DisplayPort Cyclone® 10 GX FPGA IP Design Example User Guide

ID 683603
Date 4/29/2024
Public
Document Table of Contents

2.2. Cyclone® 10 GX DisplayPort MST Parallel Loopback Design Features

The MST parallel loopback design examples demonstrate the transmission of two to four video streams from DisplayPort sink to DisplayPort source with or without Pixel Clock Recovery (PCR).
Figure 8.  Cyclone® 10 GX DisplayPort MST Parallel Loopback with PCR
  • In this variant, the DisplayPort source’s parameter, TX_SUPPORT_IM_ENABLE, is turned off and the standard VSYNC/HSYNC/DE video interface is used.
  • Due to the limitation of PLL numbers on the Cyclone® 10 GX board, by default the IP chooses only 1 stream from the input streams and transmits to the Pixel Clock Recovery block. The Test Pattern Generator (TPG) generates the remaining output streams and the streams display 1080p60 color bar image. For example, if the MST maximum stream count is four, one output video stream is chosen to display, and the remaining three video streams show the same image, which is 1080p60 color bar.
  • You can change the video to a different stream using the user_pb[1] push button. Every time you press user_pb[1], the next video stream displays.
  • The design examples support up to four streams for audio and video data.
  • The MST design examples use fixed EDID and do not support EDID passthrough.
  • You can modify the bandwidth assignment for each stream in the tx_utils.c file.

    stream 0: btc_dptxll_stream_set_pixel_rate(0,0,594000/MST_RX_STREAMS);

    stream 1: btc_dptxll_stream_set_pixel_rate(0,1,594000/MST_RX_STREAMS);

    stream 2: btc_dptxll_stream_set_pixel_rate(0,2,594000/MST_RX_STREAMS);

    stream 3: btc_dptxll_stream_set_pixel_rate(0,3,594000/MST_RX_STREAMS);

  • The maximum resolution supported for 4 stream counts is 1080p60.
Figure 9.  Cyclone® 10 GX DisplayPort MST Parallel Loopback without PCR
  • In this variant, the DisplayPort source’s parameter, TX_SUPPORT_IM_ENABLE, is turned on (“1”) and the video image interface is used.
  • The DisplayPort sink receives video and or audio streaming from external video source such as GPU and decodes it into parallel video interface.
  • The DisplayPort sink video output directly drives the DisplayPort source video interface and encodes to the DisplayPort main link before transmitting to the monitors.
  • The MST design examples support up to four streams for audio and video data.
  • The design examples use fixed EDID and do not support EDID passthrough.
  • The design examples support a total bandwidth of 594 MHz, distributed equally across the streams. For example, if you enable four streams, each stream would be 148.5 MHz.
  • You can modify the bandwidth assignment for each stream in the tx_utils.c file.

    stream 0: btc_dptxll_stream_set_pixel_rate(0,0,594000/MST_RX_STREAMS);

    stream 1: btc_dptxll_stream_set_pixel_rate(0,1,594000/MST_RX_STREAMS);

    stream 2: btc_dptxll_stream_set_pixel_rate(0,2,594000/MST_RX_STREAMS);

    stream 3: btc_dptxll_stream_set_pixel_rate(0,3,594000/MST_RX_STREAMS);

  • The maximum resolution supported for 4 stream counts is 1080p60.
Table 9.  Design Example Variant Comparison
Design Example PCR Module Enable Video Image Interface Adaptive Sync Video Interface
DisplayPort MST parallel loopback with PCR Required No Not supported Standard VSYNC/HSYNC/DE interface (txN_video_in)
DisplayPort MST parallel loopback without PCR Not required Yes Supported Video Image Interface (txN_video_in_im)