Atmega (Arduino mega) 2560 has 4 UART, but UART 0 dedicated to USB clinet interface.
For my project I need all 4 UART.
From CCT diagram ATmega16U2 USB controller UART1 connected to ATmega2560 UART0 trough 1k resistor. That means from electrical viewpoint other device can connect to ATmega2560 UART0. But open question is, what ATmega16U2 USB controller do if got unexpected data form UASRT1?
Otherwords, anybody has information, if no USB host connected to board, then ATmega16U2 USB controller ignore ist serial input?
If not, then there is any way to enabe/disable ATmega16U2 for example trough ICSP?
Thanks for any advice.