interrupt [TIM0_OVF] void timer0_ovf_isr(void)
{
//tacts++;
a=TCNT0;
TCCR0=0x00;
lcd_gotoxy(0,0);
lcd_putsf("       ");

lcd_gotoxy(0,0);
   sprintf(s," %i", a);
     lcd_puts(s);

TCCR0=0x01;


}

// Timer/Counter 0 initialization
// Clock source: System Clock
// Clock value: 16000,000 kHz
// Mode: Normal top=FFh
// OC0 output: Disconnected
TCCR0=0x01;
TCNT0=0x00;
OCR0=0x00;

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// Registers used
// SaveSREG - keep SREG during ISR execution
// TickL, TickH - store 16-bit overflow data
timer0_ovf_isr:
        in SaveSREG,SREG //1
        inc TickL//1
        brne label1//2
        inc TickH//1
label1:
        out SREG,SaveSREG //1
        reti //4
//Total: 4+1+1+2+1+1=10 clocks + interrupt response time

#include <mega32.h>
#include <delay.h>
#include <stdio.h>

#asm
.equ __lcd_port=0x15;PORTC
#endasm
#include <lcd.h>


#define FAN PORTB.4

#define FINEUP PIND.7
#define FINEDOWN PIND.4

#define SPEED_MINUS PIND.6
#define SPEED_PLUS PIND.1


#define SPEED_MIN 0x0490
#define SPEED_MAX 0x07D0

#define SPEED OCR1A





char lcd_buffer[33];
unsigned char s[8];

unsigned int a,b;

unsigned int OVF_count;


unsigned long int time;




// External Interrupt 0 service routine
interrupt [EXT_INT0] void ext_int0_isr(void)
{
a=TCNT0;
time=(OVF_count*256+a)/16;
OVF_count=0;
lcd_clear();
lcd_gotoxy(0,0);
sprintf(s,"%u", time);
lcd_puts(s);

}

interrupt [TIM0_OVF] void timer0_ovf_isr(void)
{
OVF_count++;
}




main()
{

unsigned char i,j, devices;
int temp;

OVF_count=0;


// Timer/Counter 0 initialization
// Clock source: System Clock
// Clock value: 16000,000 kHz
// Mode: Normal top=FFh
// OC0 output: Disconnected
TCCR0=0x01;
TCNT0=0x00;
OCR0=0x00;


// Timer/Counter 1 initialization
// Clock source: System Clock
// Clock value: 2000,000 kHz
// Mode: Ph. & fr. cor. PWM top=ICR1
// OC1A output: Non-Inv.
// OC1B output: Discon.
// Noise Canceler: Off
// Input Capture on Falling Edge
// Timer 1 Overflow Interrupt: Off
// Input Capture Interrupt: Off
// Compare A Match Interrupt: Off
// Compare B Match Interrupt: Off
TCCR1A=0x80;
TCCR1B=0x12;
TCNT1H=0x00;
TCNT1L=0x00;
ICR1H=0x4E;
ICR1L=0x00;
OCR1BH=0x00;
OCR1BL=0x00;


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

TIMSK=0b00000001;

// External Interrupt(s) initialization
// INT0: On
// INT0 Mode: Rising Edge
// INT1: Off
// INT2: Off
GICR|=0x40;
MCUCR=0x03;
MCUCSR=0x00;
GIFR=0x40;


SPEED=SPEED_MIN;

DDRA=0xFF;
DDRD=0x00;
PORTD=0xFF;

DDRD.5=1;

DDRB.4=1;
FAN=1;
delay_ms(500);
FAN=0;

DDRD.2=0;
PORTD.2=0;

DDRD.0=0;
PORTD.0=1;


lcd_init(8);
lcd_clear();


#asm
sei
#endasm



while (1)
{

if (!SPEED_PLUS)
{
if (SPEED<SPEED_MAX) SPEED++;
delay_ms(2);
}

if (!SPEED_MINUS)
{

if (SPEED>SPEED_MIN) SPEED--;
delay_ms(2);
}





}








}

//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

namespace FI
{
word timeMS = -1;
word freqCount = 0;

void __declspec(naked) interrupt IntHandler();
};

//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

void __declspec(naked) interrupt FI::IntHandler()
{
static word sMS = 0;
static word count = 0;

__asm
{
push ax // 14
push dx // 14
push ds // 13

mov ax, seg millisecondsCount // 4
mov ds, ax // 2

inc [count] // 19
mov ax, [word ptr millisecondsCount] // 2
mov dx, [sMS] // 2
sub ax, dx // 3
cmp ax, 3000 // 3

jnc loc2 // 4, 13

locret:

pop ds
pop dx
pop ax
iret

loc2:

add dx, ax

mov [byte ptr sMS], dl // 2
mov [byte ptr sMS+1], dh // 2
mov [byte ptr timeMS], al // 2
mov [byte ptr timeMS+1], ah // 2

mov al, [byte ptr count] // 2
mov ah, [byte ptr count+1] // 2

mov [byte ptr freqCount], al // 2
mov [byte ptr freqCount+1], ah // 2

xor al, al // 3
mov [byte ptr count], al // 2
mov [byte ptr count+1], al // 2


pop ds // 12
pop dx // 14
pop ax // 14
iret // 28

}
}

//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

float FI::GetFreq()
{
TRACE

float f1;
float f2;

_cli();

f1 = FI::freqCount;
f2 = FI::timeMS;
FI::freqCount = 0; FI::timeMS = -1;

_sti();

return 1000.0 * f1 / f2;
}

//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

// External Interrupt 0 service routine
interrupt [EXT_INT0] void ext_int0_isr(void)
{

a=TCNT0;  
b=OVF_count;
TCNT0=0x00;


if (!first_pulse)
{

// time=((OVF_count*256+a)/16);
lcd_clear();
lcd_gotoxy(1,0);
sprintf(s,"%u", b);
lcd_puts(s);        
lcd_gotoxy(1,1);
sprintf(s,"%u", a);
lcd_puts(s);        
OVF_count=0;
first_pulse=1;
TCNT0=0x00;
}
else
{
   first_pulse=0;
   OVF_count=0;
}


}


interrupt [TIM0_OVF] void timer0_ovf_isr(void)
{
OVF_count++;
}

/ Timer/Counter 1 initialization
// Clock source: System Clock
// Clock value: 2000,000 kHz
// Mode: Ph. & fr. cor. PWM top=ICR1
// OC1A output: Non-Inv.
// OC1B output: Discon.
// Noise Canceler: Off
// Input Capture on Falling Edge
// Timer 1 Overflow Interrupt: Off
// Input Capture Interrupt: Off
// Compare A Match Interrupt: Off
// Compare B Match Interrupt: Off
TCCR1A=0x80;
TCCR1B=0x12;
TCNT1H=0x00;
TCNT1L=0x00;
ICR1H=0x4E;
ICR1L=0x00;
OCR1BH=0x00;
OCR1BL=0x00;