IC Tech

Pin Timer / Counter Pada Atmega8535

• Register TCNT = register pencacah dari 0 sampai nilai maximum yg kita tentukan.
• Register TCCR =Untuk pengaturan mode  operasi  Timer/Counter
• Register TIMSK =Untuk  memilih Timer Counter  mana yg aktif.
• Register TIFR = Untuk mengetahui adanya interupsi akibat operasi Counter Timer .
• Register OC (output compare) = untuk menyimpan nilai pembanding dgn nilai pd register  TCNT.

Chip type           : ATmega8535
Compiler            : CodeVision
Clock frequency     : 4.000000 MHz
Memory model        : Small
External SRAM size  : 0
Data Stack size     : 128
Author              : pccontrol.wordpress.com 
*****************************************************/

#include <mega8535.h>
#include <stdio.h>
// Alphanumeric LCD Module functions
#asm
   .equ __lcd_port=0x15 ;PORTC
#endasm
#include <lcd.h>
unsigned char bufferperiodeL[15];
unsigned char bufferperiodeH[15]; 

// Timer 1 input capture interrupt service routine
interrupt [TIM1_CAPT] void timer1_capt_isr(void)
{

sprintf(bufferperiodeL,"%i ",ICR1L);
sprintf(bufferperiodeH,"%i ",ICR1H); 

lcd_gotoxy(0,1);
lcd_puts(bufferperiodeH);
lcd_gotoxy(4,1);
lcd_puts(bufferperiodeL);   

ICR1H=0;
ICR1L=0;
TCNT1L =0;
TCNT1H =0;
}

void main(void)
{

// Timer/Counter 1 initialization
// Clock source: System Clock
// Clock value: 3.906 kHz
// Mode: Normal top=FFFFh

// Noise Canceler: Off
// Input Capture on Rising Edge
// Timer 1 Overflow Interrupt: Off
// Input Capture Interrupt: On

TCCR1A=0x00;
TCCR1B=0x45;
TCNT1H=0x00;
TCNT1L=0x00;
ICR1H=0x00;
ICR1L=0x00;
OCR1
// Timer(s)/Counter(s) Interrupt(s) initialization
TIMSK=0x20;

// LCD module initialization
lcd_init(16);
    lcd_gotoxy(0,0);
      lcd_putsf("periode pulsa :");
// Global enable interrupts
#asm("sei")

while (1)
      {

      };
}

/*===================================================
Chip type           : ATmega8535
Author              : Pccontrol.wordpress.com
Clock frequency     : 4.000000 MHz
Memory model        : Small
External SRAM size  : 0
Data Stack size     : 128
*****************************************************/

#include <mega8535.h>
#include <stdio.h>
// Alphanumeric LCD Module functions
#asm
   .equ __lcd_port=0x15 ;PORTC
#endasm
#include <lcd.h>

unsigned int hitunganMSB;
unsigned int hitunganLSB;
 unsigned char bufferCounter[15];
 unsigned long int hitungan;
// Timer 0 overflow interrupt service routine
interrupt [TIM0_OVF] void timer0_ovf_isr(void)
{
//hitungan lebih dari 255

hitunganMSB = hitunganMSB + 1;

}

// Declare your global variables here

void main(void)
{
// Declare your local variables here

// Timer/Counter 0 initialization
// Clock source: T0 pin Falling Edge
// Mode: Normal top=FFh
// OC0 output: Disconnected
TCCR0=0x06;
TCNT0=0x00;

// Timer(s)/Counter(s) Interrupt(s) initialization
TIMSK=0x01;

// LCD module initialization
lcd_init(16);
lcd_gotoxy(0,0);
lcd_putsf("counter :");
// Global enable interrupts
#asm("sei")

while (1)
      {
      // Place your code here
      hitunganLSB = TCNT0;
      hitungan = hitunganMSB + hitunganLSB; 

      sprintf(bufferCounter,"%i ", hitungan );
   lcd_gotoxy(0,1);
   lcd_puts(bufferCounter);
      };
}

Salah satu kegunaan sinyal PWM  antara lain untuk  mengendalikan Kecepatan putaran  Motor DC.   Gambar berikut ini menunjukan berbagai bentuk PWM dan efek terhadap kecepatan Motor DC yang berbeda sesuai bentuk pulsa PWM.

Pulsa Wide Modulation

membuat pwm 25% pada output OC0 dgn Timer0

#include <mega8535.h>

// Declare your global variables here

void main(void)
{

// Port B initialization
// Func7=In Func6=In Func5=In Func4=In Func3=Out Func2=In Func1=In Func0=In
// State7=T State6=T State5=T State4=T State3=0 State2=T State1=T State0=T
PORTB=0x00;
DDRB=0x08;

// Timer/Counter 0 initialization
// Clock source: System Clock
// Clock value: 62.500 kHz
// Mode: Phase correct PWM top=FFh
// OC0 output: Non-Inverted PWM
TCCR0=0x63;
TCNT0=0x00;
OCR0=0x40;

// Timer(s)/Counter(s) Interrupt(s) initialization
TIMSK=0x00;

while (1)
      {
      // Place your code here

      };
}

PWM phase corect

5. Membuat Delay dengan Timer.
#include <mega8535.h>

interrupt [TIM0_OVF] void timer0_ovf_isr(void)
{
delay = delay + 1
}

void main(void)
{
// Timer/Counter 0 initialization
// Clock source: System Clock
// Clock value: 3.906 kHz
// Mode: Normal top=FFh
TCCR0=0x05;
TCNT0=0xD9;
// Timer0 enable
TIMSK=0x01;
// Global enable interrupts
#asm("sei")

while (1)
      {
      //program utama disini
       delay(100);   //delay 1 detik   (100*10ms=1000ms)
      };
}

Void delay(int delay_ms)
{
   TCNT0=0xD9;  //interval  timer = 10 ms
   delay=0
   while(delay<=delay_ms)
   {
    //muter2 disini
    }
}

Timer Mode CTC (clear timer on compare match)

Pada mode ini counter TCNT akan bergulir/mencacah naikkemudian akan kembali 0 saat nilai  TCNT = OCR0. Untuk menghasilkan gelombang kotak pd pin OC kita set OC0 toggle yaitu dgn memberi nilai  COM1 =0 dan COM0 =1 di register TCCR.   


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Kesimpulan cara Pengesetan register TCCR