【正文】 關T1 CLR ET1 MOV R4,04H SETB EX0 ；開啟接收回波中斷RETIOUT: RETI。外中斷0，收到回波時進入PINT0: CLR TR0 ；關計數(shù)器 CLR TR1 CLR ET1 CLR EA CLR EX0 MOV 44H, TL0 ；將計數(shù)值移入處理單元 MOV 45H, TH0 SETB 00H ；接收成功標志 RETI*延時程序*DL1MS: MOV R6, 14HDL1: MOV R7, 19HDL2: DJNZ R6, DL2 DJNZ R6, DL1 RET*顯示程序*。40H為最高位，43H為最低位，先掃描高位DISPLAY： MOV R1, 40H。G MOV R5,0F7H。G PLAY: MOV A, R5 MOV P0, 0FFH MOV P2, A MOV A, @R1 MOV DPTR, TABMOVC A, @A+DPTRMOV P0, ALCALL DLIMSINC R1MOV A, R5JNB , ENDOUT。GRR AMOV R5, AAJMP PLAYENDOUT。 MOV P2, 0FFH MOV P0, 0FFH RETTAB。 DB 0C0H,0F9H,0A4H,0B0H,99H,92H,82H,0F8H,80H,90H,0FFH,88H,0BFH；共陽數(shù)碼管 0 ,1, 2,3,4,5,6,7,8,9,不亮，A, —*距離計算程序(=計算值17/1000cm) 近似WORK: PUSH ACC PUSH PSW PUSH B MOV PSW, 18H MOV R3, 45H MOV R2, 44H MOV R1, 00D MOV R0, 17D LCALL MUL2BY2 MOV R3, 03H MOV R2, 0E8H LCALL DIV4BY2 LCALL DIV4BY2 MOV 40H, R4 MOV A, 40H JNZ JJ0 MOV 40H, 0AH ；最高位為0，不點亮JJ0: MOV A R0 MOV R4, A MOV A R1 MOV R5 A MOV R3, 00D MOV R2, 100D LCALL DIV4BY2 MOV 41H, R4 MOV A, 41H JNZ JJ1 MOV A, 40H ；此高位為0，先看最高位是否為不亮 SUBB A, 0AH JNZ JJ1 MOV 41H, 0AH ； 最高位不亮，次高位也不亮JJ1: MOV A, R0 MOV R4, A MOV A, R1 MOV R5, A MOV R3, 00D MOV R2, 10D LCALL DIV4BY2 MOV 42H, R4 MOV A 42H JNZ JJ2 MOV A, 41H ；次高位為0，先看次高位是否為不亮 SUBB A, 0AH JNZ JJ2 MOV 42H, 0AH ；次高位不亮，次高位也不亮JJ2: MOV 43H, R0 POP B POP PSW POP ACC RET *兩字節(jié)無符號數(shù)乘法程序* MUL2BY2: CLR A MOV R7, A MOV R6, A MOV R5, A MOV R4, A MOV 46H, 10HMULLOOP1: CLR C MOV A, R4 RLC A MOV R4, A MOV A, R5 RLC A MOV R5, A MOV A, R6 RLC A MOV R6, A MOV A, R7 RLC A MOV R7, A MOV A, R0 RLC A MOV R0, A MOV A, R1 RLC A MOV R1, A JNC MULLOOP2 MOV A, R4 ADD A, R2 MOV R4, A MOV A, R5 ADDC A, R3 MOV R5, A MOV A, R6 ADDC A, 00H MOV R6, A MOV A, R7 ADDC A, 00H MOV R7, AMULLOOP2: DJNZ 46H, MULLOOP1 RET *四字節(jié)/兩字節(jié)無符號數(shù)除法程序*DIV4BY2: MOV 46H, 20H MOV R0, 00H MOV R1, 00HDIVLOOP1: MOV A, R4 RLC A MOV R4, A MOV A, R5 RLC A MOV R5, A MOV A, R6 RLC A MOV R6, A MOV A, R7 RLC A MOV R7, A MOV A, R0 RLC A MOV R0, A MOV A, R1 RLC A MOV R1, A CLR C MOV A, R0 SUBB A, R2 MOV B, A MOV A, R1 SUBB A, R3 JC DIVLOOP2 MOV R0, B MOV R1, A DIVLOOP2: CPL C DJNZ 46H, DIVLOOP1 MOV A, R4 RLC A MOV R4, A MOV A, R5 RLC A MOV R5, A MOV A, R6 RLC A MOV R6, A MOV A, R7 RLC A MOV R7, A RET。 END附錄二：C51程序include define uchar unsigned chardefine uint unsigned intdefine ulong unsigned long extern void cs_t(void)。extern void delay(uint)。extern void display(uchar*)。//data uchar display(uchar*)。data uchar testok。void main (void){data uchar dispram[5]。data uint i。data ulong time。P0=0xff。P2=0xff。TMOD=0x11。IE=0x80。while (1){ cs_t()。 delay(1)。testok=0。EX0=1。ET0=1。while(! testok) display(dispram)。if (1==testok) { time=TH0。 time=(time8)| TL0。 time*=172。 time/=10000。 dispram[0]=(uchar) (time%10)。 time/=10。 dispram[1]=(uchar) (time%10)。 time/=10。 dispram[2]=(uchar) (time%10)。 dispram[3]=(uchar) (time/10)。 if (0==dispram[3]) dispram[3]=17。 } else { dispram [0]=16。 dispram [1]=16。 dispram [2]=16。 dispram [3]=16。 } for (i=0。i300。i++) display(dispram)。 }}void cs_r(void) interrupt 0{ TR0=0。 ET0=0。 EX0=0。 testok=1。}void overtime(void) interrupt 1{ EX0=0。 TR0=0。 ET0=0。 testok=2。} NAME CS_T?PR?CS_T?CS_T SEGMENT CODE PUBLIC CS_T RSEG ?PR?CS_T?CS_T CS_T: PUSH ACC MOV TH0, 00H MOV TL0, 00H MOV A, 4D SETB TR0CS_T1: CPL NOP NOP NOP NOP NOP NOP NOP NOP NOP NOP DJNZ ACC,CS_T1 POP ACC RET 。 END name delay?pr?_delay?delay segment codepublic _delay rseg ?pr?_delay?delay_delay: push acc mov a,r7 jz dela1 inc r6dela1: mov r5,50d djnz r5, $ djnz r7,dela1 djnz r6,dela1 pop acc retend NAME DISPLAY?PR?_DISPLAY?display segment code?co?_DISPLAY?display segment data EXTRN CODE (_DELAY) PUBLIC _DISPLAY RSEG ?CO?_DISPLAY?DISPLAY?_display?byte:dispbit: ds 1dispnum: ds 1 rseg ?pr?_display?display_display: push acc push dph push dpl push psw inc dispnum mov a,dispnum cjne a,4d,disp1DISP1: JC DISP2 MOV DISPNUM,00H MOV DISPBIT,0FEHDISP2: MOV A,R1 ADD A,DISPNUM MOV R0,A MOV A,@R0 MOV DPTR,DISPTABLE MOVC A,@A+DPTR MOV P0,A MOV A,DIS