Dreamcast HDMI
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DreamcastHDMI / DCHDMI


  • Updated the firmware to reflect the DCHDMI 1.3 hardware changes. The OSD now contains the following:

    • Output Resolution selection.

      Select VGA, 480p, 960p and 1080p from the OSD.

    • Scanlines.

      On/Off, Intensity, Odd/Even and Thick/Thin

    • Video Mode Setup.

      Select ForceVGA, CableSelect and SwitchTrick for startup.

    • Firmware Upgrade.

      Download and flash new firmware from OSD, and also reset DCHDMI.

    • WiFi Setup.

      Enter SSID and Password for a quick wifi configuration from OSD.

    • Reset Configuration.

      DCHDMI can now reset the dreamcast. It can also reset the USB-GDROM (to return to the menu), in which case an additional connection is necassary. This pin can also be used to press the GDEMU button. By default it's connected to the onboard LED. So here you can configure to what and if this optional wire is connected.

      • LED: use onboard diagnostic LED

      • GDEMU: connected to the button on the GDEMU

      • USB-GDROM: connected to the USB-GDROM reset circuit


  • Finished OSD with the following features:

    • Output Resolution selection.

      Select VGA, 480p, 960p and 1080p from the OSD.

    • Video Mode Setup.

      Select ForceVGA, CableSelect and SwitchTrick for startup.

    • Scanlines.

      On/Off, Intensity, Odd/Even and Thick/Thin

    • Firmware Upgrade.

      Download and flash new firmware from OSD, and also reset DCHDMI.

    • Debug Info.

      Debug information.

  • Integrated FirmwareManager into this project, as the coupling between ESP and FPGA is very tight now.

  • Added upscaling of 480i content to 960p/1080p.


  • Dynamic reconfiguration of the output resolution.

    Output resolution is now configurable via WiFi webinterface, OSD integration will follow soon.

  • Removed 10CL016 and EP4CE6 support.


Updated the old 2017 block diagram to reflect some of the changes introduced since then:

Block diagram 2018


  • Maple bus integration to read controller data

    Uses code by Marcus Comstedt (zeldin) from his MapleMojo project.
    This enables leeching controller data directly from the maple bus to control the OSD.

  • Added I2C slave implementation by Steve Fielding.

    Enables ESP to write to OSD RAM and get the controller data aquired from the maple bus to control OSD.


Mainboard 1.2e Link

Finally finalized hardware πŸŽ‰ All interference issues are solved, we're now entering beta phase!

Rolling releases

The master branch will now contain the latest stable release. Development version moved to develop.

Firmware updates are easily downloaded and installed via WiFi FirmwareManager.

Currently the following features are planned:

  • OSD
  • Output resolution switchable via OSD
  • Dreamcast video mode control (pin6)
  • 480p trick
  • 240p x2 and x3 modes
  • Disc based firmware updates


Mainboard 1.2d Link

Close to final FPGA mainboard by citrus3000psi.

Some features are currently unused (e.g. pads for maple bus integration).
They will allow some cool firmware extensions in the future (e.g. OSD)

Flat flex 1.2a

citrus3000psi designed a flat flex cable, which connects the Mainboard to the audio and video dacs.

Cylcone 10 LP (10CL025):

We switched to a bigger FPGA to support more video output modes, 10CL016 and EP4CE6 are also supported.

Output Resolution Notes 10CL025 10CL016 EP4CE6
VGA 640x480 Correct pixel/aspect ratio! βœ… βœ… βœ…
480p 720x480 Original output: usually only 640px of the available 720px are used.
Incorrect pixel/aspect ratio!
βœ… βœ… βœ…
960p 1280x960 x2 VGA βœ… βœ… ❌
1080p 1280x960 x2 VGA, framed in 1920x1080 βœ… ❌ ❌
Other firmware features
  • basic 480i line doubling

  • 240p support

  • Scanlines.
    Available by rebuilding the firmware and defining SCANLINES_EVEN/SCANLINES_ODD, SCANLINES_THICK/SCANLINES_THIN and SCANLINES_INTENSITY in Macros.qsf

  • Upcoming: OSD. Maple bus connection is already on the 1.2d mainboard. Will be used in a later firmware.


Restructured source code and updated pin assignments for citrus3000psi's DCHDMI board 1.1:

Moved older versions (without ADV7315 and/or ICS664-3) to v0.1

Restructured "firmware" site:

Details on the available versions can be found here.


Added ESP-12 based firmware management tool, for upgrading firmware via WiFi.

  • A demo of the FirmwareManager could be found here: Demo


Many thanks to citrus3000psi for his work on a QSB (quick soldering board). Check out the thread on the shmups forum: DreamcastHDMI github by chriz2600


New (auto)-build system using docker. Build system using docker


Added schematics and some information on Cyclone IV + ADV7513 + ICS664-3 build: CycloneIV-ADV7513-ICS664


A new version of the Cyclone IV + ADV7513 version is available here.

Features in this version:

  • Recoding of 480p (720x480) to VGA (640x480).

    HDTVs will display correct 1:1 instead of 8:9 pixel ratio for 4:3 aspect ratio. To achieve the required clock multiplication/division an ICS664-03 digitial video clock source is used. 320 pixel are buffered in RAM, so the delay from this will be 11.9us (microseconds, I will call this zero delay :) )

    This diagram shows the setup:

Block diagram

  • Support for 480i and 240p by line doubling with recoding to 480p as above.

  • Support for 480p/480i switching detection

Not in this version:

  • PAL 576i support


Cheaper FPGA

Instead of a DE0 Nano SOC you can also use a Waveshare CoreEP4CE6 Development Board. You can get it for 20-25$ via Aliexpress. The project folder for this is FPGA-CycloneIV. Because the board does not expose any clock pins, you have to desolder the oscillator and attach the dreamcast clock directly to the board.



I also created a board for experimenting with the Analog Devices ADV7513 HDMI Transmitter which can be found here. The verilog code for this can be found here.

Direct HDMI output from FPGA

If you want to go the "cheap" DIY route, i've made a PCB for the LVDS2TMDS part.

Dreamcast video output

Some details about the Dreamcast scaling issue on modern HDTVs: Video details link

  1. Create cheaper solution based on simple FPGA development board.
  2. Use FPGA to enable 480p mode. Currently I have to plug in a VGA cable ;)
  3. Design FPGA board with Cyclone IV FPGA and ADV7513 transmitter. I'm planning to include some RAM to be able to implement 480i as well as basic upscaling later. Edit: I don't need external RAM for line doubling.
  4. Design flat flex circuit to connect Dreamcast video DAC and audio DAC to FPGA board.
  5. Detailed HOWTOs.

Original documentation