This is a pretty basic RGB Switch design based on CBT3244AD bus switch ICs, SH1106 I²C screen, MAX7461 Loss-of-Sync detector IC and ATmega328p microcontroller.
Uses hardware-accelerated I2C library by Jeremy Cole and u8g2 library by olikraus
Sync detection and automatic switching are based on MAX7461.
Note that MAX7461 doesn't detect 31 kHz sync signals, so automatic detection can't be used with something like Dreamcast VGA to RGBs adaptors/cables.
You can find examples of screen functionality in extra/pictures
