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Small / cheap micro family with MMU for running Linux

Discussion in 'Embedded' started by Boo, Mar 11, 2014.

  1. Boo

    Boo Guest


    Does anyone have any suggestions for small / cheap embedded microcontroller
    families having an MMU and which are suitable for running the "normal" version
    of Linux ?


    Boo, Mar 11, 2014
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  2. Does anyone have any suggestions for small / cheap embedded microcontroller families having an MMU
    Krzysztof Kajstura, Mar 11, 2014
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  3. You might want to first read the MCU errata list however for the i.MX233
    before purchasing it (especially if you want to do USB isochronous reads).

    Disclaimer: I don't know how (or if) Linux handles the issue raised; I've
    only used the i.MX233 outside of Linux and not for isochronous I/O.

    Simon Clubley, Mar 11, 2014
  4. edward.ming.lee, Mar 11, 2014
  5. Boo

    Tim Wescott Guest

    This is as much a riff on my prejudices as anything else, but: "small and
    cheap" don't fit will with "Linux", at least by my definitions.

    Linux is a big-box operating system. You can get out the machete and
    whack it down considerably in size, and then you can stuff the result
    into a small (ish) processor. But when you're all done, you either have
    a huge amount of unnecessary overhead for the sorts of applications that
    fit into a small and cheap processor (by my definition of "small and
    cheap"), or you have an application that needed Linux in the first place
    because it's just plain too big for "small and cheap".

    Of course, my "small and cheap" is less than $2.00 in quantity and a
    board footprint that's less than 100mm^2, or maybe 50mm^2. Your "small
    and cheap" may be considerably bigger.
    Tim Wescott, Mar 11, 2014
  6. I assume by "normal" you mean "something that's not uCLinux" rather
    than "the current version of Ubuntu or RHEL". If the former, I don't
    think there's anything I'd consider small and cheap. If the latter,
    then there's _really_ nothing small and cheap.
    At least he didn't demand "low power" as well (in my book, "low power"
    means running off ~1V at a few hundred uA).
    Grant Edwards, Mar 11, 2014
  7. Boo

    hamilton Guest

    The biggest problem with Linux is that it runs out or RAM.
    If your board does not have 4-8Meg of RAM, it won't run at all.

    There are NO microcontrollers with that much RAM.

    So you will need a PCB with a processor and lots of RAM.

    I wish there was a FAQ about this, oh wait........

    ( Google IT )
    hamilton, Mar 11, 2014
  8. Boo

    Mel Wilson Guest

    There's this, Linux on an ATMega1284p. But it's not what he wants.


    Mel Wilson, Mar 12, 2014
  9. Boo

    Les Cargill Guest

    Would a Beaglebone be a start? Cubie board?

    They're $100 or less, smallish. How small, how cheap?

    The Cubie is a bit proprietary and Allwinner is ... odd
    as a company, but they both run full-grown Linuces.
    Les Cargill, Mar 12, 2014
  10. Boo

    Les Cargill Guest

    Is that "inexpensive"? :)
    Me too:

    $45. half a gig RAM, 1GHz, 2GB FLASH.


    $89 for 1GByte RAM,2-4 Gbytre FLASH, 1GHz.
    Uh, $45? :) This is why I said anything. A threshold has been crossed.

    Nice little boards...
    Les Cargill, Mar 12, 2014
  11. Boo

    Paul Rubin Guest

    Those are very powerful and relatively expensive boards, comparable to
    serious PC's or servers from not that long ago. I think of a
    small/cheap Linux board as comparable to the stuff found in cheap home
    wifi routers. Typically they have a $3 ARM6 or MIPS cpu with maybe 4
    meg of ram and a comparable amount of flash, plus all the network stuff.
    The whole thing retails for $30 or so.

    I think the OP just wants a CPU for use in a larger embedded product,
    but here are some complete boards that might be of interest for testing
    or whatever:

    Paul Rubin, Mar 12, 2014
  12. Boo

    Paul Rubin Guest

    "Whole thing" = complete finished appliance with enclosure, buttons,
    lights, consumer packaging, power cube, ethernet cable, etc. Not really
    comparable to the Beaglebone which is $45 for just a PC board in a
    baggie. The Beaglebone is a nice board but overkill for many purposes.
    Paul Rubin, Mar 12, 2014
  13. Boo

    upsidedown Guest

    Do you want to use some existing program running only on Linux (or
    Windows (Embedded)) ?

    For a new project, you should consider some light weight OS/kernel.
    upsidedown, Mar 12, 2014
  14. I guess the closest is the RPi, it has stacked-chip DRAM ("package on
    OP could perhaps look at

    John Devereux, Mar 12, 2014
  15. It maybe stretches the definition a bit, but Renesas' RZ/A1H has 10MB
    of on-chip SRAM. Still needs external flash storage though.

    Anders.Montonen, Mar 12, 2014
  16. Boo

    hamilton Guest


    Maximum 10 MB on-chip large-capacity RAM enables more compact system size

    Maximum 10 MB on-chip RAM enables image data for two screens of WXGA
    size image display to be recorded (used as frame buffer) without
    external SDRAM. Compared to the WVGA size (800 x 480 pixels) display of
    previous Renesas products, the product can be expanded to WXGA size
    without adding external SDRAM, enabling a more compact size to be
    obtained. Since external SDRAM is unnecessary, issues concerning the
    cost of SDRAM, mounting area, power consumption, noise, stable long-term
    supply, and so on can also be solved.

    Without looking deeper, can it run code out of video RAM ?
    hamilton, Mar 12, 2014
  17. Boo

    Stef Guest

    In comp.arch.embedded,
    It has no special purpose 'video RAM', the 10MB version just has 5 blocks
    of 2MB RAM, which you can use as you like. There are multiple internal
    busses, so in theory it can do video DMA and, for example, ethernet DMA
    while the CPU is accessing the RAM, without these 3 operations
    interfering with each other (assuming they use 3 separate RAM blocks).

    Have no experience with these yet (they are sampling or just in full
    production), but they seem to be a very good candidate for one of our
    future products. Silica should have a low-cost eval board out by now. Will
    order one as soon as that project progreses to hardware selection. The
    Renesas boards where already available last year and not too expensive

    We would not need the video for that project, but we do require the RAM.
    Stef, Mar 12, 2014
  18. Anders.Montonen, Mar 12, 2014
  19. 2014-03-11 18:04, Boo skrev:

    Atmel AT91SAM9x5 family
    Freescale iMX28 family or

    They are based on the ARM9 core.
    A more modern chip would be based on a Cortex-A<n> chip.

    Some examples with low cost board.

    Atmel SAMA5 Cortex-A5 (SAMA5 Xplained)
    Freescale iMX6 (Wandboard)
    Texas Instruments AM335x Sitara (Beagleboard)

    If you are happy with just a board, and do not want to build your own then;
    Allwinner Allwinner Ax (Olimex)

    Ulf Samuelsson
    Ulf Samuelsson, Mar 12, 2014
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