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The Arduino SdFat library provides read/write access to FAT16/FAT32 | ||
file systems on SD/SDHC flash cards. | ||
### Warning: This is SdFat Version 2. | ||
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SdFat requires Arduino 1.6x or greater. | ||
Earlier releases of Version 1 are here: | ||
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Key changes: | ||
https://github.com/greiman/SdFat/releases | ||
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Support for multiple SPI ports now uses a pointer to a SPIClass object. | ||
SdFat Version 2 supports FAT16/FAT32 and exFAT SD cards. It is mostly | ||
backward compatible with SdFat Version 1 for FAT16/FAT32 cards. | ||
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See the STM32Test example. | ||
exFAT supports files larger than 4GB so files sizes and positions are | ||
type uint64_t for classes that support exFAT. | ||
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exFAT has many features not available in FAT16/FAT32. exFAT has excellent | ||
support for contiguous files on flash devices and supports preallocation. | ||
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If the SD card is the only SPI device, use dedicated SPI mode. This can | ||
greatly improve performance. See the bench example. | ||
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Here is write performance for an old, 2011, card on a Due board. | ||
``` | ||
Shared SPI: | ||
write speed and latency | ||
speed,max,min,avg | ||
KB/Sec,usec,usec,usec | ||
294.45,24944,1398,1737 | ||
Dedicated SPI: | ||
write speed and latency | ||
speed,max,min,avg | ||
KB/Sec,usec,usec,usec | ||
3965.11,16733,110,127 | ||
``` | ||
The default version of SdFatConfig.h enables support for dedicated SPI and | ||
optimized access to contiguous files. This makes SdFat Version 2 slightly | ||
larger than Version 1. If these features are disabled, Version 2 is smaller | ||
than Version 1. | ||
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The types for the classes SdFat and File are defined in SdFatConfig.h. | ||
The default version of SdFatConfig.h defines SdFat to only support FAT16/FAT32. | ||
SdFat and File are defined in terms of more basic classes by typedefs. You | ||
can use these basic classes in applications. | ||
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Support for exFAT requires a substantial amount of flash. Here are sizes on | ||
an UNO for a simple program that opens a file, prints one line, and closes | ||
the file. | ||
``` | ||
FAT16/FAT32 only: 9780 bytes flash, 875 bytes SRAM. | ||
exFAT only: 13830 bytes flash, 938 bytes SRAM. | ||
FAT16/FAT32/exFAT: 19326 bytes flash, 928 bytes SRAM. | ||
``` | ||
explicit SdFat(SPIClass* spiPort); | ||
\\ or | ||
explicit SdFatEX(SPIClass* spiPort); | ||
The section below of SdFatConfig.h has been edited to uses FAT16/FAT32 for | ||
small AVR boards and FAT16/FAT32/exFAT for all other boards. | ||
``` | ||
/** | ||
* File types for SdFat, File, SdFile, SdBaseFile, fstream, | ||
* ifstream, and ofstream. | ||
* | ||
* Set SDFAT_FILE_TYPE to: | ||
* | ||
* 1 for FAT16/FAT32, 2 for exFAT, 3 for FAT16/FAT32 and exFAT. | ||
*/ | ||
#if defined(__AVR__) && FLASHEND < 0X8000 | ||
// FAT16/FAT32 for 32K AVR boards. | ||
#define SDFAT_FILE_TYPE 1 | ||
#else // defined(__AVR__) && FLASHEND < 0X8000 | ||
// FAT16/FAT32 and exFAT for all other boards. | ||
#define SDFAT_FILE_TYPE 3 | ||
#endif // defined(__AVR__) && FLASHEND < 0X8000 | ||
``` | ||
The SdBaseFile class has no Arduino Stream or Print support. | ||
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The File class is derived from Stream and SdBaseFile. | ||
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Open flags now follow POSIX conventions. O_RDONLY is the same as O_READ and O_WRONLY is the | ||
same as O_WRITE. One and only one of of the mode flags, O_RDONLY, O_RDWR, or | ||
O_WRONLY is required. | ||
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Open flags for Particle Gen3 and ARM boards are now defined by fcntl.h. | ||
See SdFatConfig.h for options. | ||
The SdFile class is derived from SdBaseFile and Print. | ||
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Support for particle Gen3 devices. | ||
Please try the examples. Start with SdInfo, bench, and ExFatLogger. | ||
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New cluster allocation algorithm. | ||
To use SdFat Version 2, unzip the download file, rename the library folder | ||
SdFat and place the SdFat folder into the libraries sub-folder in your main | ||
sketch folder. | ||
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Please read changes.txt and the html documentation in the extras folder for more information. | ||
For more information see the Manual installation section of this guide: | ||
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Please report problems as issues. | ||
http://arduino.cc/en/Guide/Libraries | ||
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A number of configuration options can be set by editing SdFatConfig.h | ||
define macros. See the html documentation for details | ||
define macros. See the html documentation File tab for details. | ||
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Please read the html documentation for this library in SdFat/doc/SdFat.html. | ||
Start with the Main Page. Next go to the Classes tab and read the | ||
documentation for the classes SdFat32, SdExFat, SdFs, File32, ExFile, FsFile. | ||
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Please read the html documentation for this library. Start with | ||
html/index.html and read the Main Page. Next go to the Classes tab and | ||
read the documentation for the classes SdFat, SdFatEX, SdBaseFile, | ||
SdFile, File, StdioStream, ifstream, ofstream, and others. | ||
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Please continue by reading the html documentation in SdFat/extras/html | ||
The SdFat and File classes are defined in terms of the above classes by | ||
typedefs. Edit SdFatConfig.h to select class options. | ||
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Updated 28 Dec 2018 | ||
Please continue by reading the html documentation in the SdFat/doc folder. |
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