❶ C语言中定义一个结构体如何在不同的.C文件中使用。
struct
node{
int
a;
int
b;
}
这样就定义了复一个结构制体类型node,它有两个int类型的成员,分别是a和b,定义变量是用
struct
node
st_a;
这样的形式.(例如,上式就定义了一个名为st_a的结构体变量)
❷ 求51单片机超声波避障程序
这是一个超声波避障小车的源程序，可以参考下，用的89C52单片机，舵机控制转角避障。
#include<AT89x51.H>
#include <intrins.h>
#define Sevro_moto_pwm P2_7 //接舵机信号端输入PWM信号调节速度
#define ECHO P2_4 //超声波接口定义
#define TRIG P2_5 //超声波接口定义
#define Left_moto_go {P1_0=1,P1_1=0,P1_2=1,P1_3=0;} //左边两个电机向前走
#define Left_moto_back {P1_0=0,P1_1=1,P1_2=0,P1_3=1;} //左边两个电机向后转
#define Left_moto_Stop {P1_0=0,P1_1=0,P1_2=0,P1_3=0;} //左边两个电机停转
#define Right_moto_go {P1_4=1,P1_5=0,P1_6=1,P1_7=0;} //右边两个电机向前走
#define Right_moto_back {P1_4=0,P1_5=1,P1_6=0,P1_7=1;} //右边两个电机向前走
#define Right_moto_Stop {P1_4=0,P1_5=0,P1_6=0,P1_7=0;} //右边两个电机停转
unsigned char const discode[] ={ 0xC0,0xF9,0xA4,0xB0,0x99,0x92,0x82,0xF8,0x80,0x90,0xBF,0xff/*-*/};
unsigned char const positon[3]={ 0xfe,0xfd,0xfb};
unsigned char disbuff[4] ={ 0,0,0,0,};
unsigned char posit=0;
unsigned char pwm_val_left = 0;//变量定义
unsigned char push_val_left =14;//舵机归中，产生约，1.5MS 信号
unsigned long S=0;
unsigned long S1=0;
unsigned long S2=0;
unsigned long S3=0;
unsigned long S4=0;
unsigned int time=0; //时间变量
unsigned int timer=0; //延时基准变量
unsigned char timer1=0; //扫描时间变量
/************************************************************************/
void delay(unsigned int k) //延时函数
{
unsigned int x,y;
for(x=0;x<k;x++)
for(y=0;y<2000;y++);
}
/************************************************************************/
void Display(void) //扫描数码管
{
if(posit==0)
{P0=(discode[disbuff[posit]])&0x7f;}//产生点
else
{P0=discode[disbuff[posit]];} if(posit==0)
{ P2_1=0;P2_2=1;P2_3=1;}
if(posit==1)
{P2_1=1;P2_2=0;P2_3=1;}
if(posit==2)
{P2_1=1;P2_2=1;P2_3=0;}
if(++posit>=3)
posit=0;
}
/************************************************************************/
void StartMole() //启动测距信号
{
TRIG=1;
_nop_();
_nop_();
_nop_();
_nop_();
_nop_();
_nop_();
_nop_();
_nop_();
_nop_();
_nop_();
_nop_();
_nop_();
_nop_();
_nop_();
_nop_();
_nop_();
_nop_();
_nop_();
_nop_();
_nop_();
_nop_();
TRIG=0;
}
/***************************************************/
void Conut(void) //计算距离
{
while(!ECHO); //当RX为零时等待
TR0=1; //开启计数
while(ECHO); //当RX为1计数并等待
TR0=0; //关闭计数
time=TH0*256+TL0; //读取脉宽长度
TH0=0;
TL0=0;
S=(time*1.7)/100; //算出来是CM
disbuff[0]=S%1000/100; //更新显示
disbuff[1]=S%1000%100/10;
disbuff[2]=S%1000%10 %10;
}
/************************************************************************/
//前速前进
void run(void)
{
Left_moto_go ; //左电机往前走
Right_moto_go ; //右电机往前走
}
/************************************************************************/
//前速后退
void backrun(void)
{
Left_moto_back ; //左电机往前走
Right_moto_back ; //右电机往前走
}
/************************************************************************/
//左转
void leftrun(void)
{
Left_moto_back ; //左电机往前走
Right_moto_go ; //右电机往前走
}
/************************************************************************/
//右转
void rightrun(void)
{
Left_moto_go ; //左电机往前走
Right_moto_back ; //右电机往前走
}
/************************************************************************/
//STOP
void stoprun(void)
{
Left_moto_Stop ; //左电机停走
Right_moto_Stop ; //右电机停走
}
/************************************************************************/
void COMM( void )
{
push_val_left=5; //舵机向左转90度
timer=0;
while(timer<=4000); //延时400MS让舵机转到其位置
StartMole(); //启动超声波测距
Conut(); //计算距离
S2=S;
push_val_left=23; //舵机向右转90度
timer=0;
while(timer<=4000); //延时400MS让舵机转到其位置
StartMole(); //启动超声波测距
Conut(); //计算距离
S4=S;
push_val_left=14; //舵机归中
timer=0;
while(timer<=4000); //延时400MS让舵机转到其位置 StartMole(); //启动超声波测距
Conut(); //计算距离
S1=S; if((S2<20)||(S4<20)) //只要左右各有距离小于20CM小车后退
{
backrun(); //后退
timer=0;
while(timer<=4000);
}
if(S2>S4)
{
rightrun(); //车的左边比车的右边距离小 右转
timer=0;
while(timer<=4000);
}
else
{
leftrun(); //车的左边比车的右边距离大 左转
timer=0;
while(timer<=4000);
}
} /************************************************************************/
/* PWM调制电机转速 */
/************************************************************************/
/* 左电机调速 */
/*调节push_val_left的值改变电机转速,占空比 */
void pwm_Servomoto(void)
{
if(pwm_val_left<=push_val_left)
Sevro_moto_pwm=1;
else
Sevro_moto_pwm=0;
if(pwm_val_left>=200)
pwm_val_left=0;
}
/***************************************************/
///*TIMER1中断服务子函数产生PWM信号*/
void time1()interrupt 3 using 2
{
TH1=(65536-100)/256; //100US定时
TL1=(65536-100)%256;
timer++; //定时器100US为准。在这个基础上延时
pwm_val_left++;
pwm_Servomoto(); timer1++; //2MS扫一次数码管
if(timer1>=20)
{
timer1=0;
Display();
}
}
/***************************************************/
///*TIMER0中断服务子函数产生PWM信号*/
void timer0()interrupt 1 using 0
{
} /***************************************************/ void main(void)
{ TMOD=0X11;
TH1=(65536-100)/256; //100US定时
TL1=(65536-100)%256;
TH0=0;
TL0=0;
TR1= 1;
ET1= 1;
ET0= 1;
EA = 1; delay(100);
push_val_left=14; //舵机归中
while(1) /*无限循环*/
{ if(timer>=1000) //100MS检测启动检测一次
{
timer=0;
StartMole(); //启动检测
Conut(); //计算距离
if(S<30) //距离小于20CM
{
stoprun(); //小车停止
COMM(); //方向函数
}
else
if(S>30) //距离大于，30CM往前走
run();
}
}
}
/**************************************************************************/
下面是头文件：
头文件（一）
/*--------------------------------------------------------------------------
AT89X51.H Header file for the low voltage Flash Atmel AT89C51 and AT89LV51.
Copyright (c) 1988-2002 Keil Elektronik GmbH and Keil Software, Inc.
All rights reserved.
--------------------------------------------------------------------------*/
#ifndef __AT89X51_H__
#define __AT89X51_H__
/*------------------------------------------------
Byte Registers
------------------------------------------------*/
sfr P0 = 0x80;
sfr SP = 0x81;
sfr DPL = 0x82;
sfr DPH = 0x83;
sfr PCON = 0x87;
sfr TCON = 0x88;
sfr TMOD = 0x89;
sfr TL0 = 0x8A;
sfr TL1 = 0x8B;
sfr TH0 = 0x8C;
sfr TH1 = 0x8D;
sfr P1 = 0x90;
sfr SCON = 0x98;
sfr SBUF = 0x99;
sfr P2 = 0xA0;
sfr IE = 0xA8;
sfr P3 = 0xB0;
sfr IP = 0xB8;
sfr PSW = 0xD0;
sfr ACC = 0xE0;
sfr B = 0xF0;
/*------------------------------------------------
P0 Bit Registers
------------------------------------------------*/
sbit P0_0 = 0x80;
sbit P0_1 = 0x81;
sbit P0_2 = 0x82;
sbit P0_3 = 0x83;
sbit P0_4 = 0x84;
sbit P0_5 = 0x85;
sbit P0_6 = 0x86;
sbit P0_7 = 0x87;
/*------------------------------------------------
PCON Bit Values
------------------------------------------------*/
#define IDL_ 0x01
#define STOP_ 0x02
#define PD_ 0x02 /* Alternate definition */
#define GF0_ 0x04
#define GF1_ 0x08 #define SMOD_ 0x80 /
*------------------------------------------------
TCON Bit Registers
------------------------------------------------*/
sbit IT0 = 0x88;
sbit IE0 = 0x89;
sbit IT1 = 0x8A;
sbit IE1 = 0x8B;
sbit TR0 = 0x8C;
sbit TF0 = 0x8D;
sbit TR1 = 0x8E;
sbit TF1 = 0x8F;
/*------------------------------------------------
TMOD Bit Values
------------------------------------------------*/
#define T0_M0_ 0x01
#define T0_M1_ 0x02
#define T0_CT_ 0x04
#define T0_GATE_ 0x08
#define T1_M0_ 0x10
#define T1_M1_ 0x20
#define T1_CT_ 0x40
#define T1_GATE_ 0x80
#define T1_MASK_ 0xF0
#define T0_MASK_ 0x0F
/*------------------------------------------------
P1 Bit Registers
------------------------------------------------*/
sbit P1_0 = 0x90;
sbit P1_1 = 0x91;
sbit P1_2 = 0x92;
sbit P1_3 = 0x93;
sbit P1_4 = 0x94;
sbit P1_5 = 0x95;
sbit P1_6 = 0x96;
sbit P1_7 = 0x97; /
*------------------------------------------------
SCON Bit Registers
------------------------------------------------*/
sbit RI = 0x98;
sbit TI = 0x99;
sbit RB8 = 0x9A;
sbit TB8 = 0x9B;
sbit REN = 0x9C;
sbit SM2 = 0x9D;
sbit SM1 = 0x9E;
sbit SM0 = 0x9F;
/*------------------------------------------------
P2 Bit Registers
------------------------------------------------*/
sbit P2_0 = 0xA0;
sbit P2_1 = 0xA1;
sbit P2_2 = 0xA2;
sbit P2_3 = 0xA3;
sbit P2_4 = 0xA4;
sbit P2_5 = 0xA5;
sbit P2_6 = 0xA6;
sbit P2_7 = 0xA7;
/*------------------------------------------------
IE Bit Registers
------------------------------------------------*/
sbit EX0 = 0xA8; /* 1=Enable External interrupt 0 */
sbit ET0 = 0xA9; /* 1=Enable Timer 0 interrupt */
sbit EX1 = 0xAA; /* 1=Enable External interrupt 1 */
sbit ET1 = 0xAB; /* 1=Enable Timer 1 interrupt */
sbit ES = 0xAC; /* 1=Enable Serial port interrupt */
sbit ET2 = 0xAD; /* 1=Enable Timer 2 interrupt */ sbit EA = 0xAF; /* 0=Disable all interrupts */
/*------------------------------------------------
P3 Bit Registers (Mnemonics & Ports)
------------------------------------------------*/
sbit P3_0 = 0xB0;
sbit P3_1 = 0xB1;
sbit P3_2 = 0xB2;
sbit P3_3 = 0xB3;
sbit P3_4 = 0xB4;
sbit P3_5 = 0xB5;
sbit P3_6 = 0xB6;
sbit P3_7 = 0xB7; sbit RXD = 0xB0; /* Serial data input */
sbit TXD = 0xB1; /* Serial data output */
sbit INT0 = 0xB2; /* External interrupt 0 */
sbit INT1 = 0xB3; /* External interrupt 1 */
sbit T0 = 0xB4; /* Timer 0 external input */
sbit T1 = 0xB5; /* Timer 1 external input */
sbit WR = 0xB6; /* External data memory write strobe */
sbit RD = 0xB7; /* External data memory read strobe */
/*------------------------------------------------
IP Bit Registers
------------------------------------------------*/
sbit PX0 = 0xB8;
sbit PT0 = 0xB9;
sbit PX1 = 0xBA;
sbit PT1 = 0xBB;
sbit PS = 0xBC;
sbit PT2 = 0xBD;
/*------------------------------------------------
PSW Bit Registers
------------------------------------------------*/
sbit P = 0xD0;
sbit FL = 0xD1;
sbit OV = 0xD2;
sbit RS0 = 0xD3;
sbit RS1 = 0xD4;
sbit F0 = 0xD5;
sbit AC = 0xD6;
sbit CY = 0xD7;
/*------------------------------------------------
Interrupt Vectors:
Interrupt Address = (Number * 8) + 3
------------------------------------------------*/
#define IE0_VECTOR 0 /* 0x03 External Interrupt 0 */
#define TF0_VECTOR 1 /* 0x0B Timer 0 */
#define IE1_VECTOR 2 /* 0x13 External Interrupt 1 */
#define TF1_VECTOR 3 /* 0x1B Timer 1 */
#define SIO_VECTOR 4 /* 0x23 Serial port */ #endif
头文件（二）
/*--------------------------------------------------------------------------
INTRINS.H Intrinsic functions for C51.
Copyright (c) 1988-2002 Keil Elektronik GmbH and Keil Software, Inc.
All rights reserved.
--------------------------------------------------------------------------*/
#ifndef __INTRINS_H__
#define __INTRINS_H__ extern void _nop_ (void);
extern bit _testbit_ (bit);
extern unsigned char _cror_ (unsigned char, unsigned char);
extern unsigned int _iror_ (unsigned int, unsigned char);
extern unsigned long _lror_ (unsigned long, unsigned char);
extern unsigned char _crol_ (unsigned char, unsigned char);
extern unsigned int _irol_ (unsigned int, unsigned char);
extern unsigned long _lrol_ (unsigned long, unsigned char);
extern unsigned char _chkfloat_(float); #endif