An Engineer's Guide to USB Typе-С (2024)

There are some screenshots of the UI on the Github page[1], and I wrote a little bit about trying to figure out the mess of USB-C cables that I have accumulated over the years[2] to see which supports what capabilities.

I think some videos are a great idea… now that the device is done and we're starting to send review units out, hopefully I will have some time to actually shoot them :-)

[1] https://hackaday.io/page/399874-silence-the-usb-c-cable-spea... [2] https://hackaday.io/page/399874-silence-the-usb-c-cable-spea...

Is it the most efficient? Probably not. Is it hurting the batteries of my devices? I guess?? I haven't noticed any issues with any device and that's 8 years now. Perhaps I've been lucky.

That's for charging. Data can be trickier, that's true, but often devices that use USB-C for serious stuff come with their own. Chargers from aliexpress-grade stuff I just discard to the drawer of the 1M-cables from where nothing will ever come out.

I've never seen a USB C brick that supported some alternative to PD but not PD. Do many exist? Are they still making them?

Wattage of chargers is easy enough to handle.

Every non-defective cable can do 60 watts. That's enough for the vast majority of devices. If you have defective cables just get rid of them.

> will this particular combo charge your laptop?

If your laptop doesn't have weird DRM, the answer is either "every charger and every cable works" or "every 60W or higher charger and every cable works".

> How about that smart LiPo charger, it's USB-C, but it needs at least 9 volts to charge, and not every power brick gives out that voltage.

I think that's violating the standard so you'd have similar problems even without this kind of standard. But that's basically just a 30 watt requirement in practice which goes back to being easy.

> The USB-A to usb-C cable that came with them works, but the USB-C to USB-C that you bought after, doesn't.

That one's definitely violating the standard.

> What about charging speed? Will it do fast charge?

For anything under 60 watts, just read the number on the charger.

This is the same as with other kinds of plug, which can also vary in charging speed even when they're compatible.

For higher wattage laptops in particular you might care about cable choice. That's an annoyance but also easily solved by getting only high wattage cables.

> What about a powerbank, does it charge your laptop?

You've lost me. Without USB C a laptop power bank basically wouldn't exist. Weren't we comparing to back in the day?

They existed not that long ago, before usb c pd was a stanard, many samsung phones supported it (and not PD), and those powerbricks with those usb c cables still exist and still fit into PD phones.

> Wattage of chargers is easy enough to handle.

How? Explain that to my mom, she picks up a cable that fits her phone/laptop and plugs it in. Here's the charger: https://www.ikea.com/si/sl/p/sjoess-usb-polnilnik-z-2-vrati-... It says 45 watts, will that charge her laptop? Why won't her laptop charge if she's charging a phone too? That didn't happen with her old laptop charger.

> If your laptop doesn't have weird DRM, the answer is either "every charger and every cable works" or "every 60W or higher charger and every cable works".

https://www.ikea.com/si/sl/p/smahagel-napajalni-komplet-5060...

Will this one work? It won't, no usb PD support, but it fits into my moms PC, explain that to her. The cable is on her nightstand, she plugs it in, doesn't charge.

> I think that's violating the standard so you'd have similar problems even without this kind of standard. But that's basically just a 30 watt requirement in practice which goes back to being easy.

I have a charger and a soldering iron that just says voltage too low and doesn't work. The cable fits, but it doesn't work. I know why not, now explain it to my mom.

> That one's definitely violating the standard.

Sure, but she bought such a device, the cable fits but it doesn't charge.

> This is the same as with other kinds of plug, which can also vary in charging speed even when they're compatible.

What plug? Ericsson plug fit and charged the ericsson, same for nokia... usb C fits and doesn't charge.

> For higher wattage laptops in particular you might care about cable choice. That's an annoyance but also easily solved by getting only high wattage cables.

Again, explain that to my mom. how many watts? Is 60 enough? Ikea only has 45 watts, will that work? What is a watt? Why is it only 22 watts if she's also charging a phone?

> You've lost me. Without USB C a laptop power bank basically wouldn't exist. Weren't we comparing to back in the day?

Of course laptop powerbanks existed before USB C, they gave out usually 19 volts and the guy at the store would install a proper connector to fit your laptop and you'd lose the others. You'd charge it with a charger that fit that powerbank and charged it, then charge the laptop with it.

Now you buy this: https://www.ikea.com/si/sl/p/varmfront-prenosni-polnilnik-te... 18 watts.. will it charge the laptop? Won't it? Who knows. Will the power go from the laptop to the powerbank instead? Who knows! You have to read the goddamn manual for that to see, and the manual says:

> Charging power bank > • Connect the USB-C cable to the USB-C port of the power bank first and then connect the USB cable to a USB-charger or USB-outlet that can provide sufficient power to charge the power bank. The LED indicators will display the charging status.

> Supply power to devices > • Connect the USB cable to USB-C or USB-A port of the power bank first and then connect the USB-cable to your device that you want to charge. > • The power bank will detect a connected device and start charging automatically. > • The LED indicators will display the remaining charge in the power bank during discharging.

Now explain that to my mom. The cables fit.

Yes, i know i'm complaining, but i live just far away from my parents, that it's a pain to sit into a car and drive all the way there to swap some adapters or chargers, or cables and label what goes where and for what it can be used... and debugging that over the phone is a pain.

The PD 2.0 spec came out two and a half years before samsung's first USB C phone. And the power brick that came with it wasn't USB C.

> It says 45 watts, will that charge her laptop?

I'm not sure, but a 65 watt charger definitely would. "Get 65W for a laptop" isn't any harder than any other third party power supply for a laptop. Which is optional, you don't have to get a third party supply.

> Why won't her laptop charge if she's charging a phone too? That didn't happen with her old laptop charger.

Her old laptop charger didn't have a second phone plug. If you don't want the complexity then don't use it.

> Will this one work? It won't, no usb PD support, but it fits into my moms PC, explain that to her.

Okay. To your mom: Every 60 watt or higher charger will work. That super cheap one is only 5. It can't do it.

> I have a charger and a soldering iron that just says voltage too low and doesn't work. The cable fits, but it doesn't work. I know why not, now explain it to my mom.

Every 60 watt or higher charger will work. That one's too low.

> Sure, but she bought such a device, the cable fits but it doesn't charge.

This could have happened without USB C too. If it used a barrel plug it would also be more likely to catch fire if you used the wrong one that fits.

> Again, explain that to my mom. how many watts? Is 60 enough? Ikea only has 45 watts, will that work? What is a watt? Why is it only 22 watts if she's also charging a phone?

60 is enough. 45 might work, but it might not, so only buy it if you can return it easily. [Note: Buying a third party non-USB charger for your laptop has the same flaws.] Watt is how much electricity. If you put two things on the same charger, they have to share.

> Of course laptop powerbanks existed before USB C, they gave out usually 19 volts and the guy at the store would install a proper connector to fit your laptop and you'd lose the others. You'd charge it with a charger that fit that powerbank and charged it, then charge the laptop with it.

I saw one ever in an ad. They were very niche and the average person didn't know they existed, at least around here.

> 18 watts.. will it charge the laptop? Won't it? Who knows.

If you want to be sure then go for 60.

> Now explain that to my mom.

It says to use the same order for either direction so I really doubt that actually matters. So here's the instructions for your mom: Plug it into a charger to charge it. Plug it into a phone or laptop to use it. The lights show how full it is.

> Yes, i know i'm complaining, but i live just far away from my parents, that it's a pain to sit into a car and drive all the way there to swap some adapters or chargers, or cables and label what goes where and for what it can be used... and debugging that over the phone is a pain.

And what I'm saying is that a lot of these issues are not unique to USB at all. And most of the rest can be solved by either using the chargers that came with a device or hiding/trashing the e-waste chargers you have and only using the good ones.