Timer0 overflow interrupt does not work on ATtiny10

I am trying to use the Timer0 overflow interrupt to make a little project. I used such a timer in the ATtiny45 and it worked, but with ATtiny10 no result.

So I tried an easy LED blinking program and even that didn't work.

Here is the simple code:

#define F_CPU 1000000UL // 1 MHz #include <avr/io.h> #include <avr/interrupt.h> #include <avr/sleep.h> #include <util/delay.h> volatile uint16_t overflow_val=0; ISR (TIMER0_OVF_vect){ overflow_val++; } int main(void){ DDRB = (1<<PB1); // Timer0 normal mode TCCR0A = 0x00; // Start timer with presc 1:1024 TCCR0B = (1<<CS02) | (1<<CS00); TCNT0 = 0; TIMSK0 |= (1 << TOIE0); sei(); for(;;){ if(overflow_val >= 1) { if(TCNT0 >= 145){ PORTB ^= (1 << PB1); TCNT0 = 0; overflow_val = 0; } } } return 0; } 

Hope someone can help me. Thanks!

EDIT1:

I changed line

TCCR0B = (1<<CS02) | (1<<CS00); 

to line

TCCR0B = (1 << CS01); // clk/8 

in my code to achieve an overflow every 0.524sec. But the LED is not blinking at all.

EDIT2:

Here is the size:

>avr-size test_attiny10_2.ino.elf text data bss dec hex filename 138 0 2 140 8c test_attiny10_2.ino.elf 

EDIT3:

I changed my if statement in the main as follows:

int main(void){ ... TCCR0B = (1 << CS01); ... for(;;){ if(TCNT0 >= 0xFFFE) { PORTB ^= (1 << PB1); TCNT0 = 0; } } return 0; } 

Now my LED is flashing all 0.524 seconds as it should!

So something is wrong with my volatile unit16_t variable overflow_val. Not only i tested it directly on hardware, but did also a simulation with atmelstudio. Also in the simulation the program is never entering the if statement if i use the variable overflow_val to toggle the LED.

EDIT 4

I think something is not right with my ISR fkt. I testet the following code and i never got the LED switched on.

#define F_CPU 1000000UL // 1 MHz #include <avr/io.h> #include <avr/interrupt.h> #include <util/delay.h> volatile uint8_t ovf_counter = 0; void ioinit(void){ // PB1->outputs DDRB = (1<<PB1); // Start timer with presc 1:64 TCCR0B = (1<<CS01) | (1<<CS00); // Initialize counter Overflow at 0xFFFF TCNT0 = 0; // Enable global interrupts sei(); } int main(void){ ioinit(); TIMSK0 |= (1<<TOIE0); while(1){ if(ovf_counter>=2){ PORTB = (1<<PB1); ovf_counter=0; } } } ISR(TIMER0_OVF_vect){ ovf_counter++; TCNT0 = 0; } 

i dont know what is wrong.

If i check in the while(1) loop the status of the counter register TCNT0 it works. So the counter is overflowing as it should, but it never enters on a overflow event the ISR(TIMER0_OVF_vect) function.