ARM-UART实验

串口控制三盏灯亮灭

视频

串口实验验证.mp4

代码

uart4.c

#include "uart4.h"


void uart4_init()
{
    //使能GPIOB GPIOG UART4外设时钟
    RCC->MP_AHB4ENSETR |= (0x1<<1);//GPIOB
    RCC->MP_AHB4ENSETR |= (0x1<<6);//GPIOG
    RCC->MP_APB1ENSETR |= (0X1<<16);//UART4
    //设置PB2和PG11管脚复用
    //PB2
    GPIOB->MODER &= (~(0x3<<4));
    GPIOB->MODER |=(0x2<<4); 
    GPIOB->AFRL &= (~(0XF<<8));
    GPIOB->AFRL |= (0x8<<8);
    //PG11
    GPIOG->MODER &= (~(0x3<<22));
    GPIOG->MODER |=(0x2<<22); 
    GPIOB->AFRH &= (~(0XF<<12));
    GPIOB->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));
    //设置波特率为115200
    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<<0);
    
}

//发送一个字符
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
    while(!(USART4->ISR&(0x1<<7)));
    //为空向发送数据寄存器写入a的数据
   USART4->TDR=a;//写入数据
    //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<<6)));
}

//接收一个字符
char getchar()
{
    char a;
    //先判断接收数据寄存器中有没有准备好的数据
    //如果数据没有准备好则阻塞等待
    while(!(USART4->ISR&(0x1<<5)));
    //如果数据准备好了则读取
    a=USART4->RDR;
    //读取完毕将读取到的数据返回
    return a;
}

//发送字符串
void puts(char *s)
{
    while(*s)
    {
        putchar(*s);
        s++;
    }
    putchar('\n');// '\n'切换到下一行
    putchar('\r');//'\n'回车键，切换到行头

}

//接收字符串函数
void gets(char *s)
{
    while(1)
    {
        *s=getchar();
        putchar(*s);
        if((*s)=='\r')
            break;
        s++;
    }
    *s='\0';
    putchar('\n');//换行
}

main.c

#include "uart4.h"
//封装一个strcmp函数
int strcmp(const char *s1, const char *s2)
{
    int i=0;
    while(s1[i]==s2[i])
    {
        if(s1[i]=='\0')
            break;
        i++;
    }
    int sub=s1[i]-s2[i];
    return sub;
}


int main()
{
    uart4_init();
    all_led_init();
    char buf[32];
    //char i;
    while (1)
    {
        // i = getchar();
        // putchar(i+1);
        // putchar('\n');
        // putchar('\r');
        gets(buf);
        if(strcmp(buf,"led1off")==0)
        {
            LED1_OFF();
        }
        if(strcmp(buf,"led1on")==0)
        {
            LED1_ON();
        }
        if(strcmp(buf,"led2off")==0)
        {
            LED2_OFF();
        }
        if(strcmp(buf,"led2on")==0)
        {
            LED2_ON();
        }
        if(strcmp(buf,"led3off")==0)
        {
            LED3_OFF();
        }
        if(strcmp(buf,"led3on")==0)
        {
            LED3_ON();
        }
        
    }
    
    return 0;
}

led.c

#include "led.h"

void all_led_init()//led灯的初始化
{
    //GPIOE/GPIOF时钟使能
    RCC->MP_AHB4ENSETR  |= (0x3<<4);
    //PE10设置为输出
    GPIOE->MODER &= (~(0X3<<20));
    GPIOE->MODER |= (0X1<<20);
    //PF10设置为输出
    GPIOF->MODER &= (~(0X3<<20));
    GPIOF->MODER |= (0X1<<20);
    //PE8设置为输出
    GPIOE->MODER &= (~(0X3<<16));
    GPIOE->MODER |= (0X1<<16);
    //PE10设置为推挽输出
    GPIOE->OTYPER &= (~(0X1<<10));
    //PF10设置为推挽输出
    GPIOF->OTYPER &= (~(0X1<<10));
    //PE8设置为推挽输出
    GPIOE->OTYPER &= (~(0X1<<8));
    //PE10设置为低速输出
    GPIOE->OSPEEDR &= (~(0X3<<20));
    //PF10设置为低速输出
    GPIOF->OSPEEDR &= (~(0X3<<20));
    //PE8设置为低速输出
    GPIOE->OSPEEDR &= (~(0X3<<16));
    //PE10无上拉下拉电阻
    GPIOE->PUPDR &= (~(0X3<<20));
    //PF10无上拉下拉电阻
    GPIOF->PUPDR &= (~(0X3<<20));
    //PE8无上拉下拉电阻
    GPIOE->PUPDR &= (~(0X3<<16));

    //三盏灯默认输出低电平
    GPIOE->ODR &= (~(0X1<<10));
    GPIOF->ODR &= (~(0X1<<10));
    GPIOE->ODR &= (~(0X1<<8));
}

//led1亮
void LED1_ON()
{
    GPIOE->ODR |= (0X1<<10);
}
//led2亮
void LED2_ON()
{
    GPIOF->ODR |= (0X1<<10);
}
//led1亮
void LED3_ON()
{
    GPIOE->ODR |= (0X1<<8);
}

//LED1灭
void LED1_OFF()
{
    GPIOE->ODR &= (~(0X1<<10));
}
//LED2灭
void LED2_OFF()
{
    GPIOF->ODR &= (~(0X1<<10));
}
//LED3灭
void LED3_OFF()
{
    GPIOE->ODR &= (~(0X1<<8));
}    

uart4.h

#ifndef __UART4_H__
#define __UART4_H__

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

void uart4_init();
void putchar(char a);
char getchar();
void puts(char *s);
void gets(char *s);
#endif

led.h

#ifndef __LED_H__
#define __LED_H__
#include "stm32mp1xx_gpio.h"
#include "stm32mp1xx_rcc.h"

void all_led_init();
void LED1_ON();
void LED2_ON();
void LED3_ON();
void LED1_OFF();
void LED2_OFF();
void LED3_OFF();

#endif