#include！???????????????//8051單片機頭文件
#include???????????????//數字計算頭文件

#define?LCD_BUS?P0????????????????//定義lcd顯示總線

sbit?ECHO=P1^1;???????????????????//echo端口
sbit?TRIG=P1^3;???????????????????//trig端口

sbit?lcden=P2^0;??????????????????//定義1602液晶使能端
sbit?lcdrs=P2^2;??????????????????//定義1602液晶數據命令選擇端
sbit?lcdrw=P2^1;??????????????????//1602液晶讀寫選擇端

void?delay_ms（unsigned?int?t）;???//延時函數生聲明
void?lcd_write_com（unsigned?char?com）;//寫命令函數聲明
void?lcd_write_dat（unsigned?char?dat）;//寫數據函數聲明
void?init_1602lcd（void）;?????????//液晶初始化函數聲明
void?start（void）;????????????????//啟動模塊函數聲明
void?conut（void）;????????????????//距離計算函數聲明

unsigned?char?code?lcd1[]=“Text?distance:??“;//
unsigned?char?code?lcd2[]=“0123456789.-MS=“;//
unsigned?char?code?lcd3[]=“error!“;//

unsigned?int?time;????????????????//定義計數值
unsigned?long?range;??????????????//定義距離值
bit?flag=0;???????????????????????//定義溢出標志位
unsigned?char?disbuff[4]={0000};//定義中間值數組

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