ATmega8 Used for Interfacing SD Card

Figure 1 

A 1GB micro SD card is used in this project along with an AVR Atmega8 microcontroller as the circuit is interfaced with PC for monitoring that data using MAX232.

The AVR ATmega8 or Atmega32 runs at 8MHz internal clock while being powered by a 3.3V supply along with a micro SD/SDHC and MAX232. The project illustrates how the SD card can be interfaced and the transfer of data in raw format as well as in FAT32 format can be understood. During the raw data transfer, some data are sent to any block of the micro SD. It reads a block of it, reads and writes multiple blocks, and erases multiple blocks. The data read by microcontroller from SD card is viewed using RS232. The data is sent to HyperTerminal by the microcontroller. By typing some text, the data is written to card and fed thru HyperTerminal.

The card was formatted with Windows XP (FAT32) once the raw data transfer has been achieved. The files are read by writing the FAT32 routines. This is also responsible for getting the file list using the HyperTerminal as well as finding the total/free memory of card.

Rest of the project