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When the HPD pin voltage exceeds 2V, it indicates that the display is connected to the host. When the HPD pin voltage drops below 0.8V, it indicates that the connection between the display and the host has been disconnected.

DDC Channel (I2C)

DCC: Display Data Channel. Function: Informs the host about the display manufacturer, production date, supported resolutions, etc. Purpose: To enable plug-and-play functionality.

EDID (Extended Display Identification Data) is a specification originally designed for optimizing display formats for PC monitors. It is stored in a dedicated 1Kb EEPROM memory in the display (i.e., the EDID data structure is 128 bytes).

The EDID data structure in HDMI interfaces for digital TVs differs from that of PC monitors in that the programming data can be a multiple of 128 bytes. It not only defines the display format for digital TVs but also specifies digital video and audio signals. Data beyond the basic 128 bytes is additional data, with the number of additional data blocks defined in the 127th byte of the basic data.

CEC Signal

CEC: Consumer Electronics Control. Through CEC signals, users can control devices connected to the HDMI interface. For example, One Touch Play and System Standby. For instance, when a user inserts a disc into a Blu-ray player, the TV will automatically turn on due to the CEC signal notification, and the video channel will also automatically switch to the channel connected to the player. When the user turns off the TV, the CEC signal also notifies the HDMI-connected devices to enter standby mode. As a result, a single remote control can be used to control all HDMI-connected devices.

In summary, when the HDMI cable is plugged into the device, the HPD pin is pulled high. The signal transmitter detects this high-level signal and then sends the HDMI signal. When transmitting high-speed digital signals via HDMI, both the transmitter and receiver chips employ anti-static protection circuits to support higher transmission speeds. However, some HDMI cables with subpar technology or cost-cutting measures may lack proper anti-static design or have inadequate insulation performance, leading to hot-plugging damage to devices. Therefore, selecting professional fiber optic cable brand products is crucial.