Adafruit USB Type C CC Resistor Fixer(adafruit.com) |
Adafruit USB Type C CC Resistor Fixer(adafruit.com) |
dmesg was absolutely silent about it when I plugged in or out my C-C USB cable although the device switched on when I was using a simple charger instead. I opened it up to see if there was a special switch or something to put it in firmware flashing mode, to no avail. The little documentation I had only mentioned using one of the USB port.
In the end, out of ideas, I switched cables (even though I knew my cable was perfectly fine). As soon as I plugged in a A-C USB cables, everything worked immediately...
It does not. The vast majority of sinks have absolutely no knowledge of the cable used.
This is literally device engineers not bothering to read any part of the USB-C spec, or intentionally leaving out a $0.0003 part. And no, that's not a typo - I really do mean "50k unit reel for $15".
How is the standard supposed to work with defective devices that don't implement the standard?
I have a couple of devices that do not charge on a usb c source. I have to use a USB A - C cable on their shitty usb-c ports.
Now that I know the probable reason I’m more annoyed.
No Type-C receptacle featuring device can assume there will be no Vbus voltage on attachment from the other side, regardless of CC signals.
For a simple reason that USB C-A cable assemblies exist and can be plugged to any old charger or port on the A side, which will not wait or negotiate anything. It will just source Vbus 5V right away.
If you need this fix, it will literally refuse to work with any spec-compliant USB-C device on the other side of a C-C cable. No way to miss it.
In practice, most if not all networking/hardware department carries a ethernet cable tester but somehow not true for USB cables.
You don't need a cable tester to detect this problem; just plug the device into a spec-compliant USB-C power brick with a USB-C cable and see if it fails to charge.
I'm so annoyed they cheaped out that I don't even plan on buying anything from them again.
Note that the Pi's failure mode is different - it does work with C-to-C cables as long as they don't contain e-markers. They tried to be clever and it backfired.
I don't think the right solution to problems coming from spec-violating garbage is producing differently spec-violating garbage.
$0.50 to get it manufactured somewhere in Asia, $4.00 to get it shipped to the US, tested, packaged, put on a shelf, retrieved for your order, and put in a box to ship your way.
You're not paying for the PCB, you are paying for an American warehouse worker to do their job without having to pee in a bottle and walk around dead coworkers.
Obvious counterpoint: what's going to happen when two noncompliant "always provide 5V" USB-C wall warts are connected together with a C-C cable? How well does a charger like power being fed into it?
Anyway if you connect anything non-compliant together anything can happen. My point was that always on 5V is no problem for compliant device on the other side.
Normal people don't connect two chargers together. :) You can create all kind of fun combos though. Like connecting your PC via USB-A port to a type-c charger, etc. It's all by design safe. USB-A will provide power no matter what, it doesn't matter what CC signals are.
There's no such thing on the device. A power sink with a USB-C receptacle has two 5.1kΩ resistors, one on each CC line. A power sink with a USB-C plug has a single 5.1kΩ resistor. Always. That's it - anything else in on the power source (or cable) side.
You only need to bother with anything more on the sink side once you want to either sense what's the max current provided by the source (which you can do simply by measuring the voltage on CC pins), or implement PD.
I don't understand why the USB-C module that they are using doesn't include the resistors. Then they can replace the microUSB module with USB-C module and have it work.
On the other hand: the resistor itself is basically free, and you are already putting a few dozen of them on your final PCB anyways. Adding one more resistor value barely changes the assembly process.
The people who are willing to skimp on USB-C resistors are definitely not going to splurge on a custom drop-in connector module, so it would not solve any real problem. The resistor-less devices are broken because their manufacturers do not care that they are broken. You can't engineer yourself out of that kind of greed and apathy.
Leaving off parts should result in behavior which is identical whether you connect an A-C cable or a C-C cable. Detecting the difference between them should require adding parts.
It's like saying USB cables should still carry 10Gbps data when only the VBUS and GND wires are present, because some AliExpress scammers leave out the data wires: you can't leave out trivial core parts and still expect it to work!
I know. You need the detection for the fancy stuff like PD, not for basic operation.
So why does it matter that a resistor is missing on the sink side? It's stupid.
I suppose that instead of a $0.01 resistor to request power they could have mandated some kind of (probably more expensive) circuit breaker that detects the short and shuts things off before it causes a fire, but I suspect then instead of broken devices having missing resistors you'd get ones with missing circuit breakers...
It pretty hard (maybe impossible) to design a spec that still works when manufacturers randomly omit critical components for no reason.
why tf does it matter what the other side of the cable is connected to?
The vast majority of devices follow the spec. It isn't exactly hard, you know: throw "how do i implement a usb-c port on a device" in Google and its AI summary literally contains all the information you need.
If >99% of engineers have no trouble implementing it, can you really blame the spec?
> why tf does it matter what the other side of the cable is connected to?
Because both sides of a C-C cable have the same plug, and people want it to work properly when any kind of device is attacked to either side. This means using the same cable to connect a wall charger to a smartphone, a smartphone to a laptop, or a laptop to a docking station.
Similarly, they want the same port on a power bank to be be used both to put power into the power bank and to draw power out of it. And when they do something silly like connecting two wall chargers together, they don't want their house to catch fire.
All the power source needs is a way to sense that a power sink has been plugged in, as otherwise you could connect two powered sources with each other. Type C makes it about as simple as possible. It's really not the spec's fault.