SNLS543 August 2018 DS90UH949A-Q1
Consumer Electronics Control (CEC) is designed to allow the system user to command and control up to ten CEC-enabled devices connected through HDMI using only one of their remote controls (for example, controlling a television set, set-top box, and DVD player using only the remote control of the TV). CEC also allows for individual CEC-enabled devices to command and control each other without user intervention. CEC is a one-wire, open-drain bus with an external 27-kΩ (±10%) resistor pullup to 3.3 V.
CEC protocol can be implemented using an external clock reference or the 25-MHz internal oscillator inside the DS90UH949A-Q1.