68000 running Linux kernel 3.7 and playing mp3!

I've decided to take my 11-years-old mp3 decoder board from a dusty box and plug it into my homemade 68000 board (which I call Alcetronics M68K).

The mp3 board is based on the mas3507d+dac3550 combo (one of the firsts to show on the marked back in that time).

The 68000 board is running kernel 3.7-rc8 and can handle all mp3 file bitrates (as long as the mas3507d can)!

In the video the mp3 file is read from the 4gb sdcard and sent to the mas3507d using a simple 'cat' command.

Hardware details:
The mas3507d bitstream is fed by a SPI placed on the FPGA. The demand pin from the mas3507d is controlling an interupt to the 68000 cpu.

Software details:
Developed a very simple driver to use the mas3507d as a character device.
To play mp3 I just simply dump the bitstream to the char device. In order to have 0 buffer underruns I'm using a 256K buffer.
In order to play 320kbit mp3s I had to tweak the mas3507d interrupt routine to be sufficient fast (coded some assembly).

More details can be found on:
http://mc68k.blogspot.pt/

Видео 68000 running Linux kernel 3.7 and playing mp3! канала Luis Alves