Which TMDS Channel Carries Blue and Sync in DVI?

Digital Visual Interface (DVI) relies on Transition-Minimized Differential Signaling (TMDS) to deliver high-speed serial digital video data from a source to a display. This article explains how DVI organizes its TMDS data architecture and identifies the specific channel responsible for carrying both the blue color component and critical synchronization timing signals.

In a standard single-link DVI connection, TMDS Data Channel 0 is the specific channel that carries the blue color information and the synchronization data. The interface utilizes four differential pairs in total: three dedicated data channels (Channels 0, 1, and 2) and one dedicated clock channel. Each data channel is responsible for transmitting an 8-bit color component encoded into a 10-bit TMDS character, alongside specific control or synchronization signals during video blanking intervals.

TMDS Data Channel 0 multiplexes these signals depending on the display timing:

• Active Video Period: Channel 0 transmits the primary 8-bit blue color pixel data.
• Blanking Interval: When pixel data is not being transmitted, Channel 0 transmits the Horizontal Synchronization (HSync) and Vertical Synchronization (VSync) signals.

The remaining TMDS channels handle the other primary colors and auxiliary control bits. TMDS Data Channel 1 carries the green color data and control signals CTL0 and CTL1. TMDS Data Channel 2 carries the red color data and control signals CTL2 and CTL3. The separate TMDS Clock channel provides the frequency reference that allows the receiver to synchronize and decode the incoming bitstreams across all three data channels simultaneously.