ceju.asm

超声波测距仪,采用AT89C51

ORG 0000H
AJMP MAIN
ORG 000BH
AJMP T8MS
ORG 0100H
MAIN : MOV TMOD, #10H
MOV TL0,#00H
MOV TH0,#00H
MOV R7,#00H
MOV P2,#00H
MOV 70H,#3FH
MOV 71H,#06H
MOV 72H,#3FH
MOV 73H,#4FH
CLR P1.0
MOV R6,#250
SETB EA
SETB ET0
SETB TR0
AJMP $
ORG 0150H
T8MS:CLR TR0
CJNE R7,#00H,BIT1
CLR P2.3
MOV P0,70H
SETB P2.0
MOV R7,#01H
JMP BACK1
BIT1:CJNE R7,#01H,BIT2
CLR P2.0
MOV P0,71H
SETB P2.1
MOV R7,#02H
JMP BACK1
BIT2:CJNE R7,#02H,BIT3
CLR P2.1
MOV P0,72H
SETB P2.2
MOV R7,#03H
JMP BACK1
BIT3:CLR P2.2
MOV P0,73H
SETB P2.3
MOV R7,#00H
BACK1:DJNZ R6,BACK
ACALL SERVEY
NOP
BACK:MOV TH0,#00H
MOV TL0,#00H
SETB TR0
RETI
ORG 0300H
SERVEY:SETB P1.0
ACALL DELAY
MOV TH1,#00H
MOV TL1,#00H
CLR P1.0
SETB TR1
LOOP:JB P3.2,LOOP
CLR TR1
MOV 21H,TH1
MOV 20H,TL1

MOV 61H,TH1
MOV 60H,TL1
MOV A,60H
MOV B ,#17
MUL AB
MOV 60H,A
MOV A,61H
MOV 61H,B
MOV B,#17
MUL AB
CLR C
ADD A,61H
MOV 61H,A
MOV A,B
ADDC A,#00H
MOV 62H,A
MOV R5,#24
MOV 50H,#00H
MOV 51H,#00H
MOV 52H,#00H
LOOP1:CLR C
MOV A,60H
RLC A
MOV 60H,A
MOV A,61H
RLC A
MOV 61H,A
MOV A,62H
RLC A
MOV 62H,A
MOV A,50H
ADDC A,50H
DA A
MOV 50H,A
MOV A ,51H
ADDC A,51H
DA A
MOV 51H,A
MOV A,52H
ADDC A,52H
DA A
MOV 52H,A
DJNZ R5,LOOP1
SWAP A
ANL A,#0FH
MOV DPTR ,#TAB
MOVC A,@A+DPTR
MOV 73H,A
MOV A,52H
ANL A,#0FH
MOVC A,@A+DPTR
MOV 72H,A
MOV A,51H
SWAP A
ANL A,#0FH
MOVC A,@A+DPTR
MOV 71H,A
MOV A,51H
ANL A,#0FH
MOVC A,@A+DPTR
MOV 70H,A
RET
ORG 0450H
DELAY:MOV R4,#25H
LOOP3:MOV R3,#0FAH
LOOP4:NOP
DJNZ R3,LOOP4
DJNZ R4,LOOP3
RET
TAB:DB 3FH,06H,5BH,4FH,66H,6DH,7DH,07H,7FH,6FH