I'm trying to send data both ways between an Arduino Mega 2560 slave and 2 Arduino Nano Zero (ATSAMD21G).

This example is a simplified setup and code. There will be more masters along with passive slaves on the bus (LCD, EEPROM).

[Code and results (txt files)](https://github.com/kb-/Arduino-I2C-2way-anydata/tree/f78aa10354f7706d1aa32f49d3bc647600f2b4ee)

My code is working fine with one master only and the slave active on the bus (data is sent both ways every 2s). I however notice missing transfers to the masters when more than one master is active. The 2 masters to slave transfers are working properly (once the 2 masters are on, the data is received by the slave every 2s from each master).

Is this problem due to collision? How can I handle it?