uart4.h:
#ifndef UART_H
#define UART_H
#include "stm32mp1xx_gpio.h"
#include "stm32mp1xx_rcc.h"
#include "stm32mp1xx_uart.h"
void uart4_init();
void putchar(char a);
char getchar();
#define RCCT (*(unsigned int *)0X50000A28)
#define GPIOE_MODER (*(unsigned int *)0X50006000)
#define GPIOF_MODER (*(unsigned int *)0X50007000)
#define GPIOE_OTYPER (*(unsigned int *)0X50006004)
#define GPIOE_OSPEEDR (*(unsigned int *)0X50006008)
#define GPIOE_OPUPDR (*(unsigned int *)0X5000600C)
#define GPIOE_ODR (*(unsigned int *)0X50006014)
#define GPIOF_OTYPER (*(unsigned int *)0X50007004)
#define GPIOF_OSPEEDR (*(unsigned int *)0X50007008)
#define GPIOF_OPUPDR (*(unsigned int *)0X5000700C)
#define GPIOF_ODR (*(unsigned int *)0X50007014)
void all_led_init();
void LED1_ON();
void LED2_ON();
void LED3_ON();
void LED1_OFF();
void LED2_OFF();
void LED3_OFF();
#endif
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);
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;
}
void all_led_init()//led灯的初始化
{
//GPIOE/GPIOF时钟使能
RCCT |= (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_OPUPDR &= (~(0X3<<20));
//PF10无上拉下拉电阻
GPIOF_OPUPDR &= (~(0X3<<20));
//PE8无上拉下拉电阻
GPIOE_OPUPDR &= (~(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);
}
//led3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));
}
main.c：
#include "uart4.h"
void delay(int ms)
{
int i,j;
for(i=0;i<ms;i++)
{
for(j=0;j<2000;j++)
{}
}
}
int main()
{
//串口初始化
uart4_init();
//led灯的初始化
all_led_init();
char i;
while(1)
{
i=getchar();
putchar(i);
switch (i)
{
case 'a':
LED1_ON();
LED2_OFF();
LED3_OFF();
break;
case 'b':
LED1_ON();
LED2_OFF();
LED3_OFF();
break;
case 'c':
LED1_ON();
LED2_OFF();
LED3_OFF();
break;
default:
LED1_ON();
LED2_ON();
LED3_ON();
break;
}
}
return 0;
}