Comment by coder543 | Hacker News Reader

Comment by coder543 | Hacker News Reader

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I don’t agree. I found this straightforward statement:

https://www.anandtech.com/show/16712/usbc-power-delivery-hit...

    > USB-PD R3.1 supports three charging models:
    > - Fixed voltage
    > - Programmable power supply (PPS), and
    > - Adjustable voltage supply (AVS).
    > In the fixed voltage scheme, the Standard Power Range (SPR) mode supports 3A and 5A at 5V, 9V, 15V, and 20V.

That’s about as clear as it can be, assuming AnandTech is correct.

Also keep in mind the existence of PPS as another data point. I have an Anker charger sitting in front of me that offers 3.3V-11V at 5A. 5V at 5A falls squarely in that range, as long as you have an e-marked cable that can support 5A. (I have no idea if the Pi 5 supports negotiating PPS, but it would increase compatibility with chargers if it does.)

I agree the Pi 5 should have included a buck converter or something, but I don’t think it’s correct to say they’re not standards compliant. It’s just not a common use of the standard.

It's not hard to find at all.

https://en.wikipedia.org/wiki/USB_hardware#USB_Power_Deliver...

5v3A is the limit of USB PD SPR.

No, Wikipedia is looking like it's out of date or wrong. It’s not a definitive source, especially for highly technical topics like this.

Here is another industry source which has a table that also says 5V at 5A: https://www.graniteriverlabs.com/en-us/technical-blog/usb-po...

In fact, using Wikipedia’s sources, I found the actual specs and here is another piece of supporting evidence for these other articles:

> The Fixed PDOs Maximum Current field Shall advertise at least 3A, but May advertise up to RoundUp (PDP/Voltage) to the nearest 10mA. Requires a 5A cable if over 3A is advertised.[0]

This is a footnote attached to 5V3A, indicating to me that chargers are allowed to offer more than 3A at 5V.

At a minimum, the spec seems to be ambiguously written, but I’ve only spent a few minutes skimming it. Multiple industry sources (previously linked) believe that 5V@5A is within the spec, even without using PPS.

[0]: “USB_PD_R3_1 V1.8 2023-04”

You're both correct, but USB Power Delivery, like so many things USB, is a total mess with different revisions, and versions of those revisions, that each extend and deprecate parts of the previous revision. I'm going to ignore the actual protocol used for negotiation here, but there have also been at least three different protocols.

The first revision, rev 1.0, had six fixed power profiles: 5V/2A, 12V/1.5A, 12V/3.0A, 12V/5.0A, 20V/3.0A and 20V/5.0A. These were deprecated by rev 2.0, version 1.2, which instead introduced power rules at four fixed voltages, supporting power supplies with different output powers. The maximum supported currents by the specification were 5V/3A, 9V/3A, 15V/3A and 20V/5A. These power rules were retroactively named the Standard Power Range (SPR) in rev 3.1. That revision also added the Extended Power Range (EPR), which raised all the current limits up to 5A, but only when used with electronically marked cables. EPR also added power rules at 28V, 36V and 48V, again requiring (differently) marked cables and up to 5A. So 5V/5A is a valid option, but only when used with a USB PD rev 3.1 compatible power supply and cable.

Orthogonally to the fixed power rules, rev 3.0 introduced the Programmable Power Supply, which allows a configurable voltage between 3.3V and 21V in steps of 20 mV. This was extended by rev 3.1 with voltages between 15V and 48V in steps of 100 mV, called the Adjustable Voltage Supply. As far as I'm aware this is not commonly used, and most products advertising Power Delivery support use the predefined power rules.

The standard of evolving standard. Those looking take note, don’t rush to standardize something when the tech itself is still being tweaked and iterated on. Let it iterate, document it, but don’t put standards in place when you clearly can’t track or regulate it. You just look like that boomer who just now got their Windows 10 Upgrade CD to work.

The reality is that with variable and programmable power supplies, it’s now up to the device to draw power at a balanced rate from the supply, instead of the “supply” pushing power in. Modern tech has allowed us to have supplies between 3V-48V, 500ma to 10A. All with a usbc head.

Not standardising gave us the myriad of charging and headphone plugs on mobile phones in the late 90s/early 2000s.

Hate to be that guy but tweaking and iterating power delivery systems with no standards sounds like a way to get houses burned down.

I hate USB-C. What a mess.

What good is a universal port if it's not actually universal? I would actually prefer different shapes, because then you could be pretty confident that if everything fit it was going to work. Like how USB used to be.

> What a mess.

It’s such a mess that the EU took one look at it and said “let’s make that a universal standard and force it upon everyone!” Modern USB truly is the government bureaucracy of standards.

EU has been trying to work with Apple on this almost since the lighting cable was released.

I believe there were discussions about potentially standardizing on Lighting if Apple relinquished it's tight control over the technology but they were not interested in that path.

The EU decided that Apple cannot dictate what cables are used to charge their phones to the degree of at one point charging manufacturers $4 per cable (to be fair it seems like Apple was providing the hardware so it wasn't a pure licensing charge).

Huh? I didn't say anything about Apple. The parent post didn't say say anything about Apple. The grandparent didn't say anything about Apple. The great grandparent didn't say anything about Apple. The world doesn't revolve around Apple. My criticism of the EU policy has nothing to do with the port on an iPhone.

If you're curious, my main objection to the EU is that I don't think USB-C is a good standard and I don't like the prospect of the whole industry stuck with USB-C longer than appropriate because there's no incentive to experiment and possibly come up with something dramatically better.

Is it really worse now than it was before?

Having a plug on say a laptop that can be a charger, a HID, a drive, a monitor, or all of the above with a docking station is vastly superior to the old day IMHO.

Unfortunately the cable to do that isn't cheap and is massively overkill for say a phone charger. Thus cable compatibility becomes a thing but looking at HDMI cable compatibility is always a thing.

I think the problem is what used to be complaints about niche connectors are complaints about USB-C and it feels different and more impactful even if it isn't necessarily.

After all I know back in the Mini-USB days you had manufacturers skipping the data pins to save some copper leading to frustration when you couldn't transfer files.

It is really worse. I have ton of USB-C cables doesn’t transfer data from flash lights, a lot of USB 2.0 speed cables with USB-C connector, then USB 3.0 cables rated at 5G/10Gbps without an easy way to know the difference, then Thunderbolt 3 / 4 cables one each.

Besides Thunderbolt cables, there is not a standard nor universal way to identity them. I had to test each cable by plug in an SSD then speed test the SSD.

Flash back 15 years, a cable with MicroUSB either transfer data, or not. The difference between high speed / super speed only lives in the device.

Don't forget to mention displays in this discussion.

A USB-C docking station will plug into many of my laptops, but only two will display anything on the screen.

Being able to pick and choose features like that is not user friendly. It will do everything except when they didn't feel like implementing it is not a good standard.

> I had to test each cable by plug in an SSD then speed test the SSD.

That's actually not a bad solution. The speed of a cable doesn't matter unless you have a device that needs to be fast.

Having to buy yet another adapter cable to make things work wasn't great. Nor was having to use a hub because FireWire and Thunderbolt at up space that could have been USB cables.

At least you get minimal functionality (why are you hoarding data less cables?) Better than having to go buy one because you have a billion micro USB but no FireWire to hook up that drive.

Seems to be finally coalescing around something sane with USB4 ? (USB3 having been a "beta" version...)

Isn’t USB 4 largely just TB3 without Intel certification and branding requirements?

I don't know, but isn't it likely to become for USB-C what USB 2 has become for USB-A after (I would guess?) the wild west of the USB 1 days ?

> I would actually prefer different shapes, because then you could be pretty confident that if everything fit it was going to work.

The baseline profiles for power delivery (i.e. anything up to 20V@5A) have been all but done for two, three years now - you can readily buy combinations of PD and MUX chipsets that handle everything you can throw at them, and Anker has high-quality chargers to supply the juice.

The thing where USB-C still has issues is alternate modes. USBx usually works on all ports of a laptop or PC and virtually all cables, but anything involving TB, display, debug or audio is a hit-and-miss given how incredibly difficult it is to route all these high-frequency signals and properly mux them.

Usbc is the greatest thing to happen to humanity the last 20 years.

The simple fact that we can finally share charging cables across phones is a god send, not having a single cable for all phones was the stupidest thing people had ever done.

Micro-USB was previously the phone charging standard for everyone but iPhones for a good ten year run (and even then EU sold iPhones shipped with a micro-USB to lightning converter in the box).

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