Bob

MiSTerAddons 24-Bit I/O Board

Sorg, creator of the MiSTer project, recently released an updated I/O board design, that outputs true 24-bit analog video.  This will allow cores like the PlayStation and Nintendo 64 to output at their full potential.  As Sorg doesn’t sell any hardware, we have to rely on the community to build these designs and the first store with a release is MiSTerAddons.com;  His version uses a Sega Saturn MiniDIN for video output, just like the Retro Castle cases, which makes it really easy to get composite and S-Video output;  Simply set the MiSTer.ini file and use the matching cable with no DIP-switching required.  I put it through it’s paces and it performed really well.  More info below the links, but basically, if you were looking to purchase a 24-bit compatible analog I/O board, this is currently the one to buy:

Support Sorg:  https://www.patreon.com/FPGAMiSTer
Purchase Here:  https://misteraddons.com/products/mister-fpga-io-analog-pro
Saturn RGB Cables:  https://www.retrorgb.com/saturn.html

First, this is specifically for people who need analog video output and want 24-bit color support for the few cores that support it.  If you’re only using HDMI-out, respectfully, none of this matters.  Also, you can use Direct Video to accomplish the same thing on any existing MiSTer (including using just the DE-10), however not all DAC’s work well and you lose dual-output capabilities.  That said, if you have an existing I/O board that’s already working well with your analogue setup, you can continue to use that confidently – This board is best for people buying new kits, or for purists who want simultaneous HDMI + analog output with the best quality signal.

Next, my testing was essentially just repeating Kuro’s work.  His is even more in-depth and I recommend checking out his short social media post, as well as the full data he’s compiled for more info:  https://x.com/kurohouou/status/1799554153418461672

Lastly, I wasn’t able to get pure csync out of the luma or cvbs pins on the Sega Saturn.  THIS IS NOT A PROBLEM – I’m simply letting people with Extron Crosspoints know that you can’t use an RGC Luma BNC cable, or one of those cheap BNC cables that uses composite video as sync.  I can’t think of any other scenario in which this would be an issue, but that just means Crosspoint users with have to either make a custom cable, or use csync SCART cables with SCART to BNC adapters.  Hopefully a dsub version will also be available, so Crosspoint owners can just use cheap “VGA to BNC” cables.  Dsub (VGA-style) might also be easier for people wanting to output YPbPr component video, as they can just get a cheap “VGA to RCA” cable.

I did a livestream proving these tests, however the first half was spent calibrating my oscilloscope and the next part was mostly verifying the scope and using the original MiSTerAddons I/O board as a baseline.  This was a very long and slow-paced technical stream and the focus was absolutely on getting accurate readings.  The entire two hours can be summarized as: “Bob and Voultar bent over backwards ensuring the test setup was correct and confirmed the RGBs voltage levels to be excellent”.  The voltages could be a bit lower to compensate for any tolerance differences…but I’m absolutely splitting hairs and any further tweaking could NOT be visible on-screen.  While my job requires me to be precise, for all intents and purposes, consider the RGBs video levels spot-on – Proof in the scope plots below.  You’re welcome to still watch the stream, but I’m always respectful of people’s time and want to let you know in advance this was a nerdy deep-dive:

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