Gamecube Digital Audio Interface board - Using DIT4096

[psyko_chewbacca]

It's been a long time since I've been here.

I took the time to design a breakout board for Digital Audio out on my Gamecube.

It's the best A/V improvment I could do considering I couldn't get ahold of a B012355 chip to integrate YPbPr out on my Gamecube. If I could have the datasheet of this chip I could probably writing a clone in VHDL on a powerful CPLD but too bad...

Anyway, I didn't want to start searching for a TC9231N and pay an outrageous price for an obsolete part so I went ahead and designed a breakout board to use the DIT4096 transceiver.

The PCBs are being manufactured as we speak so I don't have anything to test. I will provide feedback of my success or not in a few weeks.

The whole description of the project is located over at AssemblerGames forums:
http://www.assemblergames.com/forums/sh ... face-board

I hope this sparks an interested with some of you as I really wanted to provide an alternate solution for all the people who would like Digital Audio.

P.S.: If you ever have a "spare" B012355 chip I would gladly buy it from you. I have all the material necessary at home to try and reverse-engineer this baby. It would be great to try and find a replacement or maybe code a clone of it! Anyway I'm just asking like that. If I don't ask I have no chance of getting one!

[megalomaniac]

could save some space by dropping the power converter...
dont really need 12v input when you can just take 5v from the GC itself....
every once in a while you can find a TC9231N on ebay for about 3$ to 10$

...you even missed a sale, there was some MX chips also....

[psyko_chewbacca]

Thanks for the info, I was under the impression that there was no 5V source powerful enough to spare a few mA for this circuit, hence the 7805 regulator on the original design of this mod.

Anyway I guess it'll offer a greater flexibility.

I've seen the post about the sale on eBay of the MX chips.

I also saw your sale of your board.Congrats! It looks really neat and efficient. Will you have others to sell? I would gladly take one to start sniffing the data on the lines.

[megalomaniac]

the 7805 is only required because the digital output only has 12v and 3v...
if you plan to connect audio externally and tap signals from the component cable, then yes you need a 5v regulator....
if you plan to tap the audio signals internally, then just 5v from the GC PSU will be just fine...


the data lines on MX have been posted....ill try to find the sheet and repost
it is not such a simple task to write a program for a CPLD / FPGA.....
even without a chip you can sniff the data lines on the input to see whats going on....


i should have a few official MX boards soon (whenever they arrive)....

[psyko_chewbacca]

Well trace files for B012355 could be great but what I'd like a physical unit for is to write a simple GC program that would output different image patterns of simple RGB colors (liek 0xFF0000, 0x00FF00, 0x0000FF, 0xFFFFFF, 0x00000 and so on) just to check the digital output to the MX when I exactly know what is the analog equivalent of this particular input.

That way I could be certain of the data transmission scheme between the GC and the MX chip.

As for the coding itself I feel pretty confident. It took me less than 60 hours to code a project that involved a 800x600 72Hz VGA codec module that would take inputs from a PCM audio stereo stream passing through a 35th order digital butterworth filter. The wave forms (stereo = 2 waveforms) where to be presented on the VGA screen on two separate graphical representations. All this on a spartan 6.

I've done multiple projects on FPGAs and CPLDs but that one is the most representative to my goal here as it involves digital to analog conversion specifically for a video feed.

[dacide]

Hey Psycho,
I think digital video output is compliant with ITU 656 and here you have more information:
http://gamesx.com/wiki/doku.php?id=av:nintendodigitalav

Any chance that you project evolves to HDMI(digital video + digital audio) ?
Spartan 6 suppports LVDS outputs

[megalomaniac]

i dont remember where i found this
you might want to double check the patent number to make sure its correct...

[Cybertronic]

So any chance of figuring out a Digital to Digital connection? I can't understand why Nintendo put a digital out on their console to then shamelessly downgrade it to analog with an ASIC DAC. It's just such a waste of a good signal. I guess HDMI or DVI-D wasn't mainstream and didn't want to pay royalties? We can only hope there isn't some kind of weird encryption or container for the data stream.

[emu_kidid]

I believe they were planning on using the component port for their failed 3D TV's which Luigis Mansion was going to utilize. It might put into perspective what they were trying to achieve at the time but other factors limited their choice.