62 lines
1.9 KiB
Plaintext
62 lines
1.9 KiB
Plaintext
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Support has been added for the Arduino Due.
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You must connect your SD socket to the 6-pin "ISP connector". You must have short
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wires or a custom shield to run at full speed, 42 MHz.
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If you have problems use a lower SPI speed. You can also check for SPI
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errors by editing SdFatCobfig.h to enable CRC checking.
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You should be be able to use any digital pin for SD chip select. The default
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pin is SS which is pin 10 for Due.
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The default SPI rate is 42 MHz. You can set SD chip select and the SPI rate
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by calling:
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bool SdFat::begin(uint8_t chipSelectPin, uint8_t spiRateID);
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The second argument, spiRateID, sets the SCK rate and can be these symbols:
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SPI_FULL_SPEED - 42 MHz
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SPI_DIV3_SPEED - 28 MHz
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SPI_HALF_SPEED - 21 MHz
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SPI_DIV6_SPEED - 14 MHz
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SPI_QUARTER_SPEED 10.5 MHz
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SPI_EIGHTH_SPEED 5.25 MHz
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Large reads and writes use fast multi-block SD read/write commands. For optimal
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speed, use records that are a multiple of 512 bytes.
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Run the bench.ino example to explore large read/write speed.
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Replace this line:
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#define BUF_SIZE 100
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With a large size like this:
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#define BUF_SIZE 8192
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For best results the record size should be a power of two (512, 1024, 2048,
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4096, 8192). In this case records will be aligned with FAT cluster boundaries.
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Since Due is fast, increase the test file size by editing this line:
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#define FILE_SIZE_MB 5
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Run the PrintBenchmark.ino example to compare text formatting speed of Due
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with AVR boards.
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A number of options are available to configure SPI for the Due board.
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You can use the standard SPI.h library by editing SdFatConfig.h and set
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USE_ARDUINO_SPI_LIBRARY nonzero. You must include SPI.h in your sketch.
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Several options can be set in Sd2Card.cpp in the USE_NATIVE_SAM3X_SPI
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section. These include USE_SAM3X_DMAC to control use of DMA and
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USE_SAM3X_BUS_MATRIX_FIX to change Bus Matrix operation. Most people
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will not need to change these.
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