daveyOsborn

So anyone not following the tech chatter, here is a cliff’s notes of the scenario…

Imagine Howard on Big Bang Theory Howard on Big Bang Theory

is in the shop buying a robot. Conversation goes like this:

Howard: will the robot give me a hand job?
Sales person: I have no idea… cannot guarantee anything about that. Nothing in the specs says that it can do that.
Howerd (to the robot): if I take you home, will you give me a hand job?
robot: with pleasure.
Howard: I take it!
…
Howard (at home): robot, give me a hand-job.
robot: no

It’s not clear. The testing device claims the PSU is PD3. But why? Is the testing device guessing? Or is the PSU outright stating in the protocol “I am a PD3 PSU”?

Counter question: where does it say on there that it’s PD3.0?

Nowhere. I found no mention of PD anything which inspires some of my questions.

Perhaps it follows since stuff from the PD3 specs and that’s why that tester said it, but this is guesswork.

That’s indeed the sort of answer I was looking for. The testing device detects PD3. This somewhat suggests that electronically the PSU identifies itself as PD 3.0-compliant.

Perhaps I’m misunderstanding you but the gist of your text is “why is this item not saying what a random guy said it should say??”

I want to understand the contradiction. The testing device declares that the PSU is PD3. But the test results led the blogger to claim it’s not PPS. So where is the lying occuring? I expect the PD protocols to establish a handshake whereby each side of the handshake discloses the PD revision it adheres to. Otherwise the protocol is quite shitty.

Edit: remember that companies need to pay fees when they advertise with the standard - they can just follow its spec without advertising it at all, I can see that happening for laptop producers specially as they don’t sell their power units as generic products (i.e. with a focus to market them).

That’s interesting. I suppose the fees finance a certification effort. And I suppose that’s fair enough. But if a device claims to be PD3 not on the label but makes this claim in the electronic protocol, the claim is a claim nonetheless. And I suppose it’s legally dicey. Dell could not be easily prosecuted for false advertising if they wrote nothing on the box or label that a buyer would see. But the hardware is still lying about its capability and I would think that would (or should) have consequences.

Oh, so to be clear, an asus laptop that expects a USB PD supply can still detect whether or not it’s an OEM charger? And when it’s non-asus, it distrusts the capability and only draws 65w even if the PSU can do 100w?

IIUC, that’s a bit fucked up. I’ve read claims that either USB PD or the proprietary 3-pin predecessors are supposed to be smart enough so appliances can go easy on PSUs that are not up to the full load, but I was expecting USB PD to not have vendor favoritism problems like that. I appreciate the tip. Seems like another gotcha that can even burn above average consumers who know to a reasonable extent what they are doing.

You’re misreading the blog post. That adapter has 19.5V written on it, but it requests 20V. 19.5V is not a PD voltage.

That is not what the blog post said. We know the /result/ is 20v, not what was requested. It’s a lie and abuse to print 19.5v on an adaptor that is actually just requesting 20v. It’s certainly /possible/ that is what is happening, which obviously proves my point nonetheless. It’s yet another demonstration of the USB PD shitshow. Either way in fact. Whether the negotiation is a lie, or whether the source is saying “close enough, will send 20v”, it’s a shitshow either way.

But now it’s worse because consumers who know how to pay attention to voltage are getting a product that’s not what they signed up for.

The latter is pretty much impossible to make to spec, because it can’t negotiate voltage. A barrel jack is single-voltage by necessity.

First of all, the adapters exist. Not impossible. If you meant to say a smart negotiating one is impossible, that’s not true either. It could detect whatever the barrel passes and use that result to negotiate only for that available voltage. It could even have a voltage converter that supplies voltages that differ from the source. In fact I have a DC-DC adaptor. You probably have one and don’t know it. A USB charger that plugs into a car’s cigarette lighter converts 12v to 5v. I have one that has a variety of tips and a range of voltages. Detecting the source voltage may not be cheap, but not impossible. It would also be possible to have a cheap manual switch to specify input voltage.

Respectfully, I’m going to have to disagree. It’s much more interesting when it catches fire, and I’d rather have a protocol that sometimes doesn’t operate in order to avoid the excitement of one that sometimes explodes

If you find explosions interesting, you can go play with fireworks or watch war movies. It’s not academically interesting that tech illiterate consumers find countless ways to shoot themselves in the foot. When engineers — who /should/ know what they are doing, push a shitty standard that burns even consumers who have the basic knowledge to match devices, that’s academically interesting because it’s people we expect to be smart fucking up. When a whole industry fucks up, that’s academically interesting. I cannot charge a 5v bicycle light using a USB PD spec’d PSU because the industry fucked up on the meaning of “default”.

No matter what charging standard you use, some idiot could cut off the end, wire it to a stun gun, and send 100,000V into your phone. That doesn’t make the standard bad, it makes the adapter bad.

Dumb consumers are not in short supply. It used to be that only tech-illiterate consumers were getting burnt. Which created an incentive for consumers to gain knowledge. The nannying attempt at a remedy has enabled informed consumers to get burnt. At the same time, it dumbs down society. When expert consumers can get burnt, of course it reflects a poor standard.

And poor practices. A good standard anticipates what the market will do. They did not anticipate different product makers having a different interpretation of “default”.

but as long as nothing breaks, I’d consider it as foolproof as anything reasonably can be.

It’s now clear why you have no problems with the standard – you have a low expectation. The Lenovo PSU that supports 5v /should/ be able to charge a 5v appliance. But they botched the negotiation and absence of it.

That’s just how electricity works.

I was describing how /people/ work.

I’m not grasping what you’re saying. What is it that asus is doing on their USB PD laptops and tablets?

Look it up on youtube

I don’t do youtube, which has descended into a shitshow of Google blocking both Tor and also killing off invideous instances.

I’m getting the sense from your comments that you think that USB-PD will deliver a higher voltage than requested. This is not accurate. A device can request any of the voltages specified by PD, and the power supply will supply that voltage if it is capable of doing so. If not, it will provide 5V. It’s very possible to get a sippy that won’t power your device, but a working, PD-compliant power supply will not damage a working, PD-compliant device.

That’s not true. See the experiment I linked.

Obviously, if you get a barrel jack adapter that requests 20V and then plug it into a 5V device, you’re going to let the magic smoke out, but that’s because barrel jacks don’t do negotiation. The power supply correctly supplies 20V as requested, and then you plug that 20V into the wrong thing.

Of course. Not sure what point you’re trying to make here but the conversation was about whether the barrel adapter is compliant with the standards. Not whether you can misuse it.

That’s no part of USB spec

Do you mean the USB PD spec? It does not violate the USB spec which sets a default voltage of 5v. The adapter /would/ violate the USB PD spec if it were to claim to be USB PD compliant. But the shit-show we have is that USB-C does not imply USB PD. And so the market is full of USB-C things that are not USB PD. And often they do not claim to be USB PD as consumers are not wise enough to demand it.

Note as well the adapter I mentioned is quite dumb – just hardwires pins for the situation that the appliance expects 5v without negotiation. But it would be possible to implement a USB PD-compliant adaptor with the smarts to handshake, which would then refuse to complete the handshake in the event that the voltage supplied is not that requested. Of course it would be a bit strange to put that much sophistication into it which would likely drive the cost to that of a whole compliant PSU anyway (thus defeating the purpose). But notice the opposite has been done, whereby the adapter negotiates a voltage on behalf of a barrel device.

as there’s no way to communcate requirements through the barrel.

IIRC, it’s disputed whether the hanshake negotiation is needed for 5v. Some appliances expect to do a handshake /no matter what/, and some 5v appliances are designed to skip the negotiation entirely. If you are in the camp that says even 5v must have a handshake negotiation, then you would condemn the simple barrel to usb-c adapter (but perhaps not one that is only for a fixed input and the circuitry to do the negotiation).

Hard to blame USB for when we side-step it’s design.

The blame was not pin-pointed. I pointed out a shit show in the marketplace. There are bits of the standard you can blame, and you can also blame market actors. You can probably also blame regulators for not preventing the shit show that I described.

USB PD is also a shit show. You might want to read this:

goughlui.com/…/tested-usb-c-barrel-connector-adap…

Which shows those USB PD negotiations can get dicey. It chooses voltages thought to be close enough to what’s requested.

I’ve run into a nasty problem where a USB-C appliance needed 9v. Says in the manual something like “only use Kenwood power supplies on this device”. I thought, fuck that, USB PD is a standard for a reason. I’m not going to blow money on a proprietary OEM Kenwood USB-C PSU. Then found that many power supplies actually skip 9v. The USB PD standard makes some voltage steps optional, and some mandatory. IIRC, 9v was one of the required ones, yet it was easy to find USB-C power supplies that skipped 9v but offered 12v (or 15v, I forget). And yet 12v or 15v was one of the voltage steps that’s optional.

So in the context of copious dumb users plugging in anything that fits the socket, the data PIN likely prevented a lot of damage while at the same time enabled HP to rack in lots of money on replacement OEM proprietary PSUs. Indeed I have seen on many occasians clueless plebs at the street market selling 2nd-hand appliances and quickly trying barrels from a pile of tangled PSUs until one fits, then trying to include that with the device they are selling without looking at voltage or anything. It’s common and I’m sure lots of gear gets fried because the general population is just not smart enough.

I know how to match voltage, polarity, and current demands. And I got stung. Spent a lot of time disassembling a laptop, trying different RAM sticks, removing wifi cards and other components as I was baffled about what this fucking blicking LED means when it is not blinking in any way to convey an error code. Removed the CR2032 battery to reset the CMOS. Just got a steady non-stop blink, which the manual falsely states means it’s in sleep mode. So I was ready to conclude that the laptop was trapped in sleep mode and irreparable.

Whether it is a good design to protect from incorrect PSUs (despite that the obscure barrel connector is probably only 19.5v systems anyway), most certainly it’s a crappy design to not inform users. To fail to assign an error code. Sure, it says in the manual something like “use only approved HP power adapters” – something /smart/ consumers do not take seriously because they know that shit is a branding hussle. The data pin should not be a secret that is concealed from both the user guide and the maintenance and service guide (which HP says is not for end users… yet they still withhold the info from service people).