This hardware demonstrates a music player implemented on a DE1-SoC development board.
After an audio file is loaded into flash memory, as well as a pair of headphones and a keyboard connected to the board,
the song can be played and paused using the E and D buttons, respectively.
Playing the song in the forward and reverse directions is toggled with the F and B buttons.
R is used to restart the music player.
Finally, he song is sped up and slowed down with the KEY1 and KEY0 buttons on the DE1.
The LEDs are also used as a volume indicator.
The flash memory is interfaced with a finite state machine, flash_fsm. By default, flash_fsm reads from memory at a frequency of 22 kHz and increments the address being read from every time, so that audio samples are output sequentially and the song plays in the forward direction.
When a request to speed up, slow down, or reset the speed is asserted, the freq_ctrl module adjusts the clock divider accordingly and synchronizes the signal with the system clock to avoid metastability issues.
Meanwhile, requests asserted via keyboard are decoded by the kbd_fsm module, and the address being read from is either incremented, decremented, or held depending on whether the request is to play forward, play in reverse, or pause, respectively.
The volume indicator is controlled by a PicoBlaze microprocessor, which takes the audio data as input and outputs directly to the LEDs on the DE1-SoC (not shown in schematic; simple_ipod_solution.v for more details).
Credit is due to Yair Linn for providing the source files contained in bin and template, as well as the code in simple_ipod_solution.v not under the "my code" header. All other files in src and tb were written independently by me.