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Posts: 103 | Thanked: 10 times | Joined on Feb 2007
#1
When I see things like this:

Micro/Mini SD adapter, it makes me wonder if a micro SD (transflash) card could be adapted to RS-MMC (MMCm) size.
 
Posts: 123 | Thanked: 6 times | Joined on Dec 2005 @ Los Angeles
#2
I maybe wrong but my understanding is that SD speaks on a completely different protocol than RS-MMC / MMC Mobile, as well as having different contact locations
 
Posts: 3,841 | Thanked: 1,076 times | Joined on Nov 2006
#3
No, SD is basically a superset of MMC. SD has 4 data bit contacts while (old) MMC has 1, but SD interfaces can talk in 1-bit mode too. Newer MMC (MMC Plus) again have more contacts than SD, but all these interfaces can still interchange the cards. I believe the Reduced Size versions of MMC are just that, reduced size, but otherwise the same as MMC (sometimes there are reduced voltages as well, but interfaces can still work with all of them if made that way).
Look no further than the N800, which (with adapter, this is just for handling the different physical sizes) can handle the full range of SD/MMC/RS-MMC/mini-SD/micro-SD/MMC Plus.
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Posts: 42 | Thanked: 1 time | Joined on Mar 2007
#4
I think Tweak was right about the protocols being different. SD devices offer backwards compatibility to MMC, but MMC devices can't use SD cards. An adaptor would make a RS-MMC sized SD card that went into MMC device. I think you would need some serious circuitry to make that work and it definitely would be bigger than the difference in physical sizes of MicroSD and RS-MMC. Just my .02
 
Posts: 3,841 | Thanked: 1,076 times | Joined on Nov 2006
#5
Hm, I think you're right. I was only thinking about SD being compatible with the rest, not the other way around. On the other hand.. there are simple SD interfaces that actually read SD cards just as they would MMC cards, that is, through a 1-bit serial interface. I'm not certain if this means that MMC could read SD cards or not.
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-- Metalayer-crawler delenda est.
-- Current state: Fed up with everything MeeGo.
 
Posts: 9 | Thanked: 0 times | Joined on Aug 2007
#6
SD is backward compatable with MMC. So a MicroSD to RSMMC converter would work if such a thing existed. I've attached an SD card to my n770 and it works fine.

http://linuxjunk.blogspot.com/2007/0...d-sd-card.html
 
Karel Jansens's Avatar
Posts: 3,220 | Thanked: 326 times | Joined on Oct 2005 @ "Almost there!" (Monte Christo, Count of)
#7
Originally Posted by new299 View Post
SD is backward compatable with MMC. So a MicroSD to RSMMC converter would work if such a thing existed. I've attached an SD card to my n770 and it works fine.

http://linuxjunk.blogspot.com/2007/0...d-sd-card.html
All you need now is a SDHC kernel patch for the 770 and you can plunk in an 8GB card monster.
 
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Posts: 1,361 | Thanked: 115 times | Joined on Oct 2005 @ Toronto, Ontario, Canada
#8
I can't speak for the n880, but doesn't the door on the 770 have to be closed in order to mount the memory card? That kinda screws any sort of adapter.
 
Karel Jansens's Avatar
Posts: 3,220 | Thanked: 326 times | Joined on Oct 2005 @ "Almost there!" (Monte Christo, Count of)
#9
Originally Posted by Hedgecore View Post
I can't speak for the n880, but doesn't the door on the 770 have to be closed in order to mount the memory card? That kinda screws any sort of adapter.
If you read the mod, you'll find a mini-howto (of the sketchiest of sorts, however!) on how to short out the door thingie.

In fact, with that door mod I think the 770 would accept regular SD cards without further soldering. They'd stick out of the 770's body, of course, making all sorts of useful things obsolete, like, oh: Portability, the use of the cover... But hey! You too can have a 4GB (with a non-HC card) 770!

I wonder... Isn't there some stuff inside the 770 that can be dremeled away, so the card slot can be moved up? Do we really need the CPU?
 
Posts: 2,152 | Thanked: 1,490 times | Joined on Jan 2006 @ Czech Republic
#10
Originally Posted by Karel Jansens View Post
All you need now is a SDHC kernel patch for the 770 and you can plunk in an 8GB card monster.
In fact I have such kernel almost ready. Not sure about stability but week ago I tried to backport mmc stack from N800 kernel (including SDHC, high speed SD and >4GB MMC cards) to latest n770 2.6.16 and after all changes it still works with kingston 2gb mmc just fine. But what is more interesting for me is that this code from n800 kernel makes my transcend 4GB mmcplus card not working in n770 just like it doesn't work in n800 now (but works fine in n770 with 2.6.16 kernel). So now I'm in the process of merging changes again one by one and checking where it breaks. I thought N800 has some HW problem with this card but now it looks like it can be hopefully fixed in software. But if anyone wants to test this kernel with (high speed) SD or SDHC card in n770, let me know.

I was thinking about this SD mod for some time too, 4gb or bigger card in n770 would be nice and I don't remove the card anyway. I was reluctant to kill my only N770 with this mod and was also waiting for 4GB mmcmobile cards (which would make this mod pointless) but now I've got spare N770 one from expansys so I can start modding too :-)
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