The HDMI TX display pipeline (in the PL) is controlled by the video frame buffer read, which fetches the video layer from memory and sends the data to the HDMI TX subsystem. The HDMI TX subsystem processes data and sends it out to an external display device. The HDMI transmitter display pipeline is shown in the following figure.
As shown in the figure, the pipeline comprises three main components, each of them controlled by the APU via an AXI4-Lite base register interface. These components are described in the following paragraphs.
The video frame buffer read IP provides high-bandwidth direct memory access between memory and AXI4-Stream video type target peripherals, which support the AXI4-Stream video protocol. IP takes memory mapped AXI4 input data from DDR and converts it to AXI4-Stream format. The output is connected to HDMI transmitter subsystem. For each video frame transfer, an interrupt is generated. A GPIO is used to reset the core between resolution changes. For more information, see the Video Frame Buffer Read and Video Frame Buffer Write LogiCORE IP Product Guide (PG278).
The HDMI transmitter subsystem (HDMI TX) interfaces with PHY layers and provides HDMI encoding functionality. The subsystem is a hierarchical IP that bundles a collection of HDMI TX-related IP sub-cores and outputs them as a single IP. The subsystem generates an HDMI stream from the incoming AXI4-Stream video data and sends the generated TMDS data to the video PHY layer. For more information, see the HDMI 1.4/2.0 Transmitter Subsystem Product Guide (PG235).
The HDMI GT controller (PHY) enables plug-and-play connectivity with video transmit or receive subsystems. The interface between the media access control (MAC) and physical (PHY) layers are standardized to enable ease of use in accessing shared gigabit-transceiver (GT) resources. The data recovery unit (DRU) supports lower line rates for the HDMI protocol. An AXI4-Lite register interface is provided to enable dynamic accesses of transceiver controls/status. For more information, see the HDMI GT Controller LogiCORE IP Product Guide (PG334).