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Bit of self-promotion: I spent the last year or so designing an open-source USB-PD protocol analyzer[1], and the complexity of the protocol can be mind-boggling. Most of the time, the communication between source and sink is really straightforward, but it can get amazingly complicated when both devices are dual-role or come from the same vendor[2].

As messy as it is, however, it's also a very useful protocol that allows even small players to take advantage of the same economies of scale that large companies can take advantage of. Pity that the communication often requires dedicated chips, though thankfully those are relatively inexpensive. I was able to get an RP2350 (the same MCU that's in the Raspberry Pi Pico 2) to interface directly with USB-PD, but they could have made it easier and more accessible.

[1] https://github.com/T76-org/drpd or https://www.crowdsupply.com/t76-org/dr-pd [2] https://hackaday.io/page/399885-a-mac-and-an-ipad-walk-into-...

I've been lucky enough to get to play with a pre-release version of this and can confirm that it's a fantastic device for dealing with USB-PD power issues, as well as debugging the ridiculous number of devices out there who get USB-C power in general wrong in any number of stupid ways. I just wish I'd had one of these a couple of years ago to help sort out the mass of devices with broken USB-C power, meaning not even full-on -PD but who couldn't even get plain 5V power because the people who designed it had somehow failed to copy and paste the reference circuit from a data sheet.
What do you think of those cheap chips you can use as USB-C PD control boards ? They usually have a button some way to cycle between a few different output voltages (like 12v, 5v, 18v, etc)
It's hard to make a sweeping statement, but I can tell you that I more or less use USB-C exclusively in all my hardware designs now, and I've found that most of these “decoy boards” work well enough. The model I use[1] most often supports basic the USB-C protocol well, is easy to solder to (and remove from) an existing PCB, and is pretty robust.

I cannot stress enough how convenient being able to “plug and play” USB-PD power in an existing project is. Whenever I send a finished device to a client, I no longer have to worry about having to source a compatible power brick, or about them misplacing it. Not to mention that, for the simpler projects, I can literally get a 20W power puck from IKEA that has really good performance and costs all of $5 (Canadian). On top of that, if I find that I need more voltage, I can just change a jumper on the decoy board and I'm ready to go.

The only thing I wish more of these boards came with is better overcurrent protection; with PPS so common these days, it would be pretty easy to let the user choose an appropriate current cutoff. Oh well!

[1] https://www.amazon.ca/dp/B0CNVN1N3J?ref_=ppx_hzsearch_conn_d...

This looks awesome. Do you have video show casing you diagnosing a problem with it?
Thank you! No videos yet, though both I and out beta testers have used Dr. PD to troubleshoot a bunch of devices. One of our testers actually develops USB-C sources, so it was very interesting to interact with them (and they found oh-so-many bugs :-) ).

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...

Guides like this explain why there are so many broken USB-C devices. The guide mentions that you do not need a PD chip for 5Vs, but then tells you that USB C is a cold connector meaning 0V is on VBUS when nothing is connected and jumps straight into the complexities of the PD protocol running over the CC pins instead of explaining how to get the 5V without the PD chip first.

Then in the section where it tells you how to do that, it fails to properly explain how to connect a load switch (10 cent component at 100 units) to get around the 10uF limit. The vast majority of applications will require less than 15 W and a good chunk of them can't get away with 10uF between VBUS and GND so a schematic how to do it in the lowest cost way would have helped here.

Edit: After reading until the very end I got the impression that this is just an ad for Texas Instruments PD controllers.

Basic 5V devices just need a 5.1k resistor on each CC pin to GND. It is pretty obvious when reading the actual USB-C Connector Specification.
My phone's USB-C port is worn out, and so now it's a brick if I don't have a wireless charging dock around.

Is it physically impossible to get bandwidth and power out of something as durable as a Magsafe connector, even a larger-scale version?

USB-C uses resistors to signal the power level for 5V. There is 5.1k for USB legacy, and I forget for 7.5W and 15W. Lots of cheap devices leave out the 5.1k resistors and depend on the same resistors in the USB-C to USB-A cable.

It is perfectly fine for USB-C device to signal USB Legacy since every charger needs to support it for microUSB to USB-C cables. The other way is for device to dynamically negotiate power level with the charger, but this is different than USB PD for higher voltage.

Now I want to know, how to add larger than 10uF cap?
My new iPhone with USB C charging is such an improvement!

Thank goodness for the European Union. If it weren't for them, we'd all be stuck with these flimsy Apple charging cables forever.

Even if Lightning was possibly a nicer or smaller connector; nothing beats a true industry standard. Makes the entire “what chargers and cables to bring to connect my stuff” question so much easier.
Sadly, that's far from truth...

"back in the day", you had an ericsson charger that fit in an ericsson phone and charget that ericsson phone well... and you had a nokia charger for you nokia that charged your nokia. They physically looked different, they wouldn't fit into any other device, and when you needed a charger, you'd take the one that fit the charging hole and it would charge.

Now, you have a bunch of usb C bricks, some just 5V usb, some USB PD, some QC(2, 3).... then you have a bunch of usb C cables, some with ID chips, some without, some able to carry 15 watts, some 100 watts, and then you have devices, some that can do QC, some that can do smart PD, some with just some resistors, some without even those.

Everything fits in every hole, every charger can take any cable and any device can take the other end of the cable.... but will this particular combo charge your laptop? The cable fits.. will it charge? What about those cheap earbuds that just want 5 volts? 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. 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. What about charging speed? Will it do fast charge? Your laptop charging light is on, but the battery percentage is going down... why? What about a powerbank, does it charge your laptop? How does it know who does the charging, and who is getting charged?

I mean sure, if you know your standards, you'll know what devices need PD and which ones use QC, you'll read the specs on the power bricks, you know how many watts your laptop needs, how to switch the current directions, which devices can't do proper handshakes, and need usbA->C cables, etc, and you'll get yourself a baggie of a few power bricks and cables for different stuff, but i had to label the cables for my mom, because while everything physically fits, many combinations won't actually charge your device. 10 years ago, this wasn't a problem, since her laptop charger didn't fit her wireless earphones, now it fits and it doesn't charge them.

In practice, this complexity means you at least have a chance. Most phones and almost all low-power devices will accept power from most chargers and cables. Probably not at a maximum level, but if you're stuck somewhere you can get by.

Power-hungry laptops are trickier, but even so... I've gone a week or more trickle charging a laptop from whatever travel charger I happened to have on hand, using it for a few hours, then putting it in standby and charging it up again until finally the mfg-blessed replacement fast charger arrived. The alternative (and one I was faced with more than once in the bad old days) was "no laptop".

Worst experience I've had to date has been a Norco jump box that will charge via one high-power charger and one cable, a car charger it came with, and ... Via careful back feeding from a benchtop power supply.

I've charged a Mac with the Switch cable, and a Switch with the Mac brick. Nowadays I charge everything with the same brick from a dell laptop from 2018.

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.

Apple was a key developer of USB C and used its experience from developing lightning. They were also one of the first (if not the first) to sell USB C devices (2016 MacBook, then across the whole Mac line). I don’t know how much the EU affected their timeline; it’s unsurprising they moved to USB C on their biggest volume product last. And the lifespan of 30-pin and lightning were about the same.

This was a repeat for Apple: the first iMac was the first production USB computer and they were pilloried for that too.

There were non-apple lightning cables already.

And I have to say, the lightning connector itself is better than the usb-c connect in my opinion. I get that having the pins on the male* plug is a theoretical advantage in durability but that has not been my experience with usb-c connector durability on either end.

EDIT: usb-c has pins on the male plug. Which is what I meant. So female -> male.

> the lightning connector itself is better than the usb-c connect in my opinion. I get that having the pins on the male* plug is a theoretical advantage in durability but that has not been my experience with usb-c connector durability on either end.

I always end up picking a lot of dust out of my usb-c ports on my phones; or otherwise the port wears out and disconnects before charging completes. (Right after my wife entered the hospital in labor, I needed to scrounge around for something to clean out my phone's port because the "go" bag only had a wired charger and my phone wouldn't charge on it.)

It's why I went to a wireless charger for daily use.

---

I'm real curious why lightning never became the standard. Was Apple trying to keep it proprietary? Was there a half-hearted attempt to open it up or otherwise convince the Android ecosystem to use it?

I have not used lightning but I have found USB C to be much more fragile than USB A, although better than mini and micro. I would really rather have had evey thing be a few mm bigger and stick with A.
That's fascinating; I've only had positive experience with USB-C cables and terrible with Lightning. What kind of cables do you commonly use?
Couldn't be further from my experience. They would always eventually stop connecting.

I didn't mention the single cable for everything advantage, that goes without saying.

I've also had basically zero issue with Lightning connectors, but had a constant battle with USB-C of every kind to figure out what's charging, what's data, what's PD, and so much more hassle.

I don't get why Apple was forced to colonize by the EU when they had the market-leading connector in place for significantly longer than USB-C even existed.

"It's only USB2!" Does it have to support the faster USB3 speeds? Not really... we don't have to keep forcing everything to include the latest kitchen sink support.

Give it time. I have 10+ year lightning connnectors working great. usb c isn’t quite as sturdy
honestly, the lightning CONNECTOR was far better, but man, I really appreciate the standardization. We have one device on the house left using lightning (my wife's iPhone 13 mini) and .. well, I just wish they'd release a new mini, that's all.
> I just wish they'd release a new mini

you and a lot of other people.

that's the only reason I have lightning in the house, actually.

Pretty good summary. It can be confusing since type C is "just a connector" but it's pretty heavily coupled with the protocol now.
Always found it a bit strange that USB-C is referred to as a "new connector" when it clearly seems to be an entirely new protocol. (Unlike the previous new connectors mini and micro which were just differently-shaped plugs for the same wires)

So is the protocol technically USB 4.0 and USB-C "just" a new connector role defined by that protocol, or did they ditch the versioning and "USB-C" is its own thing?

The guide mentions that USB 4.0 is the first version to require a USB-C connector, but then later refers to the "USB-C protocol". Is that the same as USB 4.0?

USB-C is a connector. Part of the confusion is that USB specification versions have come to be associated with the protocols and speeds defined there. The basic division is between USB2 and USB3 which are separate protocols on different wires. USB-C has multiple high speed lanes.

USB 3.0 defined the SuperSpeed protocol and 5GBps speed. Later versions increased speeds, 10GBps (USB3.1), 20GBps (USB3.2). These were also called Gen1, Gen2, or now just the speeds.

Then, there are alternate modes which run other protocols over high speed lanes. DisplayPort is the most common one.

Next, USB4 defined USB4 protocol which multiplexes SuperSpeed and DisplayPort over two high speed lanes. USB4 requires USB-C. This is basically Thunderbolt standardized. Specification also defines 20Gbps, 40Gbps, and 80Gbps speeds.

It's easier to split USB 3 into two stages:

1) USB 2.0 - 480 Mbps, 0.5A (2.5W / 5V)

2) USB 3.0 on Type-A - increases data to 5/10 Gbps (e.g. for SSDs) and power to 0.9A (4.5W / 5V).

3) USB 3.0 on Type-C - adds pins to enable most of the new stuff: base 3A (15W / 5V) and up to 240W with power delivery; extra data lanes for 20 Gbps, DisplayPort for external monitors.

4) USB 4.0 on Type-C - changes protocol completely (using packets instead of fixed lanes per pin) and requires minimum speeds and the use of type-C port.

A-to-C cables act like A-to-A as they don't have extra pins - they're just easier to use.

Pre-Power Delivery lots of phone chargers used A-to-C cables with a custom protocol to negotiate power draw beyond 0.9A. And some devices pull 3A anyway just assuming there's a power brick that supports 3A attached. But technically none of that is compliant.

Perhaps you will find page 27, "USB signals over USB Type-C®", clears up the strangeness.

At least when you get to the first section, "USB 2.0 Signaling Over Type-C".

A helpful guide, but usb c usability from a consumer standpoint is atrocious. From the specs it runs so many modes, PD (at various power levels), classic 5v , alternative modes. Sadly, there’s no way of knowing which mode a device or cable is supporting.

They could have done a better job color coding the connectors like resistors, so you could know the protocols supported by the cables and devices.

I have to label my own cables according to data support, PD, max power, etc. And many of my “usb c” devices only work with usb-A to usb-C cables.

The connector design targeted the industry and not consumers. Hopefully they will improve that.

there is a timestamp as parameter, I don't know, what it is good for, but the link works without it as well
Might be for cache busting.
could be, but for pdf documents I would assume that they are not changing this much
How can I read out the bit error rate?
USB-C reminds me of HTTP: one familiar interface hiding an enormous amount of complexity underneath.

That's great for experts, but difficult for everyone else because the same connector can expose wildly different capabilities depending on the implementation.

The EPR safety design is the part worth highlighting for anyone not deep in USB PD. The handshake is deliberately structured so a single message error can't accidentally push a port into a 100W plus contract, the sink has to actively drive entry into EPR mode and the source verifies cable capability before sourcing anything above 20V. That's a sensible failsafe given how much heat and current you're dealing with at 48V and 5A. The eUSB2 section is also underrated context for why this matters beyond cables. As process nodes shrink below 7nm, the old 3.3V USB 2.0 signaling literally becomes a reliability risk to the silicon itself, which is why chipmakers had to invent a whole lower voltage PHY just to keep USB 2.0 alive on modern nodes.
Not only that, but EPR contracts must be actively maintained in order to remain in effect. The sink needs to send a ping to the source every ~500ms, or the source pops out of EPR mode and forces a renegotiation. This ensures that, if the sink crashes, the source doesn't keep pumping power into a device that can't take it anymore.
Good find!
Nice one. I need to read this later.
I use an Apple Silicon Mac and often use programmable keyboards like the Royal Kludge RK61 via USB C. when I press keys such as A, S, D, F, W, or nearby keys in quick succession, the keyboard stops responding completely until I unplug and reconnect it. I've even replaced the USB C cable with a new store bought cable, but the issue still persists.
Check if your keyboard has a way to enable n-key rollover (NKRO)

https://en.wikipedia.org/wiki/Key_rollover

You are genius! thanks this completely solved my issue, for those curious https://postimg.cc/75hV9tCK

I use usevia, all i had to do was find a keyboard definition file for my keyboard which claude found in 2 minutes!

Usb isn't the issue, you bought an extremely budget mechanical keyboard.
Also avoid Epomaker, had the same issues, but needed a full reflash (every other day), losing all my layers etc. (The import function was broken lol)
turns out it was just me not knowing my keyboard has full qmk support and can be configured via usevia, what N-key rollover (NKRO) is.

my keyboard is actually r65 by royal kludge i got that wrong!

I was gifted this keyboard and i just love its feel.