USB stands for Universal Serial Bus and ever since its formation, the USB Implementers Forum have been working hard on the “Universal” part of the equation. USB Type-C, which is commonly called USB-C, is a connector standard that signals a significant new chapter in their epic quest to unify all wired connectivity in a single specification.
Many of us were introduced to this wonder plug in 2015 when Apple launched the 12-inch Retina MacBook. Apple’s decision to put everything on a single precious type-C port had its critics, but it was an effective showcase for a connector that could handle it all: from charging, to data transfer, to video output. Since then, it has gradually spread to more devices. But as the recent story on the Raspberry Pi 4’s flawed implementation of USB-C showed, the quest for a universal connector is a journey with frequent setbacks.
For the last decade or so, we’ve been powering and charging our portable devices with USB. It’s a system that works; you charge batteries with DC, and you don’t want to have a wall wart for every device, so just grab a USB hub and charge your phone and you headphones or what have you. Now, though, we have USB Type C, with Power Delivery. Theoretically, we can pull 100 W over a USB cable. What if we could tap into that with screw terminals?
That’s the idea behind [Jakob]’s entry to the Hackaday Prize. It’s a USB 3.1 Type C to Type A adapter, but it also has the neat little bonus of adding screw terminals. Think of it as jumper cables for your laptop or phone, but don’t actually do that.
[Jakob]’s board consists of a USB Type C receptacle on one end, and a Type A plug on the other, while in between those two sockets is an STM32G0 microcontroller that handles the power negotiation and PD protocol. This gives the USB Type C port dual role port (DRP) capability, so the power connection can go both ways. Add in a screw terminal, and you can theoretically get 20 V at 5 A through a pair of wires. Have fun with that.
Right now, [Jakob] has all the files in a Gitlab with the schematic and layout available here. It’s an interesting project that has tons of applications of USB hackery, and more than enough power to do some really fun stuff.
Despite becoming common over the last few years USB-C remains a bit of a mystery. Try asking someone with a new blade-thin laptop what ports it has and the response will often include an awkward pause followed by “USB-C?”. That is unless you hear “USB 3” or maybe USB 3.1. Perhaps even “a charging port”. So what is that new oval hole in the side of your laptop called? And what can it really do? [jason] at Reclaimer Labs put together a must-read series of blog posts in 2016 and 2017 plumbing the depths of the USB 3.1 rabbit hole with a focus on Power Delivery. Oh, and he made a slick Easy Bake Oven with it too.
A single USB Type-C connector
When talking about USB-C, it’s important to start at the beginning. What do the words “USB-C” entail? Unsurprisingly, the answer is complicated. “USB Type-C” refers only to the physical connector and detail about how it is used, including some of the 24 pins it contains. Then there are the other terms. “USB 3.1” is the overall standard that encompasses the Type-C connector and new high-speed data busses (“USB SuperSpeed” and “SuperSpeedPlus”). In addition there is “USB Power Delivery” which describes power modes and even more pin assignments. We’re summarizing here, so go read the first post for more detail.
The second post devotes a formidable 1,200 words to providing an overview of the electrical specifications, configuration communication, and connector types for USB 3.1.
Marketing at its finest
The third post is devoted to USB Power Delivery. Power Delivery encompasses not only the new higher power modes supported (up to 100W!), but the ways to use the extra 10 or 13 pins available on the Type-C connector. This is both the boon and bane of USB-C, allowing apparently identical ports to carry common signals like HDMI or DisplayPort, act as analog audio outputs, and provide more exotic interfaces like PCIe 3.0 (in the form of Thunderbolt 3, which is a yet another thing this connector can be used for).
It should be clear at this point that the topics touched by “USB Type-C” are exceptionally complex. Save yourself the trouble of a 90MB specification zipfile and take a pass through [jason]’s posts to understand what’s happening. For even more detail about Power Delivery, he walks through sample transactions in a separate post.
Some time back we ran a post on those cheap USB soldering irons which appeared to be surprisingly capable considering they were really under powered, literally. But USB Type-C is slated to change that. Although it has been around for a while, we are only now beginning to see USB-C capable devices and chargers gain traction. USB-C chargers featuring the USB-PD option (for power delivery) can act as high power sources allowing fast charging of laptops, phones and other devices capable of negotiating the higher currents and voltages it is capable of sourcing. [Julien Goodwin] shows us how he built a USB-C powered soldering iron that doesn’t suck.
He is able to drive a regular Hakko iron at 20 V and 3 Amps, providing it with 60 W of input power from a USB-C charger. The Hakko is rated for 24 V operating voltage, so it is running about 16% lower power voltage. But even so, 60 W is plenty for most cases. The USB-C specification allows up to 5 A of current output in special cases, so there’s almost 100 W available when using this capability.
It all started while he was trying to consolidate his power brick collection for his various computers in order to reduce the many types and configurations of plugs. Looking around, he stumbled on the USB-PD protocol. After doing his homework, he decided to build a USB Type-C charger board with the PD feature based on the TI TPS65986 chip – a very capable USB Type-C and USB PD Controller and Power Switch. The TI chip is a BGA package, so he had to outsource board assembly, and with day job work constantly getting in the way, it took a fair bit of time before he could finally test it. Luckily, none of the magic smoke escaped from the board and it worked flawlessly the first time around. Here is his deck of slides about USB-C & USB-PD [PDF] that he presented at linux.conf.au 2017 Open Hardware Miniconf early this year. It provides a nice insight to this standard, including a look at the schematic for his driver board.
Being such a versatile system, we are likely to see USB-C being used in more devices in the future. Which means we ought to see high power USB Soldering Irons appearing soon. But at the moment, there is a bit of a “power” struggle between USB-C and Qualcomm’s competing “Quick Charge” (QC) technology. It’s a bit like VHS and Betamax, and this time we are hoping the better technology wins.
If you’ve watched the tech news these last few months, you probably have noticed the rumors that Apple is expected to dump the headphone jack on the upcoming iPhone 7. They’re not alone either. On the Android side, Motorola has announced the Moto Z will not have a jack. Chinese manufacturer LeEco has introduced several new phones sans phone jack. So what does this mean for all of us?
This isn’t the first time a cell phone company has tried to design out the headphone jack. Anyone remember HTC’s extUSB, which was used on the Android G1? Nokia tried it with their POP Port. Sony Ericsson’s attempt was the FastPort. Samsung tried a dizzying array of multi-pin connectors. HP/Palm used a magnetic adapter on their Veer. Apple themselves tried to reinvent the headphone jack by recessing it in the original iPhone, breaking compatibility with most of the offerings on the market. All of these manufacturers eventually went with the tried and true ⅛” headphone jack. Many of these connectors were switched over during an odd time in history where Bluetooth was overtaking wired “hands-free kits”, and phones were gaining the ability to play mp3 files.
For many years, the humble serial port was one of the best ways to communicate with an embedded system. Then USB ports became more popular and serial ports started to vanish. These days, even if you’re using a serial protocol to communicate with the microcontroller, it’s often over USB. And USB provides a convenient source of 5 V too. In short, we’ve made our peace with USB.
And then they go and change it. USB type C is a small connector that is reversible and has more options for power and connectivity. However, it is yet another new interface to figure out. [Scorpia] recently posted an article about USB type C that you may find useful.
USB cables? What a pain. You can never find the right type of connector when you need one, or you can’t figure out which way is up when you plug the cable in. These problems could be a thing of the past, though, with the latest version of the venerable USB connection: USB Type C. This new standard uses a single style of plug for both ends, so you can use cables either way around. The plugs also work both ways up, so you can plug it in with your eyes closed. Let’s take a look at what the USB type C connector means.
