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posted by martyb on Wednesday July 10 2019, @04:04AM   Printer-friendly
from the so-much-for-port-a-bility dept.

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

The Raspberry Pi 4 was announced two weeks ago as a major new upgrade to the line of cheap single-board hobbyist computers. The Pi 4 featured a faster CPU, options for up to 4GB of RAM, and a new, modern USB-C port for power delivery. The Pi 4 was the Raspberry Pi Foundation's first ever USB-C device, and, well, they screwed it up.

As detailed by Tyler Ward, the Raspberry Pi 4 has a non-compliant USB-C charging port and doesn't work with as many chargers as it should. Thanks to the open nature of Raspberry Pi (even the schematics are online!), Ward was able to discover that Raspberry Pi just didn't design its USB-C port correctly. Two "CC" pins on a USB-C port are supposed to each get their own 5.1K ohms resistor, but Raspberry Pi came up with its own circuit design that allows them to share a single resistor. This is not a compliant design and breaks compatibility with some of the more powerful USB-C chargers out there.

[...] The Pi 4 is not the first high-profile device to get the USB-C spec wrong. The Nintendo Switch also has a non-compliant USB-C port and has issues with certain USB-C cables as a result.

After reports started popping up on the Internet, Raspberry Pi cofounder Eben Upton admitted to TechRepublic that "A smart charger with an e-marked cable will incorrectly identify the Raspberry Pi 4 as an audio adapter accessory and refuse to provide power." Upton went on to say, "I expect this will be fixed in a future board revision, but for now users will need to apply one of the suggested workarounds. It's surprising this didn't show up in our (quite extensive) field testing program."

Probably not a dealbreaker (the cables that do work are cheaper), but could be annoying.

Previously: Raspberry Pi 4 Model B Launched


Original Submission

 
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  • (Score: 2, Interesting) by driverless on Wednesday July 10 2019, @05:58AM (4 children)

    by driverless (4770) on Wednesday July 10 2019, @05:58AM (#865293)

    It's not just that, the Pi's have been full of hardware design flaws since the very first one (no real power protection circuitry, no proper USB protection circuitry, backpowering the Pi by plugging in a USB device, ethernet-over-USB, the list goes on and on, and some of it is the most basic stuff, just copy the sample circuit from the manufacturer's data sheet). You'd think that by version 4 they'd have finally got good designers to work on it, but it seems every time they fix up one mistake they add two more.

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  • (Score: 5, Informative) by Booga1 on Wednesday July 10 2019, @10:40AM (1 child)

    by Booga1 (6333) on Wednesday July 10 2019, @10:40AM (#865333)

    I know you refer to them as flaws, but from their perspective I'm sure they were tradeoffs. When they announced they were going to make a whole computer for $25 people said it couldn't be done, not at that price at least.
    They got it made at the promised cost and achieved far more than many expected. Now there's models for $5 and even the latest ones at highest spec are only $55.

    Every time I look at any of the other similar low cost boards I see a lot of similar trade off decisions made. If they gave in to everyone's favorite pet peeve, it'd be $4 more for an eMMC slot, $3 more for some on-board EPROM, $5 more for supporting full size dual-HDMI ports, and so on until the product costs another 30-50% more or higher.

    They're not perfect, but for what they are they seem pretty reasonable to me. They're also not the only micro-PC maker any more.
    If you need something that the Raspberry Pi doesn't do there's probably an ODROID, Arduino, or other board that does. The choices are getting better every time I look.

    • (Score: 4, Interesting) by driverless on Wednesday July 10 2019, @11:27PM

      by driverless (4770) on Wednesday July 10 2019, @11:27PM (#865554)

      I know you refer to them as flaws, but from their perspective I'm sure they were tradeoffs.

      I don't think they're conscious tradeoffs, some like the USB-ethernet bridge may be, but a lot of others are just bad design. Look at one of the Pi's most notorious problems, its habit of trashing its firmware. The standard response to this is "you've used a bad SD card", and that's certainly true for a percentage of users who go with the cheapest Chinesium SD cards you can get, but it doesn't hold when you're using something like a Samsung EVO and it still trashes its firmware. For that, you have to look at the design: Cheap cellphone charger and micro USB port instead of a proper power supply and barrel jack connector, little to no power control/conditioning (unless they've fixed this in the 4), an SD card instead of eMMC, and a filesystem that's totally wrong for flash. It's wrong piled on wrong piled on wrong. Every single Pi I've ever worked with has trashed its firmware at least once, in same cases several times. Every single non-Pi I've worked with has never trashed its firmware, because the hardware was designed properly. If you compare the Pi to something like an Odroid, it's like an anti-Pi, the hardware is done right and it costs only a little more than a Pi (depending on spec). Unless your time is free (mine isn't), I'll pay a bit more and know that the device I'm using won't need constant coddling and nursing just to keep them running.

      Then there's the incidental costs. Sure, you can get a Pi for $little, but then I've had to spend more than the cost of the Pi to add a Pi-compatible power supply, a Pi-compatible USB hub, and a pile of other crap that's needed to compensate for the Pi's bad hardware design. I'm happy to pay a massive $10 more for something that isn't a Pi just to avoid all the Pi-specific crap you have to go through to get it running and keep it running. Heck, I'd pay double the price of the Pi to get something reliable, although I don't really need to do that because Pi competitors are roughly in the same price range, but properly designed.

  • (Score: 3, Interesting) by RS3 on Wednesday July 10 2019, @01:27PM

    by RS3 (6367) on Wednesday July 10 2019, @01:27PM (#865366)

    You are spot-on, IMHO. I'm often stunned by how bad some circuit designs are, when the manufacturers give free design guide circuits. Just copy the circuit, maybe tweak some values assuming you know what you're doing. It's the original open-source. Transistor and IC spec. books always did / do this.

  • (Score: 2) by DannyB on Wednesday July 10 2019, @01:52PM

    by DannyB (5839) Subscriber Badge on Wednesday July 10 2019, @01:52PM (#865374) Journal

    the Pi's have been full of hardware design flaws since the very first one (no real power protection circuitry, no proper USB protection circuitry, backpowering the Pi by plugging in a USB device, ethernet-over-USB, the list goes on and on

    Because they are designed for children to use.

    --
    People today are educated enough to repeat what they are taught but not to question what they are taught.