I used Samsung 3650. I want to buy this. There are several details to ask.

I don't think SD card is a USB flash drive. Different interfaces, different working principles and different technical contents. Just like disks and mobile hard disks, although they are both used for storage, they are not in the category of flash drives.

The following are the things in Baidu Encyclopedia, you can have a look, * * * has made progress.

SD card encyclopedia business card

SD card (Secure Digital Memory Card) is a new generation storage device based on semiconductor flash memory, which is widely used in portable devices, such as digital cameras, personal digital assistants (PDA) and multimedia players. The SD card was jointly developed by Panasonic, Toshiba and SanDisk Company of the United States in August 1999. The stamp-sized SD memory card weighs only 2 grams, but it has high storage capacity, fast data transmission speed, great mobility and good security.

Directory [hidden]

brief introduction

SD card and MMC card

Rate grade

SD card brand

Use of SD card

Identification of SD card

Development course of SD card

Mini SD and mini SD card mini SD

Micro standard definition

Write protection switch

Open standard

Technical description slow four-wire serial interface

Three transmission modes

Introduction to SDIO

Different types of MMC/SD cards

DRM function

Identification of SD card

SD card is suitable for mobile phones.

Related issues: Introduction

SD card and MMC card

Rate grade

SD card brand

Use of SD card

Identification of SD card

Development course of SD card

Mini SD and mini SD card mini SD

Micro standard definition

Technical description of open standard for write protection switch

SDIO with slow four-wire serial interface and three transmission modes introduces the DRM characteristics of different types of MMC/SD cards and the identification of SD cards.

[Edit this paragraph] Introduction

In the volume of 24mm×32mm×2. 1mm, the SD card combines SanDisk flash memory card control with MLC (multi-level unit) technology and Toshiba's NAND technologies 0. 16u and 0. 13u, and is connected with a special driver through a 9-pin interface, so there is no need for additional power supply to keep the information stored on it. Moreover, it is an integrated solid medium without any moving parts, so there is no need to worry about the damage of mechanical movement.

[Edit this paragraph ]SD card and MMC card

The technical structure of SD card is based on the multimedia card (MMC) format, and its size is similar to that of MMC, with the size of 32 mm x 24 mm x 2. 1 mm ... The length and width are the same as MMC, but it is 0.7mm thicker than MMC to accommodate larger storage units. The SD card and MMC card remain upward compatible, that is, new SD devices can access MMC, and the compatibility depends on the application software, but the SD card cannot be accessed by MMC devices. (The shape of SD card adopts the track design with the same thickness as MMC, and the structure of SD card makes SD equipment suitable for MMC). SD interface not only keeps 7 pins of MMC, but also adds 2 pins on both sides as data lines. NAND flash memory is adopted, which is basically the same as that of SmartMedia, and the average data transmission rate can reach 2MB/s. ..

[Edit this paragraph] Rate level

SD card also provides different speeds, which are calculated as 1 times the speed according to the speed calculation method of 150kB/ s optical disc. Basically, their transmission speed is six times that of standard CD-ROM (900 kB/ sec), while high-speed SD cards can transmit 66x (10 MB/ sec) and 133x or higher. Some digital cameras need high-speed SD cards to shoot movies more smoothly and take photos continuously faster. Until June 5438+February, 2005, most of the equipment followed the specification of SD card 1.0 1, and the equipment with higher speed to 133x also followed the specification of1. Devices with SD card slots can use thin MMC cards, but standard SD cards cannot be inserted into MMC card slots. SD card can be inserted into the adapter to be used on CF card and PCMCIA card; MiniSD card and microSD card can also be inserted into the adapter and used in the SD card slot. Some USB ports can be plugged into SD cards, and some card readers can also plug into SD cards. Many ports are accessed and used, such as USB, FireWire and so on. The structure of SD card can ensure the security of digital file transmission, and it is also easy to reformat, so it has a wide range of applications, and multimedia files such as music, movies and news can be conveniently stored in SD card. So many digital cameras have started to support SD cards.

[Edit this paragraph ]SD card brand

At present, there are many brands of SD cards on the market, such as SANDISK, Kingmax, Panasonic and Kingston. ● The SD card produced by ●SANDISK is the most common one on the market, which is divided into high-speed SD card and low-speed SD card. ●Kingmax SD card adopts unique integrated packaging technology (PIP), which is difficult for counterfeiters to copy. Kingmax SD card has the highest transmission rate of 10MB/ s, and has waterproof, shockproof and compressive design, which can meet various requirements of field shooting. ● Panasonic SD card, as the founder of SD standard, its technology can be said to be one of the best SD cards on the market. However, it should be noted that most Panasonic SD's are not guaranteed, so be sure to ask the important question of warranty period when purchasing. ● Kingston SD card, among many flash memory products, is the smallest one, providing a five-year warranty.

[Edit this paragraph] Use of SD card

SD card is used for the following portable digital devices: digital camera stores photos and short films; Digital cameras store photos and short films; Personal digital assistant (PDA) stores all kinds of data; Mobile phones store photos, ringtones, music, short films and other materials; The multimedia player SD card is mostly used for MP3 walkman, digital video camera, digital camera and so on. , also used in notebook computers. Its projection area is the same as that of MMC card, only slightly thicker, 2. 1mm, but the capacity of SD card is much larger, and the reading and writing speed is four times faster than that of MMC card. At the same time, the interface of SD card is compatible with MMC card, and most interfaces supporting SD card support MMC card. At present, SD card is rapidly spreading in digital cameras and is likely to become the mainstream. The rapid development of SD card this year has begun to threaten the market share of CF card. This is because the size of SD card is much smaller than that of CF card, and the gap between SD card and CF card is getting smaller and smaller in terms of capacity, performance and price. In the past two years, mobile phones supporting SD cards have become hot in the market. Therefore, the rapid growth of SD card is definitely not accidental. The most important thing is that MMC cards are also compatible with SD cards, which is one of the reasons for the rapid popularization of SD cards. Note, however, that in some products, such as mobile phones, SD cards and MMC cards are incompatible. The current SD card capacity ranges from 8MB to 32GB.

[Edit this paragraph] Identification of SD card

SD card is small in size, and consumers don't know much about it before buying it. So it's hard to distinguish from each other in appearance. Here are some common methods to distinguish the authenticity of SanDisk brand SD card: First, look at the memory card itself. Sandisk genuine memory cards have laser color-changing labels on the front, and laser color-changing will occur at different angles. Secondly, the licensed genuine cards of domestic agents all adopt the plastic packaging form similar to the above picture, except that the words "5-year warranty" in the lower right and Japanese are changed to the graphic representation of 5-year warranty. In addition, the simplest identification can be made from whether there is a gap at the bottom of the SD card. Because the number on the back of the genuine Sandisk SD card is unique, you can check the authenticity by 800 phone, but it is said that this inquiry system has not been completed.

[Edit this paragraph ]SD card development process

In 2006, the capacity of SD card was 8 16, 32,64, 128256, that is, 5 12 MB, 1 2,4,6,8 (sdhc) GB. SD/MMC card has replaced SM card developed by Toshiba and become the most widely used digital memory card format for portable digital cameras. In 200 1 year, the market share of SM cards exceeded 50%, and it dropped to about 40% in 2005, and it is still declining rapidly. Most digital camera manufacturers provide SD card support, including Canon, Nikon, Kodak, Panasonic and Konica Minolta. The three major manufacturers still insist on using their own patent formats: xD cards for Olympus and Fuji, and memory sticks for Sony. In addition, SD card has not yet entered the digital SLR camera market where CF card has an absolute advantage. (In addition to the D50 newly released by Nikon in 2005, SD is supported. ) SD card is made by Toshiba adding encryption technology hardware to MMC card technology. Because MMC cards may make it easier for users to copy digital music, Toshiba added these technologies, hoping to reassure the music industry. Similar technology is Sony's MagicGate. Theoretically, encryption technology can introduce some digital rights management measures, but this function is rarely used. Users can use USB card reader and SD card on personal computer. Some new computers have built-in card reading devices. The latest development is the built-in USB port in SD, which omits the card reader. SanDisk is designed to use a foldable sheath to protect the USB socket. Although SanDisk is not the first SD card manufacturer with built-in USB function, due to its important position in the industry. This action led other manufacturers to follow suit. The "SD" trademark is actually used for another completely different purpose: it was first used on the "ultra-density optical disc", which was developed by Toshiba and lost the battle for DVD format. That's why the word "D" looks like a CD. SD series memory cards will be sent to SD card association for certification after SanDisk completes the test, so almost all patents are in SanDisk's hands.

[Edit this paragraph ]Mini SD and Micro SD card

With the development of SD card storage technology, Mini SD and Micro SD card appear gradually.

Mini SD

MiniSD was jointly developed by Panasonic and Sandisk. In order to facilitate more users to switch between different memory cards to use mini SD, Sandisk has specially introduced an SD adapter card, which can be used together with digital cameras, PDA palmtop computers and MP3 music players that now use SD cards. Mini SD is only 37% of the size of SD card, but it has the same reading and writing efficiency and large capacity as SD memory card, and is fully compatible with standard SD card. The attached SD adapter card can also be used as a universal SD card.

Micro standard definition

Among the ultra-small memory card products, SD Association took the lead in bringing T-flash under its banner and named it Micro SD. Only the nail-sized Micro SD surprised consumers when it went on the market, and now many mobile phones also use this memory card. MMC micro and Micro SD are the smallest mini memory cards in the world at present, but their ultra-small size has greater advantages, and they can be applied to all kinds of digital products, without wasting the space of internal design of products. They are loved by product designers and have also played a role in "fueling the fire" for exquisite digital life.

[Edit this paragraph] Override the write protection switch

Seen from above, there is usually a switch on the right side of the SD card, that is, the write protection switch on the side of the SD card, while the MMC card does not. When the write protection switch is turned off, the SD card will be write-protected and can only read data. When the write protection switch is in the upper position, data can be overwritten. Because this protection switch is optional, some brands of SD cards do not have this protection switch. The principle of write protection switch is similar to write protection on cassette tapes, VHS video tapes and computer disks. The closed state means that it can be overwritten, while the open state means that it is protected. If the switch is broken, this card can only become a write-protected read-only memory card. One way to solve this problem is to seal the gap with tape, so that the card will always be writable. The SD card produced by Kingmax has no write protection switch. Because the company thinks this switch is too easy to break. The SD card it produces has the same thickness as MMC card, which is1.4 mm.

[Edit this paragraph] Open standards

Like other memory card formats, SD card is protected by many patents and registered trademarks, and the authorization can only be made by secure digital memory card Union. The current authorization agreement of the Secure Digital Card Alliance does not allow open source SD driver, which has caused a lot of arguments about open source and free software. The usual practice is to develop an open source shell, but the core is a closed source SD driver for a specific platform, which is quite different from the expected open standard. Another common practice is to adopt the older MMC mode, because according to the SD card standard, all SD cards must support MMC mode. This shows that the openness of SD card is lower than that of CF card or flash memory, and the above two formats are almost free, and only the licensing fee of alliance logo and registered trademark is required. But it is much more open than xD card or memory stick, and these two formats do not provide public document support at all.

[Edit this paragraph] Technical description

Slow four-wire serial interface

All SD and SDIO cards must support the old SPI/MMC mode. This mode supports slow four-wire serial interface (clock, serial input, serial output, chip selection), and is compatible with serial terminal interface (SPI) and many microcontrollers. Most digital cameras, digital audio players and other portable devices can only use MMC mode. Detailed documentation of this model can be purchased from MMCA for $500. But some documents about SDIO are free. Some are also available from memory card manufacturers. MMC mode does not support the encryption function of SD card. These details can't be found in free documents. But for most consumers, it doesn't matter. User systems are used to store unprotected data.

Three transmission modes

SD card * * * supports three transmission modes: SPI mode (independent serial input and serial output), 1 bit SD mode (independent instruction and data channels, unique transmission format) and 4-bit SD mode (using extra pins and some reset pins). Support four-bit wide parallel transmission) Low-speed cards usually support data transmission rate of 0~400 kilobits per second, and adopt SPI and 1 bit SD transmission mode. The high-speed card supports data transmission rate of 0 ~ 100 Mbit/s and adopts 4-bit SD transmission mode. It supports 0–25mbit/s and adopts SPI and 1 bit SD mode. For manufacturers, suppliers and host adapter manufacturers, SD/SDIO license fees are required, and the annual membership fee is $65,438+$0,000, plus $65,438+$0,500. However, manufacturers of SDIO cards and MMC adapters do not need a license fee. MMC card uses 7-pin interface, SD card and SDIO card use 9-pin interface.

[Edit this paragraph] Introduction to ]SDIO

Video lens SD socket using SDIO interface is not only used to insert memory card. Pdas and notebook computers supporting SDIO interface can be connected with devices adopting SD standard interface, such as GPS receiver, Wi-Fi or Bluetooth adapter, modem, LAN adapter, barcode reader, FM radio, TV receiver, RF authentication reader or digital camera. Other devices also announced their support, including RS-232 serial adapter, fingerprint scanner, SDIO to USB master/slave adapter (handheld devices that can support SDIO interface use USB peripherals or connect to computers), degaussing reading devices, Bluetooth /Wi-Fi/GPS radio transceivers, mobile phone modems (Personal Communication Service (PCS), CDPD, GSM, etc. ) and APRS/TNC adapter.

[Edit this paragraph] Different types of MMC/SD cards.

4GB SDHC card SD card is not the only memory card standard approved by the Secure Digital Card Alliance. Other approved formats include miniSD, microSD (known as TransFlash before the alliance adopted the standard) and SDHC. These smaller cards plus an adapter can also be used in full-size MMC/SD/SDIO slots. You know, it is very feasible to formulate SD-sized input and output equipment standards, and it is simply unrealistic to formulate smaller ones. The SD slot supports MMC cards, and smaller MMC card variants can also be compatible with devices that support SD cards. Unlike miniSD and microSD, RS-MMC slots can be compatible with full-size MMC cards. Because RS-MMC card is just a shortened MMC card. For related information, please refer to the Multimedia Card (MMC). In view of the fact that the standard capacity limit of SD card is only 4GB, which is not enough to meet the increasing capacity demand, the alliance has formulated a new SDHC standard. The appearance of SDHC card is exactly the same as that of ordinary SD card, and the lower limit of capacity is 4GB. It is estimated that the SDHC card with a capacity of up to 32GB will be launched this year.

[Edit this paragraph ]DRM function

The digital copyright protection scheme embedded in SD card is formulated according to the recordable media content protection standard (CPRM) proposed by 4C. Its core is the use of passwords (also known as "C2"). This feature is confidential. The encryption scheme of DVD-Audio is very similar to that of CPPM. SD card (Secure Digital Memory Card) is a new generation storage device based on semiconductor flash memory. The SD card was jointly developed by Panasonic, Toshiba and SanDisk Company of the United States in August 1999. The stamp-sized SD memory card weighs only 2 grams, but it has high storage capacity, fast data transmission speed, great mobility and good security. In the volume of 24mm×32mm×2. 1mm, the SD card combines SanDisk flash memory card control with MLC (multi-level unit) technology and Toshiba's NAND technologies 0. 16u and 0. 13u, and is connected with a special driver through a 9-pin interface, so there is no need for additional power supply to keep the information stored on it. Moreover, it is an integrated solid medium without any moving parts, so there is no need to worry about the damage of mechanical movement. SD card is small in size and widely used in digital cameras. It is a brand-new memory card product jointly developed by Panasonic, Toshiba and Sandisk. Its biggest feature is to ensure the security and confidentiality of data through encryption. The appearance of SD card is consistent with that of multimedia card and compatible with MMC card interface specification. Note, however, that some products, such as mobile phones, SD cards and MMS cards, are incompatible. SD card is more expensive than multimedia card with the same capacity. SD card is mostly used for MP3 walkman, digital video camera, digital camera and so on. Its projection area is the same as that of MMC card, only slightly thicker, which is 2. 1mm, but the capacity of SD card is much larger, and its reading and writing speed is four times faster than that of MMC card. At the same time, the interface of SD card is compatible with MMC card, and most interfaces supporting SD card support MMC card. At present, SD card is rapidly spreading in digital cameras and is likely to become the mainstream. The rapid development of SD card this year has begun to threaten the market share of CF card. This is because the size of SD card is much smaller than that of CF card, and the gap between SD card and CF card is getting smaller and smaller in terms of capacity, performance and price. In the past two years, mobile phones supporting SD cards have become hot in the market. Therefore, the rapid growth of SD card is definitely not accidental. The most important thing is that MMC cards are also compatible with SD cards, which is one of the reasons for the rapid popularization of SD cards.

[Edit this paragraph] Identification of SD card

SD card is small in size, and consumers don't know much about it before buying it. So it's hard to distinguish from each other in appearance. Here are some common methods to distinguish the authenticity of SanDisk brand SD card: First, look at the memory card itself. Sandisk genuine memory cards have laser color-changing labels on the front, and laser color-changing will occur at different angles. Secondly, the licensed genuine cards of domestic agents all adopt the plastic packaging form similar to the above picture, except that the words "5-year warranty" in the lower right and Japanese are changed to the graphic representation of 5-year warranty. In addition, the simplest identification can be made from whether there is a gap at the bottom of the SD card. Because the number on the back of the genuine Sandisk SD card is unique, you can check the authenticity by 800 phone, but it is said that this inquiry system has not been completed. At present, there are many brands of SD cards on the market, such as SANDISK, Kingmax, Panasonic and Kingston. The SD card produced by Sandisk is the most common one on the market, which is divided into high-speed SD card and low-speed SD card. Kingmax SD card adopts unique integrated packaging technology (PIP), which is difficult for counterfeiters to copy. Kingmax SD card has the highest transmission rate of 10MB/ s, and has waterproof, shockproof and compressive design, which can meet various requirements of field shooting. Panasonic SD card, as the founder of SD standard, its technology can be said to be one of the best SD cards on the market. However, it should be noted that most Panasonic SD's are not guaranteed, so be sure to ask the important question of warranty period when purchasing. Kingston SD card is the smallest of many flash memory products, offering a five-year warranty. With the development of SD card storage technology, Mini SD and Micro SD card appear gradually. MiniSD was jointly developed by Panasonic and Sandisk. In order to facilitate more users to switch between different memory cards, using mini SD, Sandisk has specially introduced SD adapter card, which can be used together with digital cameras, PDA palmtop computers and MP3 music players that now use SD cards. Mini SD is only 37% of the size of SD card, but it has the same reading and writing efficiency and large capacity as SD memory card, and is fully compatible with standard SD card. The attached SD adapter card can also be used as a universal SD card. Among the ultra-small memory card products, SD Association took the lead in bringing T-flash under its banner and named it Micro SD. Only the nail-sized Micro SD surprised consumers after it went on the market. At the same time, this memory card has also been used in several mobile phones of MOTO. MMC micro and Micro SD are the smallest mini memory cards in the world at present, but their ultra-small size has greater advantages, and they can be applied to all kinds of digital products, without wasting the space of internal design of products. They are loved by product designers and have also played a role in "fueling the fire" for exquisite digital life.

[Edit this paragraph ]SD card is suitable for mobile phones.

Motorola A920, Motorola A925, Motorola E680, Motorola E680I, Motorola A830, Motorola MPX, Motorola E680g, Motorola A630, Motorola MPX200, Motorola A820, Motorola ROKR E 1, Motorola ROKR E2 Motorola L7; Siemens SX56, Siemens SX 1, Panasonic X300, Panasonic SA7, Sharp GZ 100, Sharp GX32, Sharp 802SH, BenQ P30, BenQ P50, BenQ P3 1, BenQ 700, Samsung SCH-I 565438+. Philips 960, Philips 768, Philips 968, Sachim myS-7, Sanyo S/KOOC-0/03, Sanyo V80/KOOC-0/S, Kyocera 7/KOOC-0/35, NEC e808, LG C9/KOOC-0/0, Amoi M8, BenQ P3. BenQ P50, BenQ P5 1, BenQ S700, Ztel Smart Charm TCL e777 Panda e88, Panda E88+, Panda CH860, dopod 699, dopod 535, dopod 696i, dopod 700, dopod 8 18, Dopod 828 and Dopod 56544. Dopod 830, dopod 900, dopod 696, dopod 686, CECT S560, CECT GS900, CECT E2800(+), CECT Mio 8380, TOP S27-708+, TOP P505 DIBIT M7, DIBIT M9, DIBIT M8, Daxian Daxian CU928, Lenovo P930. Lenovo ET280, Lenovo ET560, Lenovo e960, Lenovo ET 180, Lenovo XP665438 Nokia 5800, Nokia n79 Mitsubishi M600, Eastcom ES2 100, DOEASY E898 HP HW65 15, HP h6365. Kloc-0/ Palm Treo Palm Treo 700w, Palm Treo 600, Palm Treo 700p blackberry 8320, etc.

[Edit this paragraph] Related questions:

Users who use SD to expand their mobile phones often encounter some distress. Sometimes the card is inserted several times, but the phone still can't read it correctly. At this time, we should think carefully and see what went wrong. The specific analysis is as follows: (1) The SD card chip is not clean. Because some users do not fully protect the chip, there are often dust or oil stains on the chip, which leads to abnormal card reading. Judgment method: observe whether the metal area on the card is dim or spotted. Treatment: Gently rub the cotton cloth with alcohol or water, and then re-insert it after the water is dry. (2) The battery voltage is unstable. Because for the sake of good card reading quality, the requirements for power supply are very strict, so sometimes the battery bought in the market is used instead of the original electricity, which can easily lead to card reading failure. Judgment method: In the case of using non-primary electricity, the standby state is not ideal, and it is necessary to doubt the cause of the battery. Solution: Change the original power supply and try again (3) The card slot is squeezed. For some ultra-thin machines, the card slot is cleverly designed. If you use some irregular batteries in the market, the card slot will be squeezed when the thickness exceeds a certain requirement, which will lead to unsmooth card reading. Judgment method: change the original electricity to see the treatment method: use the original electricity. And hold the card slot with something to move up and down. (4) The wire in the card slot is rusted or excessively bent. Because some card-reading mobile phones support hot plug, the wires in the card slot that read card data will be excessively bent or rusted due to frequent plugging and unplugging. Judgment method: aim the card slot at the sunlight and observe whether the wire contacts are at the same height. If they are uneven, that may be the problem. Solution: You can try to pick the wire down a little with a needle. (5)SD is infected with virus. For some smart phones, SD is infected with a virus on the computer, which will also lead to the inability to read cards normally. Judgment method: SD can be read by computer and scanned. Solution: Format the card on a computer or other low-end storage (such as a camera). ). If you format it on a computer, you should use the FAT format instead of the FAT32 format. (6) 6) The format of the SD card is abnormal. Because the format of the mobile phone and the computer is different, it is good to redefine the file format according to the instructions and format it with the computer. If there is a card reader on the computer, check the SD card, please be sure whether the check card format is FAT, because FAT32 E680 cannot recognize it. (7) It is easy to judge 7) The 7)SD card is broken. Insert the card into the computer with a card reader. If it can be read, the card is good. (8) There is something wrong with reading the mobile phone card. The mobile phone is broken and can only be repaired. I hope the above suggestions can help friends correctly handle some problems about reading SD card.