Small / cheap micro family with MMU for running Linux

iMX233

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.

Dual core 1.6GHz Atom with 1GB SDRAM for $29

How cheap do you need?

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.

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).

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 )

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

Mel.

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.

Is that "inexpensive"? :)

Indeed.

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...

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:

"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.

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.

I guess the closest is the RPi, it has stacked-chip DRAM ("package on package").

OP could perhaps look at

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

-a

Interesting:

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 ?

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 either.

We would not need the video for that project, but we do require the RAM.

A distributor rep claimed it can, but until the documentation is released who knows.

-a

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 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)

BR Ulf Samuelsson