Dual USB-A Card

Ohay,

I wanted to talk about a little tinkering project I am currently working on, and want to share the details and lessons so far so that others who want to replicate it can, or if someone has an idea, for them to share it.

As the title says, I am currently working on a dual USB A-card, since I almost always need two A-ports (one for a mouse, one for flash drives), of which one needs little bandwidth. So I bought this USB Hub, stripped it down to the pcb, connectors and cables, and am fiddling to squeeze them all into an expansion card that while a good bit thicker than a standard card, does not extend over the side pf the laptop, so that the ports can be spaced as much as possible to allow for slim connectors to fit next to each other.

This is what the card looks like right now, between the ports are 2.76mm, which would allow for my mouse and my external drive to fit next to each other (barely, but they do)

A sacrificial hub and a more open print to get an idea how it could fit later, and this is what my sanity check resulted in:


The 3.0 connector still worked, albeit at 2.0 speeds (I mangled the wires on the connector end, and could not fix them, and was not able to solder the 2.0 wires onto the pcb), and the ports fit as calculated. A second hub is still in the trimming down phase, and if I have success, I’ll post it here along with the functional 3d files.

18 Likes

Great idea. Would love to see something like this come to fruition. Similarly I sacrifice a USB-A for a Yubikey and don’t need a high bandwidth port.

Same here, would love to have 1 module for yubikey + mouse

If you’re having difficulty getting both ports to fit, maybe they could be slightly angled instead of parallel with the laptop chassis.

If it is wires and not pcb, turn diagonally so that thick usbs will fit as well as decrease the expansion card thickness.

Ohay,

wanted to give a short update as I have been working on that some more.

Good news is, the chassis is working, and the ports can fit inside.

The spacing is also sufficient to allow for the mouse and the 3.0 connector to be attached simultaneously.

This is sadly where the good news end. I am not good at soldering, and while applying the solder some wires came loose from the pcb, which is a problem I do not have the hands for to fix. This means that unless I prepare a third hub, or find someone good enough at soldering to fix this, I cannot proceed. If someone wishes to try for themselves, here is the .stl of the chassis, I printed it with PLA without upscaling:
ExpansionCard USB v2.STL (26.3 KB)

6 Likes

Super interesting! Was the two different receptacle types a deliberate choice, or driven by parts you had on hand?

4 Likes

Not to answer for him but from my observations of the hub he used, it looks like it provides only one USB 3.0 port and 2 USB 2.0. So this was just because there was no other choice. Assuming by receptacle you referring to the USB A ports.

1 Like

Oh. I think while this technically works, it’s probably not USB spec compliant. It’s a USB 2.0 hub, with the USB 3.0 signals passed directly through to the USB 3.0 receptacle.

3 Likes

I guess I am only interested if the 3.0 port would do PD.

PD requires a usb-c port. The CC pin used for PD signaling isn’t present on usb-a ports, even 3.0 ones.

3 Likes

Thanks! That is very good information!

1 Like

Pretty sure that’s allowed

I just double checked the USB 3.2 Specification. There is a bunch of assorted little stuff that doesn’t meet the spec if you don’t have a matched topology between USB 3.2 and USB 2.0. Most of it is covered in Chapter 11 of the spec. Like I noted before though, in practice, it’s probably going to work anyway.

5 Likes

Correct, the hub itself does work perfectly fine, each port managed their rated speed and did not appear to interfere with the other ones.

There is a lot of stuff that isn’t spec compliant but works perfectly (using 2 usb2 ports instead of a mux for usb-c or splitting a usb3 port into a usb3 only and usb2 port and using both at the same time for example). Since the usb3 and usb3 parts are entirely separate anyway it would be really weird if it didn’t work in the first place.

1 Like

Neat project! I might look into making one of my own when I get my FW16 in hopefully no more than about 3 months.

Might be interesting trying to fab a USB hub from scratch to fit in these space constraints. A quick search didn’t turn up any openhardware usb hub implementations to crib from, however.

I might try this at some point. I’m pretty decent at soldering and while I do not have a Framework Laptop, (I only have a desktop PC at the moment) I would love to try and make this work.

Considering that this is the case, why not get rid of the hub altogether and just have a dual port card with one USB 3.0 and one USB 2.0?