4->ISR & (0x1 << 6)));

}

//发送一个字符串
void hal_put_string(const char* str)
{
	//判断是否为‘\0'
	//一个一个字符发送
	while(*str)
	{
		hal_put_char(*str++);
	}
	hal_put_char('\n');
	hal_put_char('\r');


}

//接收一个字符
char hal_get_char()
{
	//1.判断接收是否有数据ISR[5]
	while(!(USART4->ISR & (0x1 << 5)));
	//2.将数据读取
	return USART4->RDR;
}


char arr[100] = {0};
//接收一个字符串
char* hal_get_string()
{
	//循环接收

	int i = 0;

	while(1)
	{
		//'\n'回车表示接收完成
		arr[i] = hal_get_char();
		hal_put_char(arr[i]);
		if(arr[i] == '\r') 
		{
			break;
		}
		i++;
	}
	arr[i] = '\0';
	hal_put_char('\n');
	return arr;
}

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()
{

	//使能初始化
	hal_uart4_init();
	hal_put_string("UART4 TEXT\n");
	hal_put_char(hal_get_char());
	while(1)
	{
		hal_put_string(hal_get_string());
	}
	return 0;
}