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Design flaw prevents the Raspberry Pi 4 from working with all USB-C cables

By Shawn Knight · 31 replies
Jul 9, 2019
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  1. The Raspberry Pi Foundation a couple of weeks back announced its latest single-board computer. The Raspberry Pi 4 Model B features multiple enhancements over its predecessor including – for the first time – a USB-C connector for power delivery.

    Unfortunately for the foundation and early adopters, an issue has been identified with the board that could hinder its use under certain circumstances.

    As Tyler Ward explains (via Ars Technica), each of the two CC pins on the USB-C port is supposed to get its own resistor but for some reason, the Foundation designed the Pi 4 to share a single resistor. This makes the implementation a non-compliant design and tampers with compatibility.

    It all boils down to the type of cable you use. Most cables should work fine although if you have an electronically marked or e-marked USB-C cable like the ones typically used to charge laptops, it may not work.

    Raspberry Pi co-founder Eben Upton told TechRepublic that smart chargers with an e-marked cable will incorrectly identify the Raspberry Pi 4 as an audio adapter accessory and refuse to provide power. Upton added that he expects the issue to be fixed in a future board revision but for now, users will need to apply a workaround [use a cable that isn’t e-marked] to circumvent the problem.

    “It’s surprising this didn’t show up in our (quite extensive) field testing program,” Upton said.

    The Raspberry Pi Foundation isn’t the only one to have flubbed this up. Nintendo’s Switch also has a non-compliant USB-C port and thus, has compatibility issues with certain USB-C cables.

    Masthead credit: Close up of Raspberry Pi 4 by mrnok

    Permalink to story.

  2. yRaz

    yRaz Nigerian Prince Posts: 2,892   +2,219

    As much as I love USB-C, it seems like it is having A LOT of problems on all ends. They tried to do too many things at once when, arguably, we we're better off having different standards instead of a "one size fits all" kinda deal
  3. wiyosaya

    wiyosaya TS Evangelist Posts: 3,993   +2,292

    SMD resistors in quantity cost probably less than $0.01 each. Whoever made the decision to go with one instead of two is the one that should, IMO, take the responsibility for this action. I have to ask "what were they thinking - that they were going to get rich saving less than $0.01 per board manufactured?"

    Specs are written for a reason. Not following the spec is questionable at best. If there are other problems (not addressed by this article) out there with USB-C, this makes me wonder if the manufacturer's of the devices with those problems did not follow the spec.
  4. mcborge

    mcborge TS Guru Posts: 576   +467

    I'm glad I haven't picked one up yet. You would have thought that this issue would have been noticed before production started. Manufacturers are so eager to get their products out the door these days it was only a matter of time before The Raspberry Pi Foundation did the same. It looks like I'll be waiting for the next revision.
  5. EEatGDL

    EEatGDL TS Evangelist Posts: 693   +376

    And here I am assuming that they go through a certification and compliance process for anything deemed "standard".
  6. Stuach

    Stuach TS Rookie

    With ALL? Click bait.... With ALL...once again....how sad... And somehow these people think they should be taken at their word... Hey ,,,look ...the new FOX news
    Last edited: Jul 9, 2019
    TheBigT42 likes this.
  7. cliffordcooley

    cliffordcooley TS Guardian Fighter Posts: 11,399   +5,021

    There was no click-bait in that heading. The heading was completely accurate this time.
  8. Stuach

    Stuach TS Rookie

    No, it says with ALL. Even at 66yo, I can read the requirements...look again...ALL...ALL... I provided the CORRECT connection. As a development board....this thing rocks
    TheBigT42 likes this.
  9. Lew Zealand

    Lew Zealand TS Guru Posts: 673   +573

    "with some USB-C cables" is more accurate but the headline is OK as it is.
  10. Stuach

    Stuach TS Rookie

    Headline :
    Design flaw prevents the Raspberry Pi 4 from working with all USB-C cables
    TheBigT42 likes this.
  11. Stuach

    Stuach TS Rookie

    See those words.... ALL...
    TheBigT42 likes this.
  12. cliffordcooley

    cliffordcooley TS Guardian Fighter Posts: 11,399   +5,021

    What is hard to understand about the phrase "doesn't work with all"? There are some cables that prevent the device from working with all.
    TheBigT42 likes this.
  13. Stuach

    Stuach TS Rookie

    No..."doesn't work with all" means it won't work with anything. Wholly hell...the entire race is done. ALL....are you daft
    TheBigT42 likes this.
  14. cliffordcooley

    cliffordcooley TS Guardian Fighter Posts: 11,399   +5,021

    You are giving the word all a specific definition when it is not. The device would have to work with every cable in order to work with all cables. You are looking at this from the wrong perspective. I bet phrases like exclusive or and exclusive nor would blow your mind.
    Slappy McPhee likes this.
  15. lexster

    lexster TS Maniac Posts: 466   +233

    It wasn't about cost. It was about not enough documentation in the wild that the engineers knew about. Lesson learned. This issue is being blown out of proportion. Use a cable/charger that isn't "E" marked, which most aren't and you're fine.
  16. Stuach

    Stuach TS Rookie

    That WAS in the description
    lexster likes this.
  17. Stuach

    Stuach TS Rookie

    I agree, these little people.... I should have a total working desktop.. But I don't code...so let me slam this so I look good
    lexster likes this.
  18. wiyosaya

    wiyosaya TS Evangelist Posts: 3,993   +2,292

    FYI - the USB Type-C specification was published on October 1, 2017. In fact, YOU can download it from the usb.org web site at this link https://www.usb.org/sites/default/f...rt_controller_specification_rev2.0_v1.0_0.pdf

    In fact, there is an even earlier compliance specification for Type-C connectors and cables that YOU can also download from here - https://www.usb.org/sites/default/files/USB_Type-C_Compliance_Document_rev_1_2.pdf

    Not enough copies out in the wild? Uh-huh.
    cliffordcooley likes this.
  19. lexster

    lexster TS Maniac Posts: 466   +233

    Ok, read through and find the spec that designates the design requirement specified by the problem discussed in this article. I'll wait...

    Implying that the designers at the RPi Foundation are less than competent is a woeful overstatement and Techspot calling it a design "flaw" is more than a bit of an overstatement as well. It's an incompatibility, not a design flaw. Context matter.
    Last edited: Jul 10, 2019
  20. amghwk

    amghwk TS Guru Posts: 523   +320

    It may or may not have been meant to be a clickbait, but it did say "all" in the heading, which is crystal clear on it's meaning which turns out not to be true when you keep reading the article since within the gist it says "most cables should work fine..." which doesn't reflect on the heading title. This is one of the situations we describe as clickbait.
  21. cliffordcooley

    cliffordcooley TS Guardian Fighter Posts: 11,399   +5,021

    OMG not another one. You people need to learn how to read. This device does not work with all cables. Why is that sentence so difficult to understand? If the device doesn't work with even one cable, it doesn't work with all of them. You two are making it sound as if the word all means 100% of the cables. That is not what it means.
  22. kenc1101

    kenc1101 TS Booster Posts: 37   +36

    I think a better wording would have been "Doesn't work with SOME USB-C cables." I agree with you that the wording is a little confusing.
    Last edited: Jul 10, 2019
  23. kenc1101

    kenc1101 TS Booster Posts: 37   +36

    Because the headline reads "Design flaw prevents the Raspberry Pi 4 from working with all USB-C cables". It doesn't say all cables, it says all USB-C cables. Which is very different. And misleading.
  24. Lounds

    Lounds TS Addict Posts: 197   +124

  25. amghwk

    amghwk TS Guru Posts: 523   +320

    Man...seriously? Okay think whatever you want.
  26. stewi0001

    stewi0001 TS Evangelist Posts: 2,198   +1,625

    This is all I could think of:
    lexster likes this.

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