TM1 EQU 5
TM2 EQU 10
ORG 0000H;
AJMP START
ORG 000BH;
AJMP TIME0;
ORG 30H;
START:   MOV P1,#0FFH;
               MOV R7,#00H;
               MOV R6,#00H;
               MOV TMOD,#00000001B;定时器0开启
               MOV TH0,#3CH;定时50MS
               MOV TL0,#0B0H;
              SETB EA ;开启中断
              SETB ET0;使能定时/计数中断0
              SETB TR0;开启定时0
LOOP:   AJMP LOOP
TIME0:
          INC R7;
          INC R6;
          MOV A,R7;
          CJNE A,#TM1,T_NEXT;定时250MS
T_L1: CPL P1.0
          MOV R7,#0;
T_NEXT:MOV A,R6
              CJNE A,#TM2,T_RET;
T_L2:     CPL P1.1
              MOV R6,#0;
T_RET:MOV TH0,#3CH;
            MOV TL0,#0B0H;
            RETI
            END