MultiMediaCard
Encyclopedia
The MultiMediaCard is a flash memory
memory card
standard. Unveiled in 1997 by Siemens AG
and SanDisk
, it is based on Toshiba
's NAND-based flash memory, and is therefore much smaller than earlier systems based on Intel NOR-based memory such as CompactFlash
. MMC is about the size of a postage stamp: 24 mm × 32 mm × 1.4 mm. MMC originally used a 1-bit
serial interface, but newer versions of the specification allow transfers of 4 or 8 bits at a time. It has been more or less superseded by SD (Secure Digital
) card, but still sees significant use because MMCs can be used in most devices that support SD cards.
Typically, an MMC is used as a storage medium for a portable device, in a form that can easily be removed for access by a PC
. For example, a digital camera
would use an MMC for storing image files. With an MMC reader (typically a small box that connects via USB or some other serial connection, although some can be found integrated into the computer itself), a user could copy the pictures taken with the digital camera off to his or her computer. Modern computers, both laptops and desktops, often have SD slots, which can additionally read MMCs if the operating system drivers support them.
MMCs are available in sizes up to and including 32 GB
. They are used in almost every context in which memory card
s are used, like cellular phone
s, digital audio players, digital camera
s and PDA
s. Since the introduction of Secure Digital
card few companies build MMC slots into their devices (an exception is some mobile devices like the Nokia 9300
communicator, where the smaller size of the MMC is a benefit), but the slightly thinner, pin-compatible MMCs can be used in almost any device that supports SD cards if the software/firmware on the device supports them.
As of July 2009, the latest specifications version 4.4 (dated March 2009) can be requested from the MMCA, and after registering downloaded free-of-charge. Older versions of the standard, as well as some optional enhancements to the standard such as MiCard and SecureMMC, must be purchased separately.
Samsung
, a major backer of MMC, provides a highly detailed datasheet which contains much of the essential information for writing an MMC driver.
As of September 23, 2008 The MMCA group has turned over all specifications to the JEDEC organization including embedded MMC (e-MMC) and miCARD assets. JEDEC
is an organization devoted to standards for the solid-state industry.
.
The only significant hardware licensors of RS-MMCs were Nokia
and Siemens
, who used to use RS-MMC in their Series 60 Symbian
smartphone
s, the Nokia 770 Internet Tablet
, and generations 65 and 75 (Siemens). However, since 2006 all of Nokia's new devices with card slots have used miniSD or microSD cards, with the company appearing to abandon the MMC standard in its products. Siemens exited the mobile phone business completely in 2006. Siemens continue to use MMC for some PLC
storage.
Version 4.x full-size cards and reduced-size cards can be marketed as MMCplus and MMCmobile respectively.
Version 4.x cards are fully backward compatible with existing readers but require updated hardware/software to use their new capabilities; even though the four-bit-wide bus and high-speed modes of operation are deliberately electrically compatible with SD, the initialization protocol is different, so firmware/software updates are required to support these features in an SD reader.
MMCmicro appears very similar to microSD but the two formats are not physically compatible and have incompatible pinouts.
mechanism intended to enable MMC to compete with SD or Memory Stick
in this area. Very little information is known about how SecureMMC works or how its DRM characteristics compare with its competitors.
(BGA) package.
Embedded MultiMediaCard (e-MMC)
e-MMC/Card Product Standard,
High Capacity, including Reliable
Write, Boot, Sleep Modes,
Dual Data Rate, Multiple Partitions
Supports and Security Enhancement
Hard Disk drives with an interface called CE-ATA
. This interface is electrically and physically compatible with MMC specification. However, the command structure has been expanded to allow the host controller to issue ATA
commands to control the hard disk drive.
Specifications
Other
Flash memory
Flash memory is a non-volatile computer storage chip that can be electrically erased and reprogrammed. It was developed from EEPROM and must be erased in fairly large blocks before these can be rewritten with new data...
memory card
Memory card
A memory card or flash card is an electronic flash memory data storage device used for storing digital information. They are commonly used in many electronic devices, including digital cameras, mobile phones, laptop computers, MP3 players, and video game consoles...
standard. Unveiled in 1997 by Siemens AG
Siemens AG
Siemens AG is a German multinational conglomerate company headquartered in Munich, Germany. It is the largest Europe-based electronics and electrical engineering company....
and SanDisk
SanDisk
SanDisk Corporation is an American multinational corporation that designs, develops and manufactures data storage solutions in a range of form factors using the flash memory, controller and firmware technologies. It was founded in 1988 by Dr. Eli Harari and Sanjay Mehrotra, non-volatile memory...
, it is based on Toshiba
Toshiba
is a multinational electronics and electrical equipment corporation headquartered in Tokyo, Japan. It is a diversified manufacturer and marketer of electrical products, spanning information & communications equipment and systems, Internet-based solutions and services, electronic components and...
's NAND-based flash memory, and is therefore much smaller than earlier systems based on Intel NOR-based memory such as CompactFlash
CompactFlash
CompactFlash is a mass storage device format used in portable electronic devices. Most CompactFlash devices contain flash memory in a standardized enclosure. The format was first specified and produced by SanDisk in 1994...
. MMC is about the size of a postage stamp: 24 mm × 32 mm × 1.4 mm. MMC originally used a 1-bit
Bit
A bit is the basic unit of information in computing and telecommunications; it is the amount of information stored by a digital device or other physical system that exists in one of two possible distinct states...
serial interface, but newer versions of the specification allow transfers of 4 or 8 bits at a time. It has been more or less superseded by SD (Secure Digital
Secure Digital
Secure Digital is a non-volatile memory card format developed by the SD Card Association for use in portable devices. The SD technology is used by more than 400 brands across dozens of product categories and more than 8,000 models, and is considered the de-facto industry standard.Secure Digital...
) card, but still sees significant use because MMCs can be used in most devices that support SD cards.
Typically, an MMC is used as a storage medium for a portable device, in a form that can easily be removed for access by a PC
Personal computer
A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator...
. For example, a digital camera
Digital camera
A digital camera is a camera that takes video or still photographs, or both, digitally by recording images via an electronic image sensor. It is the main device used in the field of digital photography...
would use an MMC for storing image files. With an MMC reader (typically a small box that connects via USB or some other serial connection, although some can be found integrated into the computer itself), a user could copy the pictures taken with the digital camera off to his or her computer. Modern computers, both laptops and desktops, often have SD slots, which can additionally read MMCs if the operating system drivers support them.
MMCs are available in sizes up to and including 32 GB
Gigabyte
The gigabyte is a multiple of the unit byte for digital information storage. The prefix giga means 109 in the International System of Units , therefore 1 gigabyte is...
. They are used in almost every context in which memory card
Memory card
A memory card or flash card is an electronic flash memory data storage device used for storing digital information. They are commonly used in many electronic devices, including digital cameras, mobile phones, laptop computers, MP3 players, and video game consoles...
s are used, like cellular phone
Mobile phone
A mobile phone is a device which can make and receive telephone calls over a radio link whilst moving around a wide geographic area. It does so by connecting to a cellular network provided by a mobile network operator...
s, digital audio players, digital camera
Digital camera
A digital camera is a camera that takes video or still photographs, or both, digitally by recording images via an electronic image sensor. It is the main device used in the field of digital photography...
s and PDA
Personal digital assistant
A personal digital assistant , also known as a palmtop computer, or personal data assistant, is a mobile device that functions as a personal information manager. Current PDAs often have the ability to connect to the Internet...
s. Since the introduction of Secure Digital
Secure Digital
Secure Digital is a non-volatile memory card format developed by the SD Card Association for use in portable devices. The SD technology is used by more than 400 brands across dozens of product categories and more than 8,000 models, and is considered the de-facto industry standard.Secure Digital...
card few companies build MMC slots into their devices (an exception is some mobile devices like the Nokia 9300
Nokia 9300
The Nokia 9300 is a Nokia Series 80 Symbian Smartphone introduced in 2005. It is used as a normal though bulky mobile phone in closed mode, when it is flipped open it can be used like a very small notebook computer with a 640×200 screen...
communicator, where the smaller size of the MMC is a benefit), but the slightly thinner, pin-compatible MMCs can be used in almost any device that supports SD cards if the software/firmware on the device supports them.
Open standard
This technology is a standard available to any company wanting to develop products based on it. There is no royalty charged for devices which host an MMC. A membership with the MMC Association must be purchased in order to manufacture the cards themselves.As of July 2009, the latest specifications version 4.4 (dated March 2009) can be requested from the MMCA, and after registering downloaded free-of-charge. Older versions of the standard, as well as some optional enhancements to the standard such as MiCard and SecureMMC, must be purchased separately.
Samsung
Samsung
The Samsung Group is a South Korean multinational conglomerate corporation headquartered in Samsung Town, Seoul, South Korea...
, a major backer of MMC, provides a highly detailed datasheet which contains much of the essential information for writing an MMC driver.
As of September 23, 2008 The MMCA group has turned over all specifications to the JEDEC organization including embedded MMC (e-MMC) and miCARD assets. JEDEC
JEDEC
The JEDEC Solid State Technology Association, formerly known as the Joint Electron Devices Engineering Council , is an independent semiconductor engineering trade organization and standardization body...
is an organization devoted to standards for the solid-state industry.
Reduced-Size MultiMediaCard (RS-MMC)
MMCs also come in a smaller form factor, about half the size: 24 mm × 18 mm × 1.4 mm. This alternate form factor is known as Reduced-Size MultiMediaCard, or RS-MMC, and was introduced in 2004. RS-MMCs are simply smaller than MMCs; by using a simple mechanical adapter to elongate the card, an RS-MMC can be used in any MMC (or SD) slot. RS-MMCs are currently available in sizes up to and including 2 GBGigabyte
The gigabyte is a multiple of the unit byte for digital information storage. The prefix giga means 109 in the International System of Units , therefore 1 gigabyte is...
.
The only significant hardware licensors of RS-MMCs were Nokia
Nokia
Nokia Corporation is a Finnish multinational communications corporation that is headquartered in Keilaniemi, Espoo, a city neighbouring Finland's capital Helsinki...
and Siemens
Siemens cellular telephones
Siemens cellular telephones were mobile phones produced by Siemens AG.In 2005 the Taiwanese company BenQ acquired the financially bleeding mobile phone subsidiary from Siemens and gained the exclusive right to use Siemens trademark for 5 years...
, who used to use RS-MMC in their Series 60 Symbian
Symbian
Symbian is a mobile operating system and computing platform designed for smartphones and currently maintained by Accenture. The Symbian platform is the successor to Symbian OS and Nokia Series 60; unlike Symbian OS, which needed an additional user interface system, Symbian includes a user...
smartphone
Smartphone
A smartphone is a high-end mobile phone built on a mobile computing platform, with more advanced computing ability and connectivity than a contemporary feature phone. The first smartphones were devices that mainly combined the functions of a personal digital assistant and a mobile phone or camera...
s, the Nokia 770 Internet Tablet
Nokia 770 Internet Tablet
The Nokia 770 Internet tablet is a wireless Internet appliance from Nokia, originally announced at the LinuxWorld Summit in New York City on May 25, 2005...
, and generations 65 and 75 (Siemens). However, since 2006 all of Nokia's new devices with card slots have used miniSD or microSD cards, with the company appearing to abandon the MMC standard in its products. Siemens exited the mobile phone business completely in 2006. Siemens continue to use MMC for some PLC
Programmable logic controller
A programmable logic controller or programmable controller is a digital computer used for automation of electromechanical processes, such as control of machinery on factory assembly lines, amusement rides, or light fixtures. PLCs are used in many industries and machines...
storage.
Dual-Voltage MultimediaCard (DV-MMC)
One of the first substantial changes in MMC was the introduction of dual-voltage cards that support operations at 1.8 V in addition to 3.3 V. Running at lower voltages reduces the card's energy consumption, which is important in mobile devices. However, simple dual-voltage parts quickly went out of production in favour of MMCplus and MMCmobile which offer capabilities in addition to dual-voltage support.MMCplus and MMCmobile
The version 4.x of the MMC standard, introduced in 2005, brought in two very significant changes to compete against SD cards: support for running at higher speeds (26 MHz and 52 MHz) than the original MMC (20 MHz) or SD (25 MHz, 50 MHz) and a four- or eight-bit-wide data bus.Version 4.x full-size cards and reduced-size cards can be marketed as MMCplus and MMCmobile respectively.
Version 4.x cards are fully backward compatible with existing readers but require updated hardware/software to use their new capabilities; even though the four-bit-wide bus and high-speed modes of operation are deliberately electrically compatible with SD, the initialization protocol is different, so firmware/software updates are required to support these features in an SD reader.
MMCmicro
MMCmicro is a micro-size version of MMC. With dimensions of 14 mm × 12 mm × 1.1 mm, it is even smaller and thinner than RS-MMC. Like MMCmobile, MMCmicro supports dual voltage, is backward compatible with MMC, and can be used in full-size MMC and SD slots with a mechanical adapter. MMCmicro cards have the high-speed and four-bit-bus features of the 4.x spec but not the eight-bit bus, due to the absence of the extra pins.MMCmicro appears very similar to microSD but the two formats are not physically compatible and have incompatible pinouts.
MiCard
The MiCard is a backward-compatible extension of the MMC standard with a theoretical maximum size of 2048 GB (2 TB) announced in 2007. The card is composed of two detachable parts, much like a microSD card with an SD adapter. The small memory card fits directly in a USB port while it also has MMC-compatible electrical contacts, which with an included electromechanical adapter fits in traditional MMC and SD card readers. To date, only one manufacturer has produced cards in this format.SecureMMC
An additional, optional, part of the MMC 4.x specification is a DRMDigital rights management
Digital rights management is a class of access control technologies that are used by hardware manufacturers, publishers, copyright holders and individuals with the intent to limit the use of digital content and devices after sale. DRM is any technology that inhibits uses of digital content that...
mechanism intended to enable MMC to compete with SD or Memory Stick
Memory Stick
Memory Stick is a removable flash memory card format, launched by Sony in October 1998, and is also used in general to describe the whole family of Memory Sticks...
in this area. Very little information is known about how SecureMMC works or how its DRM characteristics compare with its competitors.
eMMC
eMMC describes an architecture consisting of an embedded storage solution with MMC interface, flash memory and controller, all in a small ball grid arrayBall grid array
A ball grid array is a type of surface-mount packaging used for integrated circuits.- Description :The BGA is descended from the pin grid array , which is a package with one face covered with pins in a grid pattern. These pins conduct electrical signals from the integrated circuit to the printed...
(BGA) package.
Embedded MultiMediaCard (e-MMC)
e-MMC/Card Product Standard,
High Capacity, including Reliable
Write, Boot, Sleep Modes,
Dual Data Rate, Multiple Partitions
Supports and Security Enhancement
Others
Seagate, Hitachi and others are in the process of releasing SFFSmall Form Factor committee
The Small Form Factor committee is an ad hoc electronics industry group formed to quickly develop interoperability specifications ....
Hard Disk drives with an interface called CE-ATA
CE-ATA
Consumer Electronics ATA is an interface standard for the connection of storage devices and hosts in consumer electronic device such as mobile and handheld devices...
. This interface is electrically and physically compatible with MMC specification. However, the command structure has been expanded to allow the host controller to issue ATA
AT Attachment
Parallel ATA , originally ATA, is an interface standard for the connection of storage devices such as hard disks, solid-state drives, floppy drives, and optical disc drives in computers. The standard is maintained by X3/INCITS committee...
commands to control the hard disk drive.
External links
Organizations- JEDEC
- Membership: $4400/yr
- MultiMediaCard Association, merged with JEDECJEDECThe JEDEC Solid State Technology Association, formerly known as the Joint Electron Devices Engineering Council , is an independent semiconductor engineering trade organization and standardization body...
Specifications
- Embedded MMC (eMMC) Standard MMCA 4.4 (JESD84-A44)(March 2009) (login required)
- MMCplus 13 Pin Full Size MultiMediaCard (MMC) Outline (MO-277A) (login required)
- MMCmobile 13 Pin Reduced Size MultiMediaCard (MMC) Outline (MO-278A) (login required)
- MMCmicro 10 Pin Micro Size MultiMediaCard (MMC) Outline (MO-279A) (login required)
Other