The hub doesn’t have a negotiation chip to set the voltage correctly. It is likely presenting as a bus hub. Like if you do $ lsusb on Linux, you’ll see the hub and whatever is connected. That hub may be integrated into other chips or it may be stand alone as a peripheral somewhere on the board. It is basically like a digital capable splitter for the bus. It is only concerned with the data. The power is likely just passed through. For USB-C PD, it would need some complex additional circuitry to negotiate, convert voltages and do current limiting. The way the pins can be inverted by flipping the connector makes it logically complicated.
Not sure where to ask this but why do some wall powered usb-c hubs refuse the charge anything until they are plugged into a computer?
Submitted 2 weeks ago by x4740N@lemmy.world to nostupidquestions@lemmy.world
Comments
j4k3@lemmy.world 2 weeks ago
TranquilTurbulence@lemmy.zip 2 weeks ago
Speaking of passing through PD communications, I have a cheap Chinese power meter that sort of does that but not properly. Hopefully OP has a nice hub that does these things properly.
If you use a setup with a power supply, first cable, power meter and a second cable, you can measure things when connected to a chargeable device like a laptop. It obviously tells the PS to give it 12 V, which it will. Once you unplug the laptop from the second cable, the voltage reading doesn’t drop back to 5 V. Apparently the power meter doesn’t let the PS to know there’s no load any more.
As a result, you get a USB-C cable that gives you 12 V without asking any questions. Guess what happens when you plug in something that can only handle 5 V? Bad things. Don’t ask me how I know.
Anyway, once you unplug the power meter from the first cable, the PS finally gets the message and drops the voltage back to 5 V. Makes me wonder if a hub could behave the same way as my power meter.
Kolanaki@pawb.social 2 weeks ago
I’m guessing the driver on the PC regulates the power somehow and not any logic on tbe hub itself.
lordnikon@lemmy.world 2 weeks ago
Becase some devices require a signal on their comm pins to negotiate the correct voltage to charge the device. Also some devices are dicks and needs a proprietary signal in order for it to charge. Looking at you sony.
edgemaster72@lemmy.world 2 weeks ago
Sony and proprietary nonsense, name a more iconic duo
sbeak@sopuli.xyz 2 weeks ago
Apple, Samsung, all the Chinese phone brands with their proprietary fast charging standards, HP, Bambu Lab, Nintendo, Xbox, Microsoft, Google, Adobe, etc. etc.
There’s a lot of terrible companies, actually.
Jarix@lemmy.world 2 weeks ago
Nintendo and it’s propriety hardware
crandlecan@mander.xyz 2 weeks ago
Apple?
x4740N@lemmy.world 1 week ago
Whats weird is that my usb c wall powered hub will charge devices on its own if I plug it into a computer (or sometimes an android phone) first and then unplug it and plug it into the device I want to charge