I have a little confuison with it. In harwared diagrama lcd is conected to both I2C, raspberry and arduido, if so, the bus i2c oould be share? Thanks
By “Arduino”, do you mean the Atmel ATMega 329P processor?
The ATMega is the first to start when power is connected, and it sends messages to the display while the Raspberry Pi is booting. Thereafter, the Pi is in control of the display.