from Hacker News

Raspberry Pi 4 not working with some chargers

by styx31 on 7/5/19, 12:20 PM with 300 comments

• by an_d_rew on 7/5/19, 4:27 PM

  There have been a lot of comments here but I want to leave one specifically to the person or team who designed the Pi’s circuitry:

  Thank you for working on such an important project and thank you for all the things that you got right.

  I’m sure that somewhere, someone is feeling a little bit embarrassed and possibly somewhat sheepish over this and… Please don’t let one incident overshadow all the great things that have come from the existence of the Raspberry Pi!

• by gadgetoid on 7/5/19, 2:55 PM

  Ever since the very first model, sub-par, underrated power supplies have been responsible for a good slice of tech support issues with the Pi. It wouldn't be a real Pi launch without power issues.

  IIRC the Pi 3B+ was butting up against (if not exceeding) the maximum rated current for the microUSB port, so I believe the switch to USB Type-C is more about picking a port that can handle a 3A@5V supply than a conscious effort to support the dozens and dozens of terrible and near arbitrary USB Type-C supplies on the market (some output 12V with zero negotiation. You know- for giggles). I'd be surprised if they tested with more than a couple of staff phone chargers and their own-brand chargers. I can't imagine the idea of anyone using an expensive power-delivery enabled dock with a thick, 40cm Thunderbolt 3 cable really entered their minds.

  My advice to anyone buying a Pi 4 would be "Just buy a Pi-branded power-supply. They're inexpensive and guaranteed to work." Granted you might want to save a few bucks and use your phone charger... but then what are you going to use to charge your phone?

• by michaelt on 7/5/19, 12:56 PM

    The fact that no QA team inside of
    Raspberry Pi’s organization caught
    this bug indicates they only tested
    with one kind (the simplest) of USB-C
    cable.
  
    Raspberry Pi, you can do better.
  

  I'd say at least 20% of the blame lies with whatever genius decided to have multiple types of USB-C cable

  I mean, cables already suffer from having A, Type A SuperSpeed, B, B SuperSpeed, Mini-B, Micro-B, Micro-B SuperSpeed, C, and lengths from 10cm to 5m. Who'd expect adding a complete extra dimension of difference to be trouble-free?

• by pavlov on 7/5/19, 12:43 PM

  Before we had separate ports and cables for power, USB and Thunderbolt. There was no way to plug the wrong cable in the wrong port.

  With USB-C, we still have separate cables for these three types, but they all look confusingly the same. Not convinced this is an improvement.

• by cesarb on 7/5/19, 4:29 PM

  There might be yet another issue. As commented by the author of this blog post in the RPi forums (https://www.raspberrypi.org/forums/viewtopic.php?f=63&t=2438...): "Also the 5v on the connector is connected directly to the 5v rails. If the pi is powered over the GPIO then the USB-C connector is vbus hot which means it could backfeed devices when using the type C port on the pi as a USB client."

  That is, when powering the RPi4 through PoE, its USB-C connector is in an invalid configuration: it's powering VBUS when it shouldn't (that is, unlike USB-A where VBUS is always on, IIRC with USB-C it should only be turned on when the CC pins detect that the other side is either a power sink or an adapter which should source power).

• by zimbatm on 7/5/19, 1:15 PM

  TIL; there are different types of USB-C cables with functional differences.

  How do you know what type the cable is? Is is possible to detect it visually?

• by chx on 7/5/19, 5:12 PM

  How does the HN system work when I submitted the exact same URL https://news.ycombinator.com/item?id=20317687 five days ago??? We have stickied this on the usbchardware subreddit as well at the time, it's still on the top: https://www.reddit.com/r/UsbCHardware/ We have a nice wiki and if you are still confused about USB C, ask away, we try to help (chances are, I will answer :) ). You will also find a wonderful cornucopia of interesting USB C devices -- not just the usual chargers, power banks and docks but also a toothbrush, a razor, headphones, speakers, video lights, a soldering iron... we like USB C :)

• by timw4mail on 7/5/19, 12:44 PM

  The Raspberry Pi foundation has their own "official" USB-C power adapter as well (At least, they have it for pre-order). So I doubt it's the highest priority.

  I can still see this getting fixed in a future revision, but I think it will be a while. It is an issue, but it doesn't make the pi 4 useless.

• by MobileVet on 7/5/19, 12:44 PM

  Curious what led to this decision. Reference schematics exist for a reason... It seems odd to not use them.

• by consp on 7/5/19, 12:49 PM

  I would not be surprised if this is the default in the bcm2711 documentation and they simply took that as guidance.

• by ilikepi on 7/5/19, 12:32 PM

  So the take-away for consumers is...what exactly? Don't use certain types of cables to power a RaspberryPi 4? And how does one identify a cable that could cause problems?

• by seaborn63 on 7/5/19, 12:53 PM

  I read it but I have no idea what it meant. I am very interested in getting a Pi4, so can some of you more knowledgeable folks help me understand what this means?

• by crshults on 7/5/19, 12:53 PM

  Had to fire up Eagle quick and take a look at my latest design (first time using USB-C). Looks like I got lucky this time.

• by Roritharr on 7/5/19, 12:42 PM

  Wow, this is really bad.

  I have enough USB-C incompatibility in my life to make this the issue that makes me not order the Raspberry 4 until this issue is sorted out.

• by baybal2 on 7/5/19, 1:18 PM

  Usb PD + type C is hard. You have to read specs for days just to get a basic idea of the logic governing the negotiation protocol.

  I'm waiting for a single chip solution that will take upon the pain of dealing with Type-C for me.

  Besides the complexity of the spec itself, another "landmine" in dealing with Type C + PD is the divergence of different PD implementations, proprietary extensions from big brands, and... DRMed power supplies along with devices with DRMed PD devices... Yes, the electricity is now copyrighted too.

• by w0mbat on 7/5/19, 7:01 PM

  There's a project management lesson here.

  Raspberry Pi 4 was planned for 2020, but the Broadcom SOC went final much sooner than expected, so they shipped the Pi 4 this year.

  This sounds like a great thing, but the earlier release meant that the board as a whole spent less time being used internally before release, and they didn't have the time to shake out bugs like this.

  The lesson: when you move to a faster release cadence, you need to be more rigorous about QA because you have less time to find problems before release.

• by Scuds on 7/5/19, 7:54 PM

  Odroid, Latte Panda, Pine, and others went with dedicated tried and true barrel jacks.

  I appreciate re-using the same microusb cables and chargers for my iPhone and headset charger for my Pi3, and not having to handle Yet Another Wall Wart, but barrel jacks would have sidestepped this whole issue.

  Were they hoping to have users use a single cable deliver power and data over a single cable usb just like a pi zero w? https://desertbot.io/blog/ssh-into-pi-zero-over-usb

  God DAMN I hope this doesn't turn into a recall.

• by mrlambchop on 7/6/19, 2:02 AM

  The Pi people are good folk - all that is needed is to run the USB 3 conformance tests and report back the results (both as USB PD sink and source). Better to know the knowns than have a enthusiastic fan base find them and we get into discussions like this!

  I'd also recommend they put up a compatibility table of power supplies on their website in time - probably cables as well! Its a good opportunity to collaborate with the Google engineer who has been spending his non-core hours on the USB-C madness.

• by amelius on 7/5/19, 12:49 PM

  > The short summary is that bad things (no charging) happens if the CC1 and CC2 pins are shorted together anywhere in a USB-C system that is not an audio accessory.

  Why should it matter what kind of accessory it is used in?

  > Each CC gets its own distinct Rd (5.1 kΩ), and it is important that they are distinct.

  Why?

  I think this article was not written by an electrical engineer. The reason why this design is inadequate still eludes me. But, RPi should have probably used the reference design, that's clear.

• by geekamongus on 7/5/19, 7:10 PM

  I just wish I could find a 4GB Pi 4 in stock/for sale so that I could even have this problem.

• by _wmd on 7/5/19, 1:02 PM

  Pretty unfortunate design flaw, and hopefully it can be corrected, but this post is horribly finger-pointy and the tone generally stinks. Would hate to make a mistake while working around this guy

  Can the link be changed to the apparent source article? It's not as bad. https://www.scorpia.co.uk/2019/06/28/pi4-not-working-with-so...

• by moonbug on 7/5/19, 2:22 PM

  Says more about the quality of no-name usb wotsits

• by fortran77 on 7/5/19, 2:57 PM

  Everything works for me except my Apple charger. I blame Apple.