Secure Digital card: Difference between revisions

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The XO laptop has a slot for an SD card. Once inserted, the contents are shown by the [[Journal Activity]] or the GNOME file browser. See [[Journal]] for how to use an SD card in Sugar; you can move files to and from the card by dragging and dropping the file in the Journal view to the card icon at the bottom of the screen.


== Using ==
The XO laptop has 1 MMC/SD/SDHC slot. 8-gigabyte memory cards work. As larger cards are created, they will also be tested (-gnu).
*Insert card into the slot at the bottom of the screen. See below for more detailed instructions.
*In [[Sugar]], a card icon will appear at the lower left of the [[Journal]], and you can begin to use it.
*In Gnome, an icon for the card will appear on the desktop, and a window will open showing the files on the card, and you can begin to use it.
*When finished with the card, you ''must'' tell the computer before removing it, either;
:*click on it in the Journal and choose unmount,
:*click on it in the frame and choose unmount,
:*click the eject button in the GNOME file browser window, or;
:*right-click on the GNOME desktop icon and choose ''Eject''.
:If you remove the card without this step, pending changes to the card may not be written and some files may be left in a corrupted state.
*Eject the card; push it in slightly until you feel a click, then release it.


== Supported cards ==
⚫
XO uses a custom microchip for SD card access, Camera and Flash Enabler, or CaFE. CaFE includes SDHC support. SDHC is compatible at a hardware level with SD. Pierre Ossman wrote the Linux driver support for SDHC. SD cards up to something like 256 GB should be supported. cafe is driven by the sdhci driver. cafe follows the standard host controller interface for SD controllers.
* Most cards work,
* Some cards don't work,
* Most filesystems work; such as FAT16, FAT32, ext2, ext3, ext4,
* Some filesystems won't work, such as HFS+,
* Most card sizes should work; but we have not tested them all,
* Some cards work for file storage, but not for booting.


For deployments, carefully test a sample of the card being used.
⚫
Here is how SD block addressing works: The address is 32 bits. In the CaFe chip, which is compatible with the standard "SDHCI" spec, the address goes in the 32-bit chip register at offset 8. For old SD cards (not the new SDHC - High Capacity cards), the address is a byte address, so the maximum size is 4 Gbytes. For the newer SDHC cards, the address is a block number, assuming 512 byte blocks, so the maximum size is 2 TBytes. None of this is CaFe-specific, BTW. It is standard SD. In other words, SDHC just shifts the addresses by nine bits, allowing an effective 40 bit address. The other limit that's often written about, 32GB, is an artificial limit in Window's FAT formatter; Windows will use the generally incompatible NTFS instead. Linux can format FAT up to the ~300GB real limit just fine, after that we'll need to use a linux specific fs.


== Insertion ==


⚫
To properly insert the card the gold fingers on the card should be facing up and towards the front of the display. Insert the card until it is flush with the bottom of the screen, you will hear or feel a click when the card is fully seated. It is a "Push to Click in and Push to Click out (Eject)" mechanism. When ejecting, push the card in again and release. It should come out far enough to grab with fingers, Try small tweezers if you have a hard time getting the card to come out again. While not required, you can also attach a little piece of adhesive tape to the card to give an easy handle to pull on the card if it sticks.
'''Question:''' 16GB cards are starting to show up, I assume they *should* work, but has anyone tried one?


The picture shows the proper way to insert the card; your card might not have this many contacts, but it should be the same size and shape:
: Yes, there is at least [http://olpc.osuosl.org/forum/viewtopic.php?t=964&sid=748b62158cc7196a4dbb9ba0b95b52c7 one report] of 16GB SDHC cards working. —[[User:Leejc|Joe]] 13:59, 27 December 2007 (EST)


⚫
[[Image:Proper_SD_Card_Insertion.jpg]]


⚫
--[[User:KenXo|KenXo]] 11:28, 24 December 2007 (EST)
SD cards and USB flash drives are automatically mounted in the [[Journal]] activity. The [[Journal]] entry shows you how to access the add-on memory devices. You can move files to and from the storage media. [[User:Paul Bock|Paul Bock]] 13:56, 19 December 2007 (EST)


== Troubleshooting ==
'''Another Question:''' I Installed (2) different USB sticks on my new XO and also a miniSD(with SD adapter) and none of these (3) items are showing up in the Journal. I'm unable to access any of these and don't understand what I'm doing wrong. The USBs are both U3 Launchpad enable (only one is password protected). How can I make these Items work?


* Try the same card in another device.
A: Make sure both cards have different Volume labels, as that's how they're assigned a mount point. See [http://ubuntuforums.org/showthread.php?t=365661]


* Try the same card in another XO laptop,
: There's a hidden folder the OLPC puts onto all mounted media, ".olpc.store/". Try removing that, a broken database there may keep the journal from working properly. You should always be able to see the device mounted using "df" in Terminal.


* Try a new card; if new cards don't work, there may be a fault with the laptop.
: Also, make sure they are FAT-formatted (most new USB sticks come FAT-formatted)—I think both FAT16 and FAT32 work. Also, I think the sticks/cards need to be writable for Sugar to index them correctly, so if your stick or card comes with a read-only switch, make sure it is in the read/write position and not the read-only position. I don't know much about the U3 system, but you might want to try non-U3, non-password-protected sticks to eliminate the possibility that your hardware is defective. If regular, brand-new sticks are not working, it is possible there is something wrong with the hardware of your machine, in which case you may want to [[Support_FAQ#What_is_the_warranty_info.3F_RMA_process.3F | contact the support line]] to see if it needs to be replaced (within the 30 day warranty period, if possible). —[[User:Leejc|Joe]] 02:29, 29 December 2007 (EST)


* Try rebooting; some cards have been found to work differently after a reboot.
⚫
'''Note:''' The SD/MMC/SDHC memory card will only mount when inserted properly into the XO laptop. The slot will allow you to insert the card in either direction however.


⚫
* Check which way round the card is; the card will only work when inserted the right way around, and broken slots may allow you to insert the card in either direction.
⚫
To properly insert the SD/MMC/SDHC card the brass fingers on the card should be facing up and towards the front of the LCD screen. Insert the card until it is flush with the bottom of the screen, you will hear a click when the card is fully seated. [I had a hard time getting the card come out again. Using small tweezers I finally succeeded. Next time I attach a little piece of scotch tape to the SD card; this will give me an easy handle to pull the card out when it gets stuck. Geert December 28, 2007]


* Further diagnosis can be done using "dmesg | grep mmc" from the terminal shell.
The picture below shows the proper way to insert the SD/MMC/SDHC card:


== Booting ==


The XO laptop can boot from an SD card. OLPC OS can be installed onto a card. See [[Firmware/Storage#How_to_install_to_SD_card How to install to SD card]].
⚫
[[Image:Proper_SD_Card_Insertion.jpg]]


== Formatting ==
⚫
--[[User:KenXo|KenXo]] 11:28, 24 December 2007 (EST)

SD cards are pre-formatted by their manufacturers to work best for the device. It is not recommended that you reformat unless it really stops working; for example, if a freshly booted Linux refuses to mount it.

To reformat as FAT, see [[/Reformatting/Fat]]. May impact card performance.


To reformat as ext2, see [[/Reformatting/Ext2]]. May impact card performance, and will certainly reduce portability with other devices.


== Implementation ==
⚫
[[Hardware#XO-1_Laptop|XO-1]] uses a custom microchip for SD card access: the Camera and Flash Enabler (CaFE). CaFE includes SDHC support, which is hardware level compatible with SD. Pierre Ossman wrote the Linux driver support for SDHC and CaFE is driven by the sdhci driver. SD cards up to about 256 GB should be supported. CaFE follows the standard host controller interface for SD controllers.


[[XO-1.5]], [[XO-1.75]] and [[XO-4]] also support SD/MMC cards, but they don't use the CaFE ASIC.


==Wikipedia==
== Standards ==
⚫
See Wikipedia for a basic overview. SD block addressing works with a 32 bit address. In the CaFe chip, which is compatible with the standard "SDHCI" spec, the address goes in the 32-bit chip register at offset 8. For old SD cards (not the new SDHC cards), the address is a byte address, so the maximum size is 4 Gbytes. For the newer SDHC cards, the address is a block number, assuming 512 byte blocks, so the maximum size is 2 TBytes. In other words, SDHC just shifts the addresses by nine bits, allowing an effective 40 bit address. The 32 GB limit that's often written about is an artificial limit in Window's FAT formatter; Windows will use the generally incompatible NTFS file system instead. Linux can format FAT up to the ~300GB real limit just fine, after that the card will need to use a linux specific filesystem. None of this is CaFe-specific.
* [http://en.wikipedia.org/wiki/Secure_Digital_card Secure Digital card]


== See also ==
* [[wikipedia:Secure Digital card]] is a good overview of the standard.
* [http://fakememorysentinel.wordpress.com/ fake flash products].
* [http://www.kingston.com/en/support/product_verification Kingston product verification].
* [[USB drive]] - the XO also has slots for USB drives such as USB flash drives.
* [[Swap]] explains how to use an SD card as swap to allow running more instances of more complicated applications than can fit in memory.
* [[SD and USB FLASH Drive Performance]]
* [[NAND Testing]]


[[Category:Hardware]]
[[Category:Hardware]]

Latest revision as of 23:22, 8 October 2013

The XO laptop has a slot for an SD card. Once inserted, the contents are shown by the Journal Activity or the GNOME file browser. See Journal for how to use an SD card in Sugar; you can move files to and from the card by dragging and dropping the file in the Journal view to the card icon at the bottom of the screen.

Using

  • Insert card into the slot at the bottom of the screen. See below for more detailed instructions.
  • In Sugar, a card icon will appear at the lower left of the Journal, and you can begin to use it.
  • In Gnome, an icon for the card will appear on the desktop, and a window will open showing the files on the card, and you can begin to use it.
  • When finished with the card, you must tell the computer before removing it, either;
  • click on it in the Journal and choose unmount,
  • click on it in the frame and choose unmount,
  • click the eject button in the GNOME file browser window, or;
  • right-click on the GNOME desktop icon and choose Eject.
If you remove the card without this step, pending changes to the card may not be written and some files may be left in a corrupted state.
  • Eject the card; push it in slightly until you feel a click, then release it.

Supported cards

  • Most cards work,
  • Some cards don't work,
  • Most filesystems work; such as FAT16, FAT32, ext2, ext3, ext4,
  • Some filesystems won't work, such as HFS+,
  • Most card sizes should work; but we have not tested them all,
  • Some cards work for file storage, but not for booting.

For deployments, carefully test a sample of the card being used.

Insertion

To properly insert the card the gold fingers on the card should be facing up and towards the front of the display. Insert the card until it is flush with the bottom of the screen, you will hear or feel a click when the card is fully seated. It is a "Push to Click in and Push to Click out (Eject)" mechanism. When ejecting, push the card in again and release. It should come out far enough to grab with fingers, Try small tweezers if you have a hard time getting the card to come out again. While not required, you can also attach a little piece of adhesive tape to the card to give an easy handle to pull on the card if it sticks.

The picture shows the proper way to insert the card; your card might not have this many contacts, but it should be the same size and shape:

Proper SD Card Insertion.jpg

--KenXo 11:28, 24 December 2007 (EST)

Troubleshooting

  • Try the same card in another device.
  • Try the same card in another XO laptop,
  • Try a new card; if new cards don't work, there may be a fault with the laptop.
  • Try rebooting; some cards have been found to work differently after a reboot.
  • Check which way round the card is; the card will only work when inserted the right way around, and broken slots may allow you to insert the card in either direction.
  • Further diagnosis can be done using "dmesg | grep mmc" from the terminal shell.

Booting

The XO laptop can boot from an SD card. OLPC OS can be installed onto a card. See Firmware/Storage#How_to_install_to_SD_card How to install to SD card.

Formatting

SD cards are pre-formatted by their manufacturers to work best for the device. It is not recommended that you reformat unless it really stops working; for example, if a freshly booted Linux refuses to mount it.

To reformat as FAT, see /Reformatting/Fat. May impact card performance.

To reformat as ext2, see /Reformatting/Ext2. May impact card performance, and will certainly reduce portability with other devices.

Implementation

XO-1 uses a custom microchip for SD card access: the Camera and Flash Enabler (CaFE). CaFE includes SDHC support, which is hardware level compatible with SD. Pierre Ossman wrote the Linux driver support for SDHC and CaFE is driven by the sdhci driver. SD cards up to about 256 GB should be supported. CaFE follows the standard host controller interface for SD controllers.

XO-1.5, XO-1.75 and XO-4 also support SD/MMC cards, but they don't use the CaFE ASIC.

Standards

See Wikipedia for a basic overview. SD block addressing works with a 32 bit address. In the CaFe chip, which is compatible with the standard "SDHCI" spec, the address goes in the 32-bit chip register at offset 8. For old SD cards (not the new SDHC cards), the address is a byte address, so the maximum size is 4 Gbytes. For the newer SDHC cards, the address is a block number, assuming 512 byte blocks, so the maximum size is 2 TBytes. In other words, SDHC just shifts the addresses by nine bits, allowing an effective 40 bit address. The 32 GB limit that's often written about is an artificial limit in Window's FAT formatter; Windows will use the generally incompatible NTFS file system instead. Linux can format FAT up to the ~300GB real limit just fine, after that the card will need to use a linux specific filesystem. None of this is CaFe-specific.

See also

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