Two Attiny85s NACKing 5 out of 10 times after turning the power on

[oomek]

I've been trying to link 2 Attiny85s, but the connection is very unreliable. When I connect the power for both boards at the same time I always get NACK, when I connect Slave first, wait until it boots ( 5 seconds Digispark Attiny85 ) I get communication half the time. I have 2k pull up resistors.

Here is the sketch I'm using:

#include <Arduino.h>
#include "TinyWire.h"

#define MASTER 1

uint8_t array[32];
uint8_t address = 0x00;

void blink(int time, int n)
{
	for (int i = 0; i < n; i++)
	{
		digitalWrite(1, HIGH);
		delay(time / 2);
		digitalWrite(1, LOW);
		delay(time / 2);
	}
}

#if MASTER

void setup()
{
 	pinMode(1, OUTPUT);
	blink(200, 3);
	TinyWire.begin();
	for ( int i = 0; i < 32; i++)
		array[i] = i;
}

void loop()
{
	TinyWire.beginTransmission(0x46);
	TinyWire.send(address);
	for ( int i = 0; i < sizeof(array); i++)
		TinyWire.send(array[i]);

	if ( TinyWire.endTransmission() != 0)
		blink (200, 5);
	else
		blink(1000, 1);
}

#else //SLAVE

void receiveEvent(int howMany)
{
	byte c = 0;
	while (TinyWire.available() > 0)
		c = TinyWire.read();
	blink(500, 1);
}

void setup()
{
	pinMode(1, OUTPUT);
	blink(200, 3);
	TinyWire.begin(0x46);
	TinyWire.onReceive(receiveEvent);
}

void loop()
{
	delay(1);
}

#endif

[oomek]

It seems like the slave is causing that issue when begin() is called. It pulls down SCL and SDA for a moment for some reason.