All SPI pins CS, MOSI, SCK, MISO are clearly marked to allow easy attachment to you Arduino. You can read data from the SD card as well as write data to the card. This provides a wonderful way to record the data being monitored by the Arduino in real time for review at a later time. It can also be used for error logging. The Module allows you to read, write, rewrite, delete files and create files with your Arduino. The module will use either 3.3V or 5.0V, just connect the marked pin on the module to the Arduino 3.3V or 5.0V pin or a separate power supply. The module has 2 rows of 8 header pins. The two rows are connected so you have 4 grounds, 2x 3.3V, 2x 5.0V, 2x CS, 2x MOSI, 2x SCK and 2x MISO.
A cable with separable pin connectors is often useful, or use individual jumpers.
** SD card attached to SPI bus as follows:
** MOSI - pin 11 on Arduino Uno/Duemilanove/Diecimila Pin 51 on Mega2560
** MISO - pin 12 on Arduino Uno/Duemilanove/Diecimila Pin 50 on Mega2560
** SCK - pin 13 on Arduino Uno/Duemilanove/Diecimila Pin 52 on Mega 2560
** CS - depends on your SD card shield or module Pin 53 on Mega2560. Pin 4 used here for consistency with other Arduino examples
And look here as well: http://arduino.cc/en/Reference/Libraries#.Ux2mtYXJ4ro
Also, check the particular SD Module Mfr's datasheet, although most are clones...
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