;2051單片機P3口的低4位做流水燈輸出,分三種方式點亮,-----S1 控制點亮;
      org 00h
start: mov a,#0ffh
      mov p3,a
      mov 20h,#00h
     
 
 key :mov p3,#0ffh
      mov a,#11110111b   ;P2.3=0,掃描S1鍵；
      mov p2,a
      mov a,p2
      jnb acc.4,setm    ;若P2.4=0，說明S1被按下，轉(zhuǎn)setm
      ajmp st
setm: lcall de5ms
      mov a,p2
      jnb acc.4,st
      ajmp key
      
   st: setb 00h
lamp :mov a,#0ffh
      mov p3,a
      jb 00h,fun0
      jb 01h,fun1
      jb 02h,fun2
      ajmp lamp
 fun0:mov r5,#12   ;逐次點亮
loop0:mov a,#0f0h
      mov p3,a
      call delay
      mov a,#0feh
loop00:mov p3,a
      call delay
      jnb acc.3,loop0
      rl a
      anl a,p3
      orl a,#0f0h
      djnz r5,loop00
  mm0:clr 00h
      setb 01h
      ljmp lamp
fun1 :mov a,#0f0h    ;間隔點亮
      mov p3,a
      call delay
      mov r7,#12
loop1:mov a,#0feh
loop11:mov p3,a
      call delay
      jnb acc.3,loop1
      rl a
      djnz r7,loop11
  mm1:clr 01h
      setb 02h
      ljmp lamp

 fun2:mov r6,#12         ;輪流點亮
      mov a,#0f0h
      mov p3,a
      call delay
loop2:mov a,#0fah
loop22:mov p3,a
      call delay
      cpl a
      orl a,#0f0h
      mov p3,a
      djnz r6,loop22
  mm2: clr 02h
      setb 00h
      ljmp key
 de5ms:mov r5,#60       ;5ms
       x1:mov r4,#248
          djnz r4,$
          djnz r5,x1
          ret
 delay:mov r2,#50
   d1:mov r1,#20
   d2:mov r3,#248
      djnz r3,$
      djnz r1,d2
      djnz r2,d1
      ret
      end