Problem
After connecting my MiSTer to my TV setup, all my HDMI devices stopped working together. When I unplugged the DE10-Nano everything started working again. MiSTer was causing the Consumer Electronics Control (CEC) feature of HDMI to stop functioning.
This feature allows devices communicate with each other and control themselves. This means when I turn on my Playstation, the TV and receiver is automatically turned on and switched to the correct input. When another console is turned on, the receiver automatically switches to that input. It’s a handy feature and I wanted it keep it working.
Solution
Use a cable or adaptor that disables disables pin 13 in HDMI so CEC will continue to work normally with MiSTer connected.