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Topic: 1 GB microSD on MAC (Read 2 times) previous topic - next topic



I am trying to test CardInfo with an arduino mega and a 1GB mircoSD card. I am using a mac and can only format the SD card with FAT, which gives FAT16. When I run the program I get:

Initializing SD card...Wiring is correct and a card is present.
Card type: SD2
Could not find FAT16/FAT32 partition.
Make sure you've formatted the card

I formated it once on a PC with FAT32 and it worked once, however I would like to stick with my mac.

If anyone could tell me what I am doing wrong that would be greatly appreciated,

Nick Gammon

I am using a 2 Gb Sandisk MicroSD card both on my Mac and on a MicroSD reader. I'm not sure where I formatted it. I think I read that the best way to format for the Arduino use was to format on the board (run a formatting sketch).


Sadly the Mac is a poor choice for formatting SD cards.  Macs do not conform to the SD standard format.

It is likely you have formatted the card with a GUID Partition Table (GPT).  The SD standard specifies SD cards must be formatted with a MBR partition table.  Most cameras and phones accept this non-standard GPT format but Arduino has so little memory so GPT is not accepted.

Once a card is formatted GPT Windows often preserves this format.

The best way to reformat your card is to use SD Formatter from the SD association https://www.sdcard.org/downloads/formatter_3/.

You can also use the SdFormatter example sketch from the SdFat library to format you card on the Arduino http://code.google.com/p/sdfatlib/

Card less than 4 GB should be formatted FAT16 for best performance and cards 4 GB and larger must be formatted FAT32.  Also the SD standard requires this formatting.


In addition to the GPT/MBR problem, Mac, Linux, and Windows utilities do not align file structures on the correct boundaries to optimize access to the SD card's flash chips.

Most operating systems are learning about solid state drives (SSD) but OS utilities don't understand SD cards yet.

SD card manufactures produce cards that perform best when formatted according to the SD formatting standard.



Thank you for all your responses, however, I still can not get it to work. I have tried formatting it with both


I can't seem to get the library to work so the SDFormatter keeps giving me errors including:
ArduinoOutStream does not have a name.

I keep getting the same error telling me that the card is not formatted .

Thanks again for your help.

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