More about USB than you ever wanted to know 

This channel is awesome. "Borrow a Tolerance" made it's way to my algorithm and I've been glued to the screen since

I had no idea I wanted to know this much about USB. Thanks for doing this brother!!

I got recommended the tape video, enjoyed it, and just got this. Definitely subscribing.

29:47 hubs that look like this are usually quite fake. 1. The power supply that ships with it is not safety rated, it often has OBVIOUS double insulation violations. It also doesn't have very good regulation or any ripple suppression. It is also usually easily cracked open by a child. The first thing you do, crack it open and cut the mains wires to make sure it's not accidentally ever used. Then you dispose of it. 2. USB 3 SuperSpeed lines are connected directly to the first port closest to the input. The rest of the ports including the USB2 portion of the first port are on a USB2 hub chain, there is no USB3 hub inside. 3. The USB input power line is connected directly to the power supply input. This is impermissible as per USB spec, as the PSU, the shitty PSU from above, will backfeed power into the upstream computer. I suggest to block or damage the power input to make sure it can't be used. Many laptop mainboards are susceptible to die from USB backfeeding. Always design your device harness such that there is no backfeeding. More properly made USB hubs will have a Schottky diode in line with USB upstream power from PC. This makes them run substantially worse without the PSU, since the incoming voltage is dropped on the diode. Generally there's a second diode to protect it from backfeeding into its PSU as well, usually you find a single sot23 component which houses both diodes. Better would be an active diode circuit which bypasses the currently active diode with a MOSFET to avoid the power loss and voltage drop, but that would be very premium. Given the lack of diode and lack of proper USB3 support, just ditch the supplied cable and give it your own high current rated USB2 cable with beefed up power wires, this means less voltage drop on the wire and better supply to downstream devices. It can be useful as a passively powered USB2 hub like this, when used on a PC or laptop which won't mind running 3A into it. Maybe don't try that with an OTG adapter on a tablet or phone :D 16:00 devices connected without PD feature will generally only draw 7.5W (1.5A) as per USB Charging spec. 26:30 the D+ and D- lines are electrically distinct from each other on every port, they are individually actively driven, they are not in parallel. They do however all live in the same time domain, it's not a packet switched bus, only one device will be talking at a given time across the whole hub chain, and the host is responsible for assigning when devices are allowed to talk. A PC USB root hub in xHCI mode is magical and doesn't obey this rule.

Comprehensive and useful more than i had anticipated, thank you for this fine presentation.

You sir, are an invaluable resource to anybody who has access to you. A true wealth of information and deep understanding of the USB standard. I'm not sure how or why your channel and this video in particular got recommended to me, but I sure am glad it did!

Can you do a video on how to truthfully measure a AA & AAA battery power and remaining lifespan? Much arguing online!!!!

Thank you so much for this video., this is exactly what I needed as a jumping off point for teaching myself more. I will definitely be checking out the rest of your videos!

I would never have known to check my cables for these deficiencies. This is excellent information. Thank you for posting.

I honestly doubt that Apple's main motivator for their own cable is that normal usb cables are of lower quality. If Apple cared that much about quality their cables wouldn't have the problems they come with.

I first saw your video on tapes, which was great! A tool you might consider adding to your USB 3.0+ tool for your arsenal is the Chargerlab Power-z Km003c. Maybe you already have something like this and I'll find out when you do your PD video, but either way it has been a very useful tool for my troubleshooting toolkit.

your right, that was 57 min of USB knowledge that I had no idea I actually needed to know. first time to this channel, I'ma fan already......... dog toenail clippers, who knew......?!

I would love to see a detailed video on PD and QC protocols, and even some of the lesser known / brand-specific protocols like PPS, FCP/SCP, VOOC, etc.... Seems like there are many useful applications for that knowledge.

Love this channel. Info dump videos and videos about your own preferences have been my favorites (like the new labels video). Thanks

A pretty concise attempt at wading through the muck and mire of USB qualifications. Nice vid.

Thank you for explaining it very well and very thorough. Really appreciate the electrical engineering.

Excellent content. I’d love more, David.

As someone who recently dove to the bottom of the USB HID spec to which documentation doesn’t even exist, I asure you this isn’t more than I want to know lol

The thing you didn’t know name of is called a choke. They are used very often for products in amateur radio.

Great video.and looks like you have many more I will be watching. USB cables have more than I ever knew going on and this video was very educational so I appreciate you making it.

Don't say , "whole rabbit hole." Say instead, "entire rabbit hole." ;) Nice video. I love the super nerdy stuff. You certainly know your business. Great narration, clear communication, and excellent presentation. This was a long and wordy video, but sometimes that is required when instruction and information is what is on the plate. Thanks, and good job. 👍

I saw a reel and found your channel!! I'm a new subscriber!! Awesome stuff, can't wait to see what else you've put out.

me: "oh those are cool cutters" David: "Oh, by the way" me: *caught off guard* David: "The dog nail clippers are great for clean cuts" me: "oh thats what they are *takes notes*"

Most of the issues I have had to diagnose with my computer always have to do with crappy USB hardware. So many devices randomly disconnect during long sessions. USB standards are great in theory but no manufacturer seems to follow them.

Thank you so much for making this video, I've been looking for this info and you made easy to understand. Much appreciated and shared!

Your channel is amazing, I've been watching for days! I hope to see much more in the future

The lack of continuity of the shell from end to end may be intentional. In order for the shielding to function optimally, it must not provide a current flow path. By having it open at one end, it forces the interference to be shunted into the PC's ground and keeps it away from the device. Also a choke does not need to be magnetic.

Nice! This showed up in my recommendations at random, happy it did. Lots of stuff I didn’t know.

Thanks David for an hour well spent

Complete coverage, thanks.

That was a good video on USB and the different wires connected, how charging and data works.

This is so helpful! I will watch the rest later!

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Ty .. some of my people worked at Tzi for over 26 years

Ultra articulate. Great video!

Not 100% sure but the Ferrite air core choke is best but I believe there may be graphite in the rubber choke and give a weaker effect. But I would definitely go for proper graphite for sure! Great video as usual, you have helped me more than you will ever know! A big thank you.

There are so many special use cases out there concerning USB and all it's variants. For instance, the 3D printer conundrum of needing data only, but nearly no cable being data only. OR USB connectors on audio equipment where the form factor has been used for a "fancy" speaker wire. While it is not frequent that I come across these cases, I have on more than one occasion. The speaker thing being less than the 3d printer thing. I ran across one use case of 19v being sent across a USB cable. While it was very low amps it was 19v...and it was apparently for a specialized sensor dealing with water/environmental type stuff. That is why I say double check. Proper labels... BUT I do find all the info you have shared fairly accurate and more or less in line with what I understand. There are a lot of ways to cause issues with splitters or hubs tho. As a rule I just double check before mounting a new device. I try hard to keep PC stuff only on my PC USB, and everything else I power through one hub direct to AC instead of through a PC. I have, back when I started with the microcontrollers like rpi and esp stuff, fried a few things because I got confused with the powering options. So now I use a double check before powering anything.

Fantastic information, had no idea the variation in cable construction!

Dude, you are awesome foe doing this video, tysm!!🙏🙏🙏

Thank you for this . I’ve been wanting to build my own usb 3.0 because I’m tired of 2.0 and that’s all we have in my city . I buy from online but at a point where I want to give it a shot

You have earned my subscription brother.

Great vid. Much appreciated. Thank you sir.

wow ! that was very comprehensive and educative👍

Missing indepth PD and QC protocols section, as wel as some more proprietarym brand specific USB protocols.

Nice presentation. Good job.

4:51 Those are the best one to use in an environment where you have no control over the USB Connection to prevent that you infect your device with some nasty stuff. Like in a restaurant or something like that, that offers you USB "Charging" Capabilities at your Table.

I've been interested in the LaunchPad. Someone who is trying to get rid of bunch of project boards for a killer price and one of those is in there, along with a couple Uno and Pi / picos Cool to see your fixture

You need to go back and read the electrical specs for USB. Shield is only grounded at the host end. And apple have their format to get the money. Nothing else.

Some USB devices have software for initialisation in the connected computer. But not all computers are PC's, so it is not Windows' software. In the old days, all USB connections were strictly 5 Volt and so many milliamps. Now there is a wide variety of Voltages and Ampères but I wonder how misadaptations are handled.

Hey David, at 8:18 you say the board in your hand is an arduino. It looks a lot like an esp32. Am i mistaken?

I was hoping for protocol description. it just about low level power distribution in usb

Very good. I am glad to have found you. 😅

i bought one of those fancy wireless ultrasound probes from the wild west of alibaba for 1400 bucks. a bit cheaper than the 4500$ ge version which requires a 200/yr subscription. completely forgot that og usb cables came with a torroid ferite bead and used to be much thicker and last forever when you bought a 700$ flip phone back in the day.

i found this very interesting & informative, thankyou

a Charge cable for a flashlight doesnt need data wires when using a dumb device or a (Non USB-C PD) charger that has no use for it to begin with, if it did it likely would come with a proper cable, so i dont see that as being an issue, especially with how easy they are to get anyway. That aside, the fact you're using a super cheap bare bones USB Tester that has its own Quality issues similar to that of crappy USB Cables while doing a "USB informational video" is an issue for me. Yes they do the job of giving you a good enough idea of what you use it for even though its less accurate, but its still super cheap with its own downsides. 2nd issue being that super cheap USB HUB that looks like it came from 5 Below. That HUB in addition to the crappy USB meter are an issue and cause in itself for the voltage drop if the USB Powersupply is not the reason. I also happen to have that USB meter as a backup thus my reason for mentioning its flaws, personal experience testing with it With that said, a USB HUB like that is not built with power in mind in most cases, even if its supposedly able to handle up to 2.4A or whatever, its more for managing multiple devices more so than powering something with a decent power draw, which again is why the voltage dropped so much. Regarding USB ports on TVs, many of them in recent years are now designed with the possibility of using USB light strips if the user wants to, TVs that give you the option to turn off or keep on the USB port power when the TV is off is one example of a TV having that in mind. Other than those points, its an ok video for some USB information but some of the testing methods are flawed because of the above mentioned issues. That crappy USB meter is really triggering for some reason :/ Please get a higher quality one at some point

Very informative, thank you!

@25:50 sorry but USB ports are never on a bus. If they are, the device is either fake or only intended to be used with just one port (different connectors maybe). Two USB devices on the same data lines cannot work.

You no longer get a USB cable with printers, and yes the fake ferrites are very common, to the point I use a magnet to check if there is any ferrite in the bulge, often there is none, only on older cables, which are kept as they reduce RFI. The printer sales are always has the most expensive USB cables near them. The cheap ones, which do the job, but are not as high a margin, are often still in the store, just far away in the corner, almost hidden away. USB charger simple way to tell if it is good or not is to get only branded ones, and not the fakes. Almost all fakes lie about current rating, and also many of them have inferior insulation, so they can break down and apply mains to the output, and many also have horrid voltage regulation. Cheap no name ones I toss in ewaste, and get genuine ones as used, often for almost free, and use them that way.

Some Feedback: for me the voice/ sound quality was better on the "Tape" video! But i can not say why you voice in This video is not so "clear / easy to lisen", for me. 😢 Still thank you for making the Nice long all in one video.

I do know that there's 2 different charging protocols on USB C, some devices support both but a lot of very cheap ones only support USB A adapter cables, or if you connect a USB C to A and then A to C it then works. and you do need 4 conductors to pull more than 500mA since those chargers require the data pins to be tied together with a resistor to tell the device "hey pull more current up to 5v3a" so that magnetic cable as fancy as it looks is only designed to draw 5v500mA

Nice bro but you can learn more about the usb including the chip manufacturer via chipset with some other tools

The little circuit board with SCL & SDA is not USB, it is I2C (I squared C) for Integrated Circuit to Integrated circuit communication. You would need a USB cable with a converter in it.

Thank you for the information.👍

3:24 This might in some cases be a good thing....Since some cheap chinesium cgargers have floating mains go through them, which may give you a right stinger if you're not careful.

outstanding ....very well done!

Where do you buy consistently high quality cables and chargers? I don’t want to play Amazon roulette

Thank you for the video

Very interesting! Thank you!

I disagree with the apple cable argument, they certainly can figure out if the cable has data and just let you know without actually using anything proprietary in the cable apple is doing it purely for monetary reasons

Id like to add that if you have usb to some kind of 2 wire output it could have some kind of interface converting it to some kind of 2 wire coaxial cable or audio cable.

QC signals don't travel through the hub so it's impossible to get more than 5v, the QC signaling is not part of the usb communication.

I've wanted to know more about USB since before I knew it was a thing (curious about everything, or at least almost everything).

cool i have not heard of launchpad. thats friggin great. since other boards like rasppi arduino have gotten so expensive

wow, thank you

Found your type c short to day. 👍

As an engineer I agree to a certain degree that OEM manufacturers can have quality over an open market of manufacturing. However, it nieve to believe that companies like Apple are doing this because they love the custom soo much that they've designed everything perfect. On the contrary, apple has some very poor designs in certain products that actually insure failure. Also, everyone ( well smart consumers) know that auto manufacturers do the same with concepts like sealed transmissions. Its a guarantee to create revenue and definitely not designed because they just love the customer so much. They love revenue and simp customers that believe everything they say. Very silly not to know this.

at 13:34 there is a black tray with what looks like slots to fit in plastic walls to make different size space for storing your calbes and other electronics in it.. what is that brand model called. or perhaps you have a link to an example of it. I am looking for somethin like that and yours looks better than anythin i have seen.

bro thanks for this!!

"We know this is a good cable" [cuts it in half] 😸👍

Excellent

Do you have a link to the USB measuring amps volts watts device

NICE !!

I always thought the cotton inside the cable was to prevent moisture and keep it dry.

I am building weather station using an ESP32. I'd like to figure out how much power it's drawing. I would like to have solar panels power it and charge a battery that will keep the device runniing at night or dark days.

5:20 - Can you cut that cable and see inside what the wire gauge actually is? I've seen a few that are as flimsy as freebies._

Im having trouble with the explanation that the output is 5 volts dc constant. Its pulsed. With an average of 5 volts. Its indicated on the outside of the case. Its a switch mode power supply. It doesn't work the same as a constant DC supply. Hopefully, you can explain this better than me, or correct me.

excellent video SUBSCRIBED

I think we all know that Apple did not engineer proprietary cables for quality purposes since their branded cables all fail horribly near the ends, need frequent replacement and are quite profitably overpriced. Then turn around and show us why printers include their own high quality open standard cables. So now I've got to be on my toes discerning fact from fiction for the rest of the video, no thank you.

Where would you recommend one buy that?

haha! You were already a pet nail clipper weirdo like me!

Where can I get those wire strippers, I’m living in the stone age

Do you get fruit baskets and holiday cards from Brother?

that usb a to usb a splice is a tech sin. it feels almost like plugging it into a usb hub to share the power and bypass the onboard power regulation is a crime.

Very good but "Amperage" is ugly. The rest of the world calls the flow of electons Current.

ok lets git mceducated > BRB after video lets see if theres anything we dont know edit: x=5 0ver 3 ok bye nothing for average person to see here .

F+c now look at what you’ve gotten me into ha ha ha this will be interesting. Let’s see where it goes

What is cah tun?

Why do you use HDR. It makes the videos unnecessarily bright

cheap components are +/- 20% if they are that good.

A *good* cable probably shouldn't need a ferrite, but who the heck puts a fake ferrite on a cable? 😅 *Now* I've seen everything.