74HC138三八译码器和74HC573锁存器和74HC02或非门

P0口通过锁存器来控制单片机

 

 

138译码器又受到P25,26,27的控制

 

 

 

#include "reg52.h"

sbit HC_138A=P2^5;

sbit HC_138B=P2^6;

sbit HC_138C=P2^7;

void Delay(unsigned int t)

{

while(t--);

while(t--);

}

void LED_Running()

{

HC_138C=1;

HC_138B=0;

HC_138A=0;

P0=0x00;

Delay(60000);

P0=0xFF;

Delay(60000);

}

void main()

{

while(1)

{

LED_Running();

}

}

例题：让8路LED指示灯闪烁3遍然后熄灭，接着依次点亮LED指示灯，最后依次熄灭指示灯。

#include "reg52.h"

sbit HC_138A=P2^5;

sbit HC_138B=P2^6;

sbit HC_138C=P2^7;

void Delay(unsigned int t)

{

while(t--);

while(t--);

}

void LED_Running()

{

unsigned char i;

HC_138C=1;

HC_138B=0;

HC_138A=0;

for(i=0;i<3;i++)

{

P0=0x00;

Delay(60000);

P0=0xFF;

Delay(60000);

  }

Delay(60000);

for(i=1;i<=8;i++)

{

P0=0xff<<i;

Delay(60000);

}

for(i=1;i<=8;i++)

{

P0=~(0xff<<i);

Delay(60000);

}

}

void main()

{

while(1)

{

LED_Running();

}

}