back to article Raspberry Pi supremo Eben Upton talks to The Reg about Pi PoE woes

People are reporting problems with the newly released Power Over Ethernet adaptor for the new Raspberry Pi 3 Model B+, with non-functional USB ports causing much anguished wailing. The Power Over Ethernet, Hardware Attached on Top (PoE HAT) board allows a Pi 3B+ to be powered over Ethernet rather than requiring its own power …

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  1. alain williams Silver badge

    Oh dear, a fan

    pity because it is something that moves & so may fail, especially in a dusty environment, where otherwise it might be expected to just work for years.

    1. The Mole

      Re: Oh dear, a fan

      I'm sure you could just switch it out for a stonking big heatsink instead. Or just not do POE and run a real power cable. For many people I doubt the life of the fan in their environment will be a concern whilst they may care more about size/cost.

      1. Pen-y-gors Silver badge

        Re: Oh dear, a fan

        PoE has a lot of plus points. I was looking at Rasp prices a couple of days ago and saw mention of the PoE HAT. I'm only running one 'production' Pi at the moment, that is feeding a TV slide show. I've got the Pi getting updates via ethernet, but I've also got a power supply strapped to the back of the TV. I have another box on the network getting PoE so I could easily add another to the cabinet, which would mean less cabloid mess behind the telly!

        1. Doctor Syntax Silver badge

          Re: Oh dear, a fan

          "have another box on the network getting PoE so I could easily add another to the cabinet, which would mean less cabloid mess behind the telly!"

          I look on it the other way round - what's one more cable given the mess that's there already? I don't think I'd like the fan and SWMBO certainly wouldn't.

      2. Doctor Syntax Silver badge

        Re: Oh dear, a fan

        "Or just not do POE and run a real power cable."

        There are probably industrial applications where PoE has advantages.

        1. Stoneshop Silver badge

          Re: Oh dear, a fan

          There are probably industrial applications where PoE has advantages.

          My PoE switches are powered off an UPS, so anything powered via PoE automatically benefits. And the other advantage is that via those switches I can switch off or power cycle all of those devices remotely.

          In my house there's at least one Arduino in an inaccessible location that I would not think of powering any other way.

          1. Lee D Silver badge

            Re: Oh dear, a fan

            PoE has many uses.

            The fans can also be disabled - it was a "freebie" with the board, not required for the PoE to operate. Additionally, the RPi has adequate temperature control (by throttling) without any fans at all. So the "only moving part" can fail and not much will change. Or you can just turn it off.

            PoE in an official box means that these things can replace lots of things. Everything from IP phones to IP-based speakers, can be powered throughout a building from a central place (with UPS, etc.) and also be pretty invisible when in situ.

            My workplace has PoE phones, wireless (APs and bridges), cameras and speaker/alarm boxes. The Pi can directly replace at least three of those. Not to mention things like thin clients (the free utility rdesktop on a Pi is actually SOLD by a company called nComputing as a thin client for Windows or Linux remote desktops), etc.

        2. Stuart Castle

          Re: Oh dear, a fan

          I've been thinking about a project where I work where POE powered PIs may be a good thing. We have a lot of rooms that are bookable. The bookings are made largely online, and the timetables are available online.

          I was thinking about a 10 inch LCD, with a Pi for each room, displaying that room's timetable, so people can easily look up if a room is booked. I know that there are companies that sell LCDs specially set up to do this, but that's likely to be expensive, and possibly tie us into an expensive maintenance contract. Besides, I'm a technician at heart. I think a large part of me likes the idea of a home grown solution to a problem.

          POE could be handy for that, as we don't necessarily have power sockets near where we would want the displays. That said, we don't currently have ethernet sockets near them either, and as we use the same contractor for both, it would be relatively easy to get them to fit both at the same time.

          1. Glen 1 Bronze badge

            Re: Oh dear, a fan

            Re: door displays.

            Depending on how much of a project you want, you could use ereaders. Set them up pointing at a web page of the calendar and tweak the timeout settings and you have a display that looks better than the cheaper lcds

          2. bboyes

            Re: Oh dear, a fan

            @Stuart Castle - yes a great idea but watch the power budget. The PoE HAT is rated for up to 2.5A at 5V and the 7" Pi Touchscreen needs almost 500 mA alone. A 10" display likely more, mostly into the LED backlight. I bought the PoE HAT with a similar idea using the RPi 7" official touchscreen or a more sunlight-readable equivalent I found from NHD (ordered, still to be tested).

          3. the hatter

            Re: Oh dear, a fan

            Without a strong plan for a sufficiently low-power display that is still large and legible enough, you're going to end up needing a power socket for that part anyway. Even keeping within the higher currents provided by the later specs, your switch may be limited to how many can be supplied at that current, vs all 12/24/48 ports at a lower standard.

        3. bboyes

          Re: Oh dear, a fan

          "There are probably industrial applications where PoE has advantages."... yes, a few, like the hundreds or thousands of WAP boxes on college or business campuses, where running power is a real PITA, so a huge gain for PoE. Not to mention mains power supplies are a common point of failure in such deployments: another win for PoE. At the endpoint (in this case the PoE HAT) you still need a switcher from the PoE 48V to the local 5 or 3.3V but that's way easier than a mains switcher. My PoE HAT is still in the box, curious to see if I'm bitten by this bug.

    2. James Hughes 1

      Re: Oh dear, a fan

      You can turn the fan off if you wish. Usually it's controlled by the Pi itself, so only turns on when required, and will be sped up/slowed down as necessary. If off, then the Pi will use its normal temperature control system, which may throttle the CPU if it get too warm.

    3. Stevie Silver badge

      Re: Oh dear, a fan

      Agreed. Real computers are cooled by convection currents in the liquid sodium coolant.

      Or is that fast breeder reactors? I always get the two confused (which explains the prompt criticality fiasco when I deployed my home-made set-top box).

      1. Gene Cash Silver badge
        Mushroom

        Re: Oh dear, a fan

        > the prompt criticality fiasco when I deployed my home-made set-top box

        I just don't get my demon cores from Intel...

      2. David 132 Silver badge
        Happy

        Re: Oh dear, a fan

        Stevie Or is that fast breeder reactors? I always get the two confused (which explains the prompt criticality fiasco when I deployed my home-made set-top box).

        For some reason this passage from Good Omens comes to mind:

        “He plugged it in to the socket. Then he switched the socket on.

        Every light in the house went out.

        Newton beamed with pride. He was getting better. Last time he’d done it he’d blacked out the whole of Dorking, and a man from the Electric had come over and had a word with his mum.”

    4. Anonymous Coward
      Anonymous Coward

      Re: If only the the folk at Nvidia were as honest to own up to their mistakes.

      If only the folk at HP/Nvidia were as honest as Eben Upton, to own up to their poor product testing, that has left so many Geforce based laptops dead from poor Geforce GPUs/poorthermal design and the use of lead free solder. These companies have just kept kicking the can rather than properly dealing with the problem.

      Apple did something at least. Apple dropped Nvidia, though Apple have done the minimum in terms of dealing with the historic problem circa 2010-2012 iMacs, now branded 'Vintage'.

      1. Trollslayer Silver badge
        Flame

        Re: If only the the folk at Nvidia were as honest to own up to their mistakes.

        @AC

        "If only the folk at HP/Nvidia were as honest as Eben Upton, to own up to their poor product testing, that has left so many Geforce based laptops dead from poor Geforce GPUs/poorthermal design and the use of lead free solder."

        You literally have no idea about modern soldering.

        To get BGA connections at the required density requires the solder has extremely precise characteristics and unfortunately the effects resulted in joint fractures after a combination of time, changes in the solder and temperature cycles which arose from the varying workload.

        Yes, I worked at Nvidia (a non graphics division) and Jensen was genuinely upset about letting the customers and users down. I even met him once, a nice guy.

    5. bombastic bob Silver badge
      Meh

      Re: Oh dear, a fan

      the fan may be a necessity with certain Pi versions, having that circuit board over the top of the 'otherwise open' ventilation space for the CPU...

      Otherwise, it's probably cheaper to get a simple $10 PoE adaptor on amazon [several versions exist at around the same price with very good reviews], one of the 'wye splitter' variety at any rate. [yeah this was discussed on IRC last week, along with links to one particular device that fits the category of what I just said].

      but PoE is less important (to me) than having a proper power/shutdown switch... and yeah external boards exist for that, too.

      1. Lee D Silver badge

        Re: Oh dear, a fan

        The PoE hat only works with the 3B+. Only that has the pins to support it (that pull through the Ethernet pins to the board).

        And, no, it *doesn't* need the fan. Because the 3B+ doesn't need the fan and you can turn the fan off entirely perfectly safely.

  2. john.jones.name
    WTF?

    not skookum

    maybe open source the design files on github and have a competition for the best design after all plenty of undergraduate / Graduate eyeballs for V2

    1. Yet Another Anonymous coward Silver badge

      Re: not skookum

      The specs for the HAT are open source, as is the POE spec - you can make your own POE adapter.

      The problem with hardware is that (almost) nothing is to spec - in this case one brand of USB chip was a bit "optimistic"

    2. Anonymous Coward
      Anonymous Coward

      Re: not skookum

      > maybe open source the design files on github

      You are joking right? The Raspberry Pi foundation is moving further away from being open by the day.

      Circuit diagrams are incomplete if any are released at all. Component labels are no longer printed on boards. They are not only taking us back to the glory days of home computing but to the times before when only the privileged boffins in white coats were allowed access to the box of tricks.

      The foundation perpetuates an elitist attitude that no one can do things as well as they can so it should be quite instructional when they do screw up but it seems they become even more closed.

      1. James Hughes 1

        Re: not skookum

        Wow. Quite the rant.

        Just to inject semblence of truth in, we have never provided full schematics of any of the Pi boards. so to say we are geting less open is an exageration. We have had to change a little due to to becoming more competitive - ie we need to maintain our competitive advantage to remain in business. Easiest way to do that? Keep certain aspected under wraps.

        Mising component labels is a cost saving measure, and what we can fit in limited space. Not much more to it that that.

        We do not have an elistist atitude. We welcome anyone to contribute to our linux kernel, our documenation, our projects etc. As we do get some really good contributions in all those areas. What we cannot do is open csource the GPU binary blob, because we do not hold the copyright on it - that is held by Broadcom. We release what we can.

        We screw up, everyone does. This is a case in point. But we've come clean, which is more than most other companies. Be nice to understand what you mean by your last paragraph, taking in to account this exact example.

        1. Danny 2 Silver badge

          Re: not skookum

          @ James Hughes 1

          The Pi was meant as an educational computer and it is historically educational about how electronics were in the late eighties when I did my apprenticeships and many of the same problems, solutions and techniques were common.

          I'm not being sarcastic, I mourned when 'fault find to component level' changed to scrapping the apprenticeships and having the operators throw the board away and replace it, so it is heartening to read the skill set of your users. One difference is our VMEbus boards were being sold for many thousands of pounds in their thousands back when a pound could buy you a packet of cigarettes and a dram of whisky (and back when dram implied whisky not memory), so you have nothing to be defensive about.

          I, for one, welcome our new Pi over-hats. I have a Fluke 187 and I am not afraid to use it!

        2. Jason Bloomberg Silver badge

          Re: not skookum

          Just to inject semblence of truth in, we have never provided full schematics of any of the Pi boards.

          Were the original Pi A/B schematics not complete?

          Those look complete to me. If not then perhaps you could indicate what's missing.

          so to say we are geting less open is an exageration.

          It does seem later schematics are a whole lot less complete than they were.

          1. Anonymous Coward
            Anonymous Coward

            Re: not skookum

            > Were the original Pi A/B schematics not complete?

            > Those look complete to me. If not then perhaps you could indicate what's missing.

            Friends who know more than I claim that the composite video from the original Pi is not fully documented: apparently collectors of vintage televisions would like to be able to use it to generated 405 line signals but can't because the necessary details to hack away at a low level aren't available.

            1. Anonymous Coward
              Anonymous Coward

              youtube search "old composite video pi" or similar

              "the composite video from the original Pi is not fully documented: apparently collectors of vintage televisions would like to be able to use it to generated 405 line signals but can't because the necessary details to hack away at a low level aren't available."

              Are these collectors aware that lots of obscure stuff that works may not be formally documented (not least, because it might break in the next release of hardware or software) ?

              For example have they tried searching youtube for videos relevant to "old composite video pi". Based on what I found there seem to be quite a few things that can be changed relating to composite video output, seemingly changed enough to work with various old-school monitors, and/or on Pi variants without official composite video out.

              Whether the possible changes are sufficient to work with a line rate of just over 10kHz (405 lines at 50Hz) isn't immediately obvious, and I've no way to try it. But others interested in 405 line TV presumably do have skills (and time and motivation?).

              Have a lot of fun.

        3. Hans 1 Silver badge

          Re: not skookum

          James, I would hope you could stop the MPEG2 ripoff, although I know it is Broadcom pulling this one off, not the foundation, pretty please!

          Do you really think you have competition ? I mean, you have a great ecosystem of boffins and amateurs hacking on your stuff creating the most incredible things, as long as you copyright the design and layout, I guess you should be fine, right ?

          And more RAM would be nice as well, I understand that would require quite a re-design ... but, you know, I think you will have to at some point, competition already sport 2Gb, admittedly at another price-point ...

          Hove you considered adding PCI-E lanes for an M.2 port ? Killer feature, that!

          1. James Hughes 1

            Re: not skookum

            The MPG2 thing is a PITA. Unfortunately there are still two regions where the licence is required, and since we do not region encode the Pi we cannot guarantee that any Pi will not be used in those regions. We would dearly love to get rid of the whole thing - it costs us more than we make back, to run the licencing system.

      2. bombastic bob Silver badge
        Devil

        Re: not skookum

        "The foundation perpetuates an elitist attitude that no one can do things as well as they can"

        this IS a discussion about the Raspberry Pi, right?

        I haven't found any of what you said to be true. Maybe some time surfing around the web site would be a good idea.

        Sometimes the info you want _IS_ hard to find, but if you surf around a bit you'll eventually get to it. "Poorly indexed" might be a good criticism to use, and it's obviously not done deliberately.

        Some links on their web site lead more down rabbit holes than to useful information. Yeah, that's irritating. Eventually you find the right set of pages and links and VOILA it's all there! Or at least most of it. Then you download the broadcom CPU docs and surf around other sites like elinux.org and sometimes their info isn't 100% accurate, so you occasionally tear out your hair over it, but in general, it's pretty good docs for something this inexpensive and flexible.

  3. The Original Steve

    Viva ElReg and The Pi Foundation

    Great article - this kind of thing is what keeps me coming to El Reg daily (as well as the long geeky reads and of course the commentards!)

    1. Hans 1 Silver badge
      Thumb Up

      Re: Viva ElReg and The Pi Foundation

      as well as the long geeky reads and of course the commentards!

      Especially the quality of commentards, most notably James Hughes, THE Raspberry Pi engineer for VideoCore! Ok, I did not upvote James' post, because I think his claims are not 100% correct, however, I understand corporate-speak and cannot blame him for that, don't we all do it with our customers ;-)

      I do wish to congratulate the Raspberry pi team for what they have done, I have all the B+ and the first B, big fan!

  4. K Silver badge

    Hats off to 'em...

    Diagnosing, openly admitting and replacing.... basically treating their customer's as mature adults!

    There are very few organisations that would do this... most would deny the issue, take months to admit the cause and liability, then put in place a complex bureaucratic process that causes people to say "f*ck it!"

    1. James Hughes 1

      Re: Hats off to 'em...

      TBH, we should have spotted this in testing, so there will be changes to help ensure it doesn't happen again!

      1. MJB7

        Re: Hats off to 'em...

        "TBH, we should have spotted this in testing"

        Well yeah, that would have been nice. But the fact that you saying that in a public forum is not a career-limiting move is what we are applauding.

        ... although it would have been nice to see something about this in my RSS feed from the RPi blog (I'll go and sit in the nit-pickers corner shall I?)

    2. Fading Silver badge
      Gimp

      Re: Hats off to 'em...

      Cough - holding it wrong - cough

      :)

      1. Oh Matron!

        Re: Hats off to 'em...

        Too soon... :-)

    3. Stoneshop Silver badge

      Re: Hats off to 'em...

      Hats off?

      It's with this hat on that the Pi can run on PoE.

    4. Trollslayer Silver badge

      Re: Hats off to 'em...

      Especially when we commentards are immature!

  5. hammarbtyp Silver badge

    What I love about the Raspberry Pi community is that they see any problem as a opportunity to learn and fix

    1. Anonymous Bullard

      And that's why, even though there may be better boards, I go with RPi.

  6. TRT Silver badge

    So what you're saying is...

    that there's too much currants in the raspberry pi?

    1. James Hughes 1

      Re: So what you're saying is...

      Actually, not enough....

      1. el kabong

        Very brief but large current spikes flowing in the pi

        Triggering undervoltage warnings and causing it to fail. Erroneous warnings, apparently.

        1. Glen 1 Bronze badge

          Re: Very brief but large current spikes flowing in the pi

          Re: triggering undervoltage

          Whoosh.

          1. TRT Silver badge

            Re: Very brief but large current spikes flowing in the pi

            Spiky currants? Those are gooseberries.

            1. Symon Silver badge
              Coat

              Re: Very brief but large current spikes flowing in the pi

              Yes, it's raisin the temperature.

  7. Anonymous Coward
    Anonymous Coward

    Are we sure its not down to fake sd cards, or our psu's, or all the other excuses rolled out for the original Pi's by the foundation on its forums before they mostly fudged the timing issues on the usb bus bottleneck. Congratulations on admitting it this time though.

    Mines the coat with a pocketbeagle in the pocket, because once bitten forever unsmitten.

    1. James Hughes 1

      Are you talking about something from 6 years ago?

      In fact, I'm a bit confused by your timing issues on usb bottlenck statement because that doesn't ring any bells at all.

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