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Google Engineer Warns Against Perils of Buying Cheap, Third-Party USB-C Cables (hothardware.com)
MojoKid writes: A USB-C cable is just a cable. Or is it? Google engineer Benson Leung noted today that it's definitely not the case. Leung and his teammates at Google work inside of the Chromebook ecosystem, and as such, they've had lots of hands-on experience with USB-C cables. The Chromebook Pixel remains one of the very few notebooks on the market that directly supports USB-C. Nonetheless, in his experience, not all cables are built alike, and in some cases, cheap out-of-spec cables could potentially cause damage to your device. It's such a big problem, in fact, that Leung began buying cables off of Amazon and leaving his feedback on each one. Ultimately, what the problem boils down to is that some of the specifications in a cable may be not well controlled. He notes that in some bad cables, resistor values are incorrect, throwing off power specs wildly — 3A vs 2A in one example.
I bought a few packs of USB-C male and female connectors from China (to use for a non-USB application) and they were really junk. Looked like USB-C but the tolerances were terrible. Too soon for competitive quality forces to have kicked in, I suppose, but they didn't just make these bad connectors to annoy me - they must be out there in the wild too.
My God, it's Full of Source!
OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
The answer to this is: They have. I'm sure that you'll find sources if you google.
I'm not so sure about cables, but exploit devices have been found in usb chargers in airports.
I don't read AC A human right
You may not notice the quality difference with cheap analogue cables, but it is there. A bad quality digital cable will just not work, or be choppy as you noticed. That's why some say that cheap digital cables are okay, if it seems to work okay it likely is; that until they start becoming more than a cable.
Benson is a pretty fantastic engineer. He dots the i's and crosses the t's, which is somewhat rare these days.
I hope Puneet (if Puneet is still his manager, as he was Benson's and mine, when I worked with Benson) is having Google pay for the cables he's buying, instead of Benson paying for them out of pocket.
In any case, definitely take his Amazon reviews to heart: he knows what the hell he is doing, and he knows which end is the probe and which end goes in the meter. If he says a cable sucks, it sucks, and if he says it's good, it's good.
Using sense resistors in cables or charger plugs is pretty much universal and works very well. That's how phones tell the difference with between a "standard" 500mA USB port and a 2A high power charger. If the phone tried to draw 2A off a 500mA supply, odds are all the magic blue smoke would get out... (See http://blog.curioussystem.com/...)
There's nothing wrong with sense resistors when the cables are manufactured properly. The problem is if the manufacturer puts the wrong resistors in because they don't know any better or because they're cheap and they're trying to cheat with cheaper components. In the case of USB 2 stuff, pulling 2A from a 500mA brick probably wouldn't end too well. For USB-C, if you try to pull 3A+ over a wire that's only rated for 500mAh... Well... Most likely what you've got there is a 3 meter long fuse... If you're lucky, the power supply will fail safely before the heat from the additional current ignites anything.
Or more realistically, you may find the laptop gets flaky when it adjusts its power management to assume it can draw a particular amount of power from the cord only to fall short when power demands reach peak levels.
yea, the problem is that they are not just cables, they are adapters. They adapt from USB-A to USB-C. As an adapter, they need the proper resister to tell the USB-C connected device how much power they can draw.
USB type A to type C cables require a different pull-up resistor than the Type C to type C cables. Lots of vendors didn't do their due diligence and just put the USB-C spec'd pull up resistors in their A to C cables. As a result, devices try to draw too much power.
I bought one of the bad cables, and was wondering why my wall charger was flaking out. Went online, and saw the issue -- my phone was trying to pull too much juice, overloading the charger and putting it into brownout mode. Now, this is a 4-port wall charger, so my other 3 connected devices were sitting there going charging/not charging/not charging at sub 1 second intervals for the ten minutes that it took me to figure it out. After that, my charger was acting really finicky, and I didn't trust it anymore after that current overload so I junked it. So, yea. Not overblown. Actual problem.
Here's the list of cables that he tested, from the TFA. There are ten of them
http://amzn.to/1MlG3g3