Membuat Timer Atmega8

gambar 1. Simulasi timer 1 dengan proteus

Perhitungan timer :

Time value = (Required delay / clock value)-1

Ø  Required delay : waktu yang diinginkan

Ø  Clock value : clock timer1 periode

example :
- waktu yang di inginkan adalh 1 detik
- ext clock 8 Mhz
- clock value 7,813 Khz = 7813 Hz

Time value = (1s/(1/7813Hz))-1 diketahui periode adalah T = 1/F

Time value = (1s x 7813) - 1

Time value = 7812 = 0x1e84

Berikut contoh pengaturan timer1 :

gambar 2. konfigurasi chip mikrokontroller

gambar 3. konfigurasi timer 1 dengan ctc mode

berikut contoh program yang telah dibuat :

/*****************************************************

This program was produced by the

CodeWizardAVR V2.05.3 Standard

Automatic Program Generator

© Copyright 1998-2011 Pavel Haiduc, HP InfoTech s.r.l.

http://www.hpinfotech.com

Project :

Version         :

Date             : 9/22/2014

Author          : fahmibnu

Company     : 

Comments    :

Chip type                               : ATmega8

Program type                        : Application

AVR Core Clock frequency   : 8.000000 MHz

Memory model                      : Small

External RAM size                : 0

Data Stack size                     : 256

*****************************************************/

#include <mega8.h>

#include <stdlib.h>

#include <delay.h>

#define t_enter                 PINC.3

#define t_down                PINC.2

#define t_up                      PINC.1

#define t_pause               PINB.5

int count_time,temp,menit,temp_menit,up,down;

char counter_time[5],temperature[5],buf_menit[5];

void menu();

// Alphanumeric LCD functions

#include <alcd.h>

// Timer1 output compare A interrupt service routine

interrupt [TIM1_COMPA] void timer1_compa_isr(void)

{

// Place your code here

    count_time--;                //counter down per 1 detik

    if(count_time < 0 && menit != 0)

    {

        menit--;

        count_time = 59;

    }                             

    else if(count_time < 0 && menit == 0)

    {

        menit = 0;

        count_time = 0;

        TCCR1B = 0;

    }

}

// Declare your global variables here

void main(void)

{

// Declare your local variables here

// Input/Output Ports initialization

// Port B initialization

// Func7=In Func6=In Func5=In Func4=In Func3=In Func2=In Func1=In Func0=In

// State7=T State6=T State5=P State4=T State3=T State2=T State1=T State0=T

PORTB=0x20;

DDRB=0x00;

// Port C initialization

// Func6=In Func5=In Func4=In Func3=In Func2=In Func1=In Func0=In

// State6=T State5=T State4=T State3=P State2=P State1=P State0=T

PORTC=0x0E;

DDRC=0x00;

// Port D initialization

// Func7=In Func6=In Func5=In Func4=In Func3=In Func2=In Func1=In Func0=In

// State7=T State6=T State5=T State4=T State3=T State2=T State1=T State0=T

PORTD=0x00;

DDRD=0x00;

// Timer/Counter 0 initialization

// Clock source: System Clock

// Clock value: Timer 0 Stopped

TCCR0=0x00;

TCNT0=0x00;

// Timer/Counter 1 initialization

// Clock source: System Clock

// Clock value: 7.813 kHz

// Mode: CTC top=OCR1A

// OC1A output: Discon.

// OC1B output: Discon.`

// Noise Canceler: Off

// Input Capture on Falling Edge

// Timer1 Overflow Interrupt: Off

// Input Capture Interrupt: Off

// Compare A Match Interrupt: On

// Compare B Match Interrupt: Off

 

/// Timer/Counter 2 initialization

// Clock source: System Clock

// Clock value: Timer2 Stopped

// Mode: Normal top=0xFF

// OC2 output: Disconnected

ASSR=0x00;

TCCR2=0x00;

TCNT2=0x00;

OCR2=0x00;

// External Interrupt(s) initialization

// INT0: Off

// INT1: Off

MCUCR=0x00;

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

TIMSK=0x10;

// USART initialization

// USART disabled

UCSRB=0x00;

// Analog Comparator initialization

// Analog Comparator: Off

// Analog Comparator Input Capture by Timer/Counter 1: Off

ACSR=0x80;

SFIOR=0x00;

// ADC initialization

// ADC disabled

ADCSRA=0x00;

// SPI initialization

// SPI disabled

SPCR=0x00;

// TWI initialization

// TWI disabled

TWCR=0x00;

// Alphanumeric LCD initialization

// Connections are specified in the

// Project|Configure|C Compiler|Libraries|Alphanumeric LCD menu:

// RS - PORTD Bit 2

// RD - PORTD Bit 3

// EN - PORTD Bit 4

// D4 - PORTD Bit 1

// D5 - PORTD Bit 5

// D6 - PORTD Bit 6

// D7 - PORTD Bit 7

// Characters/line: 16

lcd_init(16);

// Global enable interrupts

#asm("sei")

count_time = 0;

menit = 0;

lcd_gotoxy(0,0);

lcd_putsf("  :: Welcome :: ");

lcd_gotoxy(0,1);

lcd_putsf("  Fahmibnu-ELK   ");

delay_ms(1000);

lcd_clear();

while (1)

      {

      // Place your code here   

        itoa(menit,buf_menit);

        if(menit < 10)

        {    

            lcd_gotoxy(5,0);

            lcd_putsf("0");

            lcd_gotoxy(6,0);

            lcd_puts(buf_menit);

        }  

        else if(count_time > 9)

        {

            lcd_gotoxy(5,0);

            lcd_puts(buf_menit);

        }

       

        lcd_gotoxy(7,0);

        lcd_putsf(":");                

       

        itoa(count_time,counter_time);

        if(count_time < 10)

        {

            lcd_gotoxy(8,0);

            lcd_putsf("0");  

            lcd_gotoxy(9,0);

            lcd_puts(counter_time);

        }  

        else if(count_time > 9)

        {

            lcd_gotoxy(8,0);

            lcd_puts(counter_time);

        }

        lcd_gotoxy(0,1);

        lcd_putsf("  Membuat Timer");

        menu();

        delay_ms(50);

      }

}

void menu()

{

    if (t_up == 0)

    {

        up = 1;

        if(up == 1)

        {       

            delay_ms(50);

            count_time++;

            if(count_time > 59)

            {  

                menit++;

                count_time = 0;

            }

            up = 0;

        } 

        t_up = ~t_up;

        lcd_clear();

    }

    else if(t_down == 0)

    {

        down = 1;

        if(down == 1)

        {

            delay_ms(50);

            count_time--;

            if(count_time < 0)

            {

                menit--;

                count_time = 59;

            } 

            down = 0;

        }

        t_down = ~t_down;

        lcd_clear();

    }

    else if(t_enter == 0)

    {

        while(t_enter == 0);

        TCCR1B = 0x0D;         //timer1 is on

        t_enter = ~t_enter;

    }

    else if(t_pause == 0)

    {

        while(t_pause == 0);

        TCCR1B = 0x00;         //timer1 is off

        t_c = ~t_c;

    }

}