93 lines
2.4 KiB
C++
93 lines
2.4 KiB
C++
/*
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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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** UNO: MOSI - pin 11, MISO - pin 12, CLK - pin 13, CS - pin 4 (CS pin can be changed)
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and pin #10 (SS) must be an output
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** Mega: MOSI - pin 51, MISO - pin 50, CLK - pin 52, CS - pin 4 (CS pin can be changed)
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and pin #52 (SS) must be an output
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** Leonardo: Connect to hardware SPI via the ICSP header
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created Nov 2010 by David A. Mellis
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modified 9 Apr 2012 by Tom Igoe
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This example code is in the public domain.
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*/
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#include <SPI.h>
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#include <mySD.h>
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File myFile;
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// change this to match your SD shield or module;
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// Arduino Ethernet shield: pin 4
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// Adafruit SD shields and modules: pin 10
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// Sparkfun SD shield: pin 8
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const int chipSelect = 4;
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void setup()
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{
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// Open serial communications and wait for port to open:
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Serial.begin(115200);
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while (!Serial) {
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; // wait for serial port to connect. Needed for Leonardo only
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}
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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(SS, OUTPUT);
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if (!SD.begin(17, 14, 12, 15)) {
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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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