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I want to make a small device that boots Linux off of an SD card for ARM or x86. I am trying to build this from scratch. I downloaded Linux (kernel.org) and compiled it on Ubuntu.

What kind of SD card will I need (to save Linux onto) and where can I buy an ARM processor (one that does not come pre-soldered onto the board like Raspberry Pi)?

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    \$\begingroup\$ If you need to ask where to go shopping for components, I would suggest that you may be in over your head working with a complex ARM SoC. \$\endgroup\$ – Joe Baker Feb 4 '13 at 0:21
  • \$\begingroup\$ @JoeBaker Well I have tried sparkfun, mouser, Farnell and even my local radioshack but have found nothing \$\endgroup\$ – user1922878 Feb 4 '13 at 0:22
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    \$\begingroup\$ Your major complication will be that linux requires more RAM than pretty much any microcontroller has internally, and the memory stacked atop processor packages such as Raspberry pi uses aren't likely to be something you can assemble yourself, or for many of the manufacturers even buy without involved negotiation. That leaves you doing a board with both a processor and SDRAM(s) - it's been done on 2 layers and you can find examples by searching, but it's probably not a good project to tackle until you have more experience in simpler and more forgiving designs. \$\endgroup\$ – Chris Stratton Feb 4 '13 at 0:28
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    \$\begingroup\$ I just did a search on Farnell for ARM9 and got over 50 hits, most of those should be suitable. You can probably stick to a Radio Shack SD card. \$\endgroup\$ – PeterJ Feb 4 '13 at 1:02
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    \$\begingroup\$ The problem everyone is pointing out is there's not a microcontroller that can do it, so you need an ARM + RAM + lots of support circuitry and the design will need likely need BGA and a 4 layer PCB. Take a look at the schematics at atmel.com/Images/doc6198.pdf - that's a dev board that can run Linux as is about as simple as it gets. It does use parts you can buy easily enough in one-off quantities however. \$\endgroup\$ – PeterJ Feb 4 '13 at 4:18
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Head over to Olimex, and they have a line of products called Olinuxino - with options based on ARM9 SoC (a Freescale i.MX 233 one running at 454MHz), ARM Cortex-A8 SoC (Allwinner A13) and I believe there are a few in the works based on even higher end SoC's (Cortex A9/A15).

One of the design guidelines of Olinuxino (as I understand) is that their board designs are hobbyist friendly, and for a better-than-newbie hobbyist, ability to do the PCBA using hand-soldering is part of such goals. I believe, all of their boards, are open-source HW, so that may be a good starting point.

Freescale ARM9's might be available on Mouser (or the other online distributors), but Olimex might be able to provide some hard-to-find parts, for example, they do sell the Allwinner A13 and it's matched power-management IC.

Anyhow, assembling a linux capable board requires access to tools, techniques, and skill, only fairly advanced hobbyists might have, and being able to design such a thing from scratch, IMHO, is not quite in the hobbyist territory.

Edit:

Yet another alternative could be something like ARM7TDMI SoC's, although they can only run ucLinux, I believe. I'd read somewhere that Linux kernel trunk had support for MMU-less processors added, which means, that a tiny distribution of standard Linux built for ARM7TDMI might also be feasible. Typically, ARM7TDMI's processors would be available in far more hobbyist friendly packages, with far fewer pins, and reference designs around them -- I'd expect to be far simpler. If you search for the like of Blueboard (IIRC!), you might find ready to use board, but also it's schematic. PS> I got the ARM7TDMI thought, thanks to your ARM7 tag.

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While as noted in comments to my original post, you explicitly did not ask for a pre-integrated board like the Raspberry Pi, Raspberry Pi is the way to go if you want to start working with ARM. Jumping straight to an unintegrated chip is probably a lot more work than its worth.

Freescale IMX.6 if you are looking for something with faster graphics.

Both will require an SD card. Grab one that comes as microSD with a SD adapter for maximum compatibility. Recommend going with at least 8GB

http://www.amazon.com/b?ie=UTF8&node=347996011

Edited to fix reference to miniSD, which was incorrect.

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    \$\begingroup\$ Downvoting for two reasons: First, he specifically asked for a bare processor (explicitly not the Raspberry Pi) and your went straight for the Raspberry Pi. Second, that's a plain SD card slot. Basically nothing uses miniSD, it went away very quickly when microSD became popular. \$\endgroup\$ – Joe Baker Feb 4 '13 at 2:51
  • \$\begingroup\$ learn something new every day. I have been calling SD cards mini SD for a long time. Thanks for the tip. \$\endgroup\$ – JonnyRo Feb 4 '13 at 13:30

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