用74HC138控制数码管如何消隐

#include <reg51.h>
#include <intrins.h>
#define NOP() _nop_() /* 定义空指令 */



sbit LS138A=P2^2;
sbit LS138B=P2^3;
sbit LS138C=P2^4;



void delay(unsigned int i); //函数声名
void HC595SendData(unsigned int SendVal);

// 此表为 LED 的字模 // 0 1 2 3 4 5 6 7 8 9 A b c d E - L P U Hidden _ (20)
unsigned char code Disp_Tab[] = { 0xC0,0xF9,0xA4,0xB0,0x99,0x92,0x82,0xF8,0x80,0x90,0x88,0x83,0xC6,0xA1,0x86,0xbf,0xc7,0x8c,0xc1, 0xff, 0xf7 };
unsigned char code LED7Code[] = {~0x3F,~0x06,~0x5B,~0x4F,~0x66,~0x6D,~0x7D,~0x07,~0x7F,~0x6F,~0x77,~0x7C,~0x39,~0x5E,~0x79,~0x71};


main()
{
unsigned int i,LedNumVal=1 ;
unsigned int LedOut[8];

while(1)
{ ++LedNumVal;
LedOut[0]=Disp_Tab[LedNumVal%10000/1000];
LedOut[1]=Disp_Tab[LedNumVal%1000/100]&0x7f;
LedOut[2]=Disp_Tab[LedNumVal%100/10];
LedOut[3]=Disp_Tab[LedNumVal%10];

LedOut[4]=Disp_Tab[LedNumVal%10000/1000];
LedOut[5]=Disp_Tab[LedNumVal%1000/100]&0x7f;
LedOut[6]=Disp_Tab[LedNumVal%100/10];
LedOut[7]=Disp_Tab[LedNumVal%10];


for( i=0; i<8; i++)
{ P0 = LedOut[i];

switch(i)
{
case 0:LS138A=0; LS138B=0; LS138C=0; break;
case 1:LS138A=1; LS138B=0; LS138C=0; break;
case 2:LS138A=0; LS138B=1; LS138C=0; break;
case 3:LS138A=1; LS138B=1; LS138C=0; break;
case 4:LS138A=0; LS138B=0; LS138C=1; break;
case 5:LS138A=1; LS138B=0; LS138C=1; break;
case 6:LS138A=0; LS138B=1; LS138C=1; break;
case 7:LS138A=1; LS138B=1; LS138C=1; break;

}

delay(150);
}

// LS138A=1; LS138B=1; LS138C=1;
}
}

void delay(unsigned int i)
{
char j;
for(i; i > 0; i--)
for(j = 200; j > 0; j--);
}
//不知道这样写，是不是思路错了。。请大虾们指点，如何消隐