I've been doing some work for a guy who makes data loggers and we are
looking at a new memory card for the loggers. I found these microSD cards
and I have to say I'm really impressed:
- 512MB for $18, 1GB for $30. 2GB for $90. Cost is low because they have
been made in extreme volumes.
- Unlikely to go away since they are used in most cell phones as the "sim"
card or more: the new Chocolate phone uses a 2GB version for internal music
storage.
- About the size of your thumbnail.
- Plugs into a standard SD slot with a mechanical adapter.
- Same SPI serial or nibble parallel interface as SD cards.
- Easy USB interface via "expandable" memory sticks.
- High reliability connectors that hold the entire card down at reasonable
prices.
Just seems ideal for large memory applications in the embedded world.
I'm wondering why I don't find more mentions of them on the net. There don't
appear to be any hobby projects (or maybe I used the wrong keywords). What I
have found so far is here: http://www.piclist.com/techref/mem/flash/microSD.htm
James Newton, Host wrote:
> I've been doing some work for a guy who makes data loggers and we are
> looking at a new memory card for the loggers. I found these microSD cards
> and I have to say I'm really impressed:
..
> Has anyone used them?
I've only used the SD flavor in my Treo and in a USB adapter to backup
and move files. I love 'em. Is there a particular advantage in using
microSD over SD?
Depending on your requirements, the smaller size might be a
disadvantage... Even with the larger SD size, I've occasionally dropped
one on the floor among cables and had to hunt for it for a while! Gave
new meaning to "I dropped my disk on the floor and lost data"...
Are they cheaper, or is size at that much of a premium?
--
Timothy J. Weber http://timothyweber.org
I haven't personally, but I know there are AVR projects that do.
www.avrfreaks.net/index.php?module=Freaks%20Tools&func=viewItem&item_id=516&item_type=tool
> -----Original Message-----
> From: .....piclist-bouncesKILLspam@spam@mit.edu [piclist-bouncesKILLspammit.edu]On Behalf
> Of James Newton, Host
> Sent: 06 November 2006 19:31
> To: 'Microcontroller discussion list - Public.'
> Subject: [PIC] Interfacing a PIC to a microSD or TransFlash card
>
>
> I've been doing some work for a guy who makes data loggers and we are
> looking at a new memory card for the loggers. I found these microSD cards
> and I have to say I'm really impressed:
>
> - 512MB for $18, 1GB for $30. 2GB for $90. Cost is low because they have
> been made in extreme volumes.
> - Unlikely to go away since they are used in most cell phones as the "sim"
> card or more: the new Chocolate phone uses a 2GB version for
> internal music
> storage.
> - About the size of your thumbnail.
> - Plugs into a standard SD slot with a mechanical adapter.
> - Same SPI serial or nibble parallel interface as SD cards.
> - Easy USB interface via "expandable" memory sticks.
> - High reliability connectors that hold the entire card down at reasonable
> prices.
>
> Just seems ideal for large memory applications in the embedded world.
>
> I'm wondering why I don't find more mentions of them on the net.
> There don't
> appear to be any hobby projects (or maybe I used the wrong
> keywords). What I
> have found so far is here:
> http://www.piclist.com/techref/mem/flash/microSD.htm
microchip has example code for talking to standard SD/MMC cards, presumablly it would work with theese as well.
A number of people I've talked to (not computer or electronic
enthusiasts) have said that the microSD (used to the called
Transflash) was simply too small. They couldn't imagine using it to
carry important data. I had a phone with MicroSD, and I rarely took
it out - it's pretty fiddly to remove and insert, even with the nice
push-push connectors that one can get cheaply now.
I have a phone now that uses the MiniSD, which is about the smallest
size people I've talked to think they'd like to take in and out on a
regular basis. I carry a MiniSD thumb drive so I can easily access
content on the phone, and do so on a regular basis. It beats carrying
around a miniUSB cable and dangling the whole phone off that, and is
significantly faster. My laptop has a built in SD socket, which I
store my MiniSD to SD adaptor, though I tend to use the thumb drive
anyway.
I doubt I'd recommend or use MicroSD except where space was a major
concern/feature, and accessability/ease of use was not. For instance,
many phones and devices use it merely to upgrade the internal memory -
it's never intended to be used as removable memory. That's a fine
application.
If I ever got around to making a "daycorder" all-day audio recording
device, then I'd go with MicroSD simply because the device would have
to be the size of a large button pinned on my shirt. I would also
make it so I wouldn't need to remove the card - a USB connection would
probably work here. If I expected to remove the card daily, I'd
instead use a MiniSD or SD. I think the MiniSD is about the perfect
size for regular handling, and the SD for heavy handling. Most of the
people I talk to would rather have the larger card.
http://www.sparkfun.com carries both the memory cards and the sockets
(as well as break out boards for the sockets) for anyone interested in
using one.
-Adam
On 11/6/06, James Newton, Host <.....jamesnewtonKILLspam.....piclist.com> wrote:
> I've been doing some work for a guy who makes data loggers and we are
> looking at a new memory card for the loggers. I found these microSD cards
> and I have to say I'm really impressed:
>I've been doing some work for a guy who makes data loggers and we are
>looking at a new memory card for the loggers. I found these microSD cards
>and I have to say I'm really impressed:
>
>- 512MB for $18, 1GB for $30. 2GB for $90. Cost is low because they have
>been made in extreme volumes.
>- Unlikely to go away since they are used in most cell phones as the "sim"
>card or more:
>
>
Wasn't there a Circuit Cellar article few months ago discussing these
"sim" cards?
> Are they cheaper, or is size at that much of a premium?
Mostly the size is what makes it perfect for data loggers, but also the cost
is amazingly low and they could possibly be scavenged from old cell phones.
I'm also working on another datalogger project, hadn't considered the
microSD, just normal SD cards, whats the power consumption level like
between the two.
Mat
-----Original Message-----
From: James Newton, Host [EraseMEjamesnewtonspam_OUTTakeThisOuTpiclist.com]
Sent: 06 November 2006 22:06
To: 'Microcontroller discussion list - Public.'
Subject: RE: [PIC] Interfacing a PIC to a microSD or TransFlash card
> Are they cheaper, or is size at that much of a premium?
Mostly the size is what makes it perfect for data loggers, but also the cost
is amazingly low and they could possibly be scavenged from old cell phones.
> I'm also working on another datalogger project, hadn't
> considered the microSD, just normal SD cards, whats the power
> consumption level like between the two.
Darn fine question. I don't know yet. If they run in cell phones, it can't
be too much...
>I'm also working on another datalogger project, hadn't considered the
>microSD, just normal SD cards, whats the power consumption level like
>between the two.
>
>Mat
>
>{Original Message removed}
On Nov 6, 2006, at 11:30 AM, James Newton, Host wrote:
>
> I'm wondering why I don't find more mentions of them on the net. There
> don't appear to be any hobby projects (or maybe I used the wrong
> keywords). What I have found so far is here:
>
> http://www.piclist.com/techref/mem/flash/microSD.htm
>
> Has anyone used them?
>
I've been adding miniSD cards to ARM-based media players recently: http://www.elinux.org/wiki/JuiceBoxMMCHack
There's a problem with SD cards in general in that they're heavily
licensed, and in theory you can't get specs, or use them, or buy
sockets for them, without paying $$$$ in SD-assoc membership fees.
(people get around this by using them in MMC/SPI mode, but there's
some question as to whether SD cards in general, and especially the
newer packages, always support that.) (Sparkfun apparently sells
microSD sockets. And someone pointed out that if you're careful you
can use the "adaptors" that usually come with the microSD cards as
sockets...)
MicroSD and miniSD are still somewhat more expensive than full-sized
SD, and IMHO, the "sweet point" for cheap microSD cards is almost
too large for typical embedded use. Gimme those $4 32M (full sized)
MMC cards instead...
There are a number of different "small SD" formats - mini-SD, micro-SD
and RS-MMC. RS-MMC is the one I've been using - it has a similar
physical connector to SD but is shorter. The others have incompatible
connectors but with the same signals AFAIK.
On 11/7/06, Mike Harrison <mikespam_OUTwhitewing.co.uk> wrote:
> On Mon, 6 Nov 2006 22:22:05 -0000, you wrote:
>
> >I'm also working on another datalogger project, hadn't considered the
> >microSD, just normal SD cards, whats the power consumption level like
> >between the two.
> >
> >Mat
> >
> >{Original Message removed}
> I think MicroSD is electrically the same as SD - Sparkfun do some
> connectors, breakout PCBs etc.
> www.sparkfun.com/commerce/product_info.php?products_id=8163
> The spec on that page mentions a passive SD to microSD adapter, which
> would imply it's just a pinout
> converter (like PCMCIA to CF, ISTR)
>
My wife's cellphone uses a uSD. All the uSD cards in Staples come with an
adapter to SD. So, it seems like they're electrically the same, perhaps
just a difference in packaging. The uSD is really quite small. I wouldn't
want to drop one. I'd never find it again.
> There's a problem with SD cards in general in that they're
> heavily licensed, and in theory you can't get specs, or use
> them, or buy sockets for them, without paying $$$$ in
> SD-assoc membership fees.
Huh? My understanding was that the card /makers/ had to pay the fees not the
card /users/. Are they seriously saying that if you make a device that uses
their product (and therefore sells more of their product) that you have to
pay them a fee? The sockets are available from a number of sources. The
piclist.com page references some from mouser and jameco.
> (people get around this by using them in MMC/SPI mode, but
> there's some question as to whether SD cards in general, and
> especially the newer packages, always support that.)
Huh? Where did you hear that doubt expressed? Everything I have read says
that the serial modes are required...
> (Sparkfun apparently sells microSD sockets. And someone
> pointed out that if you're careful you can use the "adaptors"
> that usually come with the microSD cards as
> sockets...)
With sockets at a few dollars there is no need, but if you get the adapters
for free, it's a cool hack.
> MicroSD and miniSD are still somewhat more expensive than
> full-sized SD, and IMHO, the "sweet point" for cheap microSD
> cards is almost too large for typical embedded use. Gimme
> those $4 32M (full sized) MMC cards instead...
Good point. This is probably my main concern: In 5 years, will you be able
to purchase a 1GB microSD card or will they all be 20GB or more?
On the other hand, I wonder if you will be able to purchase any size MMC
card. They don't seem to have that large an install base...
The "fast" four bit access mode is protected under various licensed patents.
All memory SD cards, including micro, mini, etc are supposed to
support the serial method for MMC if they use the SD trademark symbol.
I don't know about SDIO standards (whether it uses serial, 4 bit, or
both. I imagine they are register mapped devices and are largely
treated like memory)
But the synchronous serial mode is plenty fast for uC applications, so
there's no need to license anything. The only other thing the license
covers is the largely unused "secure" part of the SD (Secure Device)
spec.
> BillW said:
> > I've been adding miniSD cards to ARM-based media players recently:
> > http://www.elinux.org/wiki/JuiceBoxMMCHack
>
> Cool!
>
> > There's a problem with SD cards in general in that they're
> > heavily licensed, and in theory you can't get specs, or use
> > them, or buy sockets for them, without paying $$$$ in
> > SD-assoc membership fees.
>
> Huh? My understanding was that the card /makers/ had to pay the fees not the
> card /users/. Are they seriously saying that if you make a device that uses
> their product (and therefore sells more of their product) that you have to
> pay them a fee? The sockets are available from a number of sources. The
> piclist.com page references some from mouser and jameco.
>
> > (people get around this by using them in MMC/SPI mode, but
> > there's some question as to whether SD cards in general, and
> > especially the newer packages, always support that.)
>
> Huh? Where did you hear that doubt expressed? Everything I have read says
> that the serial modes are required...
>
> > (Sparkfun apparently sells microSD sockets. And someone
> > pointed out that if you're careful you can use the "adaptors"
> > that usually come with the microSD cards as
> > sockets...)
>
> With sockets at a few dollars there is no need, but if you get the adapters
> for free, it's a cool hack.
>
> > MicroSD and miniSD are still somewhat more expensive than
> > full-sized SD, and IMHO, the "sweet point" for cheap microSD
> > cards is almost too large for typical embedded use. Gimme
> > those $4 32M (full sized) MMC cards instead...
>
> Good point. This is probably my main concern: In 5 years, will you be able
> to purchase a 1GB microSD card or will they all be 20GB or more?
>
> On the other hand, I wonder if you will be able to purchase any size MMC
> card. They don't seem to have that large an install base...
>
> ---
> James.
>
>
> With sockets at a few dollars there is no need, but if you
> get the adapters for free, it's a cool hack.
>
> > MicroSD and miniSD are still somewhat more expensive than
> full-sized
> > SD, and IMHO, the "sweet point" for cheap microSD cards is
> almost too
> > large for typical embedded use. Gimme those $4 32M (full
> sized) MMC
> > cards instead...
>
> Good point. This is probably my main concern: In 5 years,
> will you be able to purchase a 1GB microSD card or will they
> all be 20GB or more?
>
> On the other hand, I wonder if you will be able to purchase
> any size MMC card. They don't seem to have that large an
> install base...
>
> ---
> James.
Haven't MMC cards stopped at 512k? You still get small (16k or so) one with
new cameras. SD are up to 8 gig, IIRC.
> > With sockets at a few dollars there is no need, but if you
> > get the adapters for free, it's a cool hack.
> >
> > > MicroSD and miniSD are still somewhat more expensive than
> > full-sized
> > > SD, and IMHO, the "sweet point" for cheap microSD cards is
> > almost too
> > > large for typical embedded use. Gimme those $4 32M (full
> > sized) MMC
> > > cards instead...
> >
> > Good point. This is probably my main concern: In 5 years,
> > will you be able to purchase a 1GB microSD card or will they
> > all be 20GB or more?
> >
> > On the other hand, I wonder if you will be able to purchase
> > any size MMC card. They don't seem to have that large an
> > install base...
> >
> > ---
> > James.
>
>
> Haven't MMC cards stopped at 512k? You still get small (16k or so) one with
> new cameras. SD are up to 8 gig, IIRC.
>
> Tony
>
Anything over 4GB is SDHC (as are some 4GB cards), which is not
protcol-compatible with SD (MMC and SD use 32-bit addrressing, so can
only address 4GB). I don't know if SDHC includes SPI support.
On Mon, 6 Nov 2006 11:30:39 -0800, James Newton, Host wrote:
> I've been doing some work for a guy who makes data loggers and we are
> looking at a new memory card for the loggers. I found these microSD cards
> and I have to say I'm really impressed:
>
> - 512MB for $18, 1GB for $30. 2GB for $90. Cost is low because they have
> been made in extreme volumes.
> - Unlikely to go away since they are used in most cell phones as the "sim"
> card or more: the new Chocolate phone uses a 2GB version for internal music
> storage.
That's not quite right - SIM cards use the "Smartcard" format, a piece of credit-card-like plastic card with the gold contact pads arranged in two
rows around a central long connection, like this: http://www.brightmobile.com/images/sim%20virgin.jpg (it's made in a credit-card size, then the part
around the chip/contact is broken out to insert into the phone). SD and its smaller brothers are used for storage of other things - my current phone
has a SIM as I described, and an SD slot that it used as a "disk", for storing software, music, photos, video, and basically any data files you want. The
only data on the SIM is the phone/account identity information and a small "contacts" list - probably no more than about 32kB, and maybe much less.
The SD card can be 1GB or more.
> - About the size of your thumbnail.
> - Plugs into a standard SD slot with a mechanical adapter.
> - Same SPI serial or nibble parallel interface as SD cards.
> - Easy USB interface via "expandable" memory sticks.
> - High reliability connectors that hold the entire card down at reasonable
> prices.
>
> Just seems ideal for large memory applications in the embedded world.
It's been said (and I can't remember where I saw it) that microSD cards aren't designed for regular insertion/removal the way SD, Compact Flash and
so on are, because of their size and other aspects, but are really intended to be inserted (into the phone, MP3 player, or whatever) and left there
most of the time. With my phone I often take the SD card out to transfer stuff to and from a PC (easier than finding the cable! :-) but with microSD
that's a Bad Thing! If you don't need that tiny form-factor, it's probably best to go with full-size SD. (Good grief, I'm saying "Full size" - we're
talking about something you could hide under your watch! :-)
> On Tue, 7 Nov 2006, Tony Smith wrote:
>
> > Haven't MMC cards stopped at 512k?
>
> Transcend makes MMCs up to 2GB.
>
> > SD are up to 8 gig, IIRC.
>
> Anything over 4GB is SDHC (as are some 4GB cards), which is
> not protcol-compatible with SD (MMC and SD use 32-bit
> addrressing, so can only address 4GB). I don't know if SDHC
> includes SPI support.
Oops, I meant 512MB. Anyway, 2GB is rather large, you don't see MMC being
sold that much these days.
So what do you format a > 4GB card as these days? That's the limit of
FAT32, so NTFS?
On Nov 6, 2006, at 4:43 PM, James Newton, Host wrote:
> My understanding was that the card /makers/ had to pay the fees not
> the card /users/. Are they seriously saying that if you make a
> device that uses their product (and therefore sells more of
> their product) that you have to pay them a fee?
>
Yes. This came up when we were looking for a flash card format
smaller than CF. You have to be a member ($2000/year) before you
can get the full specification. And then $1000/year for a host
license. Plus royalties, I think (maybe not for just hosts.)
> Huh? Where did you hear that doubt expressed? Everything I have read
> says
> that the serial modes are required...
The previously mentioned ARM project has had trouble reading "some"
SD cards smaller than 2G, and is reported not to work with any cards
larger than 2G (it uses SPI mode exclusively, I believe.) "serial" mode
is not entirely the same as SPI mode (apparently.) According to the
wiki
page, SPI mode is "options" on microSD. YMMV. Some of this may be mere
driver bugs.
> I wonder if you will be able to purchase any size MMC
> card. They don't seem to have that large an install base...
True. I can't tell how many "SD" capable products will also talk to
MMC (I've got some RSMMC cards on order; perhaps I'll do experiments
in the half-dozen or so SD/MMC hosts I have.)
At the rate things are going, MMC may survive simply based on being
one of the few small flash formats without licensing requirements.
On Mon, 6 Nov 2006, William Chops Westfield wrote:
> The previously mentioned ARM project has had trouble reading "some"
> SD cards smaller than 2G, and is reported not to work with any cards
> larger than 2G (it uses SPI mode exclusively, I believe.) "serial" mode
> is not entirely the same as SPI mode (apparently.) According to the
> wiki
> page, SPI mode is "options" on microSD. YMMV. Some of this may be mere
> driver bugs.
I would suspect driver bugs. The SPI protocol supports 32-bit
addressing, so there's no limitation there, but of course if the
memory address is declared as an "int" somewhere instead of an
"unsigned int", you'll hit a 2GB wall. And of course, a 4GB card
requires FAT32, while a 2GB doesn't.
> BillW said:
>
>> I've been adding miniSD cards to ARM-based media players recently:
>> http://www.elinux.org/wiki/JuiceBoxMMCHack
>>
>
> Cool!
>
>
>> There's a problem with SD cards in general in that they're
>> heavily licensed, and in theory you can't get specs, or use
>> them, or buy sockets for them, without paying $$$$ in
>> SD-assoc membership fees.
>>
>
> Huh? My understanding was that the card /makers/ had to pay the fees not the
> card /users/. Are they seriously saying that if you make a device that uses
> their product (and therefore sells more of their product) that you have to
> pay them a fee? The sockets are available from a number of sources. The
> piclist.com page references some from mouser and jameco.
>
>
>> (people get around this by using them in MMC/SPI mode, but
>> there's some question as to whether SD cards in general, and
>> especially the newer packages, always support that.)
>>
>
>
No, that was a few years ago, and revolved around Sony's Memory stick
products. The SD cards
info is available everywhere free.
> Huh? Where did you hear that doubt expressed? Everything I have read says
> that the serial modes are required...
>
>
>> (Sparkfun apparently sells microSD sockets. And someone
>> pointed out that if you're careful you can use the "adaptors"
>> that usually come with the microSD cards as
>> sockets...)
>>
>
> With sockets at a few dollars there is no need, but if you get the adapters
> for free, it's a cool hack.
>
>
>> MicroSD and miniSD are still somewhat more expensive than
>> full-sized SD, and IMHO, the "sweet point" for cheap microSD
>> cards is almost too large for typical embedded use. Gimme
>> those $4 32M (full sized) MMC cards instead...
>>
>
> Good point. This is probably my main concern: In 5 years, will you be able
> to purchase a 1GB microSD card or will they all be 20GB or more?
>
> On the other hand, I wonder if you will be able to purchase any size MMC
> card. They don't seem to have that large an install base...
>
The MMC card is just an SD card with an unlock feature missing, which
also drops a pin.
On Mon, 6 Nov 2006, William Chops Westfield wrote:
> On Nov 6, 2006, at 5:49 PM, Tony Smith wrote:
>
>> Haven't MMC cards stopped at 512k?
>
> No, you can get MMC up to 2G, after which I believe the format
> falls apart (not enough bits in addresses, or somesuch.)
There is no inherent 2GB limitation in MMC. The latest MMCs sport a
fast 8-bit interface and sizes up to 4GB, while still being backwards
compatible with older MMC controllers and SPI mode. What falls apart
at 2GB is FAT16.
> The MMC card is just an SD card with an unlock feature missing, which
> also drops a pin.
The SD card has two extra pins, and supports a wider bus and higher
bus speeds, unless you're talking about MMC 4.0, which has a wider bus
than SD. MMC is also mechanically thicker, so an SD card cannot be
inserted into an MMC slot.
> The SD cards info is available everywhere free.
>
Um, where? Are you sure you're not confusing MMC with SD?
The sdcard.org site is pretty skimpy on data beyond the bare
minimum, and pretty clear on wanting their $...
The SD card has a 4-bit transfer mode and some DRM features
not present on MMC as well, though I think those are rarely
used (they're designed for selling content on SD cards, a market
that hasn't much taken off...)
> > So what do you format a > 4GB card as these days? That's
> the limit of
> > FAT32, so NTFS?
>
> FAT32 goes up to 32GB in actual implementations, though it's
> theoretically capable of 2TB.
I'm too lazy to dig out the spec, but I assume that's by fiddling with the
sector size? I wonder how many things assume a sector is 512 bytes...
>>> The SD cards info is available everywhere free.
>> Um, where?
> www.sandisk.com/Assets/File/OEM/Manuals/SD_SDIO_specsv1.pdf
> and other big makers sites.
>
That's the SDIO extension spec, not the info on the SD memory
itself. I can find the "physical layer" spec, and I can find the
SDIO extensions, but not the basic memory card info... (or maybe
the physical layer spec is pretty much IT.)
> FAT32 goes up to 32GB in actual implementations, though it's
> theoretically capable of 2TB.
I think I had FAT32 disks under W98 that were larger than 32GB...
It wasn't till XP came along that windows insisted on NTFS for
large disks...
> MMC is also mechanically thicker, so an SD card cannot be
> inserted into an MMC slot.
Um, which is thicker? The physical layer spec says that there are
thick (2.1mm) and thin (1.4mm) SD cards, but I don't think I've ever
SEEN a thick one. 2.1mm is almost 0.1 inch, a distance us chip-monkeys
are pretty familiar with!
On Mon, 6 Nov 2006, William Chops Westfield wrote:
>> MMC is also mechanically thicker, so an SD card cannot be
>> inserted into an MMC slot.
>
> Um, which is thicker? The physical layer spec says that there are
> thick (2.1mm) and thin (1.4mm) SD cards, but I don't think I've ever
> SEEN a thick one. 2.1mm is almost 0.1 inch, a distance us chip-monkeys
> are pretty familiar with!
I got that backwards. SD is thicker so that it can't go into an MMC
slot, but an MMC can go into an SD slot.
>If you don't need that tiny form-factor, it's probably best to go
>with full-size SD. (Good grief, I'm saying "Full size" - we're
>talking about something you could hide under your watch! :-)
I know - I keep looking at USB memory sticks in the larger capacities and
thinking in terms of walking into a 1960's IBM data centre and saying "here,
plug this in and download your entire disk store please ..."
On Tue, 7 Nov 2006 15:00:24 +1100, Tony Smith wrote:
>...
> So what do you format a > 4GB card as these days? That's the limit of
> FAT32, so NTFS?
4GB is the file size limit for FAT32 - the partition size can be much bigger (I have a 300GB drive formatted as one FAT32 partition - I would have used
NTFS but it's connected to a SAMBA server which for some reason will only handle NTFS as Read-Only).
On Mon, 2006-11-06 at 23:27 -0800, William Chops Westfield wrote:
> >>> The SD cards info is available everywhere free.
> >> Um, where?
> > www.sandisk.com/Assets/File/OEM/Manuals/SD_SDIO_specsv1.pdf
> > and other big makers sites.
> >
> That's the SDIO extension spec, not the info on the SD memory
> itself. I can find the "physical layer" spec, and I can find the
> SDIO extensions, but not the basic memory card info... (or maybe
> the physical layer spec is pretty much IT.)
>
> > FAT32 goes up to 32GB in actual implementations, though it's
> > theoretically capable of 2TB.
>
> I think I had FAT32 disks under W98 that were larger than 32GB...
> It wasn't till XP came along that windows insisted on NTFS for
> large disks...
It's Microsoft that's the problem on this end. Win2k/XP will not allow
you to create a FAT32 partition bigger then 32GB. There is NO technical
reason for this, it's simply MS shoving NTFS down our throats. The
interesting bit is if you create a FAT32 partition bigger then 32GB with
another tool, both 2K and XP will have ZERO problem using it!
> So what do you format a > 4GB card as these days? That's the limit of
> FAT32
no its not, fat32 supports up to 2TB (though the formatter in 2K/XP is crippled and will only format fat32 partitions up to 32GB)
> FAT32 goes up to 32GB in actual implementations
i have a 160 gig fat32 hard drive in an external caddy running just fine with XP, i just had to format it using a win98 box.
>
>> FAT32 goes up to 32GB in actual implementations
> i have a 160 gig fat32 hard drive in an external caddy running just fine
> with XP, i just had to format it using a win98 box.
>
Is the "limitation" how many sectors are allowed per cluster? Microsoft's
FAT Overview says BPB_SecPerClus is one byte. Supposedly, for FAT16 (which
is what I'm most familiar with), this could allow 255 sectors per cluster
times 512 bytes per sector times about 65,535 clusters or 8.55e9 bytes per
disk. This would be a cluster size of 262,144 bytes. The Microsoft
document also says the cluster size must be a power of 2, so the maximum
would then be 128, or 65536 bytes per cluster. It ALSO goes on to say you
cannot have a cluster size greater than 32kBytes. So, using a 512 byte
sector, it appears the maximum sectors per cluster would be 64, and the
maximum partition size would be 2G. Again, this is for FAT16.
Is FAT32 similar, but with a larger FAT table, and with 32 bit cluster
identifiers in that table?
> -----Original Message-----
> From: RemoveMEpiclist-bouncesTakeThisOuTmit.edu [spamBeGonepiclist-bouncesspamBeGonemit.edu]On Behalf
> Of Harold Hallikainen
> Sent: 07 November 2006 19:03
> To: Microcontroller discussion list - Public.
> Subject: RE: [PIC] Interfacing a PIC to a microSD or TransFlash card
>
>
>
> >
> >> FAT32 goes up to 32GB in actual implementations
> > i have a 160 gig fat32 hard drive in an external caddy running just fine
> > with XP, i just had to format it using a win98 box.
> >
>
> Is the "limitation" how many sectors are allowed per cluster? Microsoft's
> FAT Overview says BPB_SecPerClus is one byte. Supposedly, for FAT16 (which
> is what I'm most familiar with), this could allow 255 sectors per cluster
> times 512 bytes per sector times about 65,535 clusters or 8.55e9 bytes per
> disk. This would be a cluster size of 262,144 bytes. The Microsoft
> document also says the cluster size must be a power of 2, so the maximum
> would then be 128, or 65536 bytes per cluster. It ALSO goes on to say you
> cannot have a cluster size greater than 32kBytes.
IIRC NT allowed you to break that rule and have 64k clusters, I remember the 98 resource kit saying that 98 could read and write fat16 partitions over 2 gigabytes but none of its disk utilities were comaptible with them.
> Is FAT32 similar, but with a larger FAT table, and with 32 bit cluster
> identifiers in that table?
i think that is the gist of it but i belive there are some other minor changes too.
according to wikipedia
"In order to overcome the volume size limit of FAT16, while still allowing DOS real-mode code to handle the format without unnecessarily reducing the available conventional memory, Microsoft decided to implement a newer generation of FAT, known as FAT32, with cluster counts held in a 32-bit field, of which 28 bits are currently used."
so that would mean 256 megaclusters
which keeping the 32K cluster size limit would mean 8 terabytes
i don't know why wikipedia says the actual limit is 2 terrabytes and i don't have any ms docs handy to compare but either way its big enough not to be a worry for most hard drives just yet.
Is there a way (and if so what is the best way) to access a memory
card without a filesystem from Windows (or Linux or Mac)? Something
programmatic I'm thinking - so I could just write data to a card with
a PC with custom software and simply stream it off with a PIC without
worrying about files or filesystems (or vice versa).
In linux, you could simply dd data to the device node: dd
if=myimage.bin of=/dev/sdd for example, if that's how your card is
recognized.
In Windows, there is also a way to access a device directly, by
accessing path \\.\X: . Look through this msdn entry for CreateFile,
in the Physical Access section: http://windowssdk.msdn.microsoft.com/en-us/library/ms685006.aspx
> Is there a way (and if so what is the best way) to access a memory
> card without a filesystem from Windows (or Linux or Mac)? Something
> programmatic I'm thinking - so I could just write data to a card with
> a PC with custom software and simply stream it off with a PIC without
> worrying about files or filesystems (or vice versa).
>
> -n.
>
>
> On Nov 7, 2006, at 2:31 PM, peter green wrote:
>
> >
> >
> >
Well, something I just did to allow a pic to bootload off an MMC/SD is to
do the following:
1. Format the card on the PC.
2. Write a single file with the bootload data (I am bootloading with the
hex file). Include a line of identifying text at the start of the file. I
used the company name, copyright, product model, etc.
3. When the PIC reads the card, it just looks for the identifying string
at the start of the file, then reads the file sector by sector.
It's possible there will be bad sectors that will be marked in the FAT,
which we are skipping, but I have not seen the problem as yet. I was doing
a compact bootloader in asm, so I didn't want to get into the FAT (which I
do in the application in C). By formatting the card before putting the
file on there, we SHOULD have the file in a bunch of sequential sectors.
We just have to figure out where it starts, so I used the string search.
The start of the file is always at the start of a sector, so you can just
do a string compare of your sector buffer to the string (you don't need to
see if the string starts in the second byte of the buffer, then the third,
etc.).
In my bootloader, I search for the string, then run through the hex code
checking checksums of each line, looking for end of file record. If it
passes, I find the start of the file again, then bootload.
> Is there a way (and if so what is the best way) to access a memory
> card without a filesystem from Windows (or Linux or Mac)? Something
> programmatic I'm thinking - so I could just write data to a card with
> a PC with custom software and simply stream it off with a PIC without
> worrying about files or filesystems (or vice versa).
>
> -n.
>
>
> On Nov 7, 2006, at 2:31 PM, peter green wrote:
>
>>
>>
>>
> Is there a way (and if so what is the best way) to access a
> memory card without a filesystem from Windows (or Linux or
> Mac)? Something programmatic I'm thinking - so I could just
> write data to a card with a PC with custom software and
> simply stream it off with a PIC without worrying about files
> or filesystems (or vice versa).
>
> -n.
Another option is to format the card and create a single file taking up the
entire card. So long as you avoid the first bit of the card where the FAT
table is, you can do whatever you like with the rest. You will be able to
read the card in any PC.
How big the FAT table is depends on how it's formatted, of course. The
bigger the cluster size, the smaller the FAT, so pick huge clusters
(normally a bad idea). All you need to do then is find the start of your
file (which will be noted in the FAT table anyway).
Seems to be a popular topic these days. I even noticed my local parts place
- http://www.jaycar.com.au selling SD sockets, which surprised me a bit. Popular
indeed.
>but either way its big enough not to be a worry for most hard drives just
>yet.
Guess that depends on what you're doing - it would be possible to have
multiple 1TB drives on a system with hardware RAID that the OS sees as a
single drive. It wouldn't take long to be pushing that limit - but using
FAT - well, I guess some people are into S&M ...
> so that would mean 256 megaclusters
>
> which keeping the 32K cluster size limit would mean 8 terabytes
>
> i don't know why wikipedia says the actual limit is 2 terrabytes and i don't have any ms docs handy to compare but either way its big enough not to be a worry for most hard drives just yet.
The partition table can't make partitions of over 2^32 sectors, so
there's your 2TiB limit.
On 07/11/06, Herbert Graf <RemoveMEmailinglist3TakeThisOuTfarcite.net> wrote:
> Win2k/XP will not allow
> you to create a FAT32 partition bigger then 32GB. There is NO technical
> reason for this, it's simply MS shoving NTFS down our throats. The
> interesting bit is if you create a FAT32 partition bigger then 32GB with
> another tool, both 2K and XP will have ZERO problem using it!
There are technical reasons they should strongly disrecommend FAT. But
I personally wouldn't recommend NTFS as replacement, if only because
it's closed and therefore impossible to be compatible with (you can't
copy what you can't see with certainty).
> Ahh, the beauty of alternate OS's...
The alternate OSes that allow you to choose between dozens of file
systems without any document on their relative merits might be worse,
depending on the time and experience you want to expend on it. Windows
may only have two choices, but that does make the choice pretty
trivial. Are you talking "alternative" as in "not windows" or as in
"not with a million-plus user base" ?
Ok, i hope you will all forgive me for digging up an old thread like
this one but i used search hoping to find some information regarding
my problem and this is the best result i received.
I want to implement a SD card interface into a product which will be
sold to customers but the profit will be A LOT SMALLER than that $1000
fee i have to pay to SD organisation. After looking stuff up on google
i found out that MMC is free of charge so to say and compatible with
SD cards to some extent.
Now, my question is : can i use a SD card socket and implement some
protocol of access common to both MMC and SD and still be allright in
terms of legally selling the product ?
Thank you in advance
On Fri, Nov 10, 2006 at 5:24 PM, alan smith <micro_eng2EraseME.....yahoo.com> wrote:
> I believe...not too long ago...i saw a demo board from microchip that had a CF or SD card on it. So think they are supporting it?
>
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