【正文】 nopnopnopnopnopnopDJNZ R4,intt11 。 超聲波發(fā)射完畢MOV R4,04Hlcall delay_250 。延時，避開超發(fā)射的直達(dá)聲波信號SETB EX0 。開啟接收收回波中斷 RETIOUT: RETI 。外中斷0，收到回波時進(jìn)入PINT0: nop jb ,pint0_exit CLR TR0 。關(guān)計數(shù)器 CLR EA 。 CLR EX0 。 MOV 44H,TL0 。將計數(shù)器值移入處理單元 MOV 45H,TH0 。 mov th0,00h mov tl0,00h jnb ,$ SETB 00H 。接收成功標(biāo)志 pint0_exit: RETI。 顯示程序40H為最高位，43H為最低位，先掃描高位DISPLAY: MOV R1,40H。GMOV R5,7fH。GPLAY: MOV A,R5MOV P0,0FFHMOV P2,AMOV A,@R1MOV DPTR,TABMOVC A,@A+DPTRMOV P0,ALCALL DL1MSINC R1MOV A,R5JNB ,ENDOUT。GRR AMOV R5,AAJMP PLAYENDOUT: MOV P2,0FFHMOV P0,0FFHRET。TAB: DB 18h, 7Bh, 2Ch, 29h, 4Bh, 89h, 88h, 3Bh, 08h, 09h,0ffh。共陽段碼表 0 1 2 3 4 56 7 8 9 不亮A。延時程序 DL1MS: push 06h push 07h MOV R6,14H DL1: MOV R7,19H DL2: DJNZ R7,DL2 DJNZ R6,DL1 pop 07h pop 06h RET。 距離計算程序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 。最高位為零，不點(diǎn)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 。次高位為0，先看最高位是否為不亮 SUBB A,0AH JNZ JJ1 MOV 41H,0AH 。最高為不量，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R7R6R5R4 = R3R2 * R1R0MUL2BY2: 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R7R6R5R4/R3R2=R7R6R5R4(商)...R1R0(余數(shù))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, ADIVLOOP2: 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。delay_250: push psw push 07h mov r7,0ffhdelay_250_1: nop nop nop nop djnz r7,delay_250_1 pop 07h pop psw ret 。 END