#include <xc.h>
#include <avr/io.h>
#include <util/delay.h>

#include <avr/interrupt.h>
//#include <avr/sleep.h>
//#include <util/atomic.h>
//#include <avr/wdt.h>

//tests5 tested and works (though 950Hz). unplug cable to programmer to see pin 4 active.

//reference: https://www.avrfreaks.net/forum/sample-project-attiny10
//https://blog.podkalicki.com/attiny13-blinky-with-timer-compa/
//watchdog is too slow and inaccurate to get 6000Hz

ISR(TIM0_COMPA_vect)
{
        // Toggle PB2 Hi/Low depending on current state
        PINB = 1<<2;
        //PORTB ^= _BV(LED_PIN); // toggle LED pin
}


/*
  Delay in powerdown mode. Wake up by watchdog interrupt.
 * //NOTE: see earlier code, e.g. tests3 in attiny10  elec projects 2020
 */
/*
void delay_power_down_wdt(uint8_t wdto)
{
    wdt_reset();
    wdt_enable(wdto);
    WDTCSR |= (1<<WDIE);
    //so far (with 128Khz clk) this sleep will be about 30-40 seconds.
    
    //(however, I'll add the below to)
    //adjust sleep speed here:
    
    // 0110 is 1hz at 128KHz
    //WDTCSR |= (0<< WDP3);
    //WDTCSR |= (1<< WDP2);
    //WDTCSR |= (1<< WDP1);
    //WDTCSR |= (0<< WDP0);
    
    set_sleep_mode(SLEEP_MODE_PWR_DOWN);
    sleep_enable();
    // Make sure interrups are enabled and the I flag is restored
    NONATOMIC_BLOCK(NONATOMIC_RESTORESTATE)
    {
	sleep_cpu();
	wdt_disable();
    }
    sleep_disable();
}
*/

int main(void)
{
    
    
    
    //Write CCP (to enable changing clock)
    //CCP = 0xD8;
    //change CLK to 128KHz
    //CLKMSR = 0b01;
    
    TCCR0A |= _BV(WGM01); // set timer counter mode to CTC
   // TCCR0B |= _BV(CS02)|_BV(CS00); // set prescaler to 1024 (CLK=1200000Hz/1024/256=4.57Hz, 0.22s)
    TCCR0B |= _BV(CS00); // set prescaler to 1 (CLK=1MHz/1)
    OCR0A = 167; // with one timer, ever 166.667hz we want to count once (3000hz) 
    TIMSK0 |= _BV(OCIE0A); // enable Timer CTC interrupt
        
    // PB2 change to output
    DDRB = 1<<2;
    sei();

    while(1)
    {
        //handled by interrupt
   
    }
}