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[Technical]
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[Slow four-wire serial interface
SD and SDIO cards must support older SPI / MMC mode.
This mode supports a slow four-wire serial interface (clock, serial input, serial output chip select) compatible serial terminal interface (SPI) and many microcontrollers.
Most digital cameras, digital audio players and other portable devices can only use MMC mode. The MMC model does not support SD card encryption features.
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Three transmission modes]
SD card support three transmission modes:
SPI mode (independent serial input and serial output)
An SD mode (separate instruction and data channels, exclusive transmission format)
4 SD mode (the use of additional pins and certain re-setting pins support the parallel transfer of the four wide)
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The low-speed card usually 0 to 400 kbit / s data transfer rate, SPI and an SD transfer modes.
The high-speed cards support 0 to 100 Mbit / s data transfer rate, using 4 SD transfer mode;
Support 0-25 Mbit / s, SPI and an SD mode.
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[Interface]
7-pin interface, MMC card SD Card and SDIO card uses a 9-pin interface
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[Discernible Do]
Compact body of the SD card, the average consumer will not have too much to understand before you buy, and therefore somewhat difficult to discern from the appearance, the following, I will introduce the common market, SanDisk SD card, true and false identification method:
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A look memory card itself
sandisk the authentic memory card are in front affixed with a laser variable color labels, different angles will produce laser color change.
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2. Domestic agency licensed authentic card, using packaging similar to the plastic package above.
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Look at the bottom of the SD card is whether there is a gap
As the number at the top of the back of the place of origin of the genuine SanDisk card SD card only, and can check the authenticity by telephone.
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4 SD card on the market a lot of brands, such as: SANDISK, Kingmax, Panasonic and Kingston.
SANDISK SD card
Is the most common market, divided into high and low speed SD card.
Kingmax SD cards
With a unique integrated packaging technology (PIP), making difficult for counterfeiters to imitate, the maximum transfer rate of 10MB / s, has a waterproof, shock resistance, anti-pressure three anti-design, it can meet the wild shooting various requirements. In many flash memory products, is a small volume.
Panasonic SD card
As the founder of the SD standard, its technology is one of the best available SD card. Purchase be sure to ask the warranty period on this important issue.
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Related issues
With the SD expansion cell phone users often encounter some distress, sometimes the card several times, but the phone still does not read correctly, this time needs to think about, take a look at those aspects of the problem, a specific analysis is as follows:
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1. [SD card chip is not clean
Protection of some users of the chip is not very comprehensive, it is often soiled with dust or oil denounced above, lead the reader is not normal.
Judgment method: observation card metal area whether dim or whether there are plaques.
Processing method: Use cotton Bucharest point of alcohol or water gently paint can, the water to be dry and re-insert.
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Battery voltage instability.
Good quality card reader is very stringent requirements of the power supply, it is sometimes used in the market to buy the battery instead of the original electric, but also easily lead the reader is not going well.
Judgment method: in the case of the use of non-original electric standby situation is not ideal, will have to suspect that the reason of the battery.
Approach: try change the original electric
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3 [card slot squeezed
For some ultra-thin machine slot design is very clever. If you are using some non-regular batteries on the market, the thickness exceeding certain requirements be card slot to cause extrusion, lead the reader is not smooth.
Judgment method: take a look for the original electric
Processing methods: using the original power. And card slot up to something Torr.
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4 [card slot internal wire rust or bend excessively]
Since the reader phone supports hot-swappable, frequent Choucha card card slot card reader data will lead to the wire bending excessive or rust.
Judging method: the slot facing the sun, observed that the wire contacts are at the same height, if the arrhythmia, there likely is this problem.
Approach: You can try to pin the wire down to pick.
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5. [SD infected with the virus]
For some smartphones, SD infected with a virus on your computer, cause the same can not be normal reader.
Judgment method: the SD read by the computer, the scan can.
Processing methods: the card is formatted on the computer or other low-end storage (such as a camera, etc.), such as formatted on the computer, you should take the FAT format instead of FAT32 format.
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6. [SD Card non-normal Formatting]
Format the format of the cell phones and computers are not the same, according to the instructions the computer to re-define the file format and then format it. If any reader on the computer to try and the grid SD card, please be sure to see whether the format of the card is a FAT, FAT32 E680 is unrecognizable.
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7. [SD card bad]
This is easy to judge, the card reader plugged into the computer to be able to read the card is good.
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8 phone card reader out problems
Mobile phone failure, can only be serviced.
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Hope the above suggestions can help friends read SD card correctly handle.
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The maintenance tips
, Such as SD card after the normal use of the camera, take pictures on the computer to view the photos need to flip the view when you copy the photos to the computer before proceeding directly modify the card inside, again card see the pictures on the camera, you will not be able to view the photo may make the SD card "paralyzed" after a lot of pictures to be modified to be formatted before longer normal use.
2, SD card inside the camera during shooting, such as card machine, crash, the SD card failure or life to lead out of the card inside the reader to save the re-formatting (if it is a bad card reader, copy will be much slower), format after some normal use, but the suggestion is stop using the faulty card file to open the memory card has been formatted prompt .
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【Article is excerpted from: Baidu Encyclopedia】
【Network reprint / Just reference】
【Translation is by Goolge】
