原创 5．广告灯（利用取表方式）

1．      实验任务<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

利用取表的方法，使端口P1做单一灯的变化：左移，右移。

2．      电路原理图

    同实验四原理图

3、实现程序

1．      汇编源程序

                            ORG 0000H

START:               MOV DPTR,#TABLE

<?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" />LOOP:                CLR A

                            MOVC A,@A+DPTR

                            CJNE A,#01H,LOOP1

                            JMP START

LOOP1:              MOV P1,A

                           MOV R3,#20

                            LCALL DELAY

                            INC DPTR

                           JMP LOOP

DELAY:              MOV R4,#20

D1:                     MOV R5,#248

                            DJNZ R5,$

                            DJNZ R4,D1

                           DJNZ R3,DELAY

                            RET

TABLE:              DB 0FEH,0FDH,0FBH,0F7H

                            DB 0EFH,0DFH,0BFH,07FH

                           DB 07FH,0BFH,0DFH,0EFH

                          DB 0F7H,0FBH,0FDH,0FEH

                          DB 01H

                            END

2．      C语言源程序

#include <AT89X51.H>

unsigned char code table[]={0xfe,0xfd,0xfb,0xf7,   0xef,0xdf,0xbf,0x7f,

                                               0x7f,0xbf,0xdf,0xef,0xf7,0xfb,0xfd,0xfe,0x01};

unsigned char i;

void delay(void)

{

  unsigned char m,n,s;

  for(m=20;m>0;m--)

  for(n=20;n>0;n--)

  for(s=248;s>0;s--);

}

void main(void)

{

  while(1)

    {

      if(table!=0x01)

        {

          P1=table;

          i++;

          delay();

        }

        else

          {

            i=0;

          }

    }

}

4、总结

      使用查表程序实现相对左右移位更加简单容易理解

      对IO高电平点亮LED只需要修改table表中的十六机制数字即可，需要将停止位修改为0xff

unsigned char code table[]=    {0x01,0x02,0x04, 0x08,0x10,0x20,0x40, 0x80                                                                                0x80,0x40,0xdf,0x20,0x10,0x08,0x04,0x02,0x01,0xff};。

 

<?xml:namespace prefix = v ns = "urn:schemas-microsoft-com:vml" />