51单片机步进电机正反转实验程序

按键控制可以让电机正转或倒转，按键由p0.0-0.3控制

ORG  0000H
  AJMP     START
  ORG  0050H
MAIN:  MOV  R0,#00H
START:  LCALL     START0
  LCALL     DELAY0
  JNB  P0.0,UPS
  JNB  P0.1,DWNS
  AJMP  START
UPS:;LCALL     DELAY3
       ;JNB    P0.0,$
  ;LCALL     DELAY3
       LCALL     START0
  LCALL     DELAY1
  JNB         P0.0,UPS
  JNB  P0.1,START
;  AJMP  START
  AJMP  UPS
DWNS:LCALL     START0
  LCALL     DELAY2
  JNB         P0.0,START
  JNB  P0.1,DWNS
;  AJMP  START
  AJMP  DWNS
START1: MOV  R0,#00H
START0: MOV  A,R0
               MOV  DPTR,#TAB
  MOVC  A,@A+DPTR
  JZ  START1
  MOV  P1,A
  INC R0
  RET
DELAY0: MOV  R7,#10
D1:  MOV  R6,#248
  DJNZ  R6,$
  DJNZ  R7,D1
  RET
DELAY1: MOV  R7,#5
D2:  MOV  R6,#248
  DJNZ  R6,$
  DJNZ  R7,D2
  RET  
DELAY2: MOV  R7,#40
D3:  MOV  R6,#248
  DJNZ  R6,$
  DJNZ  R7,D3
  RET
DELAY3: MOV  R7,#60
D4:  MOV  R6,#248
  DJNZ  R6,$
  DJNZ  R7,D4
  RET
TAB:  DB  07H
  DB           03H
  DB  0BH
  DB  09H
  DB  0DH
  DB  0CH
  DB  0EH
  DB  06H
  DB  00H  
  END