4.txt

基于ATmega16的超声波测距程序

/*****************************************************
File name           : 防撞报警器
Chip type           : ATmega16L
Program type        : Application
Clock frequency     : 4.000000 MHz
Memory model        : Small
External SRAM size  : 0
Data Stack size     : 256
*****************************************************/
#include <mega16.h>     
#include <delay.h>
flash unsigned char led_7[10]={0x3F,0x06,0x5B,0x4F,0x66,0x6D,0x7D,0x07,0x7F,0x6F};
flash unsigned char position[4]={0xfe,0xfd,0xfb,0xf7};  

flash unsigned int t[9] = {0,956,865,759,716,638,568,506,470};
flash unsigned char d[9] = {0,105,116,132,140,157,176,198,209};
#define Max_note    32
flash unsigned char music[Max_note] = {5,8,8,8,5,8,4,8,3,8,2,8,1,16,1,8,1,8,2,8,3,8,3,8,1,8,3,8,4,8,5,32}; 

unsigned char note_n;
unsigned int int_n;
bit play_on,point_on,stop1,begin2;
unsigned char num[2];					// 计数
unsigned char dis_buff[4];				// 显示缓冲区，存放要显示的6个字符的段码值
int counter1,counter2,s,n,time_counter;	 
  float dd;		
 unsigned char i=0;
void display(void)				// 扫描显示函数，执行时间12ms
{
	unsigned char i;
 	for(i=0;i<=3;i++)
	{
		PORTA = led_7[dis_buff[i]]; 
		if (i==3) PORTA |= 0x80;	// (1)
		PORTB = position[i]; 
       	delay_us(500);									// (2)
       	PORTB = 0xff;									// (3)
  	}
}

void time_to_disbuffer(void)			// 时间值送显示缓冲区函数
{
	unsigned char i,j=0;
	for (i=0;i<=1;i++)
	{
		dis_buff[j++] = num[i] %10;  
		
		dis_buff[j++] = num[i] /10;   

	}
}   

interrupt [TIM0_COMP] void timer0_comp_isr(void)
{ 
 if (PORTD.7==1)    
  {
  if(++counter1>=125) 
   {
      stop1=1; 
      counter1=0; 
   }  
  } 
}
interrupt [TIM2_COMP] void timer2_comp_isr(void)
{   
 if(begin2) 
  {
   counter2++;
  }   

}
// External Interrupt 0 service routine
interrupt [EXT_INT0] void ext_int0_isr(void)
{
   
   begin2=0; 
   n=counter2;
    dd=0.34*n;    
    s=dd/1;
   num[0] = s %100;  	
   num[1] = s /100;  
   counter2=0; 
   PORTD.7=1;
}

// Declare your global variables here

void main(void)
{   

    PORTA=0x40;		// PORTA初始化
    DDRA=0xFF;
    PORTB=0xFF;		// PORTB初始化
    DDRB=0xFF;
    
    DDRC=0x00;        // PORTC读入

    PORTD=0x88;
    DDRD=0x20;

// T/Cx 初始化
TCCR0 = 0x0A;			// 内部时钟，8分频（4M/8=500KHz），CTC模式
TCNT0 = 0x00;
OCR0 = 0x00;			// OCR0 = 0,1/500=2us  
TCCR2 = 0x0A;			// 内部时钟，8分频（4M/8=500KHz），CTC模式
TCNT2 = 0x00;
OCR2 = 0x00;			// OCR2 = 0,1/500=2us  
TIMSK = 0x92;			// 允许T/C0,T/C2比较匹配中断
TCCR1A=0x40;
TCCR1B=0x08;
TCNT1 = 0x00;
ICR1H = 0x00;
ICR1L = 0x00;
OCR1A = 0x00;
OCR1B = 0x00;

GICR=0x40;
MCUCR=0x03;
MCUCSR=0x00;
GIFR=0x40;

    for(i=0;i<=3;i++)
	{
	PORTA =  0x40;
	PORTB = position[i]; 
       	delay_ms(2);								
       	PORTB = 0xFF;			
       }
// num[1] = 34; num[0] =90;	
    time_to_disbuffer();

#asm("sei")

    while (1)
    { 
    
  if(s<=4000&&s>=100)
   {
      if (PORTD.7==1)
       {begin2=1;
        delay_us(250)  
        
         
       }    
      if(stop1)  
       {
         PORTD.7=0;
         stop1=0;
       }
       display();  
      time_to_disbuffer();  
  
  }
  else
    {  
    for(i=0;i<=3;i++)
	{
	PORTA =  0x40;
	PORTB = position[i]; 
       	delay_us(500);								
      	PORTB = 0xFF;			
       }
      

      }  
    }
}