嵌入式学习-ARM

STM32串口控制三盏灯亮灭

MAIN.C

c 复制代码

#include "uart4.h"
int main()
{
	uart4_init();
	gpio_init();
	char str[32];
	
	while (1)
	{
		gets(str);
		if (my_strcmp(str,"A") == 0)
		{
			led1();
		}else if (my_strcmp(str,"B") == 0)
		{
			led2();
		}else if (my_strcmp(str,"C") == 0)
		{
			led3();
		}
		puts(str);
	}
	return 0;
}

UART4.C

c 复制代码

#include "uart4.h"

void uart4_init()
{
    // 使能GPIOB GPIOP UART4
    RCC->MP_AHB4ENSETR |= (0x1);
    RCC->MP_AHB4ENSETR |= (0x1 << 6);
    RCC->MP_APB1ENSETR |= (0x1 << 16);

    // 设置PB2和PG11管脚复用
    GPIOB->MODER &= (~(0X3 << 4));
    GPIOB->MODER |= (0X1 << 5);
    GPIOG->MODER &= (~(0X3 << 22));
    GPIOG->MODER |= (0X1 << 23);
    GPIOB->AFRL &= (~(0XF << 8));
    GPIOB->AFRL |= (0X8 << 8);
    GPIOG->AFRH &= (~(0XF << 12));
    GPIOG->AFRH |= (0X6 << 12);

    // 设置串口不使能 UE=0
    USART4->CR1 &= (~(0X1));

    // 设置8位数据位
    USART4->CR1 &= (~(0X1 << 12));
    USART4->CR1 &= (~(0X1 << 28));

    // 设置没有奇偶校验位
    USART4->CR1 &= (~(0X1 << 10));

    // 设置1位停止位
    USART4->CR2 &= (~(0X3 << 12));

    // 设置16倍过采样
    USART4->CR1 &= (~(0X1 << 15));

    // 设置时钟不分频
    USART4->PRESC &= (~(0XF));

    // 设置波特率115200
    USART4->BRR &= (~(0XF));
    USART4->BRR |= (0X22b);

    // 使能发送器
    USART4->CR1 |= (0X1 << 3);

    // 使能接收器
    USART4->CR1 |= (0X1 << 2);

    // 使能uart4
    USART4->CR1 |= (0X1);
}

void gpio_init()
{
    // GPIOE GPIOF时钟使能
    RCC->MP_AHB4ENSETR |= (0X3 << 4);

    // PE10 PF10 PE8设置为输出
    GPIOE->MODER &= (~(0X3 << 20));
    GPIOE->MODER |= (0X1 << 20);
    GPIOF->MODER &= (~(0X3 << 20));
    GPIOF->MODER |= (0X1 << 20);
    GPIOE->MODER &= (~(0X3 << 16));
    GPIOE->MODER |= (0X1 << 16);

    // 设置为推挽输出
    GPIOE->OTYPER &= (~(0X1 << 10));
    GPIOF->OTYPER &= (~(0X1 << 10));
    GPIOE->OTYPER &= (~(0X1 << 8));

    // 设置为低速输出
    GPIOE->OSPEEDR &= (~(0X3 << 20));
    GPIOF->OSPEEDR &= (~(0X3 << 20));
    GPIOE->OSPEEDR &= (~(0X3 << 16));

    // 设置为无上拉电阻
    GPIOE->PUPDR &= (~(0X3 << 20));
    GPIOF->PUPDR &= (~(0X3 << 20));
    GPIOE->PUPDR &= (~(0X3 << 16));

    // 默认低电平
    GPIOE->ODR &= (~(0X1 << 10));
    GPIOF->ODR &= (~(0X1 << 10));
    GPIOE->ODR &= (~(0X1 << 8));
    //GPIOE->ODR |= ((0X1 << 10));
    //GPIOF->ODR |= ((0X1 << 10));
    //GPIOE->ODR |= ((0X1 << 8));
}

// 输出字符
void putchar(char a)
{
    // 先判断发送数据寄存器是否为空
    // 不为空阻塞等待
    // 为空向发送数据寄存器写入a的数据
    // 写入完成需要判断发送是否完成，不完成阻塞等待，完成了则函数结束
    while (!(USART4->ISR & (0X1 << 7)))
        ;
    USART4->TDR = a;
    while (!(USART4->ISR & (0X1 << 6)))
        ;
}

// 获取字符
char getchar()
{
    // 先判断接收数据寄存器种有没有准备好的数据
    // 如果数据没有准备好则阻塞等到
    // 如果数据准备好了则读取
    // 读取完毕将读取到的数据返回
    while (!(USART4->ISR & (0X1 << 5))) // 等待数据
        ;
    return USART4->RDR;
}

// 获取字符串
void gets(char *str)
{
    while (1)
    {
        *str = getchar();
        putchar(*str);    // 显示输入的字符
        if (*str == '\r') // 回车退出
            break;
        str++;
    }
    *str = '\0';
    putchar('\n'); // 换行
}

// 输出字符串
void puts(char *s)
{
    while (*s)
    {
        putchar(*s);
        s++;
    }
    putchar('\r');
    putchar('\n');
}

void led1()
{
    if (GPIOE->ODR & (0X1 << 10)) // 此时是亮 改为暗
        GPIOE->ODR &= (~(0X1 << 10));
    else 
        GPIOE->ODR |= (0X1 << 10);
}
void led2()
{
    if (GPIOF->ODR & (0X1 << 10)) // 此时是亮 改为暗
        GPIOF->ODR &= (~(0X1 << 10));
    else 
        GPIOF->ODR |= (0X1 << 10);
}
void led3()
{
    if (GPIOE->ODR & (0X1 << 8)) // 此时是亮 改为暗
        GPIOE->ODR &= (~(0X1 << 8));
    else 
        GPIOE->ODR |= (0X1 << 8);
}

int my_strcmp(const char *src, const char *dest)
{
    while (*src == *dest)
    {
        if (*dest == '\0')
            break;
        src++;
        dest++;
    }
    return *src - *dest;
}

UART4.H

c 复制代码

#ifndef __UART4_H__
#define __UART4_H__

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

void uart4_init();
void gpio_init();
void putchar(char a);
char getchar();
void puts(char *s);
void gets(char *str);
void led1();
void led2();
void led3();
int my_strcmp(const char *src, const char *dest);

#endif