Re: mp3 player
I don't think a single AVR microcontroller can be used for this task. The AVR can be used to read the information from a storage medium with FAT implemented, and to control the mp3 decoder.
MP3 decoding is very complex, and can be implemented only on DSP (at least real time). The AVR has limited resources for that, and is quite slow, even for the data transfer of high bitrate mp3s (256, 320kbps). So you need at least an AVR microcontroller and an mp3 decoder chip.[/url]