I'm trying to create communication between RPi, two Atmega328P and one Attiny85 via I2C using this library http://playground.arduino.cc/Code/USIi2c
from rambo https://github.com/rambo/TinyWire/tree/master/TinyWireS
I don't have any level shifters nor any MOSFETs. But I found on the Internet that it's possible to make safe communication if disable pull-ups to 5V. In Atmegas it was simple. But I don't know how to make it in attiny without interfering with library. In examples it's said
* Reminder: taking care of pull-ups is the masters job
But I've tested it with multimeter and pin 0(PB0/PCINT0) was high and PB2 was low without connection to anything in slave mode.
In this file here https://github.com/rambo/TinyWire/blob/master/TinyWireS/usiTwiSlave.c
there is lines like this everywhere
I don't know maybe my test was wrong and I thought slave release pin so it can be pulled up and not writes HIGH.
Is it save to connect it as it is or I should find out how to disable this HIGH state?
//Maybe I'm in the wrong forum branch. Sorry.