Wednesday, March 28, 2012

What is Multimedia Card?

MMC card (Multimedia Card) is a kind of Flash Memory card standard. It is developed by Simens and SanDisk in 1997. Based on NAND Flash Memory technology of Toshiba, it is thiner and smaller than earlier NOR Flash Memory of Intel like CF card. MMC card is as small as a stamp. That is about 24mm * 32mm * 1.5mm.

MMC card is small and light, weighs only 2g and below. It is strongly resistant to impact, and can repeatedly read-write and record for 300 thousand times. Driving voltage of MMC card is 2.7-3.6 V. At present the capacity of MMC card is as much as 2 GB. Moreover, it can be applied to almost every device which uses memory card, such as mobile phone, digital audio player, digital camera and PDA. Because of the showing up of Secure Digital, there is no firm which put MMC slot into their devices. Yet a little bit narrower, Pin to Pin MMC card can be applied to every device supoorts SD card. However, few firms, best-known Nokia, still supported MMC. 

At first MMC card uses serial interfaces, but the newer standard allows concurrently transmission of 4 bit or 8 bit information. Recent years MMC card technology has almost replaced by SD card. But as MMC card can be read by device which supports SD card, it still works.

MMC card is released by Simens and SanDisk which focuse on CF in 1997. January, 1998, 14 companies establish MMC association (MultiMediaCard Association, MMCA in short.) there are already 84 more members now. The target of MMC development is digital video, music, cellphone, PDA, e-book, toy, and so on. The size of it is only 32mm * 24mm * 1.4mm, and only weighs 1.5g. MMC also combines storage unit with controller. Smart controller guarantees the compatibility and flexibility. MMC storage card can be divided into MMC and SPI two kinds of operating modes. MMC is the normal default mode and has all of the features of MMC. SPI mode is the second optional mode of MMC storage card. This mode is a subset of MMC protocol. It is mainly used for system that need small number of card (usually one), and low data transmission rate (compared to MMC protocol). This mode can reduce the design cost to minimum, but the performance is not as good as MMC.

Designed as a low cost data platform and conmmunication medium, the port design of MMC is very simple: there are only 7 pins. The cost of port is under 0.5 dollar. In the port, power supply used 3 pins and data manipulation uses only 3 pins serial bus (in SPI mode 1 more pin is used for choosing chip). 

The operating voltage of MMC is 2.7-3.6 V. Read-write current is only 27mA and 23mA. The consumption is very low. The read-write mode includes stream transmission, multi-piece and single piece. The minimum data transmission is counted in piece. The default piece is 512 bytes.

There is small size MMC card. It is half size of normal size MMC card: 24mm * 18mm * 1.4mm. This optional size MultiMediaCard, or RS-MMC, is released in 2004. It is only smaller size MMC card. Use a machinery connection to extend it, any RS-MMC card can be used at MMC (or SD) card slot. The largest capacity of RS-MMC card can be 1 GB at present. 

The only two important hardware licensors of RS-MMC are Simens and Nokia. They often put RS-MMC card in use of Nokia's 60 series Symbian smart phone, Nokia's 770 Internet tablet PC and Simens' 65 and 75 production. The newer RS-MMC card applied in Nokia's new phone (like Nokia 6630 and Nokia 6680) supports low voltage (1.8V, not 3V) mode to reduce power consumption. These cards are called double voltage RS-MMC (DV-RS-MMC). If RS-MMC card satisfys the standard of movable type MMC card, it can be sold as movable type MMC card. These low voltage cards are backward compatible with old RS-MMC devices. Double voltage card and movable MMC is part of 4.x standard of MMC.

MMC 4.x and secureMMC
4.x (4.0, 4.1, etc.) standard is released in 2005 (MMCA system standard 4.1). This new standard brought in MMC4 which is called MMCplus and has more effective performance (it uses tha same structure and size with MMC but there are more pins) and RS-MMC4 which is sold as movable MMC. Movable MMC4 is a reprint of old RS-MMC, because it uses the same way and standard of connection with RS-MMC. Yet its size is about half of normal MMC card. This standard also defines secureMMC standard. The encipherment feature is similar to Secure Digital or MagicGate Memory Sticks. 

Different types of MMC/SD cards
SD card is not the only stsndard of Flash Memory which acquires the admission from Secure Digital Card Association. Other Secure Digital Card format includes miniSD and microSD (it is called TransFlash before being admitted by Secure Digital Card Association).
These small size cards can be used in full size MMC/SD/SDIO slot through a converter (connected to electric circuit and physical connection). However, the difficult point is t to make input/output device on SD card size, and it will be more unpractical to make on smaller size.
Because SD slot still supports MMC card, the smaller variant of MMC which has developed alone also supports SD devices. Different froms miniSD and microSD (they are totally different from SD. Making machinery converter is very unpractical), RS-MMC slot keeps being backward cpmpatible with full size MMC card, because RS-MMC is only shorter than MMC card. More information about these variant please refer to MMC.

Other information
1. About the brands of MMC: recently most of users choose PQI. The price of PQI is the lowest, so there are many fake ones. There are two kinds of PQI. One is the first generation low speed blue dolphin card. The fake blue cards are at the most. It is suggested not to buy it. The other one is the second generation orange card. If you want to buy PQI, it is suggested to buy this kind.
Other good brands of MMC: EagleTec, KingMAX, SanDisk.

2. About the capacity of MMC: generally speaking, 128M or 256M is enough. From the practical angle of view, MMC is mainly used for storing application software, ring, and pictures, etc. If there is no need to watch video on phone regularly, 128 M is enough. Otherwise 256M is better. A music lover may consider about 256M or bigger one.

3. About the identification of compatibility of MMC card: when buying a MMC card, it is strongly suggested to try it to see if it works. And it is not enough if it "works", it is also important to check the compatibility of the card. You can set the storage to MMC card, and then take a few minutes video with sound. If the MMC is not completely compatible, there will be no sound when playing the video. You can also put a SIS form software into the interal storage of the phone (smaller than 4M), and then change the file attribute through SELEQ to "read only". Then when you are trying the card you can install the software on MMC to see if it works. That is because changing the file attribute to "read only" avoids the file disappearing after installation. If there is any need to try other cards, you can continue installing this file. Pay attention to that when the attribute is changed to "read only", it no longer can be deleted. So remember to change it back when you need to delete it.

4. About the distinguishing of new or used MMC: Check the contact point. Generally there is no scratch on new card.

5. About the formatting of MMC: Generally MMC newly bought can be used directly. If there is any need to formatting, just make sure the battery of phone is full before formatting on the phone. It is very slow to format the card on the phone. If you use the card reader to format MMC on computer, you have to change the file layout to FAT (that is FAT16). Otherwise the FAT32 won't be identified on the phone.

6. About the basic contents of MMC on 6600: After formatting on the phone, MMC will automatically form the following 6 contents: images, mp3, sounds, videos, system, and others.
●images - the direct content is for placing photos and pistures. There is a hidden content "_paibin" for preview pictures.
●mp3 - for placing mp3 files.
●sounds - for placing ring files. There are two folders: digital, for placing wav files; simple, for placing midi files.
●videos - for placing video files.
●sysetm - for placing system files. It cannot be seen unless using a FileMan or SeleQ or other software.

Reparation of MMC
There are usually three kinds of MMC card damage. First, computer cannot read the card because of having not set password. Second, the card cannot be formatted because of password. Third one is the I/O mistake.

Computer cannot read the card because of having not set password.
Let's firatly see the problem of not being able to read the card without setting password. Basically, this problem is caused by the nonsupport of hot-plug and misoperation of card reader, and that makes logical error of the card. You can use the Norton disc reparation tool or Hrad Disc Restoration to repair. No more specific operation process but one point to mention: if put MMC card into the card reader and the system keeps reading the card with no response or even apparently dead, and the light of card reader keeps shining, at this situation, the two afore mentioned tools will not work, because they can never recognize MMC card. Here is a way I have studied to solve the problem: find a MMC card with the same capacity and put it into the card reader. Click the right button "format", and the firmatting menu will come up, then you unplug the card, the menu will not disappear. At this time you plug in the problematical card, and then choose "FAT32" formatting. The process may be very long, or the Windows cannot finish the formatting. Don't give up, repeat this procedure. Probably the chance is one-tenth. Once the formatting is finshed, you should click the right button, choose "attribute", "Error Check", to repair the bad sector. If there is any physical damage of MMC card, the process might be very long and slow. After that, choose "FAT" formatting.

The card cannot be formatted because of password
About the causes of not being able to format because of password: the causes may be a great many. Most of them are the poping up of password after formatting MMC card. Another one is being locked after reboot because of using SeleQ to set Logo or background with volume E images or MBM images. There are many other causes, too. The card cannot be formatted in XP system to solve these problems, because the computer will not recogniaze the card. I have tried to set password to format but it doesn't work. The perfect solution at present is to use 9210C or 9300 to format. There is specific process on the BBS. I have studied two strategies. First, find a KODAK or CANON camera which support MMC card, and then use the camera to format the card. Generally it doesn't need password, because compared to the phone, camera has a simpler setting with no buttons. It is better to choose a lower configuration as long as it supports MMC. The second way is solve the problem in the phone which causes the mistake. I have tried this way using QD but it is not very clear if it works in other phones. The specific process is: install SeleQ through Bluetooth in the phone storage (If you install it in the card, "system error" will come up), and then reboot the phone. After that you will see volum E in the SeleQ. You should delete all of the files of the MMC card. Then there will be two MMC prefixal files in SYSTEM, volum C. Delete both of them. The card cannot be read by now, but you can try the first solution now. 

I/O mistake
About I/O mistake, it's better to send the card for guarantee repair. It's no use to repair it with disc reparation tool because "I/O mistake" will directly come up and the computer can never read the card. 

Recommended software of reparation: FlashDoctor and mmcmedic.  

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