Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Raspberry Pi admits to faulty USB-C design on the Pi 4

arstechnica.com

Post reply on HN
Print view View original

121–130 of 165 posts

Re: Raspberry Pi admits to faulty USB-C design on the Pi 4

#121

Post by addicted »

ksec wrote: post #86
loeg wrote: post #46

Earlier quoted context omitted.

This has always been a criticism of USB C and it proves true time and time again. USB-C tries to be too many things to too many people and ends up with a huge matrix of incompatibility as a result.

Which is the single reason why I hate USB-C, and I don't want USB-C to replace lightning. And yet people keep saying USB-C will get better, the controller will get better, the quality of USB-C cable will get better. And Time and Time again it has proved vendors only care about cost, not quality.

There are some very bad lightning connectors too.

In fact, you can buy lightning connectors that will destroy your iphone.

Poor quality implementations in order to save costs have nothing to do with USB-C vs Lightning.

In fact, because Apple charges so much to be able to build official lightning devices, people are more likely to go with unofficial cables from unknown brands. At least USB-C cables and chargers are a lot cheaper for reputed brands to manufacture officially.

Re: Raspberry Pi admits to faulty USB-C design on the Pi 4

#122

Post by giobox »

groovybits wrote: post #33

From a Pi consumer perspective, this is not that big of a deal. However, it damages the purpose (in name) of USB C. Isn't C supposed to be the 'all purpose' spec? If we have popular manufacturers failing to follow the spec, we end up with cables marked as 'compatible with Raspberry Pi' or 'compatible with Nintendo Switch'. To the average consumer (and even most techies), USB C was supposed to be the 'one size fits al…

I find it incredible that presumably no one tried using a MacBook charger before this shipped. If they did and didn't document the shortcoming that's arguably just as bad.

Surely a not insignificant number of customers have MacBooks? If I was writing some test specs this use case would almost certainly feature, given the MacBook Pro's USB C adapter must be one of the most widespread high power USB C charger designs in existence. Especially when the stock device does not ship with a power supply, not like it was unforeseeable some customers would just use the chargers they already have.

Re: Raspberry Pi admits to faulty USB-C design on the Pi 4

#123

Post by silversconfused »

michaelt wrote: post #110
silversconfused wrote: post #84

Earlier quoted context omitted.

You needed a $5 AC power extension cord.

Carry around a 3,000 watt mains extension, because someone decided making USB C cables all support 100 watts was just too demanding, eh?

Well sure if it's for a airconditioned-hottub-phone, but I'm pretty sure a small 600 watt cable would be more cost effective here.

Re: Raspberry Pi admits to faulty USB-C design on the Pi 4

#124

Post by silversconfused »

oceanswave wrote: post #96
silversconfused wrote: post #83

Earlier quoted context omitted.

Too complex and overreaching is certainly a valid fault.

If a spec defines a fully working part, and you go off and tackle the complexity by designing your own part that turns out to be non-compliant, then the blame is on the spec?

Hey, it worked(?) for the web!

Re: Raspberry Pi admits to faulty USB-C design on the Pi 4

#125

Post by kllrnohj »

Sinergy2 wrote: post #75
kllrnohj wrote: post #23

Earlier quoted context omitted.

They chose to use a standard so yes it's a problem that they didn't follow it. It's pretty cut & dry here. Fortunately in this case it fails to 0V so it's not a dangerous or damaging failure, but still the spec literally hands you a schematic. Is it that hard to just copy it? Why did they even try to be clever and use their own design in the first place just to save a single 5.1k ohm resistor?

I can give the automotive electronics perspective here. Suppose that resistor costs 2c, including the actual part cost, PCB space, pick-and-place machine time (inc. more frequent spool replacement). Further suppose you expect to sell one million of this device. $0.02 x 1E6 = $20k If you are the circuit designer making, say, $150k, you just justified about a month of your salary (after accounting for benefits and othe…

If it was purely about saving costs why even use USB-C, though? They could have just said that a 3A micro-usb supply is now required for USB power. The Pi4 isn't actually using any of the increased power delivery provided by USB-C PD, which is in the higher voltage range, after all. It just wants 5V 3A, which micro-usb can certainly handle as well (there are a variety of such power supplies for previous Pi's in fact).

Seems like a really questionable cost-savings maneuver to switch to a way more complicated & expensive connector for nearly no reason, and then penny pitch on one resistor.

Re: Raspberry Pi admits to faulty USB-C design on the Pi 4

#126

Post by Someone »

m463 wrote: post #112
umvi wrote: post #73

Earlier quoted context omitted.

USB in general seems like a deep, deep rabbit hole. You could devote your entire career to becoming a USB expert. The USB 2.0 spec is like 700 pages long. The 3.0 spec is like 500 pages long and requires you to be familiar with the 2.0 spec at the very start. I started digging into USB for a project and the rabbit hole kept going deeper and deeper; I never fathomed the amount of complexity hidden under the hood of US…

That said, the serial cables that preceeded USB had very simple specs that put the brunt of interconnection complexity on the user. 7 bits even parity? 8 bits no parity? hardware or software flow control? how do I know the modem is connected? lots o' fun!

”had very simple specs”

The specs weren’t that simple (why would a serial port connector need 25 wires?).

It’s more the implementations that were simple, going down to 5, 3 or even 2 wires (https://en.m.wikipedia.org/wiki/RS-232#3-wire_and_5-wire_RS-...)

Re: Raspberry Pi admits to faulty USB-C design on the Pi 4

#127

Post by StreamBright »

umvi wrote: post #73
loeg wrote: post #46

Earlier quoted context omitted.

This has always been a criticism of USB C and it proves true time and time again. USB-C tries to be too many things to too many people and ends up with a huge matrix of incompatibility as a result.

USB in general seems like a deep, deep rabbit hole. You could devote your entire career to becoming a USB expert. The USB 2.0 spec is like 700 pages long. The 3.0 spec is like 500 pages long and requires you to be familiar with the 2.0 spec at the very start. I started digging into USB for a project and the rabbit hole kept going deeper and deeper; I never fathomed the amount of complexity hidden under the hood of US…

The question is: do we really need these rabbit holes?

Re: Raspberry Pi admits to faulty USB-C design on the Pi 4

#128

Post by Causality1 »

teilo wrote: post #72
loeg wrote: post #46

Earlier quoted context omitted.

This has always been a criticism of USB C and it proves true time and time again. USB-C tries to be too many things to too many people and ends up with a huge matrix of incompatibility as a result.

And the criticism is completely invalid here. The power spec is very clear and unambiguous, and there is only one way to get it right. It is not the fault of the spec when manufacturers cannot be bothered to produce a circuit that has already been designed for them in the spec itself.

I wish there was some kind of patent or trademark law that could be used to punish companies who advertise with the word "USB" or "Type-C" without adhering to the spec.

Re: Raspberry Pi admits to faulty USB-C design on the Pi 4

#129

Post by megous »

soared wrote: post #51

Interesting that two major-ish companies sell products that are out of spec (rpi and Nintendo). Is there any insight on why these decisions were made? Business and engineering opinions would be equally interesting.

Nintendo has 6k employees, rpi foundation has like 1/100th of that. They are not really comparable.

Re: Raspberry Pi admits to faulty USB-C design on the Pi 4

#130

Post by monocasa »

michaelt wrote: post #106
teilo wrote: post #72

Earlier quoted context omitted.

And the criticism is completely invalid here. The power spec is very clear and unambiguous, and there is only one way to get it right. It is not the fault of the spec when manufacturers cannot be bothered to produce a circuit that has already been designed for them in the spec itself.

Blame for this problem is 80% on RPi, no doubt, but I'd say 20% of the problem is someone deciding to allow multiple cables, some with active components in them. If they'd instead specified that every detachable USB C cable must be 40 Gbps / 100 watt capable, and any lower-spec cable must be captive to the device (like mouse and keyboard cables are) then this problem wouldn't have happened.

What happens with A to C converters and legacy cables? Or do we just not support A devices anymore?
Post reply on HN