1.复习串口实验的流程,熟练编写代码
2.串口发送指令控制硬件工作
a b c d
led1_on led1_off
代码:
main.c
#include "uartt.h"
//封装延时函数
void delay(int ms)
{
int i,j;
for(i=0;i<ms;i++)
{
for(j=0;j<2000;j++);
}
}
int main()
{
all_led_init1();
//1.串口初始化
uart4_init();
char a;
//现象是发送一个a串口工具打印一个b
while(1)
{
//2.从串口读取一个字符
a=mygetchar();
//3.将读取到的字符+1发送回去
myputchar(a);
if(a == 'a')
{
led1_on1();
led2_off1();
led3_off1();
}
else if(a == 'b')
{
led1_off1();
led2_on1();
led3_off1();
}
else if(a == 'c')
{
led1_off1();
led2_off1();
led3_on1();
}
}
return 0;
}
uartt.c
#include "uartt.h"
//串口初始化
void uart4_init()
{
//1.UART4和GPIOB\GPIOG的时钟使能
RCC->MP_AHB4ENSETR |= (0x1<<2);//使能GPIOB时钟
RCC->MP_AHB4ENSETR |= (0x1<<6);//使能GPIOG时钟
RCC->MP_APB1ENSETR |= (0X1<<16);//使能UART4时钟
//2.设置PB2和PG11的管脚复用
GPIOB->MODER &= (~(0x3<<4));
GPIOB->MODER |= (0x2<<4); //设置复用
GPIOB->AFRL &= (~(0XF<<8));
GPIOB->AFRL |= (0X8<<8);//设置uart4功能复用
GPIOG->MODER &= (~(0x3<<22));
GPIOG->MODER |= (0x2<<22); //设置复用
GPIOG->AFRH &= (~(0XF<<12));
GPIOG->AFRH |= (0X6<<12);//设置uart4功能复用
//3.先去设置串口禁用,方便设置数据格式
USART4->CR1 &= (~0X1);
//4.设置8位数据位
USART4->CR1 &=(~(0x1<<28));
USART4->CR1 &=(~(0x1<<12));
//5.设置没有奇偶校验
USART4->CR1 &=(~(0x1<<10));
//6.设置16倍采样
USART4->CR1 &=(~(0x1<<15));
//7.设置1位停止位
USART4->CR2 &=(~(0x3 <<12));
//8.设置1分频
USART4->PRESC &=(~(0xf << 0));
//9.设置波特率为115200bps
USART4->BRR = 0x22b;
//10.发送器、接收器使能
USART4->CR1 |=(0x1<<3);
USART4->CR1 |=(0x1<<2);
//11.串口使能
USART4->CR1 |= (0x1 << 0);
}
//封装函数发送一个字符数据
void myputchar(char i)
{
//1.判断TDR寄存器是否为空,如果为空,向TDR寄存器中写入数据
while(!(USART4->ISR & (0x1 << 7)));
USART4->TDR = i;
//2.阻塞等待数据传输完成,函数返回
while(!(USART4->ISR & (0x1 << 6)));
}
char mygetchar()
{
char c;
//判断RDR寄存器是否有就绪数据,如果有就读取,否则等待
while(!(USART4->ISR&(0X1<<5)));//数据传输完成,函数结束
c=USART4->RDR;
return c;
}
void all_led_init1()
{
// 1.使能外设时钟
RCC_MP_AHB4ENSETR |= (0x3 << 4);
// 2.设置PF10 PE10 PE8为输出输出
GPIOE->MODER &= (~(0x3 << 20));
GPIOE->MODER |= (0x1 << 20);
GPIOF->MODER &= (~(0x3 << 20));
GPIOF->MODER |= (0x1 << 20);
GPIOE->MODER &= (~(0x3 << 16));
GPIOE->MODER |= (0x1 << 16);
// 3.设置推挽输出
GPIOE->OTYPER &= (~(0x1 << 10));
GPIOF->OTYPER &= (~(0x1 << 10));
GPIOE->OTYPER &= (~(0x1 << 8));
// 4.设置输出速度为低速
GPIOE->OSPEEDR &= (~(0x3 << 20));
GPIOF->OSPEEDR &= (~(0x3 << 20));
GPIOE->OSPEEDR&= (~(0x3 << 16));
// 5.设置无上拉下拉
GPIOE->PUPDR&= (~(0x3 << 20));
GPIOF->PUPDR &= (~(0x3 << 20));
GPIOE->PUPDR &= (~(0x3 << 16));
}
void led1_on1()
{
GPIOE->ODR |= (0x1 << 10);
}
void led2_on1()
{
GPIOF->ODR|= (0x1 << 10);
}
void led3_on1()
{
GPIOE->ODR |= (0x1 << 8);
}
void led1_off1()
{
GPIOE->ODR &= (~(0x1 << 10));
}
void led2_off1()
{
GPIOF->ODR &= (~(0x1 << 10));
}
void led3_off1()
{
GPIOE->ODR &= (~(0x1 << 8));
}
uartt.h
#ifndef __UARTT_H__
#define __UARTT_H__
#include"stm32mp1xx_gpio.h"
#include"stm32mp1xx_rcc.h"
#include"stm32mp1xx_uart.h"
#define RCC_MP_AHB4ENSETR (*(unsigned int *)0X50000a28)
void uart4_init();
void myputchar(char i);
char mygetchar();
void all_led_init1();
void led1_on1();
void led2_on1();
void led3_on1();
void led1_off1();
void led2_off1();
void led3_off1();
#endif
运行结果:
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