@Daniel_Gilbert that would be awesome, especially if USB-C + USB-A could be achieved.
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Could make it data only or making dedicated Power and Data like how lighting Headphone and charging splits work.
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Maybe notches like these will help to keep good grip on card, without reducing inner space? (this is battery cover from ancient Motorola V.100 phone, seen this design on many covers)
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This seems amazing, I’m not really a tech guy by any means but I’d totally use this to save a slot and just use it for charging and simple usb functions and have a separate single usb-c expansion card to use for a usb-c hub. I’ll just have to wait and see though, but really this is exciting.
edit: so sorry got an error when pressing reply and naturally I just pressed it again lol.
Would be totally into the 2 USB-C Ports on 1 Expansion Card Solution 
For me, it wouldn’t necessarily be important to have DP Support on it, a dedicated HDMI or DP Port does that job just as well.
What would be important to me though, is a decent data transfer rate up/down on both the USB-C’s, so that it really stays usable and the doubling of ports makes sense.
Also Power Delivery on at least one of the 2 USB-C ports would be wonderful.
Maybe a solution like on a Thunderbolt 3 Docking Station could be achieved, where Power Delivery an some other functions (hdmi, usb, etc.) run through 1 usb-c spec thunderbolt port.
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I’d really like the 2 USB-C in 1 Expansion Card.
In my case, I wouldn’t need any PD kind of thing. Normal USB3 power would be enough. Not sure how much it is… 7.5W, is it?
I don’t need it to provide 30W. If I ever do, I’d just use the normal USB-C
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Problem is, how big? Unless there is a standard size for oversized ports it’ll be tough to not have your laptop slanted, you would need a certain height on one size and the exact same height on the other
My suggestion is to try to stick to 1x, 1.5x and 2x height. I suspect a 2x height would even be enough for a 4-port USB-C oriented vertically
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Re: height, this isn’t a formal ergonomics analysis but a quick balancing of two extra expansion cards underneath gave a pretty good feel typing on the raised keyboard.
There will be a bit of an issue with the points of contact since the card itself probably should not have an angled geometry (which would force it to work on only one side or the other), but if it remains rectangular-prism-shaped then only the leading edge will touch the ground - maybe a rounded soft rubber lining along the bottom edges to spread the weight a bit?
Not being an EE at all myself, thought it might be useful to share a link to a hub that looks like it would be a double USB-C candidate if only it could be lopped in half (or a third perhaps): https://www.amazon.com/Purgo-Adapter-2018-2016-Delivery-Thunderbolt/dp/B07K5ZR6HS/ . Maybe somebody is knowledgeable enough to infer what kind of board is being used in the Purgo offerings and if it is adaptable to Framework expansion cards?
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I think this is worth it for several reasons as I have several devices that use USB-C that don’t even require USB 3.0 performance.
- Keyboard
- Mouse
- Microphone
So, in short, take my money! I’ll be happy to have dual USB-C with limited performance.
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So, my notion for the dual-height cards was that they could be pentagon-shaped; that way they present a flat surface (albeit ~half the card’s width) regardless of which side it’s on. (Not regular pentagons, obviously; rather a rectangle with one side replaced by a very short isosceles triangle.)
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Well, I just got my Framework laptop, so I might start working on this project soon! It sounds like there’s a decent amount of interest in a simple 2x USB-C module, even without power input or DisplayPort support.
I’m not sure why I assumed that the laptop would have a dedicated USB-C port just for charging (aside from the 4 modular ones), but that’s not the case. Oh well…
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@Kieran_Levin, thanks for your useful explanations and suggestions!
USB signaling is new to me, so thanks for bearing with me.
At the moment I’m considering using the following:
- Texas Instruments TUSB8020B for the main hub controller
- Diodes Incorporated PI3USB302-A to mux the SS signals
- Other components (power switches, regulators) using TIDU428 as a guide (this is the Texas Instruments TIDA-00287 2-Port USB 3.0 Hub Reference Design)
This would be a simple 2-port hub without PD. I think setting both ports to 1.5A would be the most flexible, as long as tripping the current sensor wouldn’t potentially cause any damage to the laptop. I don’t really like the idea of the two ports having different power specifications. Does this make sense, or would it be better to have them both be limited to 900mA?
Do you think this configuration is feasible, or am I still missing an important concept?
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I think it’s better 1.5A because external hard drives run at 5V~1A, according to the sticker.
However, the ones I own seem to run just fine from USB 3.0 (USB-A. No Power Delivery). They run on a standard USB-A→USB-B-3.0-micro cable.
I also have 2.5’’ drives but they run from an external power source so they would work regardless.
Additionally, I’ve connected a hub to my PC for testing and I can run up to 2 hard drives (although they cannot start at the same time. One of them “clicks” for the first second while the first one starts turning. They don’t “click” while in use). If I use 3 drives, they “click” if all 3 are turning and two are being written to. If one is being written to, sometimes it clicks and recovers in the same second.
Note: The “click” is actually a sound from a rudimentary monotone speaker inside the drive.
Alternatively, I can use all 4 ports and connect phones to it for charging and they all charge slowly but power goes to all of them (in the only one I see that info:) equivalent to normal USB 2.0 power.
How much power does a hub with those components consume?
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@Daniel_Gilbert it looks workable from a part selection, however have you checked if you have enough space for all the parts and passives?
Tripping the current sensor will not damage the laptop.
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Thanks @Kieran_Levin!
I’m looking into the layout, but I think it could work, considering a 4-layer board that would have components on both top and bottom.
One issue: I’m suspecting this setup would also require some USB Type-C port controllers, ie. something like a UTC2000 or TPS25810 for each port, in order to detect the cable orientations and tell the mux chip what to do. Is this right?
The biggest issue is that these types of controller chips appear to be almost universally out of stock everywhere. Any suggestions?
I’m starting to see the appeal of something like your initial suggestion of the USB5826C, since even though it’s expensive and over-featured (6 ports), it does all the muxing internally. However, it looks like it also needs an external Type-C controller (like the UTC2000) according to its datasheet, unless I’m reading it incorrectly…
Oh yeah, it’s also out of stock everywhere too…
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Parts are out of stock all over the place. My company currently has an entire team of people doing almost nothing other than supply continuity so we can keep making stuff. The idea sounds promising, though. Keep it up!
@Daniel_Gilbert a lot of designs would want to use a PD controller. however since you are just doing usb 3.2 you could get away with something a bit simpler if you do not implement VCONN or PD (which should not be necessary for just usb3.2 + 5V output).
You can add the appropriate Rp pullup to each CC pin, and detect when it drops below the threshold voltage to determine the cable orientation by sensing Rd.
You might do this with a small mcu with 4 adc channels.
I agree using an all integrated type-c hub would be an easier solution
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Laypersons question; It appears from the CAD modeling like there is enough space fit 2 PCB’s in the module. One board to control each individual USB-C port. What engineering restrictions prevent that?