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Raspberry Pi admits to faulty USB-C design on the Pi 4
- jakeogh 7y ago"E-marked cables are fully featured USB-C cables with chips inside" That's um... awful.
- deleted 7y ago[deleted]
- jhbhjjhvhjkgh 7y agoThe whole USB-C PD spec is overly complicated but in this case these chips are to ensure that someone doesn't push 4a/19v over an improperly built USB-C cable - that can lead to fire and burns. Also, other cables may have chips in them for data negotiation, specifically TB3/PCI encapsulation (the data rate is so high that over 6 inches you start to run into issues).
- jakeogh 7y agoSo, the spec allows an under-gauged cable to be plugged into a power outlet, and then relies on software (instead of a fuse) to not start a fire. I'm looking for a word... worse than awful...
- BoorishBears 7y agoHow do you spec a fuse for out of spec usage? What's stopping me from connecting a strand of magnet wire between both sides?
- jakeogh 7y agoA consumer does not solder USB connectors together with magnet wire. Power plug compatibility which relies on software for fire safety is a bad idea.
- BoorishBears 7y agoOk? But the kind of supplier willing to under-design cables will gladly do stuff that's barely a step up? I literally don't understand your proposed alternative unless you're saying all cables should be spec'd to handle the max amount of voltage... in which case people would still under-design. If the fuse is designed to keep cables for some voltage X from going up in flames, how will it keep cables for some voltage X-Y from going up in flames while also allowing Voltage X, when both are in spec?
- wlesieutre 7y agoYou can plug a 5 amp rated extension cord into a residential plug on a 15A breaker and the breaker won’t protect you from overloading the cable with 15A. So yes, those sorts of light duty cables have their own fuse to prevent this. But I really would not trust all the no-name vendors flooding the market with shitty USB cables to include correct safety measures in all of their cables, so requiring cables to specifically request higher power levels seems like a better precaution to rely on in this case.
- deleted 7y ago[deleted]
- tjohns 7y ago(a) A fuse only prevents over-current based on the port's rating, not the cable's. It wouldn't help here. (b) USB-C has several modes of operation. The thinner cables aren't under-speced in the lower-tier modes. They're perfectly fine for powering a mouse or carrying low-speed (USB 2.0 class) data. But not for charging a laptop, or other high current / data-rate uses.
- jhbhjjhvhjkgh 7y agoNo, what the spec does is say that if the cable doesn't have a max rating, it'll top out at 5V (and .5a, I believe). Then, it does negotiation with the cable and the device to insure that it can provide the voltage the device needs. And yes, PSUs MUST negotiate voltage or be 5V only and all USB-C devices must accept at least the 5V voltage.
- gumby 7y agoIs it? I think you want some smarts to talk to so 100W isn't pushed down a cable with wires too thin to handle it. And the high frequency modes (TB3, DP, etc) all require a lot of handshaking, signal conditioning etc to work, stuff that can't necessarily be done at the host connector side.
- thijsvandien 7y agoReminder to self: being an early adopter sucks virtually always. Edit: Sure, the issue is rather easy to circumvent, but anyone would have preferred not to have it. At the very least, it affects the resale value. My point is that whenever the answer to the question 'do I need it absolutely right away?' is no, it's better to wait a bit, no matter how much you intend to buy it at some point.
- ehonda 7y agoLucky me I didn't have any problems with mine because I: - Bought the most basic kit that included a power supply and heat sinks - Bought a $10 acrylic case with a fan so cooling also is not an issue for me
- 542458 7y agoEh, it’s not too bad. I found a cable that works and I’ll stick to it. Even with previous-gen Pis there was always a bit of futzing with cables to find one that has small enough voltage drop to not get power warnings (even some otherwise “good” cables really cheap out on copper). The USB C thing is still an issue, and I’m glad it’ll be fixed, but it’s really not that big of a deal.
- hazeii 7y agoHaving chopped up quite a few USB cables to power Pi's from fixed supplies (for professional use), I can totally relate to this. Even thick 'quality' cables commonly have dinky little copper wires inside, wrapped in lots of plastic. The only cables we found that were decently made were Molex ones which cost around 10UKP each at the time (a price we were happy to pay).
- ahartmetz 7y agoFor me, the USB cable that came with the 5V/2A charger that came with my phone did the trick. A fairly common source of high current capable USB cables.
- gambiting 7y ago
- fit2rule 7y agoDamn, did they just Osborne themselves? I for sure have decided to hold off on a Pi-4 until this issue is fixed, since its really a hassle. Maybe a smarter move would've been to bundle the Pi-4 charge (non E-cable) to avoid dissatisfaction with this mis-design ..
- gruez 7y agoThem fixing this issue in a future revision is almost a given (it's a simple fix), so them making that statement doesn't really affect anything. Therefore it's not really the Osborne effect in the sense that people are holding off for a better product, people are holding off buying because it's defective.
- jhbhjjhvhjkgh 7y agoor you can just buy a $5 cable on amazon it sucks but it's not a deal breaker.
- walrus01 7y agoIt's really only an issue if you're trying to power a pi4 from a high powered USB-C power delivery source source like a macbook, macbook air or macbook pro AC wall adapter. It would be a waste of money to use a $18 USB-C cable on a pi4. I can see how this would be discovered quickly, since a lot of the early purchasers of the pi4 probably tried to power them up using the nearest USB-C power source at hand, which was their laptop's power adapter. If you use a USB-C phone charger or any of the cheaper USB-C power sources intended to power things under 20 watts, it shouldn't be an issue. But they definitely do need a new board revision.
- baq 7y agoThey provide their own charger. It works, I’ve got one.
- tjohns 7y agoYes, but it's an extra expense. If you've got spare USB-C chargers you could use, it's tempting to wait.
- jbarberu 7y agoWhile this isn't great, as a consumer I don't really see too big of a problem. If I get a raspberry pi to use for home automation or as a media center, do I really need it to work with every USB-C cable? I'd think I'd just find one that works and let that be the dedicated raspberry 4 cable. If you're building a product based on Raspberry Pi that you're selling to others, then sure I could understand the outrage.
- solarkraft 7y agoYou might want to use a type c charger you already have or a power bank.
- protomyth 7y agoOr the person buying it is the increasingly number of non-technical people buying Raspberry Pis. To them, its just broken and needs to be returned.
- kllrnohj 7y agoThey 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?
- inflatableDodo 7y ago>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? See also: People who like to get all creative with encryption library implementations in commercial settings. If implementing a standard protocol, unless you have a very good reason otherwise, you should; 1. Go and find the guide by the people who designed it. 2. Read the guide and make test thingies till you are sure you understand it. 3. Now go and do what the guide tells you to do.
- seiferteric 7y agoIs it possible to fix? Sounds like it's just missing a resistor? Break out the soldering iron and maybe could it could be salvaged.
- HeWhoLurksLate 7y agoPart of the problem with this seems to be that the extra pads are not exposed, making it really hard to do fix without removing the connector.
- makomk 7y agoThe problem isn't just the missing resistor, it's that two pins are tied together when they shouldn't be. I don't think it's feasible to fix that on such a dense multilayer board.
- Havoc 7y ago>a board revision with a spec-compliant charging port should be out sometime in the "next few months." wohoo. Glad I waited. Hoping they make some incremental gains on the heat situation too
- Luyt 7y agoNormal-sized HDMI connectors would be great, too.
- solarkraft 7y agoHow hard is it to to copy a [expletive] schematic? Edit: I'm serious. What convinced them to implement a design different from the example in the spec that simply does not work (hello, testing?)?
- SSilver2k2 7y agoThe USB-C spec is 300 pages with multiple errata and revisions. It's not just one schematic.
- openthc 7y agoFTA: Benson Leung seems to think they should have copied figured 4-9 -- https://medium.com/@leung.benson/how-to-design-a-proper-usb-c-power-sink-hint-not-the-way-raspberry-pi-4-did-it-f470d7a5910 https://medium.com/@leung.benson/how-to-design-a-proper-usb-... I don't think a long and imperfect specification is a good excuse for getting this one wrong -- since this specific part of the spec is a MUST and accurate.
- thumb 7y agoYes, forget due diligence. It's too much work.
- rolltiide 7y agoGreat maybe theyll deliver the 8gb model while theyre at it
- kylec 7y agoQuadrupling the memory over the previous version wasn't enough for you?
- rolltiide 7y agono it wasn't there are references to an 8gb model already so no need to act surprised when they do launch it
- ars 7y agoThere is no 8gb model, there is no memory chip of that type that would fit in the spot.
- rolltiide 7y agohm alright, thank you
- groovybits 7y agoFrom 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 all' connector. We're slowly heading in the opposite direction.
- oftenwrong 7y agoUSB Type-C is an example of the second-system effect: http://catb.org/jargon/html/S/second-system-effect.html http://catb.org/jargon/html/S/second-system-effect.html
- ChristianBundy 7y agoAlternatively: https://en.wikipedia.org/wiki/Second-system_effect https://en.wikipedia.org/wiki/Second-system_effect
- m463 7y agoalternatively, "There are 14 competing standards"... https://xkcd.com/927/ https://xkcd.com/927/
- umvi 7y agoSo basically Type-C is like the F-35 of the USB world?
- CriticalCathed 7y agoUSB C has confused me for the same reason. I read often about how there is no expectation that two USB-C cables/ports will work together. Why design them to fit together if they won't always work right?
- weberc2 7y ago
- chadlavi 7y agoI preordered, and it hasn't shipped yet. I wish there were an option to wait and get a fixed one later instead.
- heywire 7y agoI ended up cancelling my pre-order from Element 14, you could potentially do the same depending on who you ordered from. I didn't cancel because of this, but just because I got really busy with work and I know it'll be a few months before I get to pull it out of the drawer. Better to let someone else have it to use than take a pre-order spot for my desk drawer.
- agumonkey 7y agoThey should offer group labs to DIY fix the pcb
- soared 7y agoInteresting 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.
- echeese 7y agoProbably a mix of complicated standards, NIH, lack of standards compliance testing, and "works on my machine"
- topspin 7y agoWell, I followed through to Benson Leung's post where he cites and transcribes the actual USB-C specification and I'm not surprised that the spec is occasionally ignored. The supposedly 'normative' circuit diagram deviates from a conventional circuit diagram. If you want an engineer to pay attention to your instruction don't invent some ad-hoc diagram technique; be concrete and prescriptive, and assume you're dealing with a low caliber worker, because 99% of the time that's exactly who will get tasked to deal with your specification. [1] https://medium.com/@leung.benson/how-to-design-a-proper-usb-c-power-sink-hint-not-the-way-raspberry-pi-4-did-it-f470d7a5910 https://medium.com/@leung.benson/how-to-design-a-proper-usb-...
- qtplatypus 7y agoHow does it diverge from a conventional circuit diagram?
- topspin 7y agoSee the circuit diagram above labeled "Excerpt from the reduced Pi4 Model B schematics..." that appears above the spec diagram? That is what I mean by a "conventional" diagram. That is the sort of diagram that people tasked with engineering boards (as opposed to writing standards) are use to dealing with all day. The spec diagram looks like an abstract block diagram, as opposed to a concrete circuit. Now, you are very likely to say something like "but the spec diagram is a correct circuit diagram and the engineer should be expected to comprehend and correctly implement a circuit using it." And you're not wrong. But unfortunately, as is clearly evident by the frequency of failure to convey the intent of the spec, this expectation is too great. It shouldn't be but it is. That's a difficult thing to accept. For many it is simply impossible to accept. But yet that's the cold, simple truth and standing on ceremony doesn't change it. When it costs money, in the form of lost sales due to disappointed customers or excessive support costs, "better" (as in more concrete, prescriptive) circuit diagrams are provided. One can see this in the datasheets and application notes from successful component manufacturers. They do this because they have to take the calls when engineers misunderstand things or need their hand held. They do this because they hear from managers and executives when their products are not "easy" to integrate. Standards authors don't feel this pressure, so the subtle and easily dismissed gap between what appears in standards documents and what people actually want (and therefore pay attention to) is wider. What is wanted is something that appears nearly indistinguishable from what the engineer would expect to see while using Altium or Eagle or KiCad or some other commonly used EDA tool, and not a specification sufficient generalization.
- kawsper 7y ago>a board revision with a spec-compliant charging port should be out sometime in the "next few months." Are they going to change the boxes and their product spec to remove USB-C from it when they are not USB-C compliant?
- w0mbat 7y agoI think the Pi team unintentionally became dependant on the time window they normally spent using test boards based on pre-release versions of the Broadcom sytem-on-a-chip. When the Broadcom chip went final really early they ended up shipping a half-baked version of the board along with it.
- tracker1 7y agoI mentioned in an earlier thread, I had so much trouble using any charger I already had with the 3B+, I just assumed it wouldn't work with most chargers this time either and ordered a kit with an official one.
- ageofwant 7y agoSame, I traced it back to my penchant for buying cheap shit cables. Measure the voltage at the back of the USB connector on the Pi3, it should be > 4.9 always.
- Bob995 7y agoDo I still need to pay them extra cash to get video codecs codes?
- vardump 7y agoI have two RPi4B 4GB models. They work perfectly with the very cheap PSU/charger ($8) from the Raspberry Pi Foundation. $8 is less than a cost of a USB-C cable. If you want to complain something about the product, I think unfinished software would deserve more attention. The current desktop performance doesn't reflect the capabilities of the system. I guess it'll significantly improve once OpenGL ES 3.2 (and hopefully Vulkan!) drivers will be complete. Other minor issue I had was RPi4B not recognizing the HDMI display. I had to manually force it and this caused loss of HDMI audio. Using the official Raspberry Pi branded micro-HDMI cable. I hope Raspbian will eventually have a 64-bit version. Out-of-order cores can benefit from more registers in 64-bit mode. More registers allows the compiler to reduce true and false dependencies, leading to faster code execution. CPU wise it's nice, quad Cortex A72 is a huge boost compared to A53. Hardware accelerated omxplayer can play 4K HEVC content nicely. USB 3 ports have up to 4 Gbit/s bandwidth, and it's not shared with the now truly full speed gigabit ethernet. I'm very happy with the product. RPi4B is a very capable system for its price. And it'll just get better over time.
- Luyt 7y agoThere is a 64-bit Kali Linux image for the Raspberry Pi. https://www.offensive-security.com/kali-linux-arm-images/ https://www.offensive-security.com/kali-linux-arm-images/
- xparco 7y agoSuch a cheap and ghetto design....typical Linux nerd stuff