arduino stuffs
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diff --git a/libraries/SD/src/utility/SdFatmainpage.h b/libraries/SD/src/utility/SdFatmainpage.h new file mode 100644 index 0000000..0a42e85 --- /dev/null +++ b/libraries/SD/src/utility/SdFatmainpage.h @@ -0,0 +1,202 @@ +/* Arduino SdFat Library + Copyright (C) 2009 by William Greiman + + This file is part of the Arduino SdFat Library + + This Library is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation, either version 3 of the License, or + (at your option) any later version. + + This Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with the Arduino SdFat Library. If not, see + <http://www.gnu.org/licenses/>. +*/ + +/** + \mainpage Arduino SdFat Library + <CENTER>Copyright © 2009 by William Greiman + </CENTER> + + \section Intro Introduction + The Arduino SdFat Library is a minimal implementation of FAT16 and FAT32 + file systems on SD flash memory cards. Standard SD and high capacity + SDHC cards are supported. + + The SdFat only supports short 8.3 names. + + The main classes in SdFat are Sd2Card, SdVolume, and SdFile. + + The Sd2Card class supports access to standard SD cards and SDHC cards. Most + applications will only need to call the Sd2Card::init() member function. + + The SdVolume class supports FAT16 and FAT32 partitions. Most applications + will only need to call the SdVolume::init() member function. + + The SdFile class provides file access functions such as open(), read(), + remove(), write(), close() and sync(). This class supports access to the root + directory and subdirectories. + + A number of example are provided in the SdFat/examples folder. These were + developed to test SdFat and illustrate its use. + + SdFat was developed for high speed data recording. SdFat was used to implement + an audio record/play class, WaveRP, for the Adafruit Wave Shield. This + application uses special Sd2Card calls to write to contiguous files in raw mode. + These functions reduce write latency so that audio can be recorded with the + small amount of RAM in the Arduino. + + \section SDcard SD\SDHC Cards + + Arduinos access SD cards using the cards SPI protocol. PCs, Macs, and + most consumer devices use the 4-bit parallel SD protocol. A card that + functions well on A PC or Mac may not work well on the Arduino. + + Most cards have good SPI read performance but cards vary widely in SPI + write performance. Write performance is limited by how efficiently the + card manages internal erase/remapping operations. The Arduino cannot + optimize writes to reduce erase operations because of its limit RAM. + + SanDisk cards generally have good write performance. They seem to have + more internal RAM buffering than other cards and therefore can limit + the number of flash erase operations that the Arduino forces due to its + limited RAM. + + \section Hardware Hardware Configuration + + SdFat was developed using an + <A HREF = "http://www.adafruit.com/"> Adafruit Industries</A> + <A HREF = "http://www.ladyada.net/make/waveshield/"> Wave Shield</A>. + + The hardware interface to the SD card should not use a resistor based level + shifter. SdFat sets the SPI bus frequency to 8 MHz which results in signal + rise times that are too slow for the edge detectors in many newer SD card + controllers when resistor voltage dividers are used. + + The 5 to 3.3 V level shifter for 5 V Arduinos should be IC based like the + 74HC4050N based circuit shown in the file SdLevel.png. The Adafruit Wave Shield + uses a 74AHC125N. Gravitech sells SD and MicroSD Card Adapters based on the + 74LCX245. + + If you are using a resistor based level shifter and are having problems try + setting the SPI bus frequency to 4 MHz. This can be done by using + card.init(SPI_HALF_SPEED) to initialize the SD card. + + \section comment Bugs and Comments + + If you wish to report bugs or have comments, send email to [email protected]. + + \section SdFatClass SdFat Usage + + SdFat uses a slightly restricted form of short names. + Only printable ASCII characters are supported. No characters with code point + values greater than 127 are allowed. Space is not allowed even though space + was allowed in the API of early versions of DOS. + + Short names are limited to 8 characters followed by an optional period (.) + and extension of up to 3 characters. The characters may be any combination + of letters and digits. The following special characters are also allowed: + + $ % ' - _ @ ~ ` ! ( ) { } ^ # & + + Short names are always converted to upper case and their original case + value is lost. + + \note + The Arduino Print class uses character + at a time writes so it was necessary to use a \link SdFile::sync() sync() \endlink + function to control when data is written to the SD card. + + \par + An application which writes to a file using \link Print::print() print()\endlink, + \link Print::println() println() \endlink + or \link SdFile::write write() \endlink must call \link SdFile::sync() sync() \endlink + at the appropriate time to force data and directory information to be written + to the SD Card. Data and directory information are also written to the SD card + when \link SdFile::close() close() \endlink is called. + + \par + Applications must use care calling \link SdFile::sync() sync() \endlink + since 2048 bytes of I/O is required to update file and + directory information. This includes writing the current data block, reading + the block that contains the directory entry for update, writing the directory + block back and reading back the current data block. + + It is possible to open a file with two or more instances of SdFile. A file may + be corrupted if data is written to the file by more than one instance of SdFile. + + \section HowTo How to format SD Cards as FAT Volumes + + You should use a freshly formatted SD card for best performance. FAT + file systems become slower if many files have been created and deleted. + This is because the directory entry for a deleted file is marked as deleted, + but is not deleted. When a new file is created, these entries must be scanned + before creating the file, a flaw in the FAT design. Also files can become + fragmented which causes reads and writes to be slower. + + Microsoft operating systems support removable media formatted with a + Master Boot Record, MBR, or formatted as a super floppy with a FAT Boot Sector + in block zero. + + Microsoft operating systems expect MBR formatted removable media + to have only one partition. The first partition should be used. + + Microsoft operating systems do not support partitioning SD flash cards. + If you erase an SD card with a program like KillDisk, Most versions of + Windows will format the card as a super floppy. + + The best way to restore an SD card's format is to use SDFormatter + which can be downloaded from: + + http://www.sdcard.org/consumers/formatter/ + + SDFormatter aligns flash erase boundaries with file + system structures which reduces write latency and file system overhead. + + SDFormatter does not have an option for FAT type so it may format + small cards as FAT12. + + After the MBR is restored by SDFormatter you may need to reformat small + cards that have been formatted FAT12 to force the volume type to be FAT16. + + If you reformat the SD card with an OS utility, choose a cluster size that + will result in: + + 4084 < CountOfClusters && CountOfClusters < 65525 + + The volume will then be FAT16. + + If you are formatting an SD card on OS X or Linux, be sure to use the first + partition. Format this partition with a cluster count in above range. + + \section References References + + Adafruit Industries: + + http://www.adafruit.com/ + + http://www.ladyada.net/make/waveshield/ + + The Arduino site: + + http://www.arduino.cc/ + + For more information about FAT file systems see: + + http://www.microsoft.com/whdc/system/platform/firmware/fatgen.mspx + + For information about using SD cards as SPI devices see: + + http://www.sdcard.org/developers/tech/sdcard/pls/Simplified_Physical_Layer_Spec.pdf + + The ATmega328 datasheet: + + http://www.atmel.com/dyn/resources/prod_documents/doc8161.pdf + + +*/ |