root / arduino-1.0 / libraries / SD / examples / ReadWrite / ReadWrite.ino @ 58d82c77
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1 | 58d82c77 | Tom Mullins | /* |
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2 | SD card read/write |
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3 | |||
4 | This example shows how to read and write data to and from an SD card file |
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5 | The circuit: |
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6 | * SD card attached to SPI bus as follows: |
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7 | ** MOSI - pin 11 |
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8 | ** MISO - pin 12 |
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9 | ** CLK - pin 13 |
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10 | ** CS - pin 4 |
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11 | |||
12 | created Nov 2010 |
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13 | by David A. Mellis |
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14 | updated 2 Dec 2010 |
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15 | by Tom Igoe |
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16 | |||
17 | This example code is in the public domain. |
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18 | |||
19 | */ |
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20 | |||
21 | #include <SD.h> |
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22 | |||
23 | File myFile; |
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24 | |||
25 | void setup() |
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26 | { |
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27 | Serial.begin(9600); |
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28 | Serial.print("Initializing SD card..."); |
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29 | // On the Ethernet Shield, CS is pin 4. It's set as an output by default. |
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30 | // Note that even if it's not used as the CS pin, the hardware SS pin |
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31 | // (10 on most Arduino boards, 53 on the Mega) must be left as an output |
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32 | // or the SD library functions will not work. |
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33 | pinMode(10, OUTPUT); |
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34 | |||
35 | if (!SD.begin(4)) { |
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36 | Serial.println("initialization failed!"); |
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37 | return; |
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38 | } |
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39 | Serial.println("initialization done."); |
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40 | |||
41 | // open the file. note that only one file can be open at a time, |
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42 | // so you have to close this one before opening another. |
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43 | myFile = SD.open("test.txt", FILE_WRITE); |
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44 | |||
45 | // if the file opened okay, write to it: |
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46 | if (myFile) { |
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47 | Serial.print("Writing to test.txt..."); |
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48 | myFile.println("testing 1, 2, 3."); |
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49 | // close the file: |
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50 | myFile.close(); |
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51 | Serial.println("done."); |
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52 | } else { |
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53 | // if the file didn't open, print an error: |
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54 | Serial.println("error opening test.txt"); |
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55 | } |
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56 | |||
57 | // re-open the file for reading: |
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58 | myFile = SD.open("test.txt"); |
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59 | if (myFile) { |
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60 | Serial.println("test.txt:"); |
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61 | |||
62 | // read from the file until there's nothing else in it: |
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63 | while (myFile.available()) { |
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64 | Serial.write(myFile.read()); |
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65 | } |
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66 | // close the file: |
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67 | myFile.close(); |
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68 | } else { |
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69 | // if the file didn't open, print an error: |
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70 | Serial.println("error opening test.txt"); |
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71 | } |
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72 | } |
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73 | |||
74 | void loop() |
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75 | { |
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76 | // nothing happens after setup |
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77 | } |
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78 |