Would you like to learn more? Here’s a programmable emarker (VL151) datasheet, it lists a ton of fun info you will be able to get out of an average emarker! It’s required for anything more than USB 3 speeds or 3A current, and there’s a myriad of parameters that could be encoded into an emarker, including even, ahem, country codes. An emarker is a memory chip inside the cable plug that encodes the cable capabilities and parameters, and taps into the CC channel in order to transmit them. How does it check cable capability, exactly? By reading the cable’s “emarker”. When a power supply is capable of providing more than 3 A over a cable, it won’t do that instantly – first, it will check that the cable can handle such a current, and that the device connected is able to accept it. Plus USB-C has facilities to distinguish between different cables! Let me show you. 2.0-cables are also thinner, lighter and more flexible – you really don’t want to use a Thunderbolt cable when you want to charge your laptop on the go. The undeniable benefit of having so many cable variations is that you can actually buy a $5 USB-C cable when you only need $5 worth of capabilities, and a $40 cable when you need $40 worth. How do you figure out which ones you have? Let’s simplify the situation to the three-by-four case and mostly dismiss the exceptions – over time, the weird cables will become less and less prominent, as even bargain bin manufacturers will learn to keep it together. Of course, you can indeed buy these by accident, or intentionally. There’s also plenty of blatantly out-of-spec cables out there – like charging-only cables without 2.0 pins, which is blasphemous as per USB specification. Three for 3 A, 5 A, or EPR 5 A, and four for cable speeds. This gives us a three-by-four matrix of “which cable you might have on hand”. If you thought there might just some cabling variability that introduces additional small permutations inside and outside the specification, you are, unfortunately, correct. Plus, there’s active USB-C cables that put the signal through redrivers or fiber optics for achieving long-distance operation. Now, there’s a new USB 3 standard which wants higher speeds, and needs higher-specced cables. It used to be that you’d have USB 2-only and USB 3-only Type C cables, as well as Thunderbolt-certified cables. Then, there are at least four variations of data transfer speeds. However, there are no 3 A EPR cables, so it’s a tiny bit less confusing than it sounds. That’s two more categories, SPR (20 V max) and EPR (48 V max). Last year, USB-C group introduced EPR, raising maximum voltage from 20 V to 48 V, and requiring changes to cables and connectors to increase isolation between power and data pins. Of course, as you would guess, the bargain bin cables might be undersized for even 3 A, but most cables will pass 3 A no problem. Sorting Cables Into (Mental) Boxesįor a start, there are two variations of current capability – 3 A and 5 A, with 3 A being the bare minimum for any cable out there, and 5 A support being optional. Still, let’s go through it, and you’ll see that they’re easier to tell apart than it might look. Good news is – for most of the time, majority of these cables will be suitable for simple tasks like charging and data transfer, and situations where you need a very specific cable are going to be rare enough. Now, I’m afraid, there’s twelve of them, purely following the spec, and there’s way more when counting all the out-of-spec cables. Purely following the specification, there used to be six types of USB-C to USB-C cables out there. Also, while cables like “Type-C to DisplayPort” might look like cables at a glance, they are adapters with a meaningful amount of active circuitry in them. While cables like USB-A to USB-C are popular, they are quite simple you get USB 2.0 or USB 3.0 data and 2 A of current at most, and the USB-C plug is usually hardwired as “host, will supply five volts”, which is defined by a pullup resistor. I’d like to clarify that I’m only talking about USB C male – USB C male cables here. Yes, it’s pretty bad, and one could argue it’s getting worse. You might have a bunch of USB-C cables, and they all might look exactly the same, but you’ve likely experienced that they’re not the same internally, and often there’s not a label in sight. I will also show you that things don’t have to be that bad for you, as long as you’re willing to apply a few tricks and adjust your expectations. USB-C cables and connectors: these are controversial topics, and rightfully so – I don’t want to pull any punches.
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