Worklog OpeN64 - a work in progress open source N64 motherboard recreation

[cy]

Alrighty, I've kept this under wraps for long enough. For the past couple of months, I've been working on and off (mostly off) on a project I've been calling "OpeN64". This project aims to recreate ALL functionality of the original Nintendo 64 motherboard. This essentially means making a motherboard that will behave EXACTLY like the original N64 motherboard and have room for ALL of it's original components so you can relocate everything from an original board onto it.

As of right now, I'm only aiming to recreate an 03 revision motherboard since that board supports the RAM swap. To do so, I've been utilizing the Inside Gadgets N64 motherboard scan that was posted to the N64 compendium a while back. In order to achieve all of this, I want to move one step at a time and recreate a trimmed N64 motherboard first so I'll be able to populate that and hopefully improve my time trying to troubleshoot this project in the event that it doesn't work. Only after I have successfully recreated and stress tested a trimmed N64 motherboard will I move on to adding the remaining voltage regulators, and other critical components a normal unmodified N64 has.

No, this isn't an April fools joke. I'm genuinely serious about this project! To prove that, here are a few screenshots of the work I've done in CAD:

The schematic is unfinished right now. Really, I've been trying to start by making symbols for the major components, making all the connections in the schematic, and then making those same connections in KiCAD's PCB Editor. This may not be the best practice, but it makes the tedium of this project a lot more tolerable.

I wasn't able to get all the components on screen for this screenshot, but I think you get the idea.

@Y2K Was suggesting I use a better naming schematic that labels the function of each trace. I'm willing to do that, but documentation on each line's functionality is limited, and I'm not an electrical engineer. With that said, Y2K gave me a few diagrams and a solid path forward to better documenting the RCP lines myself, so stay tuned!

Here's a shot of it from the 3d preview for good measure.

A lot of these components in the PCB editor don't even have schematic data for them yet. I kind of just went crazy making footprints one day and today I decided to rearrange them just to get an idea of what progress for this project was looking like. I'd say all in all, it's coming along really well! At least the front is anyway! I haven't started making ANY connections for any components that don't yet have a schematic. Really, the extra footprint placements are just a mock up so I can get a better idea of how my progress is coming along.

Right now what I want from the community is feedback or suggestions on how I can make this project better. Remember that as of right now, my main focus is NOT to recreate the ENTIRE motherboard for historical purposes or to try and make an 1:1 copy of it aesthetically and visually. My goal with this project it to copy it's functionality electronically meaning my goal for now is just to make it function. Once I have a stable and functional motherboard that electronically recreates the N64's functionality to the best of my ability, we can look into possibly making it look the same aesthetically (I.E. 100% identical trace routing, silk screen, etc). I'm not certain that I'm willing to go that far with this project however. I think that recreating everything the best I can so that every component can be relocated from an original N64 board and made functional is what matters, at least for now.

I'd like to thank @YveltalGriffin @Y2K @cheese and @thedrew for giving me help and feedback on this project already. Of course I'm not anywhere near finished, but you guys have given me an outstanding starting point for this!

 

[Stitches]

Love seeing these recreation projects! Great way to salvage damaged and corroded systems and make some tidy functional units out of them

 

[cy]

Love seeing these recreation projects! Great way to salvage damaged and corroded systems and make some tidy functional units out of them

Thank you! I won't lie though, the primary intention with this project is definitely an N64 AIO. A fully open sourced N64 motherboard isn't going to be much extra work after I get a simulated trim working though, so I figured I may as well go all the way with it. 75% of the work will already be done anyways.

 

[cy]

It's been a month and a half and I've done almost nothing on this project. I was waiting on someone to do a Rev 3 motherboard scan for me, but after waiting for over a month and a half, that still hasn't happened. I'm not mad or trying to call anyone out or anything, it's been a weird and complicated mess though, and I'm hoping we end up with proper scans eventually. If not, I'll just get a decent quality scanner and take some scans of my own.

All that aside, I've gone ahead and renamed a bunch of the lines I had in my schematic to be more in line with what they actually do:

RCP:

CPU:

RAM:

I've added a few additional components to the schematic since last posting about this too. Here's what it's looking like now:

I've noticed that I seem to be running out of space. I'm not certain if there's a way to fix that and re-scale the workspace, but I have run into a wall once or twice that limits how far I can go in a given direction. I'm assuming this can easily be fixed, and if it becomes more of a problem I'll probably research it and find whatever it is I'm running into.

On another note, I've found a temporary workaround for not having proper board scans:

This is from a UV light I purchases for curing solder mask that I bought for a different project. I found that it was strong enough to help me easily see where and how the traces are routed on the board. This is critical for knowing how all the capacitors and resistors are routed as there's a ton of silk screen that obstructs them in the more densely packed areas. This trick also works with my phone's flashlight, but I'll have to use something else if I want to be able to light one end of the board and take a picture of the opposite end.

The RCP, CPU, RAM, and Disk Drive expansion slot do block some of the light as do a few caps and other components. Luckily, the trim I messed up for my initial Cyxty Four build is working as a wonderful sacrifice! Before I even started this project I had removed the RAM, CPU, and RCP, I'll have nothing to lose by removing a few other components from it.

Here's how that looks with my new light trick:

I've got a few stray wires and various components on the board still, but this is going to help a lot with making a proper schematic and properly routing things on the board in the PCB editor.

This trick is by no means a replacement for a full proper board scan, but it should be enough to move me past the finish line for this project in the off chance that those 03 board scans never end up happening.

The final thing I'll share is some of the Compendium work I've done. There's still a lot to do before I make this into a proper compendium, and honestly, making a full on compendium was never one of my goals with this project (this project alone will kind of act as a compendium in a lot of ways). It certainly won't happen unless and until we have proper board scans of this layer and the copper layer of this mobo revision. Even then I'm not certain I'll want to make a complete one. This one I'm working on now is really just being used as a guide to help me verify my work.

I'd like to thank @Y2K for helping me enable a proper dark theme for the schematic and symbol editors, and @YveltalGriffin for further advice on making this project a reality. I'd also like to thank @thedrew for giving me advice and feedback on what I've done so far. I'm hoping to get more work done on this project soon.

 

[CrazyGadget]

It's been a month and a half and I've done almost nothing on this project. I was waiting on someone to do a Rev 3 motherboard scan for me, but after waiting for over a month and a half, that still hasn't happened. I'm not mad or trying to call anyone out or anything, it's been a weird and complicated mess though, and I'm hoping we end up with proper scans eventually. If not, I'll just get a decent quality scanner and take some scans of my own.

My fault OG