4.c~

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};  

bit mark1=0,mark3=0;
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=5000,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;
 	  i=0; 
     while(i<=3) 
            {
		PORTA = led_7[dis_buff[i]]; 
		if (i==3) PORTA |= 0x80;	
		PORTB = position[i]; 
               
         if(++time_counter>=20) 
         {i++;
         time_counter=0;
         PORTB = 0xFF; }
        }		
       	 
}

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)
{ counter1++; 
  if(counter1==125)
   {
     mark1=1;
     counter1=0;
   } 

}

interrupt [TIM2_COMP] void timer2_comp_isr(void)
{   

  counter2++;

}
// External Interrupt 0 service routine
interrupt [EXT_INT0] void ext_int0_isr(void)
{
  mark3=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=0xFF;
    DDRD=0xFF;

// 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 = 0x02;			// 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;

#asm("sei")

    while (1)
    { 
    
 
  if (PORTD.7==1)
       {       
         if(mark1)   
         { 
          PORTD.7=0;  
          mark1=0;
          TIMSK = 0x80;
         }
       }    
  if (mark3)
       {  TIMSK = 0x02;
     mark3=0;
     n=counter2;
     dd=0.34*n;    
     s=(int)dd;
    num[0] = s %100;  	
    num[1] = s /100;  
    PORTD.7=1;
    counter2=0;
    TIMSK = 0x82;
   }    
  if(s<=4000&&s>=100)
   {
      time_to_disbuffer(); 
       display();   
  }
     if(s>4000)
    { i=0; 
     while(i<=3)
       {
    	 PORTA =  0x40;
   	 PORTB = position[i]; 
       if(++time_counter>=20)   
       {i++;
         time_counter=0;
         PORTB = 0xFF; }
        }		
       	 					
     	 			
     }
    
  if(s<100)
    { i=0; 
     while(i<=3)
       {
    	 PORTA =  0x3F;
   	 PORTB = position[i]; 
       if(++time_counter>=20)   
       {i++;
         time_counter=0;
         PORTB = 0xFF; }
        }		
       	 					
     	 			
     }
  }
}