vhdl - How to Get Audio Out via the Wolfson WM8731 CODEC on the Altera DE2-115 educational FPGA board? -


my group , trying create synthesizer out of de2-115 board our undergraduate capstone project.

the thing can't figure out how frequencies mapped "keys" outputted through audio port on board. we've scoured web , provided documentation included datasheets codec can't figure out how work in vhdl.

has ever worked outputting audio through wm8731 , if so, willing out?

i did years ago, wasn't hard, used nios processor sopc builder.

i used altera university program ip cores available here.

these cores provides different functionality related de2 , possibly other altera sponsered-board.

according logs, used 3 of these cores make audio work.

the altera_up_avalon_audio_and_video_config, used configure audio codec chip @ initialization.

the second ip provide data in/out interface audio chip: altera_up_avalon_audio.

the last 1 altera_up_avalon_clocks. can't remember does, name imply it's necessary clocking of audio chip. think takes input clock , generate pll provide right clock codec.

as said, used nios processor, still according log, c code used is:

void audio_isr(void* context, alt_u32 id) {     const int len = 2682358;     static signed char *ptr = test_snd;     unsigned int x[128];      alt_up_audio_dev *audio_dev = (alt_up_audio_dev *)context;      unsigned int n = alt_up_audio_write_fifo_space(audio_dev, alt_up_audio_right);      for(unsigned int = 0; < n; i++) {         x[i] = 0x800000 + ((int)*ptr++) << 9;          if (ptr > test_snd+len) {             ptr = test_snd;             printf("done\n");         }     }      alt_up_audio_write_fifo(audio_dev, x, n, alt_up_audio_right);     alt_up_audio_write_fifo(audio_dev, x, n, alt_up_audio_left); }  static void audio_init(void) {     alt_up_audio_dev *audio_dev = alt_up_audio_open_dev (audio_0_name);     if ( audio_dev == null)         printf ("error: not open audio device \n");     else         printf ("opened audio device \n");     alt_up_audio_reset_audio_core(audio_dev);     alt_up_audio_disable_write_interrupt(audio_dev);     alt_up_audio_disable_read_interrupt(audio_dev);      alt_irq_register(audio_0_irq, (void *)audio_dev, audio_isr);     alt_up_audio_enable_write_interrupt(audio_dev); }

i don't remember how worked. enough deserve commit, still test, don't give importance. final code way complicated present here.

hopefully, enough started on right track, use altera's ip. these ip clear-source afair, if don't want nios, should simpler start source scratch.


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