194 lines
6.5 KiB
Plaintext
194 lines
6.5 KiB
Plaintext
Please check the changes.txt file!
|
|
|
|
For those who don't like too much documentation read QuickStart.txt.
|
|
|
|
The Arduino SdFat library provides read/write access to FAT16/FAT32
|
|
file systems on SD/SDHC flash cards.
|
|
|
|
This library requires Arduino 1.0 or greater.
|
|
|
|
To use this library place the SdFat folder into the libraries
|
|
subfolder in your main sketches folder. You may need to create
|
|
the libraries folder. Restart the Arduino IDE if it was open.
|
|
|
|
SdFat assumes chip select for the SD card is the hardware SS pin. On a
|
|
168/328 Arduino this is pin 10 and on a Mega this is pin 53. If you are
|
|
using another pin for chip select you will need call SdFat::begin(chipSelectPin)
|
|
or SdFat::begin(chipSelectPin, sckRateID) with second parameter set to the
|
|
SPI rate ID.
|
|
|
|
If you have a shield like the SparkFun shield that uses pin 8 for chip
|
|
select you would change the line:
|
|
sd.begin();
|
|
to
|
|
sd.begin(8);
|
|
or
|
|
sd.begin(8, SPI_HALF_SPEED);
|
|
to use a slower SPI clock.
|
|
|
|
If the example uses
|
|
sd.init();
|
|
change it to:
|
|
sd.begin(8, SPI_FULL_SPEED);
|
|
|
|
|
|
A number of configuration options can be set by editing SdFatConfig.h
|
|
#define macros. Options include:
|
|
|
|
ALLOW_DEPRECATED_FUNCTIONS - enable or disable deprecated functions.
|
|
|
|
USE_SD_CRC - enable or disable SD card crc checking.
|
|
|
|
USE_MULTIPLE_CARDS - enable or disable use of multiple SD card sockets.
|
|
|
|
USE_SERIAL_FOR_STD_OUT - use Serial for the default stdOut.
|
|
|
|
ENDL_CALLS_FLUSH - enable a flush() call after endl.
|
|
|
|
SPI_SD_INIT_RATE - set the SPI rate for card initialization.
|
|
|
|
LEONARDO_SOFT_SPI - use software SPI on Leonardo Arduinos.
|
|
|
|
MEGA_SOFT_SPI - use software SPI on Mega Arduinos.
|
|
|
|
USE_SOFTWARE_SPI - always use software SPI.
|
|
|
|
|
|
If you wish to report bugs or have comments, send email to
|
|
fat16lib@sbcglobal.net
|
|
|
|
Read changes.txt if you have used previous releases of this library.
|
|
|
|
Read troubleshooting.txt for common hardware problems.
|
|
|
|
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, SdFile, ifstream, ofstream.
|
|
|
|
The SdFile class implements binary files simular to Linux's stdio.
|
|
|
|
The classes ifstream, ofstream, istream, and ostream follow the
|
|
C++ iostream standard when possible.
|
|
|
|
Many examples are included in the SdFat/examples folder.
|
|
|
|
There are many tutorials and much documentation about using C++ iostreams.
|
|
|
|
http://www.cplusplus.com/ is a good C++ site.
|
|
|
|
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 limited 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.
|
|
|
|
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.
|
|
|
|
A feature to use software SPI is available. Software SPI is slower
|
|
than hardware SPI but allows any digital pins to be used. See
|
|
SdFatConfig.h for software SPI definitions.
|
|
|
|
An unmodified Adafruit GPS shield can be use on an Arduino Mega
|
|
by defining MEGA_SOFT_SPI in SdFatConfig.h.
|
|
|
|
|
|
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.
|
|
|
|
The example sketch SdFatFormatter.pde will format smaller cards FAT16
|
|
so they can be used with SdFat.
|
|
|
|
|
|
The SdFat/examples directory has the following sketches. Older examples
|
|
are in the extras/examplesV1 folder.
|
|
|
|
AnalogLogger - A simple data logger for one or more analog pins.
|
|
|
|
append - This sketch creates a large file by successive
|
|
open/write/close operations.
|
|
|
|
average - A demonstration of parsing floating point numbers
|
|
|
|
bench - A read/write benchmark.
|
|
|
|
benchSD - A read/write benchmark for the standard Arduino SD.h library.
|
|
|
|
bufstream - ibufsteam to parse a line and obufstream to format a line
|
|
|
|
cin_cout - Demo of ArduinoInStream and ArduinoOutStream
|
|
|
|
eventlog - Append a line to a file - demo of pathnames and streams
|
|
|
|
fgets - Demo of the fgets read line/string function.
|
|
|
|
fgetsRewrite - Demo of rewriting a line read by fgets
|
|
|
|
formating - Print a table with various formatting options
|
|
|
|
getline - Example of getline from section 27.7.1.3 of the C++ standard
|
|
|
|
HelloWorld - Create a serial output stream
|
|
|
|
MiniSerial - SdFat minimal serial support for debug
|
|
|
|
OpenNext - Open all files in the root dir and print their filename
|
|
|
|
PrintBenchmark - A simple benchmark for printing to a text file.
|
|
|
|
QuickStart - A sketch to quickly test your SD card and SD shield/module
|
|
|
|
RawWrite - A test of raw write functions for contiguous files.
|
|
|
|
readCSV - Read a comma-seperated value file using iostream extractors
|
|
|
|
readlog - Read file. Demo of pathnames and current working directory
|
|
|
|
ReadWriteSdFat - SdFat version of Arduino SD ReadWrite example
|
|
|
|
rename - A demo of SdFat::rename(old, new) and SdFile::rename(dirFile, newPath)
|
|
|
|
SdFormatter - This sketch will format an SD or SDHC card.
|
|
|
|
SdInfo - Initialize an SD card and analyze its structure for trouble shooting
|
|
|
|
Timestamp - Sets file create, modify, and access timestamps
|
|
|
|
TwoCards - Example using two SD cards
|
|
|
|
To access these examples from the Arduino development environment
|
|
go to: File -> Examples -> SdFat -> <Sketch Name>
|
|
|
|
Compile, upload to your Arduino and click on Serial Monitor to run
|
|
the example.
|
|
|
|
|
|
Updated 01 Dec 2012
|