SD card sticking out ? Use RSMMC


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by mikerr » Wed Jul 04, 2012 8:25 pm
If you think the SD card sticks out too much, try using an RSMMC card

These are pin compatible with SD cards, and are just half the length

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They just slot right into an unmodified Pi and sit more or less flush with the edge:
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by Mortimer » Wed Jul 04, 2012 8:58 pm
I thought MMC was notoriously slow, not available in particularly high capacities, difficult to get hold of, and expensive when you do find any.
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by Montala » Wed Jul 04, 2012 9:00 pm
This looks like an excellent solution.

Has anyone else tried it, and if so, are there any downsides to the idea?

One drawback I can see though is that there don't seem to be many of this type of card around now, and none at all larger than 2GB which is a shame.

Edit: Just found one on Ebay for £8.95 (http://www.ebay.co.uk/itm/2GB-DualVolta ... 030wt_1142)
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by KenT » Wed Jul 04, 2012 9:16 pm
I happened to be looking at a SD card in a bright light and it looked like the memory chip only came half way up the card so it may be possible to hacksaw an ordinary card in half.

Caveat Emptor!
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by Montala » Wed Jul 04, 2012 9:55 pm
KenT wrote:I happened to be looking at a SD card in a bright light and it looked like the memory chip only came half way up the card so it may be possible to hacksaw an ordinary card in half.

Caveat Emptor!

Now that you mention it, I am sure I once read an article confirming that was indeed possible... perhaps only with certain brands though... I can't recall the exact details.

Nice thought anyway!
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by dom » Wed Jul 04, 2012 10:31 pm
Montala wrote:This looks like an excellent solution.

Has anyone else tried it, and if so, are there any downsides to the idea?


I think MMC cards are limited to 1-bit wide transfers (SDCARDs usually support 4-bit wide transfers) so the MMC card is likely to be slow.

@mikerr
what do you get with a:
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by Dilligaf » Wed Jul 04, 2012 10:33 pm
Someone needs to manufacture and sell a "MicroSD Pidaper", basically a half height micro sd adapter, then a micro sd would sit flush.
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by wolfgangmob » Thu Jul 05, 2012 6:59 am
Montala wrote:
KenT wrote:I happened to be looking at a SD card in a bright light and it looked like the memory chip only came half way up the card so it may be possible to hacksaw an ordinary card in half.

Caveat Emptor!

Now that you mention it, I am sure I once read an article confirming that was indeed possible... perhaps only with certain brands though... I can't recall the exact details.

Nice thought anyway!



It's possible but hard to know without sacrificing a few cards in the proccess, also I only see this happening in low capacity SDHC cards, but if you do find one let us know.
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by Jim JKla » Thu Jul 05, 2012 7:12 am
The inverse could be an issue if you regularly change or re-image your cards.

At this time it's not a game changer and if we get to the stage where the number of RPi sales are such that it's worth somebody manufacturing a solution then one of the manufactures will probably produce either the micro adaptor solution or a cut down card.

Until then there's no harm thinking about it. If you can get the memory volume into a micro SD then it's not beyond the bounds to squeeze the connections into a smaller package.

Although I would suggest physically cutting the card is a drastic option akin to trimming your feet rather than buying bigger shoes. :D
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by Mortimer » Thu Jul 05, 2012 8:26 am
Is the basic history of these things:

(1) MMC
(2) SD-card
(3) SDHC
(4) SDXC

In which case any MMC solution is only likely to be very slow by todays standards, and limited in capacity, it is unlikely that RS-MMC is going to see much if any further development.

Kingston Technology's site doesn't list any MMC products in its current line up, including RS-MMC. Their support page contains some information about them, including a PDF DATASHEET. At 2MB/s R/W speed, I don't think they will be quick enough, and I don't think the reduction in size will offset that disadvantage.
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by TommyboyNL » Thu Jul 05, 2012 8:37 am
My 16GB class10/UHS1 45MB/s SanDisk card has a clear-like casing, and is only half-full, so it's possible to cut those in half.
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by mikerr » Thu Jul 05, 2012 9:37 am
Yes, this particular kingston card is no speed demon - I'm getting just over 2.2 MB/sec (close to mortimer's quote) which is slow - but didn't seem that slow on booting.

I wonder if that's the limit of MMC, or modern ones are faster ?
(this one was found at the bottom of a drawer - I've no idea how old it is or where it came from ;) )

Modern ones may be just SDHC in RSMMC physical format as they are pin compatible.
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by dom » Thu Jul 05, 2012 10:17 am
mikerr wrote:I wonder if that's the limit of MMC, or modern ones are faster ?


http://en.wikipedia.org/wiki/MultiMediaCard
suggests 20MHz @ 1-bit per cycle, so 2.5MB/s is the maximum limit.
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by RaTTuS » Thu Jul 05, 2012 11:51 am
but you only need it for /boot
the rest can be on USB HD ;-p
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by azerty » Sat Jul 07, 2012 3:22 am
Dilligaf wrote:Someone needs to manufacture and sell a "MicroSD Pidaper", basically a half height micro sd adapter, then a micro sd would sit flush.

Something like this, maybe?
Image
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by Montala » Sat Jul 07, 2012 10:48 am
azerty wrote:
Dilligaf wrote:Someone needs to manufacture and sell a "MicroSD Pidaper", basically a half height micro sd adapter, then a micro sd would sit flush.

Something like this, maybe?
Image

That does indeed look VERY interesting!
Is it a proprietary device, or a purpose made 'one off'... or just a clever bit of 'Photoshopping'? ;)
Please tell us more!
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by clickykbd » Sat Jul 07, 2012 1:48 pm
I thought I read that micro adapters were problematic in general... i assume this one is not! Tell us more. Stop being a tease. ;-)
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by Dilligaf » Sat Jul 07, 2012 4:13 pm
azerty wrote:
Dilligaf wrote:Someone needs to manufacture and sell a "MicroSD Pidaper", basically a half height micro sd adapter, then a micro sd would sit flush.

Something like this, maybe?
Image


Cool, that would work. Ideally the micro sd slot would be rotated 90 deg counter clockwise from the pic in order to make removal easier. Maybe raised enough that the socket overhangs the end of the sd socket and remains flush with the side of the board.

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by azerty » Sat Jul 07, 2012 6:46 pm
Montala wrote:That does indeed look VERY interesting!
Is it a proprietary device, or a purpose made 'one off'... or just a clever bit of 'Photoshopping'? ;)
Please tell us more!

I made this to go with an add-on board I'm making that has IO connectors hanging off the edge, which prevent the use of a full sized SD card. There's nothing proprietary about it, you can find specs for SD cards online with a bit of searching, so it was pretty easy to make.
I assure you it is real. ;)
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clickykbd wrote:I thought I read that micro adapters were problematic in general... i assume this one is not! Tell us more. Stop being a tease. ;-)

The adapter is a bit loose due to being a little thinner and narrower than it should be, but otherwise I haven't run into any issues using it. What kind of problems with micro adapters did you read about?
Dilligaf wrote:Cool, that would work. Ideally the micro sd slot would be rotated 90 deg counter clockwise from the pic in order to make removal easier. Maybe raised enough that the socket overhangs the end of the sd socket and remains flush with the side of the board.

It's certainly possible, but it'll be a bit tricky. Micro SD cards are 15 mm long, and there's only 14.5 mm from the top of the socket to the edge of the board.
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by bircoe » Sun Jul 08, 2012 4:29 am
How bout these?

Little bit expensive as they're for the Apple brigade but they certainly look the goods!

http://www.kickstarter.com/projects/1342319572/the-nifty-minidrive

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Image

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by Montala » Sun Jul 08, 2012 4:07 pm
bircoe wrote:How bout these?

Little bit expensive as they're for the Apple brigade but they certainly look the goods!

http://www.kickstarter.com/projects/1342319572/the-nifty-minidrive

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Well found!

As it appears they have already passed their target by a considerable amount, it looks as if these should definitely be available in November!

Although quite expensive at $30 (about £20 or so?) I am very tempted to go for one... unless anyone can see a good reason why they wouldn't work in a RasPi.

Not being an Apple Mac owner (or fan!) myself, and therefore not that familiar with their design, I can't really see the difference between the 'standard' and the 'Pro' models... unless it is just the'width' of the aluminium front bit?

What do others think of them... apart from the price ! :?:
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by bircoe » Tue Jul 10, 2012 9:56 am
The Pro ones have round corners on the end piece where the air ones are right angles...

I see no reason why it wouldn't work in the Pi, on the electrical front it should work in any device that accepts an SD card... however there would be obvious physical issues with using these in other devices that stick to the SD standard.

Another thing I've been thinking about doing is relocating the SD slot via a fly cable to suit what ever case/custom enclosure I go with.
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by Montala » Tue Jul 10, 2012 12:07 pm
bircoe wrote:The Pro ones have round corners on the end piece where the air ones are right angles...

I see no reason why it wouldn't work in the Pi, on the electrical front it should work in any device that accepts an SD card... however there would be obvious physical issues with using these in other devices that stick to the SD standard.

I have also been advised that "The only difference between the "standard" and "pro" models is the width. The Pro model is ever so slightly wider (about 1.5mm or so) at the front.
It looks therefore as if the 'standard' model will be fine for for the RasPi... so I might just go for one!
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by wolfgangmob » Tue Jul 17, 2012 9:34 pm
Another option is a combo adapter for micro SD to SD/USB then just cut off the USB side of the adapter.
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by podly » Tue Jul 17, 2012 10:07 pm
wolfgangmob wrote:Another option is a combo adapter for micro SD to SD/USB then just cut off the USB side of the adapter.


What do you mean? Any links to this kind adapter?

cheers,
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