I am using this micro-sd card reader, and my wiring configuration is as follows (double and triple checked):

3.3v goes to 3.3v on the Arduino UNO
GND goes to Ground on Arduino UNO
D0 goes to pin 12 on Arduino UNO
D1 goes to pin 11 on Arduino UNO
CLK goes to pin 13 on Arduino UNO
D3 goes to pin 4 on Arduino UNO

When I run the 'basic' example from the TMRpcm library, everything compiles and uploads properly with no warnings. Looking at the Serial Monitor, I get "SD Fail", which, according to the comments, means that the SD card failed to initialize. The card is present, and works in my computer. Do I have something wired wrong, or is there another issue?


I have tried using a different pin for D3, and changed the code as needed. Still no luck.

  • Without a ton of knowledge about your situation, it seems like the SD card isn't the proper format, the reader is bad, or the card isn't in all the way. Can you try a different card? Is the read only switch enabled? Aug 4, 2014 at 23:13
  • The card is in all the way. It clicks into place. I don't see a read-only switch on the card or the reader. The reader may be bad, but the LED on board the reader comes on when the arduino is plugged in, which leads me to believe that is not the case. I don't have a second card on hand at the moment. What format does the card need to be in? FAT32?
    – jaredad7
    Aug 4, 2014 at 23:17
  • As far as I can tell, FAT32. Also, a SDXC might be a problem here... Aug 4, 2014 at 23:23
  • Didn't know what that was before now, but it looks like they're all larger than 32 GB. Mine is 8. I'm fairly certain it's FAT32. I had trouble with a FAT32 header it was trying to pull in earlier with the wrong path.
    – jaredad7
    Aug 4, 2014 at 23:27

2 Answers 2


See https://github.com/greiman/SdFat

Ensure it works with the sdinfo example, and then you can just use the sdformatter example to format the card.


Check if the reader is plugged in correctly. This will give a PEBKAC error.

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