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I'm trying to find a suitable high capacity (4-16GB) memory for an embedded application. Clearly this is going to be some kind of NAND flash memory. I need to be able to write to it at at least 16.5Mbit/s and I'd like to be able to read all of the data off it within a reasonable amount of time, say 10-20 minutes, so need to be able to read at around 13MB/s. I've had a good look around but I'm still not sure what the best option is.
Here's what I've come across so far:

  • SD card memory
    • high capacity
    • acceptable speeds
    • easily obtainable (can buy in stores..)
    • reasonable price (< $20)
    • *must pay royalties (~$3000/year, can't really justify this expense)
  • eMMC
    • high capacity
    • acceptable speed
    • *difficult to obtain unless in 1000+ quantities (only want to buy 10-50 at this point)
    • reasonable price (< $20)
    • no royalties, i think?

So is there any way to get around the SD royalties? Is there any way to get my hands on eMMC chips without having to commit to buying 1000+? Are there any alternatives to these two options? I've also looked for other high capacity memory chips however they seem to require purchasing in 1000+ quantities as well (checking on: find chips/octopart/mouser/digikey).

AKR
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MattCochrane
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    Where did the SD-card royalties thing come from? – John U Sep 04 '13 at 14:39
  • Is bare NAND flash chips a suitable solution? – pjc50 Sep 04 '13 at 15:10
  • The only royalties thing I know of is something to do with FAT. Not entirely sure what exact implementation has a patent, but you can always pick a free filesystem (of which some are very similar to FAT and just work around the patent). – jippie Sep 04 '13 at 17:29
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    @JohnU, from what I can tell SD's protocols are patented and to use them in a host/ancillary product requires membership in the SD Association ([Licensing Link][1]). pjc50, I've had a little look and they seem to be hard to find in small quantities as well. Do you have some idea of where to buy them? [1]: https://www.sdcard.org/developers/licensing/ – MattCochrane Sep 05 '13 at 01:23
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    If that's true (and no I can't be bothered to read the licensing doc) there's a hell of a lot of stuff out there using SD cards without a license. – John U Sep 05 '13 at 14:09
  • They may use the SPI interface to SD cards, not the 4-bit wide one that IIRC needs a spec doc to be purchased. – HL-SDK Jun 04 '14 at 02:22

2 Answers2

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Regarding SD royalties check out this post.
Do I need to pay SD Royalties

Most decent companies will offer samples of their products. You won't lose out by asking and most vendors understand that developers need samples before committing to a large purchase.

Note that I believe some vendors may have already paid the SD royalty cost so it would be in your interest to ask your memory supplier if royalties are required, otherwise you may just end up topping up the SD association's bank balance for no good reason.

EMMc cards appear to be very very fast although because they are new and haven't yet been widely adopted like SD cards are at the present...you'd need to weight that up in your design.
Hope it helps.

Community
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Peter H
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Can you explain your concern on royalites a bit more? Also are you implementing all the software to talk directly to the card via the SD interface? Is so, then yes you would need to pay to get access to all the details on how SD works. If you were to use embedded Linux then the drivers are already done.

Note that SD cards are not very reliable, particularly on sudden power loss. And there's a big problem with counterfit parts, so beware. Do not buy a card on EBay and assume it will match the description.

user43995
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