Im connecting an SD card module to arduino pro with 3.3v , the card is getting initialized , but im getting an error message that FAT 32 partition is not available , but it is already in FAT 32 format , is this an voltage issue ? should i connect it to a 5v line? Ive tried it two libraries SD and sdfat libraries , im getting same results, im using 8gb memory card
A SD card is 3.3V.
Have you read this: Arduino.cc forum about SD Formatter ?
Perhaps it is a cheap module with bad contacts.
Perhaps your 8GB card is not compatible. Do you have another memory card ? Preferably older and less memory.
Perhaps you use long wires, or a breadboard with bad contacts.
In most cases it should work without problem. When the initialization is okay then the wiring is probably okay. Therefor I suspect that the card itself or the partition on it, is not compatible.