USB-C and Legacy USB Power Delivery Schemes and Compatibility - Page 1
Forum section: electronics / projects

author: starhawk
author_rank: Regular Contributor
timestamp: April 29, 2020, 07:53:12 am
content: Mods: yes, I know there's a computery subsection, but this is waaay more electronics than modern PC-ness usually goes into. I'd rather not argue (that usually doesn't go so well) so please read this post in full (skimming doesn't count, I hope you understand why...) before you move it. This is a "help me help you" kind of thingI'm trying here, really!This is, at 33, making me feel like an angry old guy villain on Scooby Doo. "You meddlin' kids, with yer dang USB-C cables an' your special power distribution 'n' chargin' modes an' yer smartphones and Androids an' Firefox extensions an' [incomprehensible muttering] -- get off my friggin' lawn and DON'T COME BACK!!"My idea of a good time spent livening up a boring afternoon is often to take an eBay-issue stick computer (HK/CN "Intel Compute Stick" clone, at least by way of form factor) or "Mini PC" (basically the same stuff but in a Roku-style form factor instead) and throw a power supply, keyboard, and display at it from the Junk Pile of Ultimate Randomness that is my closet space (LOL). This usually ends in a combination of two ways: one, I spend money on eBay on little bits of flotsam that I didn't expect to need but wind up needing anyways; and two, I do in fact eventually manage to club the sorry kludge-bag of parts into actually workingMost of the time, power for these things is 5vDC throughout. Nice to have only one power rail!However, this time I'm staring down a wee techno-beastie of a slightly different sort. I recently bought an HK/CN-origin "no-name" USB-C multi-converter type gadget for my phone. Phone, FWIW, is a Samsung Galaxy S9. The gadget is sort of like those USB-C "universal laptop dock" type things, but for the phone. A male USB-C port witha deplorably short cable goes to a housing with two USB 3.0 type "A" ports, a full-size SD card slot, a "TF" (MicroSD) card slot, and an HDMI port. I've pried it open and looked at the guts... it's structurally a USB 3.0/3.1 hub chip (Genesys Logic GL3224) with a USB 3.0 SD card reader chip (VIA Labs Inc VL813-Q7) and USB-Type-C Alt Mode DisplayPort bridge[?] chip (VIA Labs Inc VL100-Q3) hanging off two of the four ports of the central hub chip. There's also a DP-to-HDMI bridge chip (Parade Tech PS176HDM) in between the DP chip and the HDMI port, because otherwise Bad Things Would Happen.Ultimately what I'm looking here is a way to power my phone and the USB phone-dock-thing (I *swear* that's a technical term!) at the same time, from a 5vDC source. I have a 5v 6a power brick in mind"Normally" (i.e. in Yonder Good Olde Days of USB2.0 and earlier) I could just splice together a simple wiring harness. 5vDC in via barrel jack to a MicroUSB port for the screen, and wires spliced into the cable (or, more likely, wires bodged onto the dock-side PCB connection for the USB port headed towards the phone) for the dock and phone. If I wanted to dangle a second hub off it (extremely likely!), and I also wanted touch input from the LCD (it's a Waveshare-knockoff 7" IPS LCD with capacitive touch, meant for a RasPi... 1024x600, works for me! I like small screens...), I could cut the red wire out of a regular Micro-USB to USB-A cable and hang that off one USB 3.0 dock port, with the hub on the other, its cable cut in similar fashion and wires soldered onto its PCB for extra power delivery.That said, this is USB-C and that's a whole new ball game indeedUltimately what I want to know is -- can I splice in extra power the "old fashioned" way, maybe with a Schottky diode on the phone side so that if it gets the wrong idea nothing goes KABOOM(FTR, for that I have RK44 diodes and SR260 diodes -- which do I want here?), or do I need some fancy schmancy "active" solution like an extra flipping hub or something?...oh, a note about screens -- if the one I have doesn't work, I can save up for better. Either way, I'd prefer to find out myself, so let's ignore the tiny resolution/size/etc for now, please!

author: MasterBuilder
author_rank: Regular Contributor
timestamp: April 29, 2020, 08:42:47 am
content: I'm having difficulty visualising this, How about some pictures?

author: starhawk
author_rank: Regular Contributor
timestamp: April 29, 2020, 05:32:12 pm
content: Here... this is what we artist types (I'm an artist, a writer, computer nerd, *and* electronics hobbyist!) call a "bad napkin sketch"good for conveying ideas that seem highly technical to the easily-overwhelmed but most certainly do not involve complex terrestrial-origin astrophysics calculstions...

author: starhawk
author_rank: Regular Contributor
timestamp: April 30, 2020, 09:11:02 pm
content: Gee, this thread sure is popular :-/...a response would be greatly appreciated!

author: tooki
author_rank: Super Contributor
timestamp: May 01, 2020, 08:03:24 am
content: Quote from: starhawk on April 30, 2020, 09:11:02 pmPro tips:1. Walls of text, like your original post, are far less likely to get read than concise posts. Much of what you wrote is irrelevant. The question literally boils down to “can I power a USB-C docking station from just 5V?”2. Whining about the lack of replies merely 4h after providing essential information (the sketch) will put people off, since it comes off as entitled and demanding — and hypocritical. After all, the first reply took under one hour, and thenyourreply to that took over 8h. Many people do not look at the forums hourly or even daily, so you have to allow for some time.

author: starhawk
author_rank: Regular Contributor
timestamp: May 02, 2020, 01:35:47 am
content: 1a. I would not consider my first post a "wall of text"... really, anything higher than garden edging would be a stretch to me. But, then, I'm a budding novelist on top of everything else, so I'm pretty well stuck on maximum verbosity. Also background info, at least in my experience, tends to be useful.1b. Note that I deeply abhor social media in general and Twitter in particular because of its effects on the perception of information quantities. The world is far too complicated in almost every respect to fit inside a bumper-sticker slogan, media sound-bite, or Tweet, and I'm of the position that the resultant vast oversimplification of things in obedience to the medium, is the source of a lot of today's issues with polarization and various forms of offensive behavior. Far too much is 'lost in transmission' (if you'll permit me to coin the phrase) to really be able to avoid ticking someone off at some point.2. Guilty as charged. I missed the timestamps... that one *is* my fault, and I apologize for it.EDIT (immediately after posting) -- to clarify, I want to power a USB-C docking station and HDMI LCD from a 5v power bank, and I want to charge the phone attached to the docking station through its USB-C cable at the same time. If relevant, the power bank is a 10,400mAH BlackWeb with two outputs, one labeled "tablet" and one unlabeled. Max rated output is 3.4a @ 5v.

author: tooki
author_rank: Super Contributor
timestamp: May 02, 2020, 01:25:38 pm
content: Quote from: starhawk on May 02, 2020, 01:35:47 amI worked for years as a technical writer and translator. Trust me, for the small amount ofpertinentinformation contained, it’s a wall of text. You have to understand (and this has nothing to do with social media) that in technical contexts like this, people largely skim, not read.The more text you write, the smaller the percentage of it that actually gets read.So the best comprehension is achieved with concise writing.Technical writing (which is the blanket term for writing that isn’t literary or academic: instructions, memos, informational correspondence, references, documentation, etc.) is the exact opposite of literary and academic writing, which is what we are taught in school. And many of the rules taught for literary/academic writing (such as using various words for the same thing, flowery descriptions, verbosity, complex sentence structures, etc.) are the exactoppositeof what’s needed for effective technical writing. (Journalistic writing is sort of a blend of the two, and the mark of a good journalistic writer is a text that’s creative enough to be engaging, yet consistent and clear enough to avoid ambiguity or confusion.)My guiding principle in technical writing is: “If it doesn’t add, it subtracts”. In other words, unless something is clearly, unambiguously helping, then it is detracting and should be jettisoned. (Explicitly not an option: for a word’s net contribution to be neutral.)Writing concise text ishard. Being wordy is easy. (The acid test for this: coming up with terminology for user interface commands and the like. You can sometimes spend months (!) working on what ends up as a two-word menu item, because having an entire sentence with explanatory text simply isn’t an option.’I don’t mean any of this as an attack, just as information from one writer to another, since the creative writing world is totally unlike the technical writing one.As for your query:Can you just get a USB-C (with PD) power bank?

author: starhawk
author_rank: Regular Contributor
timestamp: May 02, 2020, 11:05:48 pm
content: Re tech writing, OK that I can understand and agree with... although I'd see this as closer to 'journalistic' than either tech writing *or* creative/"prose" writing...Whatever, it doesn't matter.Re power banks... I have the one I want to use. I chose it for three specific reasons -- its relatively high capacity, its relatively high maximum output, and the fact that it has a numeric LED display that tells its current charge percentage in real time -- a critical factor, since I can't hook it up to either a phone or a computer and expect the host system to report capacity the way eg a laptop battery would work. (AFAIK there are no SMBus-compatible power banks!) I also currently lack the budget for another purchase of that sort -- while I could explain that, suffice to say for now that (a) I'm on a *very* thin shoestring budget, of the "a $5 Starbucks latte is an aspiration" sort, and that (b) although I can give you the *full* explanation and I'm happy to do so (I'm fairly open about it, in fact) -- boy, if you thought my first post was long...

author: MasterBuilder
author_rank: Regular Contributor
timestamp: May 03, 2020, 09:39:52 pm
content: I wouldn't risk my smartphone plugging it in to some combination of stuff like this. I'd charge the smartphone directly off the power bank. U have described some suspicious quality hub which may have plenty of dodgy design features and I suppose it may do some harm to the smartphone. Having lots of USB stuff together like this is also a recipie for intermittent connections and associated headaches.But with that said I don't see why the scheme u have described wouldn't work.

author: starhawk
author_rank: Regular Contributor
timestamp: May 04, 2020, 12:52:13 am
content: Thanks!I have a bunch of stuff going on right now (as usual...) but if I can remember in the next day or two or three, I'll post pictures of the inside and housing of the dock device. It's actually pretty well engineered, to my eye...

author: starhawk
author_rank: Regular Contributor
timestamp: May 10, 2020, 01:05:45 am
content: Geez guys, took me long enough! Here's your pix, as an Imgur album.https://imgur.com/a/NoOtTmK

author: tooki
author_rank: Super Contributor
timestamp: May 10, 2020, 02:12:27 am
content: Quote from: starhawk on May 02, 2020, 11:05:48 pmPlease, I implore you to believe me: this issquarelytechnical writing. It's about conveying ideas precisely, not about flourish and creativity in wording. Nothing about a forum post is remotely journalistic. (Or rather, it shouldn't be. Nobody wants backstory and sidetracked babble. Just what's proximately relevant to the question.)Quote from: starhawk on May 10, 2020, 01:05:45 amPlease just upload them here, so they don't go missing if/when imgur shuts down. (There was already one imagepocalypse after one major image hosting service shut down.)

author: starhawk
author_rank: Regular Contributor
timestamp: May 12, 2020, 04:34:47 am
content: I can pretty well assure you that Imgur -- from everything I've heard literally ever -- is going absolutely nowhere but bigger, but... eh, WTH.Gimme a few, it's actually easier for me to re-download them and then upload again here, rather than to pull them off my phone. (I'm a computer hardware nerd, not a phone nerd! Forgive me, please...) But, yeah, I'll put 'em up local.

author: starhawk
author_rank: Regular Contributor
timestamp: May 12, 2020, 05:31:09 am
content: The images are attached to this post. These are reduced in size to ~650k (ish) each using EZGIFcom's JPEG Optimizer. (Normally I have a local program for that, but that's on another computer and it's late and I'm lazy.) Filenames from Imgur.Before anyone asks, I did that specifically because I've been accused of image-spamming forums before (and other seemingly-minor transgressions) and I generally can't talk fast enough to avoid a bad dayso I figured I'd best play it safe.I also took the time to make a ZIP archive of the original photos, and upload it to my Google Drive. After all, the files are uhm a lot bigger than 650k-ish to begin with. Besides, Google is forever, and, additionally, I have stuff still in there that has to do with a Linux Distro's support forum that I left about two years ago (!) and certain versions of that distro that were around at the time (it's one of those rare distros where there's actually a reasonable chance that a non-trivial portion of that forum might actually be using stuff from 2016 and perhaps even earlier, so it's still potentially relevant, as such), it's not like anything I stick in there is going away any time soon, eitherBut, if anyone feels moved to mirror it, go right ahead. Permissions are set to "anyone with the link can view/download/etc" so there shouldn't be a problem there.Archive Link --https://drive.google.com/file/d/18LSjK6QROYDsiJN1Iy5EemkqaF3IZLAM/view?usp=sharing"USB-C Phone Dock.zip" -- ~17.0 MB / 17,872,798 B (per Google's accounting) -- seven *.jpg images inside.Files and sizes: "1 - 3Ac2pEg.jpg" (2.0 MB) / "2 - jTtjjYe.jpg" (1.8 MB) / "3 - gMLzDbN.jpg" (1.5 MB) / "4 - aBsHt5U.jpg" (1.8 MB) / "5 - 0kHn3Cc.jpg" (1.3 MB) / "6 - iDxsr4d.jpg" (4.8 MB) / "7 - HWueV8X.jpg" (4.6 MB)License: anyone who wants to download and/or use these images, in whole or in part, in any way and for any purpose, can do so, without any further restriction(s) and/or need to request permission (etc) from me or others, except as restricted and/or prohibited by applicable law(s), as determined and defined by a fair and just proceeding, or a series thereof, by a legitimately-recognized court of law holding correct and proper jurisdiction. Additionally, I personally disavow any liability and/or liabilities under all such law(s), as described heretofore, that may be incurred by the actions taken by those person(s) who download and/or use these images, in whole or in part, to the greatest extent permissible by said law(s), and I transfer such liability and/or liabilities, sum total and in their entirety, upon such person(s) as described heretofore, irrevocably and without expiration or limitation except as defined under such law(s) as described heretofore.Ya'll have fun with that...

author: tooki
author_rank: Super Contributor
timestamp: May 13, 2020, 06:52:49 am
content: Quote from: starhawk on May 12, 2020, 04:34:47 amI didn’t say it because of idle speculation, but becauseit has already happened before, to another of the biggest players. Nobody thought it would ever happen, until suddenly it did. So your assurances are, unfortunately, totally meaningless.(I think the one I’m thinking of is photobucket, which didn’t close, but disabled embedding in third party sites unless you had an expensive paid account. It happened literally overnight with no warning, and broke millions and millions of images across the web. Years later they changed it to more reasonable terms.)

author: starhawk
author_rank: Regular Contributor
timestamp: May 13, 2020, 10:18:46 pm
content: I know the one... it's the jerk one with the frog logo. I think they finally killed themselves off. Used to use em, too... till that happened. I remember it better than I'd like to...