I know that this topic is very popular and that there are tons of tutorials around, but I can't make it work. As the title says, I am trying to make the FatFs work with ATMEGA328P to read a file and send the text through the serial port. I already read the thread named "[TUT] [C] Getting SD/MMC card working painlessly with FatFS" but it seems to not be updated since the example codes shown there differ a little from the last version R0.11a. The disk_initialize(0) method returns STA_NOINIT, but the f_mount function returns FR_OK, which is weird, and the f_read function returns FR_NOT_READY. Since I do not have a debugger yet, I see the return codes by sending them to the PC by UART. I am using Atmel Studio 7.0 and I interfaced the MCU with the SD card through a microSD card breakout and a CD4050 IC powered from a 3.3V regulator. I attached the code in order to avoid doing a very long post. I would appreciate very much if someone could help me find what am I doing wrong. Thank you very much in advance! P.S. I do not have much experience with AVR-GCC :s .