root / arduino-1.0 / libraries / SD / examples / ReadWrite / ReadWrite.ino @ 58d82c77
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/* |
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SD card read/write |
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This example shows how to read and write data to and from an SD card file |
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The circuit: |
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* SD card attached to SPI bus as follows: |
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** MOSI - pin 11 |
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** MISO - pin 12 |
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** CLK - pin 13 |
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** CS - pin 4 |
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|
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created Nov 2010 |
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by David A. Mellis |
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updated 2 Dec 2010 |
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by Tom Igoe |
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This example code is in the public domain. |
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*/ |
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#include <SD.h> |
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File myFile; |
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void setup() |
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{ |
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Serial.begin(9600); |
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Serial.print("Initializing SD card..."); |
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// On the Ethernet Shield, CS is pin 4. It's set as an output by default. |
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// Note that even if it's not used as the CS pin, the hardware SS pin |
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// (10 on most Arduino boards, 53 on the Mega) must be left as an output |
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// or the SD library functions will not work. |
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pinMode(10, OUTPUT); |
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if (!SD.begin(4)) { |
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Serial.println("initialization failed!"); |
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return; |
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} |
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Serial.println("initialization done."); |
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// open the file. note that only one file can be open at a time, |
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// so you have to close this one before opening another. |
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myFile = SD.open("test.txt", FILE_WRITE); |
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// if the file opened okay, write to it: |
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if (myFile) { |
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Serial.print("Writing to test.txt..."); |
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myFile.println("testing 1, 2, 3."); |
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// close the file: |
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myFile.close(); |
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Serial.println("done."); |
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} else { |
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// if the file didn't open, print an error: |
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Serial.println("error opening test.txt"); |
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} |
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// re-open the file for reading: |
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myFile = SD.open("test.txt"); |
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if (myFile) { |
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Serial.println("test.txt:"); |
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// read from the file until there's nothing else in it: |
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while (myFile.available()) { |
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Serial.write(myFile.read()); |
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} |
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// close the file: |
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myFile.close(); |
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} else { |
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// if the file didn't open, print an error: |
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Serial.println("error opening test.txt"); |
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} |
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} |
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void loop() |
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{ |
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// nothing happens after setup |
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} |
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