HDMI Intel® Arria 10 FPGA IP Design Example User Guide

ID 683156
Date 11/12/2021
Public

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2.5.2. HDMI RX Components

The HDMI RX top components include the RX core top-level components, optional I2C slave and EDID RAM, IOPLL, transceiver PHY reset controller, RX native PHY, and the RX reconfiguration management blocks.
Figure 9. HDMI RX Top Components
Table 10.  HDMI RX Top Components
Module Description
HDMI RX Core

The IP receives the serial data from the Transceiver Native PHY and performs data alignment, channel deskew, TMDS decoding, auxiliary data decoding, video data decoding, audio data decoding, and descrambling.

I2C Slave
I2C is the interface used for Sink Display Data Channel (DDC) and Status and Data Channel (SCDC). The HDMI source uses the DDC to determine the capabilities and characteristics of the sink by reading the Enhanced Extended Display Identification Data (E-EDID) data structure.
  • The 8-bit I2C slave addresses for E-EDID are 0xA0 and 0xA1. The LSB indicates the access type: 1 for read and 0 for write. When an HPD event occurs, the I2C slave responds to E-EDID data by reading from the on-chip RAM.
  • The I2C slave-only controller also supports SCDC for HDMI 2.0 and 2.1 operations. The 9-bit I2C slave address for the SCDC are 0xA8 and 0xA9. When an HPD event occurs, the I2C slave performs write or read transaction to or from SCDC interface of the HDMI RX core.
  • Link training process for Fixed Rate Link (FRL) also happens through I2C interface. During an HPD event or when the source writes a different FRL rate to the FRL Rate register (SCDC registers 0x31 bit[3:0]), the link training process starts.
    Note: This I2C slave-only controller for SCDC is not required if HDMI 2.0 or HDMI 2.1 is not intended.
EDID RAM

The design stores the EDID information using the RAM 1-Port IP. A standard two-wire (clock and data) serial bus protocol (I2C slave-only controller) transfers the CEA-861-D Compliant E-EDID data structure. This EDID RAM stores the E-EDID information.

  • When in TMDS mode, the design supports EDID passthrough from TX to RX. During EDID passthrough, when the TX is connected to the external sink, the Nios® II processor reads the EDID from the external sink and writes to the EDID RAM.
  • When in FRL mode, the Nios® II processor writes the pre-configured EDID for each link rate based on the HDMI_RX_MAX_FRL_RATE parameter in the global.h script.
Use the following HDMI_RX_MAX_FRL_RATE inputs for the supported FRL rate:
  • 1: 3G 3 Lanes
  • 2: 6G 3 Lanes
  • 3: 6G 4 Lanes
  • 4: 8G 4 Lanes
  • 5: 10G 4 Lanes (default)
  • 6: 12G 4 Lanes
IOPLL

The HDMI RX uses two IOPLLs .

  • The first IOPLL (pll_tmds) generates the RX CDR reference clock. This IOPLL is only used in TMDS mode. The reference clock of this IOPLL receives the TMDS clock. The TMDS mode uses this IOPLL because the CDR cannot receive reference clocks below 50 MHz and the TMDS clock frequency ranges from 25 MHz to 340 MHz. This IOPLL provides clock frequency that is 5 times of the input reference clock for frequency range between 25 MHz to 50 MHz and provides the same clock frequency as input reference clock for frequency range between 50 MHz to 340 MHz.
  • The second IOPLL (iopll_frl) generates the FRL clock for the RX core. This reference clock receives the CDR recovered clock.

    FRL clock frequency = Data rate per lanes x 4 / (FRL characters per clock x 18)

Transceiver PHY Reset Controller

The Transceiver PHY reset controller ensures a reliable initialization of the RX transceivers. The reset input of this controller is triggered by the RX reconfiguration, and it generates the corresponding analog and digital reset signal to the Transceiver Native PHY block according to the reset sequencing inside the block.

RX Native PHY

Hard transceiver block that receives the serial data from an external video source. It deserializes the serial data to parallel data before passing the data to the HDMI RX core. This block runs on Enhanced PCS for FRL mode.

RX CDR has two reference clocks.

  • Reference clock 0 is connected to output clock of IOPLL TMDS (pll_tmds), which is derived from the TMDS clock.
  • Reference clock 1 is connected to a fixed 100 MHz clock. In TMDS mode, RX CDR is reconfigured to select reference clock 0, and in FRL mode, RX CDR is reconfigured to select reference clock 1.
RX Reconfiguration Management

In TMDS mode, the RX reconfiguration management block implements rate detection circuitry with the HDMI PLL to drive the RX transceiver to operate at any arbitrary link rates ranging from 250 Mbps to 6,000 Mbps.

In FRL mode, the RX reconfiguration management block reconfigures the RX transceiver to operate at 3 Gbps, 6 Gbps, 8 Gbps, 10 Gbps, or 12 Gbps depending on the FRL rate in the SCDC_FRL_RATE register field (0x31[3:0]).

The RX reconfiguration management block switches between Standard PCS/RX for TMDS mode and Enhanced PCS for FRL mode.

Refer to Figure 10.

Figure 10. RX Reconfiguration Sequence FlowThe figure illustrates the multi-rate reconfiguration sequence flow of the controller when it receives input data stream and reference clock frequency, or when the transceiver is unlocked.

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