Hi all, We currently have a (client's) product that uses an MMC (SPI mode) for datastorage, the client would like to change this to SD card. After searching the web, I did find the SD card simplified physical layer spec, but not much else. The www.sdcard.org site keeps giving me timeouts. I also get the impression that I will need to become a member before I can view any usefull stuff on that site. From what I understand, it is possible to access an SD card as if it where an MMC (both in SPI mode), with only a minor difference in initialization. Is this true? The client would also like the possiblity to change to 4-bit mode later on. All signals will be routed through programmable logic. We will not be using any of the security features. Has anyone found more usefull information on the web? Any tips? -- Stef (remove caps, dashes and .invalid from e-mail address to reply by mail) Everyone is more or less mad on one point. -- Rudyard Kipling
Migrating from MMC to SD card
Started by ●October 28, 2004
Reply by ●October 28, 20042004-10-28
Stef <stef33d@yahooi-n-v-a-l-i-d.com.invalid> wrote:> After searching the web, I did find the SD card simplified physical > layer spec, but not much else. The www.sdcard.org site keeps giving me > timeouts. I also get the impression that I will need to become a member > before I can view any usefull stuff on that site.You should only have to be an SD member to implement the 'secure' stuff (which, to me, suggests that some "security by obscurity" may be involved --- bad idea!). I don't quite see what your client is trying to gain by this move, though. -- Hans-Bernhard Broeker (broeker@physik.rwth-aachen.de) Even if all the snow were burnt, ashes would remain.
Reply by ●October 28, 20042004-10-28
In comp.arch.embedded, Hans-Bernhard Broeker <broeker@physik.rwth-aachen.de> wrote:>Stef <stef33d@yahooi-n-v-a-l-i-d.com.invalid> wrote: > >> After searching the web, I did find the SD card simplified physical >> layer spec, but not much else. The www.sdcard.org site keeps giving me >> timeouts. I also get the impression that I will need to become a member >> before I can view any usefull stuff on that site. > >You should only have to be an SD member to implement the 'secure' >stuff (which, to me, suggests that some "security by obscurity" may be >involved --- bad idea!).We don't need the secure stuff, so that should not be a problem. But where would I find the complete SD spec minus secure stuff?>I don't quite see what your client is trying to gain by this move, though. >Mainly for capacity reasons. They've heard SD's with 4GB are already announced. There is also a concern for he future of MMC, which seems to be loosing terrain. And because SD and MMC ar physically compatible, they can keep using the MCC and be ready for SD. -- Stef (remove caps, dashes and .invalid from e-mail address to reply by mail) After all my erstwhile dear, My no longer cherished, Need we say it was not love, Just because it perished? -- Edna St. Vincent Millay
Reply by ●October 28, 20042004-10-28
> After searching the web, I did find the SD card simplified physical > layer spec, but not much else. The www.sdcard.org site keeps giving me > timeouts. I also get the impression that I will need to become a member > before I can view any usefull stuff on that site.SanDisk has some publicly available documents. I'm not sure where to find them on their site, but I know I have them archived somewhere... if only I could find them :)
Reply by ●October 28, 20042004-10-28
In article <slrnco1hi9.cj7.stef33d@internet.stef.home>, Stef wrote:> From what I understand, it is possible to access an SD card as if it where > an MMC (both in SPI mode), with only a minor difference in initialization.If your code implements the MMC spec as documented by Sandisk, it should work with an SD card. You don't have to do any special initialization. When I tested my MMC code with an SD card, the only real "difference" I found was that SD cards tended to be slower in responding to commands; the MMCs I was using always responded in the 8 clock cycles following the command while the SD cards had a longer Ncr: 16 or more clock cycles. But the MMC spec allows Ncr to be 64 clock cycles, so this is still within spec. -- John W. Temples, III
Reply by ●October 28, 20042004-10-28
In comp.arch.embedded, Lewin A.R.W. Edwards <larwe@larwe.com> wrote:> >SanDisk has some publicly available documents. I'm not sure where to >find them on their site, but I know I have them archived somewhere... >if only I could find them :)If you mean these, I found them. ;-) http://www.sandisk.com/oem/application-notes.asp -- Stef (remove caps, dashes and .invalid from e-mail address to reply by mail) I just remembered something about a TOAD!
Reply by ●October 28, 20042004-10-28
In comp.arch.embedded, John Temples <usenet@xargs-spam.com> wrote:>In article <slrnco1hi9.cj7.stef33d@internet.stef.home>, Stef wrote: >> From what I understand, it is possible to access an SD card as if it where >> an MMC (both in SPI mode), with only a minor difference in initialization. > >If your code implements the MMC spec as documented by Sandisk, it >should work with an SD card. >It's not my code, so we will have to see but this sounds very promising. -- Stef (remove caps, dashes and .invalid from e-mail address to reply by mail) There's a fine line between courage and foolishness. Too bad it's not a fence.
Reply by ●October 29, 20042004-10-29
> > Has anyone found more usefull information on the web? Any tips? > > > > -- > > > Google for __ ProdManualSDCardv1.9.pdf __ should give you a link to adocument> in Sandisk webpage > > > HTH > > Josep Duran > >
Reply by ●October 29, 20042004-10-29
On Thu, 28 Oct 2004 23:58:20 +0000, stef33d@yahooI-N-V-A-L-I-D.com.invalid (Stef) wrote:>In comp.arch.embedded, >John Temples <usenet@xargs-spam.com> wrote: >>In article <slrnco1hi9.cj7.stef33d@internet.stef.home>, Stef wrote: >>> From what I understand, it is possible to access an SD card as if it where >>> an MMC (both in SPI mode), with only a minor difference in initialization. >> >>If your code implements the MMC spec as documented by Sandisk, it >>should work with an SD card. >> >It's not my code, so we will have to see but this sounds very promising.You can send some more instructions to the SD card once it is initialised, and the SPI will speed up to 25MHz. The slower data rates are so the SD card is compatible with the MMC card. The SD card socket is thinner I think, so that MMC cards can't be used with it, but SD cards can be used with the MMC socket. Contact your local Sandisk distributor, and ask for the following document: Sandisk Secure Digital Card Product Manual Version 1.9 (there may be a later version than this) Document Number 80-13-00169 December 2003 You will have to sign an NDA though to get it. Make sure that you check the operation of cards from different manufacturers as well because they may not have exactly the same implementation as Sandisk. Regards David Milne
Reply by ●October 29, 20042004-10-29
> >SanDisk has some publicly available documents. I'm not sure where to > >find them on their site, but I know I have them archived somewhere... > > If you mean these, I found them. ;-) > http://www.sandisk.com/oem/application-notes.aspNo, this document is called something like SD_Architecture_1.0.pdf. Didn't see it on that page you pointed to.