Attiny45 Timer0 prescaler issue

Other Hardware 3rd Party Boards
1

Hello everyone!

I would like to ask a question about programming an Attiny45 via Arduino as ISP.
I attempted to write a simple software to create a PWM signal on pin 5 via manipulating the timer0 registers. The code looks the following:

void setup()
{
DDRB = (1<<PB0);

TCCR0A |= (1 << COM0A1) | (1 << WGM01) | (1 << WGM00);
OCR0A = 150;

//Set timer0 prescaler:
TCCR0B |= (1 << CS00);

}

void loop()
{
}

No matter if I change the board to another attiny45 or an attiny85, I cannot manupulate the prescaler when I try to set those bits which can divide the internal counter clock. With 16MHz internal clock setting, burning the bootloader to the chip, then uploading this sketch, I can measure a 1kHz signal with variable duty cycle on the mentioned leg (by changing OCR0A between 0 and 255). What did I miss?

Thank you for the help in advance!

:Niz

2

Try:
TCCR0B = (1 << CS00 ) ;
Instead of
TCCR0B |= (1 << CS00) ;

Depending on the Arduino core, timer 0 can already be set up for millis() etc.

If that doesn’t get you anywhere, load the blink sketch and confirm the blink rate is about once per second.

3

Do not assume registers are in their power-on state at the beginning of setup. They are not - all cores configure the available timers for use with millis and/or analogWrite for pwm.

When you take over a timer, set all the timer's registers to the values you want.

Or override main() and do everything yourself (and be aware that nothing will be set up for you and analogWrite/tone/millis/micros/delay won't work). If you do this, you can assume all registers start in their powerup state.