Wanted: USB-C to eDP board to interface the Display Kit

We want to help foster development of ways to re-use every module in the Framework Laptop. There is already a healthy ecosystem around the Mainboard and an interesting board to interface the Input Kit. Next on the list in terms of value would be the Display Kit.

It is somewhat possible to interface the Display Kit using one of these https://www.aliexpress.us/item/2251832860412151.html?spm=a2g0o.order_list.0.0.788f18028HAngg&gatewayAdapt=deu2usa4itemAdapt&_randl_shipto=US as discussed in HDMI controller board for display panel - #18 by nrp. However, a much better board would be something very similar, but:

  1. Directly using the IPEX 20879-040E connector so that a replacement cable isn’t needed.
  2. Using a USB-C receptacle instead of a USB-C plug to make it less fragile.
  3. Using open source firmware to make it easier to add and adjust functionality.

If anyone out there is interested in developing something like this, we’d be happy to provide funding for components and board fabrication along with extra Display Kits for testing as well as provide technical feedback.

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Great news, this is exactly what I’m specifically working on right now!

This is specifically a board for Mainboard replacement purposes, that fits to the top left of the fan. It uses a cheaper USB connector, as there’s no TB4 requirement here. The board is for using the Framework laptop chassis as a KVM, following up on this idea.

6-layer PCBs, Aisler sponsors the first revision. All I have left to do for this one is to get to a place with a lasercutter (ETA 4 days) and check the replacement USB-C port mechanics (specifically, X offset as pictured, so that USB-C card plugs in well), then I’ll layout diffpairs, and will have this board in a month’s time. I’ll be selling it on my store, as I do with other components.

Uses my Altmode Friend RP2040+FUSB302 module for negotiating DP altmode, and indeed, it will be fully open firmware. That said, zero percent of the firmware is currently written, as the “PCB shipping” part for the AF got delayed for an entire month now through a string of unfortunate events. The PCBs are currently waiting for me at home while I’m on vacation, having arrived a few days after I left - for the second time now =D

Will keep you updated on the progress. Did post this on Discord, but otherwise, I usually post about projects when they’re ready-to-go! Oh oh, just remembered, I oughta add a buck regulator to this one, for backlight voltage generation - TODO.

Currently outdated files+readme but to-be-updated repo here.

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Also, something I want to say! If you want to develop such a card still, you absolutely should. My projects do take a two-three months to materialize! And, for instance, this board would prolly indeed be better with a different connector, and a CCG3 chip or whichever it is that Framework cards use to negotiate DisplayPort. Here, since it’s MB reuse, I have to use a different connector, and I have to also make use of this board as my Altmode Friend testing field. If you want to develop a thing like this but with a different spin, do join the FrmW Discord, I’d gladly help you along your route!

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Wow, this is amazing. On the buck regulator, technically it should be ok without. The panel can accept 5V to 21V on the backlight rail (though it may not work if USB voltage drops to 4.5V). The panel 3.3V rail can pull ~200mA though, so it probably makes sense to use a buck regulator there and run the RP2040 on it too.

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oh that’s seriously good news! I should check the panel datasheet once more sometime, seems like I’ve missed things =D WRT buck - yeah, the next board will have a buck; that’s why there’s a 30-pin FPC connector, there’ll be a switching reg on the bottom board. Until that board’s done, the poor 1117 pictured goes up to 1A and ought to be enough for prototyping this specific board in the meantime; that said, I should prolly rotate it 180 degrees, because it’ll need heatsinking than that =D (and, add caps, of course)

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Would it be a potentially good idea to build a dedicated board and build it into a portable monitor and integrate a VESA-type mount? More than happy to do so with a CCG3 as I have a fair amount of experience with them.

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Yep, that would certainly be interesting. That was the direction I was implying when starting the thread. It could also potentially be interesting to design it in a way that it can mount directly into the Top Cover, potentially re-using the hinge or antenna screw bosses.

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A combination of both this and the board for the input kit would make a great lapdock!

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yep, that’s the idea - so that after this one, I need a single board for power management + joining this and the input dock boards together, and the device ought to be ready from there! PM’s an interesting thing to have to figure out, given that there’s an internal battery but I haven’t yet got connectors and don’t yet know how to charge it, but, oughta be doable.

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This is seriously cool! I’ve been using my NexDock Touch as a portable KVM, but this would be far more useful!

Why is there no Thunderbolt 4 requirement? Surely it would make sense to provide Thunderbolt 4 hub service with the unit?

Sadly, it would not make sense, as Thunderbolt is unreachable for hobbyist use, and this would grow from “something that the community could work on” to “something that a sizeable company could pull off if they had enough resources”. Intel has a track record of screwing small companies over, too; while TB would be cool, it’s not something Intel will cooperate with you on, and you’ll need cooperation aplenty. Plus, as Intel’s Thunderbolt chips are quite expensive and have quite high requirements, it’d make the boards prohibitively expensive to get ICs for and manufacture, as opposed to the “DP passthrough+USB 2.0 peripherals” route.

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Thanks for the reply. At first I thought, oh yeah of course. But then I thought the original laptop was not the product of a sizeable company :slight_smile: and that the ports provided Thunderbolt connectivity, but were not branded as such. And also if you intend to use the display then DP over USB will surely need to be accomodated? So I am thinking the hobbyist will have to swallow some cost implications of that. Maybe it could be accomodated by taking an existing USB C hub, and shucking it to allow it to be installed within the Frame.work shell and coupled to the board that allows the connection to the display/keys/track pad. Any way thanks again for your efforts, and all the best going forward.

Short answer - Framework is a company that leveraged their relationships with larger companies and investments to make this possible, and those are not something the community can pull off, again. This isn’t even about the branding, it’s about all the “things you need for using Thunderbolt on your boards” that I’ve listed, which are risk factors, and require resources that the community doesn’t and can’t have.

DP over USB

DisplayLink? It’s somewhat more achievable, but the returns on time investment are going to be diminishing; in part because of the high resolution required.

the hobbyist will have to swallow some cost implications of that.

that’s not the way to go; as it stands, this makes the project out of reach for people like Josh and me. It’s already going to be somewhat expensive for me to make. if you increase the entry level like that with not enough justification, yeah, it’s going to be way less likely to materialize.

taking an existing USB C hub

it’s somewhat viable, but quite non-repeatable, time required to embed it in a decent way will be large, and it’ll have the cost jump up tremendously. Thunderbolt hubs do command a price increase, and you’ll have to use TB for this if you want anything extra aside from DisplayPort (as the screen is 4-lane).