STM32 (register)-matrix keyboard

1; Hardware;
prepare a 2*2 matrix keyboard, connect to PB8,
9 , 10, 11 respectively; 2; matrix keyboard principle;
let pa8, 9 output high level, pa10, 11 input; when pa10, 11 detects high At the level, the value of i is obtained. Then flip, let pa8,9 input, pa10,11 output high level; when high level is detected in pa8,9, get the value of j; then determine which button is through i,j;
3; keyboard.c function implementation;

在这里插入代码片
#include "keyboard.h"
#include "stm32f10x.h"
#include "delay.h"
#include "usart.h"
#include "led.h"
u8 key_scan(void)
{
    
    
 u8 i=0,j=0;
 uart_init(72,9600);//串口时钟，波特率设置；
 //开启时钟
 RCC->APB2ENR |=1<<3;
 //端口模式配置
 GPIOB->CRH &=0XFFFF0000;
 GPIOB->CRH |=0X00003388;
 //关闭端口
 GPIOB->ODR &=~(1<<8);
 GPIOB->ODR &=~(1<<9);
 GPIOB->ODR &=~(1<<10);
 GPIOB->ODR &=~(1<<11); 
 //高低电平配置
 PBout(10)=1;
 PBout(11)=1;
 PBin(8)=0;
 PBin(9)=0;
 //清零
 i=0,j=0;
 //检测电平变化
 if(PBin(8)==1 || PBin(9)==1)
 {
    
    
  delay_ms(10);
  if(PBin(8)==1 )
   i=1;
  if(PBin(9)==1 )
   i=2;
 }
 else
 {
    
    
  return 0;
 }

//同上
 GPIOB->CRH &=0XFFFF0000;
 GPIOB->CRH |=0X00008833;
 GPIOB->ODR &=~(1<<10);
 GPIOB->ODR &=~(1<<11);
 GPIOB->ODR &=~(1<<8);
 GPIOB->ODR &=~(1<<9);
 PBout(8)=1;
 PBout(9)=1;
 PBin(10)=0;
 PBin(11)=0;
 if(PBin(10)==1 || PBin(11)==1)
 {
    
    
  delay_ms(10);
  if(PBin(10)==1) j=1;
  else if(PBin(11)==1)
   j=2;
 }
 else
  return 0;

//通过i,j值确定按键位置
 if(i==1 && j==1)
  return 1;
 else if(i==1 && j==2)
  return 2;
 else if(i==2 && j==1)
  return 3;
 else if(i==2 && j==2)
  return 4;
  else
  return 0;
}

4: Implementation of keyboard.h function;

在这里插入代码片
#ifndef _KEYBOARD_H_
#define _KEYBOARD_H_
#include "sys.h"

u8 key_scan(void);

#endif

5: Main function realization;

在这里插入代码片
int  main(void)
{
    
    
 u8 h;//接收返回值
 Stm32_Clock_Init(9);//PLL倍频设置系统时钟
 delay_init(72);//延迟函数时钟
 uart_init(72,9600);//串口初始化
 LED_Init();//led初始化
 while(1)
 {
    
    
  h=key_scan();//获取返回值
  LED0=0;//检测程序是否运行
  switch(h)//串口输出按键位置
  {
    
    
   case 1:printf("按键1\r\n");delay_ms(1000);break;
   case 2:printf("按键2\r\n");delay_ms(1000);break;
   case 3:printf("按键3\r\n");delay_ms(1000);break;
   case 4:printf("按键4\r\n");delay_ms(1000);break;
   default :printf("无按键按下\r\n");delay_ms(1000);break;
  }
 }
}

Please correct me if there are any errors! ! !