// CodeVisionAVR C Compiler
// (C) 1998-2001 Pavel Haiduc, HP InfoTech S.R.L.

// I/O registers definitions for the ATmega16


#pragma used+
sfrb TWBR=0;
sfrb TWSR=1;
sfrb TWAR=2;
sfrb TWDR=3;
sfrb ADCL=4;
sfrb ADCH=5;
sfrw ADCW=4;      // 16 bit access
sfrb ADCSRA=6;
sfrb ADMUX=7;
sfrb ACSR=8;
sfrb UBRRL=9;
sfrb UCSRB=0xa;
sfrb UCSRA=0xb;
sfrb UDR=0xc;
sfrb SPCR=0xd;
sfrb SPSR=0xe;
sfrb SPDR=0xf;
sfrb PIND=0x10;
sfrb DDRD=0x11;
sfrb PORTD=0x12;
sfrb PINC=0x13;
sfrb DDRC=0x14;
sfrb PORTC=0x15;
sfrb PINB=0x16;
sfrb DDRB=0x17;
sfrb PORTB=0x18;
sfrb PINA=0x19;
sfrb DDRA=0x1a;
sfrb PORTA=0x1b;
sfrb EECR=0x1c;
sfrb EEDR=0x1d;
sfrb EEARL=0x1e;
sfrb EEARH=0x1f;
sfrw EEAR=0x1e;   // 16 bit access
sfrb UBRRH=0x20;
sfrb UCSRC=0X20;
sfrb WDTCR=0x21;
sfrb ASSR=0x22;
sfrb OCR2=0x23;
sfrb TCNT2=0x24;
sfrb TCCR2=0x25;
sfrb ICR1L=0x26;
sfrb ICR1H=0x27;
sfrb OCR1BL=0x28;
sfrb OCR1BH=0x29;
sfrw OCR1B=0x28;  // 16 bit access
sfrb OCR1AL=0x2a;
sfrb OCR1AH=0x2b;
sfrw OCR1A=0x2a;  // 16 bit access
sfrb TCNT1L=0x2c;
sfrb TCNT1H=0x2d;
sfrw TCNT1=0x2c;  // 16 bit access
sfrb TCCR1B=0x2e;
sfrb TCCR1A=0x2f;
sfrb SFIOR=0x30;
sfrb OSCCAL=0x31;
sfrb OCDR=0x31;
sfrb TCNT0=0x32;
sfrb TCCR0=0x33;
sfrb MCUCSR=0x34;
sfrb MCUCR=0x35;
sfrb TWCR=0x36;
sfrb SPMCR=0x37;
sfrb TIFR=0x38;
sfrb TIMSK=0x39;
sfrb GIFR=0x3a;
sfrb GICR=0x3b;
sfrb OCR0=0X3c;
sfrb SPL=0x3d;
sfrb SPH=0x3e;
sfrb SREG=0x3f;
#pragma used-

// Interrupt vectors definitions


// Needed by the power management functions (sleep.h)
#asm
	#ifndef __SLEEP_DEFINED__
	#define __SLEEP_DEFINED__
	.EQU __se_bit=0x40
	.EQU __sm_mask=0xB0
	.EQU __sm_powerdown=0x20
	.EQU __sm_powersave=0x30
	.EQU __sm_standby=0xA0
	.EQU __sm_ext_standby=0xB0
	.EQU __sm_adc_noise_red=0x10
	.SET power_ctrl_reg=mcucr
	#endif
#endasm



int zkb;
int zq;          
int t1,t2;


// Timer 2 overflow interrupt service routine
interrupt [5] void timer2_ovf_isr(void)
{
// Reinitialize Timer 2 value
//每次觸發為20微秒
TCNT2=0xEC;           //反轉值，理論值為0xEC 但是實測值為0xEF  有點沒搞懂  ??

  if((--zq)==0)
  {      
    PORTB^=0B00000001;    //PORTB.0 反轉  
    if(PORTB.0==1){
      zq=t1; 
    }else
    {
      zq=t2;
    }          
  }
}

// Declare your global variables here
void delay_1ms(void); //函數聲明，本實驗中會用到這兩個函數
void delay_nms(unsigned int n);   


void main(void)
{             
int aa=20;     

/*初始化參數*/
zkb=1500;    
t1=zkb/20;        
t2=(20000-zkb)/20; 
zq=t1;

/********************************************/
 
PORTB=0x00;
DDRB=0x00;
DDRB.0=1;      //置為輸出

PORTB.0=1;

// Timer/Counter 2 initialization
// Clock source: System Clock
// Clock value: 1000.000 kHz
// Mode: Normal top=FFh
// OC2 output: Disconnected
ASSR=0x00;
TCCR2=0x02;
TCNT2=0xEF;
OCR2=0x00;

// Timer(s)/Counter(s) Interrrupt(s) initialization
TIMSK=0x40;

// Global enable interrupts
#asm("sei")

while (1)
      { 
        //下面是測試代碼
        delay_nms(150); 
        zkb+=aa;
        if(zkb==1000||zkb==2000){    //標準應該是1000至2000
          aa=-aa;          
          delay_nms(500);
        }
        t1=zkb/20;        
        t2=(20000-zkb)/20;
        
      }
}     

void delay_1ms(void)//1ms延時函數
{
  unsigned int i;
  for (i=0;i<150;i++)
  {
  } 
}   

void delay_nms(unsigned int n)//延時n毫秒
{
  unsigned int i;
  for (i=0;i<n;i++)//執行n次1毫秒延時
  delay_1ms(); 
}