What is the smallest USB-C hub

I’d like to test the L5’s ability to interface with a host of different USB hardware like an external GPS dongle, an RTL-SDR dongle, an Arduino micro-controller, and even a female USB port for transferring photos from my digital camera. The hubs they sell with USB 2.0, 3.0, HDMI, and SD cards are quite big for my needs. Does anyone know of a “USB-C hub” that is more like a simple OTG cable. I know there is some hardware in the hub that makes the magic work, but I’m hoping there’s something smaller out there. Just a simple USB-C to USB 3.0 would be great.

One of the limits of Android phones running Linux is the lack of USB data connection. This is a huge benefit to the L5. The need for a big USB-C hub negates that a little. I want to use the L5 on the road, not necessarily docked or with a hub hanging out the bottom. Thanks!

1 Like

I guess you’ll need pass-through charging (probably), for example product like: https://www.aliexpress.com/item/1005004520684327.html (but I never used one, just typing here some direction that should work for your purpose).

On the other hand, if you don’t need charging of the phone then a simple and compact USB-C M to USB-A F adapter will do the job.

I guess the question is whether you will need to test for hours on end so that the Librem 5 might go flat while testing or, alternatively, whether you can pause testing for a few hours in order to switch the Librem 5 over to a charger.

A related answer would be … if you will not need charging of the phone provided that the device does not take so much power that the phone’s battery goes flat then you can buy a USB-C extension cable with auxiliary power input at the device end and use a USB-C to USB-A adapter with that.

1 Like

Maybe take a look at the Pinephone’s dock. Its one of the smaller ones I’ve ever seen.

I guess we come back to the idea that Librem 5 v2 could have a second USB-C and/or a micro-HDMI port in order to avoid the need for a USB-C hub.

Let us face it:

  1. Many users complain about the battery life of Librem 5.
  2. Many users struggle with the topic docking stations/hubs for Librem 5.
  3. Many users would like to use Librem 5 in convergence mode with external monitor.
  4. Many users would like to take advantage of the general-purpose PC nature of Librem 5 and this includes the use of USB connected peripherals.

Adding an additional USB-C would allow the users to use the first USB-C in order to charge/power the Librem 5 as often as possible while still having a second USB-C for attaching peripherals or an external display.
As the USB-C to HDMI converters are a potential source of problems, it would be great to have a micro-HDMI. Example could be Nokia e7 which had a mini-HDMI

Carrying around a docking station and the whole fuzz of finding a proper docking station is user unfriendly and unpleasant experience that could be avoided for a large portion of the users.

1 Like

It’s just occurred to me that Purism sells a hub. Does it not work?


1 Like

I expect it does. Purism started selling the hubs just recently, so people who got their Librem 5 earlier, had to look for solutions themselves and it is just frustrating how hard it is to find a hub that would both charge the Librem 5 with more than 0,5 A and deliver stable HDMI signal. Apparently, the manufacturers don’t care about Linux compatibility.

It is really great that Purism started offering this option and I would definitively recommend to those who still have not received their Librem 5 to add the hub as an accessory (under the assumption that it works fine).

1 Like

Right, I can certainly understand the frustration of trying to find a suitable dock or hub beforehand, I was just bringing to light that one should be easy to find now since Purism has one in their shop.

I’m using https://www.delock.de/produkt/64062/merkmale.html with my linux laptops. It connects usb keyboard and mouse, hdmi 4k display, and usb-c power (to supply power to the laptops via the hub). I expect this hub to work just fine with the librem 5.

64062 is not available anymore: https://www.delock.de/produkt/62854/merkmale.html seems to be an alternative.

1 Like

Thank you.
The 2 docks you are suggesting use the PS176 chip.
The one I use at the moment which works but is still not perfectly stable (there are interruptions in the video signal from time to time) uses the PS186 chip.
Both seem to be very similar, but yours (PS176) appears to be more tolerant to older formats. I could give it a try.

Btw. this is exactly what I am talking about regarding having a micro HDMI slot for the Librem 5. When I plug HDMI cable to my notebook it just works. No thoughts, no fuzz, no instability - it just works.
And when the Librem 5 has no HDMI port, one needs to make thoughts regarding the specs and quality of the external USB-C to HDMI converter because the experience shows that one cannot take for granted that using a random USB-C hub will just work.

PS176 - DisplayPort™ to HDMI™ 2.0 - Parade Technologies, Ltd.
PS186 - DisplayPort™ 1.4a to HDMI™ 2.0b Protocol Converter - Parade Technologies, Ltd.


Verdict: Insufficient.

I never got above 5V 0,5A negotiated with this USB-C Hub. With the power supply I usually use, I even get only 5V 0,1A

Here the test results:

Maybe someone could add the results to the wiki overview with USB-C hubs/Docking Stations.
Video Signal: works
Charging: insufficient

1 Like

To me it looks like that following thread provides important background on pass-through negotiation: https://forum.digikey.com/t/simple-way-to-use-usb-type-c-to-get-5v-at-up-to-3a-15w/7016/, explaining prerequisites related to establishing successful charging (from some hub) of there connected sink (PD 5V device).

The Delock 64062 works out of the box with the Librem 5. I’m typing this from my Librem 5.

The hub receives power from a Dell laptop charger, has a Thinkpad keyboard and Logitech mouse connected via usb-a, and a 43" 4k LG connected via hdmi.

I’ll post photos later this week.

1 Like

Please make a measurement of the POWER_SUPPLY_CURRENT_MAX.
In the screenshot I posted you will see the command I use to cat the value.

In general, almost all hubs work, but the 2 differences that separate the more suitable hubs from the less suitable hubs are:

  1. Negotiated Power Supply Current Max.
    2.000.000 and above is good.
    1.500.000 is kind of okay.
    1.000.000 is borderline acceptable (sometimes sufficient to charge the battery, sometimes insufficient and leads to discharging of the battery).
    Less than 1.000.000 is not sufficient for convergence without discharging the battery.

Please note that different power supplies with perform differently with the hub.

  1. Availability and stability of the video signal.

With a Dell laptop charger connected to the Delock hub:

purism@pureos:~$ cat /sys/class/power_supply/tps6598x-source-psy-0-003f/uevent

With the Librem 5 charger connected to the Delock hub the Librem 5 receives the same amount of power (initially I had written that with the Librem 5 charger the hub did not provide power, but now it appears that that setup does work).

The Librem 5 charger connected to the Librem 5 gives:

purism@pureos:~$ cat /sys/class/power_supply/tps6598x-source-psy-0-003f/uevent 

The Dell charger connected to the Librem 5 gives the exact same output as the Librem 5 charger.

The video signal through the hub over hdmi to the 4k display is perfectly stable. It seems hard on the Librem 5 though: mouse and keyboard input is not exactly snappy.

1 Like

1 Like

Awesome results. It is a pity that the new generation showed worse performance for me.

1 Like

Yes :frowning_face:

https://www.delock.de/produkt/64157/merkmale.html seems like a hub that could handle anything but that is much bigger (it is a docking station actually).