#include

#defineucharunsignedchar

#defineuintunsignedint

ucharint_flag;

uintqian,bai,shi,ge;

uinti;

floatdistance;

//AlphanumericLCDModulefunctions

#asm

.equ__lcd_port=0x18;PORTB

#endasm

#include

//ExternalInterrupt0serviceroutine

interrupt[EXT_INT0]voidext_int0_isr(void)

{#asm("sei")

if(int_flag)

{

distance=i*17.3;

}

elseif(int_flag==0)

{

i=0;

int_flag=1;

TCCR0=0x0A;

}

}

//Timer0outputcompareinterruptserviceroutine

interrupt[TIM0_COMP]voidtimer0_comp_isr(void)

{

i++;

}

//Declareyourglobalvariableshere

voidmain(void)

{

//Declareyourlocalvariableshere

//Input/OutputPortsinitialization

//PortAinitialization

//Func7=InFunc6=InFunc5=InFunc4=InFunc3=InFunc2=InFunc1=InFunc0=In

//State7=TState6=TState5=TState4=TState3=TState2=TState1=TState0=T

PORTA=0x00;

DDRA=0x01;

//PortBinitialization

//Func7=InFunc6=InFunc5=InFunc4=InFunc3=InFunc2=InFunc1=InFunc0=In

//State7=TState6=TState5=TState4=TState3=TState2=TState1=TState0=T

PORTB=0x00;

DDRB=0x00;

//PortCinitialization

//Func7=InFunc6=InFunc5=InFunc4=InFunc3=InFunc2=InFunc1=InFunc0=In

//State7=TState6=TState5=TState4=TState3=TState2=TState1=TState0=T

PORTC=0x00;

DDRC=0x00;

//PortDinitialization

//Func7=InFunc6=InFunc5=InFunc4=InFunc3=InFunc2=InFunc1=InFunc0=In

//State7=TState6=TState5=TState4=TState3=TState2=TState1=TState0=T

PORTD=0x04;

DDRD=0x00;

//Timer/Counter0initialization

//Clocksource:SystemClock

//Clockvalue:2000.000kHz

//Mode:CTCtop=OCR0

//OC0output:Disconnected

TCCR0=0x00;

TCNT0=0x00;

OCR0=0xc8;

//Timer/Counter1initialization

//Clocksource:SystemClock

//Clockvalue:Timer1Stopped

//Mode:Normaltop=FFFFh

//OC1Aoutput:Discon.

//OC1Boutput:Discon.

//NoiseCanceler:Off

//InputCaptureonFallingEdge

//Timer1OverflowInterrupt:Off

//InputCaptureInterrupt:Off

//CompareAMatchInterrupt:Off

//CompareBMatchInterrupt:Off

TCCR1A=0x00;

TCCR1B=0x00;

TCNT1H=0x00;

TCNT1L=0x00;

ICR1H=0x00;

ICR1L=0x00;

OCR1AH=0x00;

OCR1AL=0x00;

OCR1BH=0x00;

OCR1BL=0x00;

//Timer/Counter2initialization

//Clocksource:SystemClock

//Clockvalue:Timer2Stopped

//Mode:Normaltop=FFh

//OC2output:Disconnected

ASSR=0x00;

TCCR2=0x00;

TCNT2=0x00;

OCR2=0x00;

//ExternalInterrupt(s)initialization

//INT0:On

//INT0Mode:Anychange

//INT1:Off

//INT2:Off

GICR|=0x40;

MCUCR=0x01;

MCUCSR=0x00;

GIFR=0x40;

//Timer(s)/Counter(s)Interrupt(s)initialization

TIMSK=0x02;

//AnalogComparatorinitialization

//AnalogComparator:Off

//AnalogComparatorInputCapturebyTimer/Counter1:Off

ACSR=0x80;

SFIOR=0x00;

//LCDmoduleinitialization

lcd_init(16);

//Globalenableinterrupts

#asm("sei")

PORTA.0=1;

delay_us(15);

PORTA.0=0;

while(1)

{

qian=(int)distance/1000;

bai=(int)distance00/100;

shi=(int)distance0/10;

ge=(int)distance;

lcd_gotoxy(0,0);

lcd_putchar(qian+48);

lcd_putchar(bai+48);

lcd_putchar(shi+48);

lcd_putchar(ge+48);

delay_ms(200);

PORTA.0=1;

delay_us(15);

PORTA.0=0;

int_flag=0;

};

}