Question

51单片机控制的超声波测距仪程序

51单片机编程产生40kHz方波由P3.6口输出。单片机AT89C51发出短暂的40kHz信号，经放大后通过超声波换能器输出；反射后的超声波经超声波换能器作为系统的输入，锁相环对此信号锁定，产生锁定信号启动单片机中断程序，读出时间t，再由系统软件对其进行计算、判别后，相应的计算结果被送至LED数码管进行显示。P2口显示个位P1口显示十位P0口显示百位（汇编和单片机C语言都行）求哪位高人给编译下

Answer 1

？？？到此一游

Answer 2

/*--------------------------------------
超声测距器单片机程序
MCU AT89C51 XAL 12MHz
2008.2.25
--------------------------------------*/
#include <reg51.h>
#define uchar unsigned char
#define uint unsigned int
#define ulong unsigned long

extern void cs_t(void);
extern void delay(uint);
extern void display(uchar*);
data uchar testok;
/*主程序*/
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 = (time<<8) | 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; i<300; i++) display(dispram);
}
}
//
/*超声接收程序（外中断0）*/
void cs_r(void) interrupt 0
{
TR0 = 0;
ET0 = 0;
EX0 = 0;
testok = 1;
}

/*超时清除程序（内中断T0）*/
void overtime(void) interrupt 1
{
EX0 = 0;
TR0 = 0;
ET0 = 0;
testok = 2;
}

;-------------------------------------
;超声发生子程序（12M晶振38.5Hz）
;-------------------------------------
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 TR0
CS_T1: CPL P1.0
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
DJNZ ACC, CS_T1
POP ACC
RET
;
END


;-------------------------------------
;延时100机器周期*参数（1~65535）
;-------------------------------------
NAME DELAY
?PR?_DELAY?DELAY SEGMENT CODE
PUBLIC _DELAY
RSEG ?PR?_DELAY?DELAY
_DELAY: PUSH ACC ;2
MOV A, R7 ;1
JZ DELA1 ;2
INC R6 ;1
DELA1: MOV R5, #50D ;2
DJNZ R5, $ ;2
DJNZ R7, DELA1 ;2
DJNZ R6, DELA1 ;2
POP ACC ;2
RET ;2
;
END

;---------------------------------------
; 四位共阳LED动态扫描显示程序
; P0为段码口，P2为位选口（低电平有效）
; 参数为要显示的字符串指针
;---------------------------------------
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 1
DISPNUM: DS 1
RSEG ?PR?_DISPLAY?DISPLAY
_DISPLAY: PUSH ACC
PUSH DPH
PUSH DPL
PUSH PSW
INC DISPNUM
MOV A, DISPNUM
CJNE A, #4D, DISP1
DISP1: JC DISP2
MOV DISPNUM, #00H
MOV DISPBIT, #0FEH
DISP2: MOV A, R1
ADD A, DISPNUM
MOV R0, A
MOV A, @R0
MOV DPTR, #DISPTABLE
MOVC A, @A+DPTR
MOV P0, A
MOV A, DISPNUM
CJNE A, #2D, DISP3
CLR P0.7
DISP3: MOV P2, DISPBIT
MOV R6, #00H
MOV R7, #0AH
LCALL _DELAY
MOV P0, #0FFH
MOV P2, #0FFH
MOV A, DISPBIT
RL A
MOV DISPBIT, A
POP PSW
POP DPL
POP DPH
POP ACC
RET
DISPTABLE:DB 0C0H,0F9H,0A4H,0B0H,99H,92H,82H,0F8H,80H,90H,88H,83H,0C6H,0A1H,86H,8EH,0BFH,0FFH
; "0", "1", "2", "3","4", "5","6","7", "8","9","A","B","C", "D", "E","F", "-", " "
END

这个给你参考~