Trouble with SD Card Module Detection/Initialization on Arduino Mega (Works Fine on UNO)

[123_cookie]

Hello everyone,

I’m facing an issue with initializing the SD card module on an Arduino Mega. We’re using the following wiring and code, but the SD card is either not detected or the initialization fails when we run it on the Mega. Interestingly, it works fine on an Arduino UNO with the same code and wiring.

Wiring:
VCC→ 5V
GND→ GND
MISO→ Pin 50
MOSI→ Pin 51
CK→ Pin 52
CS→ Pin 53 (also defined as SD_CS in the code)

Problem:

• On the Arduino Mega, the SD card is not detected or initialization fails, and I get the message "SD Card failed or not detected."
• However, the same SD card and same code work perfectly fine on an Arduino UNO.

Things I’ve tried:

1. Checked wiring: Verified that all the connections are correct (VCC to 5V, GND to GND, MISO to Pin 50, MOSI to Pin 51, SCK to Pin 52, and CS to Pin 53).
2. SD card format: Ensured the SD card is properly formatted (FAT32) and the files on it are accessible.
3. Tested the SD card on UNO: It works fine on the UNO, so the card itself is not the issue.
4. Checked the power supply: The Arduino Mega is powered through USB and should provide enough power for the SD card module.
5. Tried changing the CS pin: We also tried changing the CS pin from 53 to 10 and 4, but the SD card is still not being detected on the Mega.

I used the SD Card Module attached below.

Has anyone encountered a similar issue with the Arduino Mega? Are there any special considerations when using the Mega with the SD card module, or could there be a specific hardware conflict?

I would appreciate any suggestions or insights you can provide!

Thanks in advance!

#include <SPI.h>
#include <SD.h>

#define SD_CS 53  

void setup() {
    Serial.begin(115200);
    Serial.print("Initializing SD card...");

    pinMode(53, OUTPUT);

    if (!SD.begin(53)) {
        Serial.println("SD Card failed or not detected.");
        return;
    }
    Serial.println("SD Card initialized successfully.");

    Serial.println("Listing files on SD card...");
    File root = SD.open("/");
    printDirectory(root, 0);
    Serial.println("Done.");
}

void loop() {}

void printDirectory(File dir, int numTabs) {
    while (true) {
        File entry = dir.openNextFile();
        if (!entry) {
            break; // No more files
        }
        for (uint8_t i = 0; i < numTabs; i++) {
            Serial.print("\t");
        }
        Serial.print(entry.name());
        if (entry.isDirectory()) {
            Serial.println("/");
            printDirectory(entry, numTabs + 1);
        } else {
            Serial.print("\tSize: ");
            Serial.println(entry.size(), DEC);
        }
        entry.close();
    }
}

[markd833]

An almost identical post appeared yesterday - see if they had any success:

SD card module works fine in Arduino Uno but it doesn't work in Mega

Hi! We are having trouble in initializing the SD Card using the arduino mega, but we tried in uno and it works just fine. How do we fix this? we tried simple codes like: #include <SPI.h> #include <SD.h> #define SD_CS 53 void setup() { Serial.begin(9600); Serial.print("Initializing SD card..."); pinMode(SD_CS, OUTPUT); if (!SD.begin(SD_CS)) { Serial.println("SD Card failed or not detected."); return; } Serial.println("SD Card initialized successfully…

[123_cookie]

Thank you for pointing that out! Yes, that post is actually from a friend of mine, and we are both facing the same issue with the SD card module on the Arduino Mega. We’ve tried the same troubleshooting steps and used the same code, but unfortunately, we haven’t been able to resolve the issue yet.

I wanted to ask again just in case there might be new suggestions or insights since it's been a little while since that post.

[docdoc]

You need to know if your SD module (link, please?) is 5V compatible or not.
I say this because many SD card adapters work at 3v3 signals only, so if your SD module has a level shifter it's ok using it with a 5V Arduino. Although many people say that it may work without level shifter, it probably worked first and then suddenly stopped when connected to the Mega (meaning it's probably gone).
So, double check the specifications to see if the module allows you to use it with 5V, and if in doubt test it back with UNO and see if it's still alive (hope so).

EDIT: I see someone made a modification/hack to the module, by adding a couple of diodes:

SD card module with Arduino Mega not working. [SOLVED]

The full-size SD card module like the one linked by the OP is suitable for use only with 3.3V processors. While it has a 3.3V regulator to provide power to the SD card, the MOSI, SCK and CS lines coming in from the processor only have pullup resistors to 3.3V on the module, not level shifters. But those lines coming from a Mega would be 5V lines, which probably exceeds the absolute maximum voltage you can apply if the card is running at 3.3V. The 10K pullups would have no significant effect on t…

[123_cookie]

Here's the link to the Micro SD Card module we are using: Micro SD Card Module

EDIT: Thank you, we are actually trying that solution as of the moment (adding diodes).

[david_2018]

Your link does not work, but going by the picture you have a different adapter than the one with the diode modification.

The adapter you have has a level shifter (the 74HC125), but has a different problem. The MISO line is not properly tri-stated when the card is not selected. This is not a problem unless you have another SPI device connected at the same time.

[docdoc]

Shopee wont let me in and see the item, it requires a logged user...
Anyway, looks like is declared as "interface with 3V or 5V devices" but I still doubt it does, unless I see level shifters on the input pins. Most of the sites just report what chinese suppliers say, but I usually say we need to take them with a pinch of salt.

My opinion is you need that hack to let it work (hoping it isn't dead yet...). And I buy things from reliable sellers, giving full details and datasheets, not just search for the site with the lowest price.

[david_2018]

@docdoc

My opinion is you need that hack to let it work

That modification appears to be for a completely different SD adapter board.

This appears to be the adapter OP is using:
https://forum.arduino.cc/t/i-cannot-find-the-datasheet-for-catalex-microsd-card-adapter/347407
I really don't see any reason it should not work with a Mega, since it functions with an UNO. I have had problems with these modules having poor quality sockets, requiring inserting and removing the SD card a few times before getting a good connection.