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News New Raspberry Pi 3 variant returns to Model A+ design

Discussion in 'Article Discussion' started by bit-tech, 15 Nov 2018.

  1. bit-tech

    bit-tech Supreme Overlord Staff Administrator

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  2. Chicken76

    Chicken76 Member

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    I don't see the point of the model A+. You lose Ram, you lose useful USB (by this I mean the possibility to set it up easily with a keyboard and mouse, mandating a hub or an expensive wireless kit) and most importantly you lose ethernet, and with it also the PoE capability. And it's hardly any cheaper. For this price there are clones with 2GB Ram, gigabit ethernet, USB 3.0, better GPU, etc.

    Taking out useful stuff is not the direction you should be going into, Raspberry Pi Foundation. The competition is tripping over themselves adding features at lower prices, and you're taking out stuff?

    Looking forward for the floppy disk drive interface in Raspberry Pi 4.
    </sarcasm_filled_disappointment>
     
  3. Gareth Halfacree

    Gareth Halfacree WIIGII! Staff Administrator Super Moderator Moderator

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    Power, size, and weight. Price is a key point, too - it's a third cheaper, give or take - but it's power, size, and weight that are the key. For a robotics project, the Pi Zero is too limited (needs a special adapter to use a camera, only has a crappy single-core 32-bit processor) but the Pi 3B+ is too hefty (big, heaviest Pi on offer, draws nearly 6W under load and north of 2W at idle, and has the useless USB and Ethernet ports you're not even going to use.)

    The Pi 3A+ is the answer. Smaller and lighter than the Pi 3B+, loses the bits roboticists and other embedded types don't care about, retains the bits they do care about (Wi-Fi, Bluetooth, full-size CSI), and has the same performance (so long as your workload fits in 512MB, of course.) For anyone working on embedded computer vision, the 3A+ is the Pi for which they've been waiting.

    If you're wanting a Pi to run as a desktop, the 3B+ is a better choice - but the 3A+'ll do in a pinch, as you can connect Bluetooth keyboards and mice to keep the USB port free. They're not that expensive: here's a laptop-style arrangement for under £15.
     
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  4. Chicken76

    Chicken76 Member

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    I admit Gareth, I haven't considered a model built specifically for a single purpose. I suppose if that market is big enough, it's worth making a dedicated model.

    I'm just exasperated by the slow pace at which the Foundation is updating and adding features to the general-purpose Pi.
     
  5. Gareth Halfacree

    Gareth Halfacree WIIGII! Staff Administrator Super Moderator Moderator

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    There's a reason for that: compatibility. The Pi family is, to my knowledge, absolutely unique in the world of single-board computers for one sole reason: you can take the latest Raspbian operating system, flash it to a microSD card, and run it on absolutely any model. I mean, you'll need a microSD-to-SD adapter to plug it into anything older than the Model B+ and a daughterboard for any of the Compute Modules, but it'll run just fine and dandy.

    When I say "any model," I mean any model. The microSD I used for testing the Pi 3A+ can not only be shoved into my pre-production Raspberry Pi Model B sample, but it can also go into any one of the 50 original Alpha boards - boards almost completely unrecognisable as a Raspberry Pi - without the slightest modification and it'll run just fine. Scratch 2 won't work, and that's about the only problem you'll run into.

    The reason this works: the fact that they're all based on the BCM283x SoC family. Each revision has bumped up the processor side - BCM2835 was single-core 32-bit 700MHz later bumped to 900MHz, BCM2836 was quad-core 32-bit 900MHz, BCM2837 was quad-core 64-bit 1.2GHz, BCM2837B0 was quad-core 64-bit 1.4GHz - but left the VideoCore-IV alone because that's the entire heart of the design. (Broadcom originally built it for set-top boxes, y'see, hence the powerful-for-the-era GPU and weak CPU of the BCM2835).

    That's great for compatibility, but adds a major problem to the mix: you can't upgrade anything except the CPU side. The GPU handles everything from boot onwards; change the GPU, you've not got a BCM283x any more. That's why even after all these years the Pi doesn't have a SATA port, only has one USB lane, is limited to an absolute maximum of 1024MB of RAM, and has the same approaching-seven-year-old GPU.

    I've used a lot of words to get to the good news, though: as hinted at in the article, things may be changing in the future. Co-founder Eben Upton told me during our interview a few weeks ago that the Pi 3A+ represents 'tidying up Classic Raspberry Pi' - hinting pretty heavily that the Raspberry Pi 4, which I have to stress doesn't even exist as a design yet and is in the very early "what would we like to see on it" stage, could finally move away from the BCM283x to something with a beefier GPU, more USB lanes, and possibly additional connectivity like SATA - along with, finally, more than 1GB of RAM.

    If it does, backwards compatibility will be lost - but it may be a sacrifice worth making, because like you say there are plenty of boards out there happy to take people's money for more RAM, faster processors, and extra connectivity, so the demand is obviously high.
     
  6. yuusou

    yuusou Well-Known Member

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    I just want gigabit ethernet and usb3.
    T'is all.
     
  7. Gareth Halfacree

    Gareth Halfacree WIIGII! Staff Administrator Super Moderator Moderator

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    Then you want the Pi 3B+, which comes with gigabit Ethernet as standard...

    ...which tops out at 300Mb/s because it's still sharing a single USB lane to the SoC. Still, it's better than the 80Mb/s of the older models!
     
  8. yuusou

    yuusou Well-Known Member

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    But it's still usb 2.0. :(
     
  9. Gareth Halfacree

    Gareth Halfacree WIIGII! Staff Administrator Super Moderator Moderator

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    Aye: that, along with there only being a single lane of it no matter how many physical USB ports it has, is another peculiarity of the BCM283x family. That ain't changing until (or unless) a future PI ditches backwards compatibility and moves to a new SoC family.
     
  10. jb0

    jb0 Active Member

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    That would be kinda amazing.
     
  11. Chicken76

    Chicken76 Member

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    Gareth, I'm not buying the backwards compatibility part. You could have another SoC with firmware that can handle initializing from a different address in the bootloader. Raspbian could include kernel modules for all versions of the Pi. Everything else should be abstracted. Who writes machine-specific code these days? That's the job of the driver. Use the available APIs.
     
  12. Gareth Halfacree

    Gareth Halfacree WIIGII! Staff Administrator Super Moderator Moderator

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    You haven't done much work in the wonderful world of Arm, have you?
     
  13. Chicken76

    Chicken76 Member

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    None. How bad could it be? :eyebrow:
     
  14. Gareth Halfacree

    Gareth Halfacree WIIGII! Staff Administrator Super Moderator Moderator

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    <dissolves into hysterical laughter>
     
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  15. Chicken76

    Chicken76 Member

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    That bad, huh?
     
  16. Gareth Halfacree

    Gareth Halfacree WIIGII! Staff Administrator Super Moderator Moderator

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