Clear Timer on Compare Match(CTC) Mode problem

[Razu Ahmmed]

I have faced problems in working with CTC in atmega. I can not produce interrupt after 1 second using CTC. I observed that the value of OCR1AH is not compared with with TCNT1H .What can be done?
Suggest needed.My code is following........

#include <built_in.h>

int a=0;

void Timer1compa_ISR() org IVT_ADDR_TIMER1_COMPA
{
PORTB=~PORTB;
PORTD=0xFF;
}


void main()
{
int i;
DDRB=0xFF;
DDRD=0xFF;
DDRC=0xFF;

SREG_I_bit=1;

TIMSK |= (1<<OCIE1A);

TCNT1L=0;
TCNT1H=0
i=4870;
OCR1AL=Lo(i);
OCR1AH=Hi(i);
TCCR1B |= (1<<WGM12);

TCCR1B=0x0D; /*start timer with presscaler of clk/1024*/
/*Timer/Counter1, Output Compare A Match Interrupt Enable*/


while(1)
{
PORTB=0x0F;
}
}

 

[alexan_e]

You are missing

// timer1 compare match A ISR on
TIMSK=0x10;

I also don't know why you use TCCR1B |= (1<<WGM12); when in the next line you write a new value TCCR1B=0x0D;

Alex

P.S. actually the TIMSK exists in your code.
I an not familiar with your compiler but maybe the value is the problem, can you use OCR1A=i ?
There should also be somewhere a global enable interrupt (for example it is sei() in avrgcc)

 

[Razu Ahmmed]

Here i have a problem like i am using mikroC as compiler , in it the following code is not accepted ....
OCR1A=i;
when i declare such as......
OCR1AL=i;
then it is accepted but it is only possible when ( i<255 )
if i>255
then i have to declare it like
OCR1AL=Lo(i);
OCR1AH=Hi(i);
but in this case the OCR1AH value is not compared with the value of TCNT1H only the value of OCR1L value is compared as a result i could not able to compare a large time.
I can not understand actually what i have to do. Help needed..

 

[Razu Ahmmed]

CTC problem in atmega with mikroC compiler

I need a normal code of Timer1 CTC for atmega in mikroC. I have made a simple code but i can not understand where is my error i can not compare time when i>255.
Help needed.
#include<built_in.h>

unsigned int i;

void inerrupt_ISP() org IVT_ADDR_TIMER1_COMPA
{
PORTB = ~PORTB ;
}

void square_wave_init(void)
{
DDRB = 0xFF;
TIMSK |= (1<<OCIE1A);
TCNT1L=0;
i=4870;
OCR1AL = i;
OCR1AH=Hi(i);
TCCR1B |= (1<<WGM12);
TCCR1B |= (1<<CS10) | (1<<CS12);
//TCCR1A=0b01010000;
}
void main()
{
square_wave_init();
SREG_I_bit=1;
while(1){ ;
}

}