ARM学习

uart.c

#include "uart4.h"
void uart4_config()
{//使能GPIOB\GPIOG\UART4的外设时钟RCC->MP_AHB4ENSETR |= (0x1<<1);RCC->MP_AHB4ENSETR |= (0x1<<6);RCC->MP_APB1ENSETR |= (0x1<<16);//设置PG11和PB2为管脚复用功能//PB2GPIOB->MODER &= (~(0x3<<4));GPIOB->MODER |= (0x2<<4);//PG11GPIOG->MODER &= (~(0x3<<22));GPIOG->MODER |= (0x2<<22);//设置PG11为UART4_TX功能GPIOG->AFRH &= (~(0xf<<12));GPIOG->AFRH |= (0X6<<12);//设置PB2为UART4_RX功能GPIOB->AFRL &= (~(0xf<<8));GPIOB->AFRL |= (0X8<<8);//设置串口不使能USART4->CR1 &= (~0x1);//设置8位数据位USART4->CR1 &= (~(0x1<<12));USART4->CR1 &= (~(0x1<<28));//设置没有校验位USART4->CR1 &= (~(0x1<<10));//设置时钟频率不分频USART4->PRESC &= (~0xf);//设置16倍过采样USART4->CR1 &= (~(0x1<<15));//设置1位停止位USART4->CR2 &= (~(0x3<<12));//设置波特率为115200USART4->BRR=0X22B;//使能发送器USART4->CR1 |= (0X1<<3);//使能接收器USART4->CR1 |= (0X1<<2);//使能串口USART4->CR1 |= (0X1<<0);//使能ＧＰＩＯ的外设时钟RCC-> MP_AHB4ENSETR |=(0x3<<4);//设置ＰＥ１０为输出GPIOE->MODER &= (~ (0x3<<20));GPIOE->MODER |= (0x1<<20);//设置ＰＦ１０为输出GPIOF->MODER &= (~ (0x3<<20));GPIOF->MODER |= (0x1<<20);//设置ＰＥ８为输出GPIOE->MODER &= (~ (0x3<<16));GPIOE->MODER |= (0x1<<16);//设置ＰＥ１０为推挽输出GPIOE->OTYPER&= (~ (0x1<<10));//设置ＰＦ１０为推挽输出GPIOF->OTYPER &= (~ (0x1<<10));//设置ＰＥ８为推挽输出GPIOE->OTYPER&= (~ (0x1<<8));//设置ＰＥ１０为低速输出GPIOE->OSPEEDR &= (~ (0x3<<20));//设置ＰＦ１０为低速输出GPIOF->OSPEEDR &= (~ (0x3<<20));//设置ＰＥ8为低速输出GPIOE->OSPEEDR &= (~ (0x3<<16));//设置ＰＥ１０为无上拉下拉电阻GPIOE->PUPDR &= (~ (0x3<<20));//设置ＰＦ１０为无上拉下拉电阻GPIOF->PUPDR &= (~ (0x3<<20));//设置ＰＥ８为无上拉下拉电阻GPIOE->PUPDR &= (~ (0x3<<16));//三盏灯默认是关闭GPIOE->ODR&= (~ (0x1<<10));GPIOF->ODR &= (~ (0x1<<10));GPIOE->ODR&= (~ (0x1<<8));
}//发送单个字符
void putchar(char dat)
{//当发送数据寄存器中没有数据时可以发送while (!(USART4->ISR & (0x1<<7)));//当TDR中有数据时阻塞等待没有数据USART4->TDR = dat;//向发送数据寄存器中写入数据//等大传输完成函数结束while (!(USART4->ISR & (0x1<<6)));
}//接收单个字符
char getchar()
{//当接收数据寄存器中有有效数据时读取while (!(USART4->ISR & (0x1<<5)));//将读取到的数据返回return USART4->RDR;}//发送字符串
void puts(char *s)
{while(1){if(*s=='\0')break;putchar(*s);s++;}//发送一个回车putchar('\n');putchar('\r');
}//接收字符串
void gets(char *s)
{while(1){//循环接收单个字符，当检测到回车键‘\r’被按下，结束*s=getchar();putchar(*s);if(*s == '\r')break;s++;} //在接收的字符串最后补上一个'\0'*s='\0';putchar('\n');putchar('\r');//发送一个'\n'表示在串口工具下一行进行显示
}int strcmp(char *s,char *q)
{while(*s == *q && *s ){s++;q++;}return *s -*q;
}

uart.h

#ifndef __UART4_H__
#define __UART4_H__
#include "stm32mp1xx_gpio.h"
#include "stm32mp1xx_uart.h"
#include "stm32mp1xx_rcc.h"
void uart4_config();
void putchar(char dat);
char getchar();
void puts(char *s);
void gets(char *s);
int strcmp(char *s,char *q);
#endif

main.c

#include "uart4.h"void dealy_ms(int ms)
{for(int i = 0;i<ms;i++){for(int j = 0;j<2000;j++){}}
}int main()
{//uart4初始化uart4_config();char a[40];while(1){gets(a);if( strcmp(a,"on")==0){GPIOE->ODR |=  (0x1<<10);GPIOF->ODR |=  (0x1<<10);GPIOE->ODR |= (0x1<<8);}if(strcmp(a,"off")==0){GPIOE->ODR&= (~ (0x1<<10));GPIOF->ODR &= (~ (0x1<<10));GPIOE->ODR&= (~ (0x1<<8));}puts(a);  //现象，发送a,输出b}return 0;
}