代码：
#include "stm32mp1xx_gpio.h"
#include "stm32mp1xx_rcc.h"
#include "stm32mp1xx_uart.h"void delay_ms(int ms)
{int i,j;for(i=0;i<ms;i++){for(j=0;j<2000;j++);}
}
void init();
char getc();
void putc(char data);
void puts(char *data);
char *gets(void);
int main()
{init();//初始化puts("jntm test");while(1){puts(gets());}return 0;
}
void init(){/*RCC章节*///设置UART4的RCc时钟使能//RCC_MP_APB1ENSETR[16]->1RCC->MP_APB1ENSETR |= (0x1<<16);//设置GPIOB和GPIOG的时钟使能//RCC_MP_AHB4ENSETR[6]->1//RCC_MP_AHB4ENSETR[1]->1RCC->MP_AHB4ENSETR |= (0x1<<1);RCC->MP_AHB4ENSETR |= (0X1<<6);/*-- GPIO章节--*///设置PG11和PB2功能复用为UART4功能//PG11//GPIOG_MODER[23:22]->10GPIOG->MODER &= (~(0X3<<22));GPIOG->MODER |= (0X2<<22);//GPIOG_AFRH[15:12]->0110 GPIOG->AFRH &= (~(0xf<<12));GPIOG->AFRH |= (0x6<<12);//PB2//GPIOB_MODER[5:4]->10//GPIOB_AFRL[11:8]->1000GPIOB->MODER &= (~(0x3<<4));GPIOB->MODER |= (0X2<<4);GPIOB->AFRL &= (~(0xF<<8));GPIOB->AFRL |= (0x8<<8);/*--UART4章节--*///禁用串口if(USART4->CR1 & 0X1){delay_ms(500);USART4->CR1 &=(~(0x1 << 0));}//设置数据8个数据位 CR1[28]->0 CR1[12]-》0USART4->CR1 &= (~(0X1<<28));USART4->CR1 &= (~(0X1<<12));//设置没有校验位CR1[10]->0USART4->CR1 &= (~(0X1<<10));//设置1个停止位CR2[13:12]->00USART4->CR2 &= (~(0x3<<12));//设置16倍采样 CR1[15]->0USART4->CR1 &= (~(0X1<<15));//设置波特率为115200 BRR=0X22BUSART4->BRR |= 0X22B;//设置1分频 PRESC[3:0]->0000USART4->PRESC &= (~(0XF << 0));//使能发送器 CR1[3]->1USART4->CR1 |= (0X1<<3);//使能接收器 CR1[2]->1USART4->CR1 |= (0X1<<2);//使能串口 CR1[0]->1USART4->CR1 |= (0X1);
}
void putc(char data)
{
//判断发送数据寄存器有没有数据，没有数据时可以发送while(!(USART4->ISR&(0X1<<7)));USART4->TDR=data;//将要发送的数据保存在发送寄存器中while(!(USART4->ISR&(0X1<<6)));//数据传输完成，函数结束
}
char getc(void)
{char ch;while(!(USART4->ISR & (0x1 << 5)));ch = USART4->RDR;return ch;
}
void puts(char *data){char *c=data;for(;*c!='\0';c++){putc(*c);}putc(*c);putc('\n');putc('\r');
}
char data[50]="";
char *gets(void){int i;for(i=0;i<49;i++){data[i]=getc();putc(data[i]);if(data[i]=='\r')break;}data[i]='\0';putc('\n');return data;}
what a pity,can't run
now，it can run
