4*3 matrix button program

/********************************************************
 *
 * 4*3 matrix key read and write function
 *
 ********************************************************/
//Button reading and writing program
//Row 1 P65 //Row 2 P62 //Row 3 P51 //Row 4 P67 P5:1 P6:257
//Column 1 P63 //Column 2 P64 //Column 3 P66
//Key decoding
//Row 4: 0,1,2;Row 1: 3,4,5;Row 3: 6,7,8;Row 2: 9,10,11;
//*0#   123   789   456   
const uchar key_rel[]={0x0a,0x00,0x0b,0x01,0x02,
0x03,0x07,0x08,0x09,0x04,0x05,0x06}; 
void scan_key(void)
{ fly i;
keybuf=0xff;
get_bit=0;
/*Method 1: row output, column input, affects AT24C02, LED flashes
//The port direction of sleep wake-up, undervoltage detection, and sound and light indication does not need to be changed
//Line output 0
//P5CR&=0x0d; //0000 1101 initialize P5 to all output ports
P5CR=0xf0;
P6CR&=0x5b;//0101 1011
// Column input 1
P6CR|=0x58;//0101 1000/
//Method 2: Column output, row input, column 1 string 10K, if low level cannot be output, it may not be recognized
// Will not affect AT24C02, LED indication, other operations require redefining the port direction
//Output column 0
P6CR&=0xa7;//1010 0111
//Line input 1
P5CR|=0x02;//0000 0010
P6CR|=0xa4;//1010 1000*/
/*Method 3: Use method 2 to scan the columns first, and then read and write column 1 separately
//Column 1 reading and writing experiment
P5CR=0xf0;
P6CR&=0x5b;//0101 1011
// Column input 1
P6CR|=0x58;//0101 1000/
KH1=0;KH2=0;KH3=0;KH4=0;
if(KL1==0)keybuf=0x01;//A key is pressed in column 1
while(KL1==0);
// Column 23, read and write */
// Final version of the key reading and writing program, low level scan line 2, all lines are pulled low
//Line output 0
P6CR&=0x5b;//0101 1011
// Column input 1
P6CR|=0x58;//0101 1000/
for(i=0;i<4;i++)
  {switch(i)
    {//No AT24C02 operation, try not to open KH4 to power AT24C02
    case 0:KH1=1;KH2=1;KH3=1;KH4=0;break;//Scan line 4
    case 1:KH1=0;KH2=1;KH3=1;KH4=0;break;//Scan line 1
    case 2:KH1=1;KH2=1;KH3=0;KH4=0;break;//Scan line 3
    //Finally scan the red and green LED common terminals, pull them all low, and no LED lights up during full scan
    case 3:KH1=0;KH2=0;KH3=0;KH4=0;break;//Scan line 2
    }
  delay(200);
  if(KL1==0){keybuf=0x00;get_bit=1;break;}
  if(KL2==0){keybuf=0x01;get_bit=1;break;}
  if(KL3==0){keybuf=0x02;get_bit=1;break;}
  }
if(get_bit==1) //Get the key value
  {get_bit=0;
  //Delay to remove jitter
  //delay(250);//
  //The scan status has been saved
  switch(keybuf)
    {case 0x00:if(KL1==0)get_bit=1;;break;
    case 0x01:if(KL2==0)get_bit=1;;break;
    case 0x02:if(KL3==0)get_bit=1;;break;
    default:keybuf=0xff;
    }
  if(get_bit==1)
    {keybuf=i+i+i+keybuf; //decode key
    i=key_rel[keybuf];//decode key
    keybuf=i; //Get the key value
    //Button sound and light indication
    buzzer();
    //Wait for the button to pop up
    KH1=0;KH2=0;KH3=0;KH4=0;
    delay(80);
    while((KL1&&KL2&&KL3)==0);
    }
  else keybuf=0xff;
  }
else keybuf=0xff;//Invalid key
//Line 2 invalid reading and writing analysis
//TCC pin CONT instruction 0x0*
}
/********************************************************
 *
 *   END  key_scan
 *
 ********************************************************/