ATtiny2313 Timer Speed

#include "Arduino.h"

#define ledPin 1

void dw(unsigned char port, bool on) {

  if (on) {

    PORTD |= (1 << port);

  } else {

    PORTD &= ~(1 << port);

  }

}

ISR(TIMER1_COMPA_vect) {

  int t = 5000;

  static int b;

  b = b + 1;

  dw(ledPin, (b > t));

  if (b > t * 2)

    b = 0;

}

void setup() {

  DDRD = DDRD | (1 << ledPin);

  TIMSK |= (1 << OCIE1A);

  TCCR1A = 1 << COM1A0;            // toggle OC1A on Compare Match

  TCCR1B = 1 << WGM12 | 1 << CS10; // CTC, no prescaler

  OCR1A = 9;                       // compare A register value to 10 (zero relative)

  TCCR0A = 0x83;                   // Timer/Counter 0 initialization

  TCCR0B = 0x01;                   // Clock source: System Clock and Clock value: 16000,000 kHz

  TCNT0 = 0x00;                    // Mode: Fast PWM top=FFh

  OCR0A = 0x00;                    // OC0A output: Non-Inverted PWM

  OCR0B = 0x00;                    // OC0B output: Disconnected

  sei();

}

// The loop function is called in an endless loop

void loop() {

}