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melonHD

YveltalGriffin

First Wii U Trimmer
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melonHD is a video converter module I designed based around Lontium Semiconductor's LT6711A. It accepts an HDMI 2.0 input signal (up to 2160p) and outputs USB-C DisplayPort 1.2 Alt Mode.



melonHD's purpose is to enable easy USB-C video output in any portable that has HDMI output. Here's a stock, unmodified Wii, with a Wii2HDMI connected to the melonHD carrier board, connected to a Dell portable USB-C monitor.

1737698771818.png


The castellated module is easy to solder to a carrier board, so anyone can easily integrate it into their portables. I've released a carrier board reference design that follows best practices.



Feature List
  • Super compact 17 x 13mm 0.8mm-thick castellated PCB
  • 480p - 2160p HDMI 2.0 input and USB-C DP 1.2 Alt Mode output
  • Pin-strappable VBUS PDO selection: 5V/3A, 9V/3A, 12V/3A, or 15V/3A
  • Powered directly from 5V - 15V VBUS with onboard voltage regulators
  • HPD (hotplug detect) output pin


melonHD is powered by the downstream-facing port. This can be a little confusing if you're unfamiliar with the USB-C protocol. Basically, your USB-C monitor needs to be able to provide power to melonHD, while melonHD sends it video data. Most DP Alt Mode sinks support this mode of operation.

The reason melonHD works this way is so it can request power to charge your portable's batteries while your portable is docked. This is identical to how a Nintendo Switch works. Please see the diagram for a more detailed breakdown.

image (20).png


One key feature of melonHD is the customized LT6711A firmware, which allows the user to select what VBUS voltage the module requests from the downstream-facing port. Based on how you pinstrap the module, you can request 5V/3A, 9V/3A, 12V/3A, or 15V/3A. This lets you charge your portable's batteries quickly without sacrificing DP Alt Mode output. Of course, whether you can get higher voltages depends on the capabilities of the downstream port you connect to.

1737699488019.png


Also, the melonHD module has an "HPD" output pin. This pin is low when melonHD negotiates for a power-only contract, such as when you plug a charger into the USB-C port. But when you plug in a USB-C monitor, melonHD will negotiate a DP Alt Mode contract and the HPD pin will go high. This is useful for enabling GCVideo DVI only when a USB-C monitor is connected, and not when a charger is connected. You could also use it to turn off your portable's screen when an external display is connected, just like a Nintendo Switch.

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How Do I Get It?!

Unfortunately, the melonHD module itself is not open source and never will be, due to legal limitations. The GitHub repository contains documentation, usage guidelines (coming soon), and an open source carrier board reference design.

In the near future, I will manufacture a small run of melonHD modules and sell them to the community. I'll bump this thread when that happens.
 
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Super awesome work congratulations!
Do you have an idea of the price roughly? >$100?
With the Lontium chip is it possible to pass along controller data? I was wondering what would be the solution for a dock that would have both video out and controller ports
 
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That sounds super awesome!
I'll be waiting for when you can buy it. And like what supertazon said, it would be amazing if you could also make it pass controller data and use it with a dock.
 

cy

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Congrats on getting this working! Does this confirm the potential for a Nintendo Switch style dock for a Wii portable? One that charges the console AND feeds video through? Also, do you think you could have PCBWay or JLCPCB assemble these boards for you? It'd be great to avoid the challenging assembly process yourself in the future if possible.
 

YveltalGriffin

First Wii U Trimmer
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Thanks, everybody!

Do you have an idea of the price roughly? >$100?
The modules will cost ~21USD each to produce. I will probably sell them for 40-50USD each to recoup some development costs, since the project has cost me around $1000.

And like what supertazon said, it would be amazing if you could also make it pass controller data and use it with a dock.
Doing this without flagrant violations of the USB spec is tricky.

One option would be reducing melonHD's DP lane count from 4 to 2, which would free up 4 SuperSpeed pins for GCC data. However, you'd need an external mux to handle flipping the SS lanes depending on cable orientation. It would be very janky and kind of defeats the purpose of the LT6711A, which handles muxing internally.

Another approach is some sort of GCC to USB transceiver. You would need a Pi Pico inside the dock to collect 4-player SI data and turn it into USB packets. This would be piped over the USB 2.0 lines, and another RP2040 inside the portable would convert it back to 4 SI outputs.

The best option is to simply install 4 WavePhoenixes inside your portable. :D

Congrats on getting this working! Does this confirm the potential for a Nintendo Switch style dock for a Wii portable? One that charges the console AND feeds video through? Also, do you think you could have PCBWay or JLCPCB assemble these boards for you? It'd be great to avoid the challenging assembly process yourself in the future if possible.
Yep, a Switch-style dock is the exact usecase melonHD targets! It should work perfectly with off the shelf docks like the Steam Deck's and the AYANEO Multi Docking Station.

Since the board is too high-spec for JLC to manufacture, I'll be using PCBWay's PCBA service.
 

Pablo

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Might be tempted to be stupid and buy like 4 or something lol
 
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