SD card won't initialize on Mega,but works fine on Uno

Hello,
Im having trouble getting Mega to work with an SD,I have checked all the connections and they are all good and on the same code Uno works,but Mega doesn’t.I’m sure the connections are right(50,51,52,53) and I used the sample code from official SD lib:

/*
  SD card read/write
 
 This example shows how to read and write data to and from an SD card file 	
 The circuit:
 * SD card attached to SPI bus as follows:
 ** MOSI - pin 11
 ** MISO - pin 12
 ** CLK - pin 13
 ** CS - pin 4
 
 created   Nov 2010
 by David A. Mellis
 modified 9 Apr 2012
 by Tom Igoe
 
 This example code is in the public domain.
 	 
 */
 
#include <SD.h>

File myFile;

void setup()
{
  
 // Open serial communications and wait for port to open:
  Serial.begin(9600);
   while (!Serial) {
    ; // wait for serial port to connect. Needed for Leonardo only
  }

  Serial.print("Initializing SD card...");
  // On the Ethernet Shield, CS is pin 4. It's set as an output by default.
  // Note that even if it's not used as the CS pin, the hardware SS pin 
  // (10 on most Arduino boards, 53 on the Mega) must be left as an output 
  // or the SD library functions will not work. 
   pinMode(10, OUTPUT);
   
  if (!SD.begin(4)) {
    Serial.println("initialization failed!");
    return;
  }
  Serial.println("initialization done.");
  
  // open the file. note that only one file can be open at a time,
  // so you have to close this one before opening another.
  myFile = SD.open("test.txt", FILE_WRITE);
  
  // if the file opened okay, write to it:
  if (myFile) {
    Serial.print("Writing to test.txt...");
    myFile.println("testing 1, 2, 3.");
	// close the file:
    myFile.close();
    Serial.println("done.");
  } else {
    // if the file didn't open, print an error:
    Serial.println("error opening test.txt");
  }
  
  // re-open the file for reading:
  myFile = SD.open("test.txt");
  if (myFile) {
    Serial.println("test.txt:");
    
    // read from the file until there's nothing else in it:
    while (myFile.available()) {
    	Serial.write(myFile.read());
    }
    // close the file:
    myFile.close();
  } else {
  	// if the file didn't open, print an error:
    Serial.println("error opening test.txt");
  }
}

void loop()
{
	// nothing happens after setup
}

Any help will be appreciated :slight_smile:

mrleongalaxyum:
Hello,
Im having trouble getting Mega to work with an SD,I have checked all the connections and they are all good and on the same code Uno works,but Mega doesn’t.I’m sure the connections are right(50,51,52,53) and I used the sample code from official SD lib:

/*

SD card read/write

This example shows how to read and write data to and from an SD card file
The circuit:

  • SD card attached to SPI bus as follows:
    ** MOSI - pin 11
    ** MISO - pin 12
    ** CLK - pin 13
    ** CS - pin 4

created   Nov 2010
by David A. Mellis
modified 9 Apr 2012
by Tom Igoe

This example code is in the public domain.

*/

#include <SD.h>

File myFile;

void setup()
{
 
// Open serial communications and wait for port to open:
 Serial.begin(9600);
  while (!Serial) {
   ; // wait for serial port to connect. Needed for Leonardo only
 }

Serial.print(“Initializing SD card…”);
 // On the Ethernet Shield, CS is pin 4. It’s set as an output by default.
 // Note that even if it’s not used as the CS pin, the hardware SS pin
 // (10 on most Arduino boards, 53 on the Mega) must be left as an output
 // or the SD library functions will not work.
  pinMode(10, OUTPUT);
 
 if (!SD.begin(4)) {
   Serial.println(“initialization failed!”);
   return;
 }
 Serial.println(“initialization done.”);
 
 // open the file. note that only one file can be open at a time,
 // so you have to close this one before opening another.
 myFile = SD.open(“test.txt”, FILE_WRITE);
 
 // if the file opened okay, write to it:
 if (myFile) {
   Serial.print(“Writing to test.txt…”);
   myFile.println(“testing 1, 2, 3.”);
// close the file:
   myFile.close();
   Serial.println(“done.”);
 } else {
   // if the file didn’t open, print an error:
   Serial.println(“error opening test.txt”);
 }
 
 // re-open the file for reading:
 myFile = SD.open(“test.txt”);
 if (myFile) {
   Serial.println(“test.txt:”);
   
   // read from the file until there’s nothing else in it:
   while (myFile.available()) {
    Serial.write(myFile.read());
   }
   // close the file:
   myFile.close();
 } else {
  // if the file didn’t open, print an error:
   Serial.println(“error opening test.txt”);
 }
}

void loop()
{
// nothing happens after setup
}



Any help will be appreciated :)

Set Pin 53 (SS) to output.

Also, does your shield use the ISP header? If it does not, you will have to cross wire from 11…13 to 50…52.

You say it does not work. What does it not do?

Do you get the “initialization failed!” message or no message, or something else?

Chuck.