Multimedia card

Complete guide

Among the portable memory cards used in MP3/mobile phones/digital cameras/digital camcorders, CF cards and SM cards are familiar to everyone, but when it comes to mmc You may not be familiar with cards and sd cards. This article will give you a detailed introduction to mmc cards.

The full name of MMC is "MultiMediaCard"-so it is usually called "Multimedia Card". It is a small and large-capacity flash memory card. It was developed by the American SANDISK company and the German Siemens company in 2000. Jointly developed, Amkor Technology provides the most advanced module packaging technology services. The more common types are 16MB and 32MB. Initially, SanDisk provided its self-developed IC die, components and materials, and then Amkor based on its best solution. The supply chain management system provides components and materials for SanDisk. At present, it is quite mature. Major manufacturers such as Hitachi, Sandisk, Infineon, etc. are mass-producing MMC cards and have been widely used in mobile phones, digital cameras, digital camcorders, MP3 and other digital products.

This flash memory-based mobile memory card launched by SanDisk was once known to be the smallest in the world. Its size is about the size of an ordinary postage stamp, and its thickness is about the same as that of an IC card, which is comparable to similar products. A lot smaller. Due to its light weight and ease of use, large storage capacity, and increasing market share, it is now widely used in various mobile multimedia products, such as MP3 players, digital camcorders, digital cameras, mobile phones, PDAs, and other emerging Electronic products provide memory that can be read and written repeatedly for these products.

There is a slot under it, with this slot we can use our nails to plug and insert it! It has a number and 7 pins on the back, arranged on it, and the oblique port can prevent it from being inserted backwards. Its size is about 32mm×24mm×1.4mm, weight is less than 2g, 7-pin pin, its volume is even smaller than SmartMedia, it is not afraid of shocks, it can read and write 300,000 times repeatedly, and the driving voltage is 2.7 -3.6V, the current maximum capacity is mostly 64M, and larger capacity products will continue to appear. However, the current price is still relatively high, 32MB is only 500 yuan, compared to 64MB only 360 yuan CF and SM cards are indeed a bit more expensive.

MMC is used more on some MP3 players. For example, the latest MPEN32 and JUMPER II from Maxell on this site are two MP3 players that use MMC. You can find relevant evaluation articles from Found on this site. Many of the series of MP3 players launched by Lenovo last year also use this MMC card. In addition, digital cameras using this MMC card have also begun to appear. For example, KYOCERA's Finecam S3 is a product that can use both MMC and SD cards at the same time. For mobile phones with MP3 function, such as the most familiar Siemens 6688, this MMC card is used. In addition, some models of digital video cameras are also using it to store still photos, such as CANON450I and so on.

Flash memory card type

Flash card is a memory that uses Flash Memory technology to store electronic information. It is generally used in digital cameras, handheld computers, MP3 and other small As a storage medium in digital products, it looks small and looks like a card, so it is called a flash memory card. According to different manufacturers and different applications, flash memory cards may include SmartMedia (SM card), Compact Flash (CF card), MultiMediaCard (MMC card), Secure Digital (SD card), Memory Stick (memory stick), XD-Picture Although the appearance and specifications of these flash memory cards are different, the technical principles are the same. The memory cards used as mobile phones include MMC cards, RS-MMC cards, SD cards, mini SD cards, T-Flash cards, Sony memory sticks, and CF cards.

Access speed

Access speed refers to the data transfer speed of the flash memory card when data is written or read. Different types of flash memory cards use different interface specifications, and naturally their access speeds are also different. Even the same type of memory card is interfered by factors such as the manufacturing level of various manufacturers, the pros and cons of the card reader, and even the performance of the host connected to it. In practice, it also exhibits different access speeds. The same card used in different cameras may also show differences in speed, which is affected by differences in the performance of the camera's flash card interface. The access speeds of flash memory cards claimed by various manufacturers are basically the highest access speeds of flash memory cards in a certain state, which is basically impossible to achieve in practical applications. The concept of double-speed flash memory cards is also widely circulated in the market, such as 40-times CF cards. Double-speed is the speed calculation concept of optical storage devices. 1x speed is equal to 150KB/s data transmission speed, then 40x speed will reach 6MB per second. Speed. However, in actual applications, these high-speed flash memory cards have not reached such a high speed, and may be able to reach or close to such a high speed on a specific digital camera or card reader device. However, in most applications, high-speed flash memory cards are indeed faster than ordinary flash memory cards, but it does not exceed the access speed of ordinary flash memory cards by so many times.

Types of flash memory cards

MMC card

The MMC (MultiMedia Card) card was launched in 1997 by Siemens and SanDisk, which first launched CF. In January 1998, 14 companies jointly established the MMC Association (MultiMedia Card Association for short MMCA), which now has more than 84 members. The development goal of MMC is mainly for digital imaging, music, mobile phones, PDAs, e-books, toys and other products. It is claimed to be the smallest Flash Memory storage card in the world, with a size of only 32mm x 24mm x 1.4mm. Although thicker than SmartMedia, the overall volume is smaller than SmartMedia, and lighter than SmartMedia, only 1.5 grams. MMC also integrates the storage unit and the controller on the card, and the intelligent controller enables MMC to ensure compatibility and flexibility.

MMC memory card can be divided into two working modes: MMC and SPI. MMC mode is the standard default mode and has all the characteristics of MMC. The SPI mode is the second optional mode for MMC memory cards. This mode is a subset of the MMC protocol. It is mainly used for only a small number of cards (usually 1) and low data transfer rate (and MMC). Compared with the protocol) system, this mode can minimize the design cost, but the performance is not as good as MMC. MMC is designed as a low-cost data platform and communication medium. Its interface design is very simple: only 7 pins! The interface cost is less than US$0.5, compared with the interface cost of SmartMedia and Memory Stick more than US$1. In the interface, the power supply is 3-pin, and the data operation only needs a 3-pin serial bus (SPI mode plus 1 pin for chip selection).

The operating voltage of MMC is 2.7V to 3.6V, the write/read current is only 27mA and 23mA, and the power consumption is very low. Its read and write modes include streaming, multi-block and single-block. The smallest data transfer is in blocks, and the default block size is 512 bytes.

Representative models: Nokia N-Gage QD, 7710, 6600, 3650, etc.

RS-MMC card: Full name (Reduced Size MultiMediaCard). This card standard was originally published by MMCA (Multimedia Card Association) in November 2002. Its size is only half of the standard MMC card, but it inherits all the advantages and performance characteristics of the latter. Through the adapter card, it is also suitable for the original MMC and SD interface devices that support MMC.

Representative models: Samsung D710, 730, V500, SPH-V4400, Nokia 6260, 6630, 6670, 7610, Siemens S65, Panasonic X700, etc.

SD card

SD card (Secure Digital Memory Card) is a new generation of memory device based on semiconductor flash memory. The SD card was jointly developed by Japan's Panasonic, Toshiba and American SanDisk in August 1999. An SD memory card the size of a postage stamp weighs only 2 grams, but it has high memory capacity, fast data transfer rate, great mobility and good security.

The SD card combines SanDisk flash memory card control with MLC (Multilevel Cell) technology and Toshiba (Toshiba) 0.16u and 0.13u NAND technology in a volume of 24mm×32mm×2.1mm. The pin interface interface is connected with a special drive, and no additional power supply is needed to keep the information memorized on it. Moreover, it is an integrated solid medium without any moving parts, so there is no need to worry about damage to mechanical movement. The SD card data transfer and physical specifications are developed by MMC, the size is similar to MMC, the size is 32mm x 24mm x 2.1mm. The length and width are the same as MMC, except that it is 0.7mm thick to accommodate a larger capacity storage unit. SD card and MMC card maintain upward compatibility, that is, MMC can be accessed by new SD devices, and compatibility depends on application software, but SD card cannot be accessed by MMC devices. (The SD card has the same thickness as the MMC guide rail design, so that the SD device can be suitable for MMC)

In addition to retaining the 7-pin MMC, the SD interface also adds 2 more pins on both sides. As a data line. It uses NAND-type Flash Memory, which is basically the same as SmartMedia, and the average data transfer rate can reach 2MB/s.

The structure of the SD card can ensure the security of digital file transfer, and it is also easy to reformat, so it has a wide range of applications. Multimedia files such as music, movies, news, etc. can be easily saved to the SD card In. Therefore, many digital cameras have also begun to support SD cards.

Many memory card companies have developed SD cards. Panasonic is currently the most important manufacturer of SD cards. In 2000, the SD card capacity has been divided into 4 different levels from 8MB to 64MB to meet different occasions. The data transfer rate is 2MB/s. By the end of 2001, the capacity of a single card had reached 512MB, and the data transfer rate had also increased to 10MB/s. A high-performance memory card with a capacity of 1GB and a data transfer rate of 20MB/s was launched in 2003, and the capacity is expected to reach 4GB by 2005.

Representative models: Dopod 515, 535, 818, Mitac MIO8390, LGG910, Lenovo ET960, etc.

Mini SD Card

Full name (Mini Secure Digital Memory Card). The miniSD card is a development of the SD card, and its performance is not much different from the traditional SD card. The miniSD card, like the SD card, has a data transfer speed of 2MB per second. Like the traditional SD card, the miniSD card also has a hardware data write-protection switch, which can avoid the risk of accidentally deleting the stored content. The miniSD card is characterized by small size (only 21.5×20x1.4mm in size, which is 40% smaller than the original SD card), stable performance, can be used with a dedicated adapter card, and fully compatible with standard SD card slots. Moreover, the miniSD card uses a low-power design, which is more suitable for mobile communication equipment than SD cards, so it mainly attacks the information terminals of mobile phones, PDAs, and PDAs. Representative models: Dopod 565, 575, moto MPX220, etc.

T-Flash card: Full name (TransFLash is produced by) Motorola and SANDISK jointly developed and launched in 2004. It is an ultra-small card (11*15*1MM). TF card can be used as SD card after SD card converter.

Supported models: MOTOROLA A780, E398, C975, etc.

Sony Memory Stick

The Memory Stick is developed by Sony. The size is 50mm x 21.5mm x 2.8mm and weighs 4 grams. It adopts a delicate and eye-catching blue shell (the new MG is white) and has a write-protect switch.

Unlike many Flash Memory memory cards, the Memory Stick specification is non-public, and there is no standardization organization. Sony’s own appearance, agreement, physical format, and copyright protection technology are used. To use its specifications, you must negotiate and sign a license with Sony. The Memory Stick also includes the controller. It uses a 10-pin interface, the data bus is serial, the highest frequency can reach 20MHz, the voltage is 2.7V to 3.6V, and the average current is 45mA. It can be seen that this specification is quite similar to the MMC that appeared at about the same time.

Sony emphasizes that its interface with an independent pin slot is easy to insert or withdraw from the slot, and it is not easily damaged; and it will never touch each other, which greatly reduces the error caused by the contact of the needle and the needle, so that data transmission More reliable; easier to clean than pin-type memory cards.

In addition to its compact size, extremely high stability, copyright protection, and easy use in various memory stick products, the advantage of memory sticks lies in Sony’s extensive use of this technology. Products, such as DV camcorders, digital cameras, VAIO personal computers, color printers, Walkman, IC recorders, LCD TVs, etc., and a full line of accessories such as PC card converters, 3.5-inch floppy disk converters, parallel export converters and USB readers Makes the memory stick can easily realize the connection with PC and Mac.

After the launch of the memory stick, Samsung, Aihua, Sanyo, Casio, Fujitsu, Olympus, Sharp and other companies have expressed their support for this format. Sony is currently seeking recognition of the memory stick format from the home electronics industry and the IT industry. Sony will introduce more products representing the latest development of memory sticks to the domestic market in the future.

The disadvantage of the memory stick is that it can only be used in Sony digital cameras, and the capacity is not large enough.

Support Sony Ericsson P908, P910C, S700C, etc.

CF card

The CF card (Compact Flash) was first introduced by SanDisk in 1994. The CF card has the PCMCIA-ATA function and is compatible with it; the CF card weighs only 14g and is only the size of a matchbook (43mm x 36m x m3.3mm). It is a solid product, that is, there are no moving parts when working. The CF card uses flash technology, which is a stable storage solution that does not require a battery to maintain the data stored in it. For the stored data, the CF card is more secure and protective than the traditional disk drive; it is 5 to 10 times more reliable than the traditional disk drive and type III PC card, and the power consumption of the CF card Only 5% of small disk drives. These excellent conditions make most digital cameras choose CF cards as their preferred storage media.

Although the CF card was originally a storage card using Flash Memory, with the development of CF cards, various non-Flash Memory cards using CF card specifications also began to appear, and CFA later developed CF+ The specifications of the CF card extend the scope of the CF card to other areas other than Flash Memory, including other I/O devices and disk storage, and a Type II specification that updates the physical specifications (IBM’s Microdrive is a Type II CF card), The difference between Type II and the original Type I is that Type II is 5mm thick. CF card supports 3.3V and 5V voltage at the same time, any CF card can work under these two voltages, which makes it have a wide range of use. The compatibility of the CF storage card is also reflected in the combination of the Flash Memory storage module and the controller, so that the external equipment using the CF card can be made relatively simple, and different CF cards can be used with a single mechanism. Read and write, don't worry about compatibility issues, especially when CF card upgrades, the compatibility of old devices can also be guaranteed.

CF card has a lot of platform support, including DOS, Windows 3.x, Windows 95, Windows 98, Windows CE, OS/2, Apple System 7, Linux and many kinds of UNIX.

CF card, as a worldwide storage industry standard, guarantees the compatibility of CF products and the backward compatibility of CF cards; as CF cards become more and more widely used, various manufacturers are actively improving CF cards The technology promotes the launch of a new generation of advanced mobile devices that are small in size, light in weight, and low in energy consumption, thereby improving work efficiency. CFA is headquartered in Palo Alto, Canada, and its members are entitled to free CF cards, CF trademarks and CF technical details. CFA members include 3COM, Canon, Kodak, HP, Hitachi, IBM, Panasonic, Motorola, NEC, SanDisk, Seiko (Epson) and Socket Communications, etc. more than 120. And one of the major digital camera production and R&D manufacturers has established a special organization to engage in the development of CF products.


  • RS-MMC card

  • CF card

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    SM card

  • SD card

  • xD card

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