Multimedia card
| Storage medium Multimedia Card (MMC)
|
|
 32 MB multimedia card |
|
| General | |
|---|---|
| Type | Semiconductor memory |
| capacity | 2 MB to 128 GB (eMMC up to 256 GB) (miCard up to 2 TB) |
| size |
Full: 24mm × 32mm × 1.4mm Reduced: 24mm × 18mm × 1.4mm Micro: 12mm × 14mm × 1.1mm |
| Reading speed |
up to 20 MB / s (eMMC up to 250 MB / s) |
| Writing speed |
up to 17 MB / s (eMMC up to 125 MB / s) |
| use | Mobile devices: digital cameras , MP3 players , PDAs , PNAs , cell phones , smartphones (eMMC) |
| origin | |
| developer | Igentix, SanDisk |
| idea | 1997 |
| successor | SD memory card |
.gif)
A multimedia card ( MMC ) is a digital storage medium .
The MMC standard was created in 1997 by the Siemens - daughter Ingentix with SanDisk developed. A multimedia card saves data using flash memory . It is 24 mm × 32 mm × 1.4 mm (full size) and has seven pins that are controlled by an integrated controller with a 1-bit bus width and a 20 MHz clock rate. The storage capacity was between 2 MB and 8 GB. The writing speed was 2.5 MB / s. MMCs were used, for example, in digital cameras , MP3 players, PDAs , printers and cell phones .
In February 2004 the MMCA (Multimedia Card Association) introduced a new standard (MMC 4.0). With 13 PINs, it supports optionally increased bus widths to 4 bits and 8 bits and higher clock rates to 26 MHz and 52 MHz, including higher read and write speeds of up to 416 Mbits / sec. Since the manufacturers may use the new brand names ( MMCplus ™ and MMCmobile ™) or the generic designations (MMC and RS-MMC) for version 4.1 cards at their own discretion , these can be identified by the two-row contact strips. With a clock frequency of 26 MHz or the optional 52 MHz clock, the MMCplus and MMCmobile cards achieve a maximum data rate of 26 MByte / s or 52 MByte / s in 8-bit mode.
With the exception of the eMMC, the multimedia card has now been almost completely replaced by the SD memory card . The MMC interface lives on in the CE-ATA specification.
short history of development
- MMC v1.0 (September 1996)
- MMC v2.11 (June 1999)
- the SD card is based on this standard
- MMC v3.31 (May 2003)
- Dual voltage cards
- MMC v4.x (April 2005)
- Smaller form factor (micro)
- Wider bus (4 or 8 bits)
- Faster bus (26 MHz or 52 MHz)
- SecureMMC
- MMCplus (> 4 GB)
- eMMC (December 2006)
Reduced size multimedia card
The so-called RS ‑ MMC is a version of the MMC that has been reduced by half and was used in particular in cell phones. It can also be used in normal MMC devices via an adapter. The largest RS-MMCs held 4 GB at the end of development in 2007. The card is 24mm × 18mm × 1.4mm and the pins were identical to the full-size card.
Some later devices (mostly cell phones) only supplied a supply voltage of 1.8 volts , in this case a dual voltage card was required ( RS ‑ MMC DV or MMCmobile ™, also available up to 4 GB). These cards could then be operated with two different operating voltages of 1.8 V or 3.3 V.
Multimedia card micro
The MMCmicro ™ memory cards were also available at the beginning of 2005 . This variant was only around a third as big as the RS-MMC. The card was only 12 mm × 14 mm × 1.1 mm in size, hardly bigger than a fingernail. It supports operation with a data bus width of 4 bits, since there are no additional pins, but not 8 bits.
According to Samsung, the card achieves a read performance of 10 MB / s and a write rate of up to 7 MB / s. The card has been specially developed for mobile phones and digital cameras. It works with an operating voltage of 3.3 or 1.8 volts.
The cards were available up to a memory size of 16 GB and could also be read in MMC full-size slots using an adapter, which was usually included.
Multiple interface memory card
miCARD ™ is a versatile storage solution and has a size of 12 × 21 × 1.95 mm. It uses the MMC interface (standard MMC 4.2) for internal applications (data transmission with low power consumption) and the USB 2.0 standard for external applications with transmission speeds of up to 480 Mbit / s with full compatibility with electrical, mechanical and software. Like an RS-MMC, it is supplied with an adapter; the actual card fits into a USB port, while the card with adapter fits into conventional MMC card slots. It was released in the third quarter of 2007 with an initial capacity of 8 GB.
Secure MultiMedia Card
SecureMMC supports OMA DRM 2.0 and user encryption ; in addition, several on-card applications and can communicate in parallel with the host and remote servers via Internet protocol channels. The SecureMMC 1.1 or 2.0 standard is an additional, optional part of the MMC 4.x specification.
Embedded MultiMedia Card
An eMMC ™ is an energy and space-saving storage medium specified by JEDEC , based on the MMC standard v5.1, which was developed for use as internal data storage in mobile devices. It supports operation with an 8-bit data bus width. In terms of performance, this memory is comparable to an SD card and is therefore built into compact end devices. Since the eMMC is bootable, this storage medium is also suitable for operating systems such as Android , Chrome OS , iOS or Windows . The memory size ranged up to 256 GB in 2017.
While few companies are installing MMC slots in devices as of 2018, the embedded MMC (eMMC) is still widely used in consumer electronics as the primary means of integrated storage in portable devices. It offers an inexpensive bootable flash storage system and is integrated like an expensive SSD .
In the case of smartphones in particular, eMMCs are increasingly being replaced by UFS , which achieve significantly higher write and read speeds.
connections
For communication with the card reader, older full and reduced-size MMS cards have 7 pins, the newer 13 pins on the bottom. Pins 8 and 9 have contact options in both the first and second row of contacts. With newer MMCs that do not support the optional 8-bit bus mode, the second row of contacts is often missing (e.g. with the MMCmicro adapter) and therefore only has contacts 1–9.
MMC card readers v4.x that support optional 8-bit bus mode, contact i. d. R. contacts 1-7 of the first row and 8-13 of the second row; which only support the 4-bit bus mode often only use contacts 1–9 in the first row.
Pins 1–7 and 1–9 of the first row are in the same position as on the full-size SD cards and also have the same function, pins 10–13 are outside the contact possibilities of the SD specification.
The MMCmicro cards have 10 pins on the bottom.
| Pin code | Surname | Type | description | ||||
|---|---|---|---|---|---|---|---|
| Full u. Reduced size | micro adapter S |
micro | |||||
| up to v3.x | v4.x | ||||||
| 1 | - | RSV | - | reserved | |||
| - | 1 | DAT3 | I / O / PP | Data line [bit 3] | |||
| 2 | CMD | PP / OD | Command and response | ||||
| 3 | VSS | S. | Dimensions | ||||
| 4th | VDD | S. | Power supply | ||||
| 5 | CLK | I. | Tact | ||||
| 6th | VSS | S. | Dimensions | ||||
| 7th | DAT0 | I / O / PP | Data line [bit 0] | ||||
| - | 8th | DAT1 | I / O / PP | Data line [bit 1] | |||
| - | 9 | DAT2 | I / O / PP | Data line [bit 2] | |||
| - | 10 | - | DAT4 | I / O / PP | Data line [bit 4] | ||
| - | 11 | - | DAT5 | I / O / PP | Data line [bit 5] | ||
| - | 12 | - | DAT6 | I / O / PP | Data line [bit 6] | ||
| - | 13 | - | DAT7 | I / O / PP | Data line [bit 7] | ||
| - | |||||||
compatibility
MMCs of the various MMC standards are compatible with one another, but MMCs without dual volts do not work on 1.8-volt devices.
- Older MMCs (7 contacts) are upwardly compatible with newer full or reduced-size MMC slots (13 contacts). They work in 1-bit bus mode at 20 MHz.
- Newer full or reduced-size MMC (13 contacts) and MMCmicro cards with adapter (9 contacts) are downwards compatible with older MMC slots (7 contacts). Since only pins 1–7 of the outer row of contacts are connected, only the 1-bit bus mode with 20 MHz can be used.
Devices with an SD memory card slot (full size) are usually compatible with multimedia cards. In this way, MMCs can usually also be operated in devices that are designed for SD memory cards.
- Older full or reduced-size MMCs (7 contacts) are fully compatible.
- With newer full or reduced-size MMC (13 contacts) and MMCmicro cards with adapter, only the outer row of contacts of the MMC (pins 1–9) has contact, so only a maximum of 4-bit bus mode is possible.
MMCmicro cards cannot be used in the microSD slot, as the two formats have incompatible pin assignments.
However, it is not possible to operate SD cards in devices that are only designed for MMC. To avoid incorrect use, SD cards have a slightly thicker casing and do not fit into MMC slots.
Overview
| default | Type | Max. Storage H ( in GB) |
Read rate H ( in MB / s) |
Write rate H ( in MB / s) |
Size (in mm) |
contacts | 1.8V | 3.3V | Bus clock ( in MHz) |
1 bit SPI mode | 1 bit MMC mode | 4 bit MMC mode | 8 bit MMC mode | GDR fashion |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 2.x | MMC | 4th | 2.5 | 24 × 32 × 1.4 | 7th |
|
|
20th |
|
|
|
|
|
|
| RS ‑ MMC | 4th | 24 × 18 × 1.4 | 7th |
|
|
20th |
|
|
|
|
|
|||
| 3.x | RS ‑ MMC DV | 4th | 7th |
|
|
20th |
|
|
|
|
|
|||
| 4.x | MMCplus, MMC G |
8th | 20 K | 17 K | 24 × 32 × 1.4 | 13 |
|
|
20/26/52 |
|
|
|
|
|
| MMCmobile, RS ‑ MMC G , RS ‑ MMC DV G |
4th | 24 × 18 × 1.4 | 13 |
|
|
20/26/52 |
|
|
|
|
|
|||
| MMCmicro | 16 | 10 | 7th | 12 × 14 × 1.1 | 10 9 A |
|
|
20/26/52 |
|
|
|
|||
| miCard | 8th | 12 × 21 × 1.95 |
|
|
||||||||||
| SecureMMC | 128 | 24 × 32 × 1.4 | 7th |
|
|
20th |
|
|
|
|
||||
| 13 |
|
|
20/26/52 |
|
|
|
|
|||||||
| 5.x | eMMC | 64 | 250 | 125 |
|
Web links
- What is an MMC card? In: tchibo.de.
Individual evidence
- ↑ MMC vs. SD card. In: diffen.com. Retrieved July 16, 2020 .
- ↑ a b c Andreas Donath: miCard: Another memory card standard. In: golem.de. June 4, 2007, accessed July 16, 2020 .
- ↑ a b c d e Jim Elliott: Introducing eMMC 5.1: The Next Step in Relentless Flash Innovation. In: samsungsemiblog.com. Samsung Semiconductor, Inc., February 17, 2015, accessed February 15, 2018 .
- ↑ a b c Embedded and Removable Memory Standards. MMC standard 4.3. (No longer available online.) In: mmca.org. MultiMediaCard Association, 2007, archived from the original on November 26, 2009 .
- ↑ a b What is MMC? In: mmca.org. MultiMediaCard Association, 2007, archived from the original on February 2, 2008 ; accessed on July 14, 2020 (English).
- ↑ a b c d e f MultiMediaCard (MMC) Technology & MultiMediaCard Association - Frequently Asked Questions. In: mmca.org. MultiMediaCard Association, 2007, archived from the original on February 2, 2008 ; accessed on July 14, 2020 (English).
- ↑ a b Andreas Donath: SecureMMC Standard 1.1 adopted. In: golem.de. February 15, 2006, accessed July 16, 2020 .
- ↑ a b c d e f g h i j k l MMC - History. In: hardwarebook.info. Retrieved July 17, 2020 .
- ↑ MultiMediaCard Association, JEDEC Adopt eMMC Trademark. (No longer available online.) In: ihs.com. Information Handling Services January 4, 2007, archived from the original on July 18, 2011 ; accessed on January 4, 2007 .
- ↑ Christian Möller: eMMC vs SSD. In: techoxid.de. Christian Möller, Kanalstrasse 79, 51379 Leverkusen, June 30, 2017, accessed on January 3, 2020 .
- ↑ Michael Günsch: Mobile flash memory: SanDisk increases to 256 GB for eMMC and iOS memory sticks. In: computerbase.de. ComputerBase GmbH, February 27, 2017, accessed on August 15, 2018 .
- ↑ MMC - pinouts. In: hardwarebook.info. Retrieved July 19, 2020 .
- ↑ MMCplus - pinouts. In: hardwarebook.info. Retrieved July 19, 2020 .