HDMI Intel® Arria 10 FPGA IP Design Example User Guide

ID 683156
Date 11/12/2021
Public

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2.5.3. Top-Level Common Blocks

The top-level common blocks include the transceiver arbiter, the RX-TX link components, and the CPU subsystem.
Table 11.  Top-Level Common Blocks
Module Description
Transceiver Arbiter

This generic functional block prevents transceivers from recalibrating simultaneously when either RX or TX transceivers within the same physical channel require reconfiguration. The simultaneous recalibration impacts applications where RX and TX transceivers within the same channel are assigned to independent IP implementations.

This transceiver arbiter is an extension to the resolution recommended for merging simplex TX and simplex RX into the same physical channel. This transceiver arbiter also assists in merging and arbitrating the Avalon® memory-mapped RX and TX reconfiguration requests targeting simplex RX and TX transceivers within a channel as the reconfiguration interface port of the transceivers can only be accessed sequentially.

The interface connection between the transceiver arbiter and TX/RX Native PHY/PHY Reset Controller blocks in this design example demonstrates a generic mode that applies for any IP combination using the transceiver arbiter. The transceiver arbiter is not required when only either RX or TX transceiver is used in a channel.

The transceiver arbiter identifies the requester of a reconfiguration through its Avalon® memory-mapped reconfiguration interfaces and ensures that the corresponding tx_reconfig_cal_busy or rx_reconfig_cal_busy is gated accordingly.

For HDMI applications, only RX initiates reconfiguration. By channeling the Avalon® memory-mapped reconfiguration request through the arbiter, the arbiter identifies that the reconfiguration request originates from the RX, which then gates tx_reconfig_cal_busy from asserting and allows rx_reconfig_cal_busy to assert. The gating prevents the TX transceiver from being moved to calibration mode unintentionally.
Note: Because HDMI only requires RX reconfiguration, the tx_reconfig_mgmt_* signals are tied off. Also, the Avalon® memory-mapped interface is not required between the arbiter and the TX Native PHY block. The blocks are assigned to the interface in the design example to demonstrate generic transceiver arbiter connection to TX/RX Native PHY/PHY Reset Controller.
RX-TX Link
  • The video data output and synchronization signals from HDMI RX core loop through a DCFIFO across the RX and TX video clock domains.
  • The auxiliary data port of the HDMI TX core controls the auxiliary data that flow through the DCFIFO through backpressure. The backpressure ensures there is no incomplete auxiliary packet on the auxiliary data port.
  • This block also performs external filtering:
    • Filters the audio data and audio clock regeneration packet from the auxiliary data stream before transmitting to the HDMI TX core auxiliary data port.
    • Filters the High Dynamic Range (HDR) InfoFrame from the HDMI RX auxiliary data and inserts an example HDR InfoFrame to the auxiliary data of the HDMI TX through the Avalon® streaming multiplexer.
CPU Subsystem

The CPU subsystem functions as SCDC and DDC controllers, and source reconfiguration controller.

  • The source SCDC controller contains the I2C master controller. The I2C master controller transfers the SCDC data structure from the FPGA source to the external sink for HDMI 2.0 operation. For example, if the outgoing data stream is 6,000 Mbps, the Nios® II processor commands the I2C master controller to update the TMDS_BIT_CLOCK_RATIO and SCRAMBLER_ENABLE bits of the sink TMDS configuration register to 1.
  • The same I2C master also transfers the DDC data structure (E-EDID) between the HDMI source and external sink.
  • The Nios® II CPU acts as the reconfiguration controller for the HDMI source. The CPU relies on the periodic rate detection from the RX Reconfiguration Management module to determine if the TX requires reconfiguration. The Avalon® memory-mapped slave translator provides the interface between the Nios® II processor Avalon® memory-mapped master interface and the Avalon® memory-mapped slave interfaces of the externally instantiated HDMI source’s IOPLL and TX Native PHY.
  • Perform link training through I2C master interface with external sink

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