The show stopper for this specific hub part, is you need to support muxing of the SS signals to both sides of the type C port, otherwise you will only be able to plug in your device/cable in one direction, or add an external SS mux, which will probably not fit.
Microchip offers other parts that offer the hub+multiple type-C downstream ports. They seem to double up on the SS transceivers so two sets are used for each port An example is the 5826C.
You can see them parametric-search | Microchip Technology as the parts ending in “C”.
The other consideration for this is power and type-c signalling. You will need to split the input port power (max 15W) to the two downstream ports.
You could do this without PD protocol by using type C resistors on the two dfp ports by setting the RP resistor value for 1.5A or 900mA.
You should also consider the power draw of the hub itself, which is about 1W. So if you set both downstream ports to 1.5A and someone plugged in two high power devices, you will trip the over current sensor in the laptop. You could limit one of the ports to 900mA, or assume that people will not plug in two devices that both are high power.
Since you are looking at microchip parts, take a look at AN1953 section 3. For how type c signalling works without needing PD controllers.
Personally, I think this is a great idea even without passing through DP Alt Mode or power input. Other expansion cards can make use of that functionality, while this is being used for more mundane tasks like connecting to thumb drives/phones.
Check the official spec to see how big the plugs can be, and plan at least 1-2mm of additional space. Right now I’m worried that plugging in two cables won’t work as the plug’s moulding is quite a bit bigger than the connectors themselves.
Apart from that, as a USB only hub without alt modes, I can see this work. More functionality, as others have said, will be tricky.
Even subject to the limitations that have been discussed here on what types of I/O can be managed over a double-port expansion card, I’d cast a vote in favor of double-USB-C and double-USB-A cards. Particularly in combination with the idea elsewhere for double-height cards (What new Expansion Card types do you want to see released? - #72 by matthew3), it could be pleasing to have the two slots on the back end of the computer filled with USB-Cx2 and USB-Ax2 that would also give the keyboard a bit of an upward tilt that I’ve found somewhat more comfortable to type on, probably because of the years of typing on regular desktop keyboards that have the little feet extended. Would also relax some of the spatial constraints, I imagine.
Another vote in favor of more USB ports, however limited they may be. Increased height modules acting as feet giving better airflow also seems very good to me.
Another vote in favor of more USB ports, however limited they may be. Increased height modules acting as feet giving better airflow also seems very good to me.
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)
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.
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
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
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?
