pimoroni-pico/examples/pico_audio/demo.cpp

#include <stdio.h>
#include <math.h>

#include "pico/stdlib.h"

#include "synth.hpp"
#include "audio.hpp"

#define PICO_AUDIO_PACK_I2S_DATA 9
#define PICO_AUDIO_PACK_I2S_BCLK 10

#define SONG_LENGTH 384
#define HAT 20000
#define BASS 500
#define SNARE 6000
#define SUB 50

using namespace synth;

synth::AudioChannel synth::channels[CHANNEL_COUNT];

// Gadgetoid's amazing masterpiece!
const int16_t notes[5][SONG_LENGTH] = {
  { // melody notes
    147, 0, 0, 0, 0, 0, 0, 0, 175, 0, 196, 0, 220, 0, 262, 0, 247, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 175, 0, 0, 0, 0, 0, 0, 0, 175, 0, 196, 0, 220, 0, 262, 0, 330, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 349, 0, 0, 0, 0, 0, 0, 0, 349, 0, 330, 0, 294, 0, 220, 0, 262, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 247, 0, 0, 0, 0, 0, 0, 0, 247, 0, 220, 0, 196, 0, 147, 0, 175, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0,
    147, 0, 0, 0, 0, 0, 0, 0, 175, 0, 196, 0, 220, 0, 262, 0, 247, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 175, 0, 0, 0, 0, 0, 0, 0, 175, 0, 196, 0, 220, 0, 262, 0, 330, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 349, 0, 0, 0, 0, 0, 0, 0, 349, 0, 330, 0, 294, 0, 220, 0, 262, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 247, 0, 0, 0, 0, 0, 0, 0, 247, 0, 220, 0, 196, 0, 147, 0, 175, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0,
    147, 0, 0, 0, 0, 0, 0, 0, 175, 0, 196, 0, 220, 0, 262, 0, 247, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 175, 0, 0, 0, 0, 0, 0, 0, 175, 0, 196, 0, 220, 0, 262, 0, 330, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 349, 0, 0, 0, 0, 0, 0, 0, 349, 0, 330, 0, 294, 0, 220, 0, 262, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 247, 0, 0, 0, 0, 0, 0, 0, 247, 0, 262, 0, 294, 0, 392, 0, 440, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
  },
  { // rhythm notes
    294, 0, 440, 0, 587, 0, 440, 0, 294, 0, 440, 0, 587, 0, 440, 0, 294, 0, 440, 0, 587, 0, 440, 0, 294, 0, 440, 0, 587, 0, 440, 0, 294, 0, 440, 0, 587, 0, 440, 0, 294, 0, 440, 0, 587, 0, 440, 0, 392, 0, 523, 0, 659, 0, 523, 0, 392, 0, 523, 0, 659, 0, 523, 0, 698, 0, 587, 0, 440, 0, 587, 0, 698, 0, 587, 0, 440, 0, 587, 0, 523, 0, 440, 0, 330, 0, 440, 0, 523, 0, 440, 0, 330, 0, 440, 0, 349, 0, 294, 0, 220, 0, 294, 0, 349, 0, 294, 0, 220, 0, 294, 0, 262, 0, 247, 0, 220, 0, 175, 0, 165, 0, 147, 0, 131, 0, 98, 0,
    294, 0, 440, 0, 587, 0, 440, 0, 294, 0, 440, 0, 587, 0, 440, 0, 294, 0, 440, 0, 587, 0, 440, 0, 294, 0, 440, 0, 587, 0, 440, 0, 294, 0, 440, 0, 587, 0, 440, 0, 294, 0, 440, 0, 587, 0, 440, 0, 392, 0, 523, 0, 659, 0, 523, 0, 392, 0, 523, 0, 659, 0, 523, 0, 698, 0, 587, 0, 440, 0, 587, 0, 698, 0, 587, 0, 440, 0, 587, 0, 523, 0, 440, 0, 330, 0, 440, 0, 523, 0, 440, 0, 330, 0, 440, 0, 349, 0, 294, 0, 220, 0, 294, 0, 349, 0, 294, 0, 220, 0, 294, 0, 262, 0, 247, 0, 220, 0, 175, 0, 165, 0, 147, 0, 131, 0, 98, 0,
    294, 0, 440, 0, 587, 0, 440, 0, 294, 0, 440, 0, 587, 0, 440, 0, 294, 0, 440, 0, 587, 0, 440, 0, 294, 0, 440, 0, 587, 0, 440, 0, 294, 0, 440, 0, 587, 0, 440, 0, 294, 0, 440, 0, 587, 0, 440, 0, 392, 0, 523, 0, 659, 0, 523, 0, 392, 0, 523, 0, 659, 0, 523, 0, 698, 0, 587, 0, 440, 0, 587, 0, 698, 0, 587, 0, 440, 0, 587, 0, 523, 0, 440, 0, 330, 0, 440, 0, 523, 0, 440, 0, 330, 0, 440, 0, 349, 0, 294, 0, 220, 0, 294, 0, 349, 0, 294, 0, 220, 0, 294, 0, 262, 0, 247, 0, 220, 0, 175, 0, 165, 0, 147, 0, 131, 0, 98, 0,
  },
  { // drum beats
    BASS, -1, 0, 0, 0, 0, 0, 0, SNARE, 0, -1, 0, 0, 0, BASS, -1, BASS, -1, 0, 0, 0, 0, 0, 0, SNARE, 0, -1, 0, 0, 0, 0, 0, BASS, -1, 0, 0, 0, 0, 0, 0, SNARE, 0, -1, 0, 0, 0, BASS, -1, BASS, -1, 0, 0, 0, 0, 0, 0, SNARE, 0, -1, 0, 0, 0, 0, 0, BASS, -1, 0, 0, 0, 0, 0, 0, SNARE, 0, -1, 0, 0, 0, BASS, -1, BASS, -1, 0, 0, 0, 0, 0, 0, SNARE, 0, -1, 0, 0, 0, 0, 0, BASS, -1, 0, 0, 0, 0, 0, 0, SNARE, 0, -1, 0, 0, 0, BASS, -1, BASS, -1, 0, 0, 0, 0, 0, 0, SNARE, 0, -1, 0, 0, 0, 0, 0, 
    BASS, -1, 0, 0, 0, 0, 0, 0, SNARE, 0, -1, 0, 0, 0, BASS, -1, BASS, -1, 0, 0, 0, 0, 0, 0, SNARE, 0, -1, 0, 0, 0, 0, 0, BASS, -1, 0, 0, 0, 0, 0, 0, SNARE, 0, -1, 0, 0, 0, BASS, -1, BASS, -1, 0, 0, 0, 0, 0, 0, SNARE, 0, -1, 0, 0, 0, 0, 0, BASS, -1, 0, 0, 0, 0, 0, 0, SNARE, 0, -1, 0, 0, 0, BASS, -1, BASS, -1, 0, 0, 0, 0, 0, 0, SNARE, 0, -1, 0, 0, 0, 0, 0, BASS, -1, 0, 0, 0, 0, 0, 0, SNARE, 0, -1, 0, 0, 0, BASS, -1, BASS, -1, 0, 0, 0, 0, 0, 0, SNARE, 0, -1, 0, 0, 0, 0, 0, 
    BASS, -1, 0, 0, 0, 0, 0, 0, SNARE, 0, -1, 0, 0, 0, BASS, -1, BASS, -1, 0, 0, 0, 0, 0, 0, SNARE, 0, -1, 0, 0, 0, 0, 0, BASS, -1, 0, 0, 0, 0, 0, 0, SNARE, 0, -1, 0, 0, 0, BASS, -1, BASS, -1, 0, 0, 0, 0, 0, 0, SNARE, 0, -1, 0, 0, 0, 0, 0, BASS, -1, 0, 0, 0, 0, 0, 0, SNARE, 0, -1, 0, 0, 0, BASS, -1, BASS, -1, 0, 0, 0, 0, 0, 0, SNARE, 0, -1, 0, 0, 0, 0, 0, BASS, -1, 0, 0, 0, 0, 0, 0, SNARE, 0, -1, 0, 0, 0, BASS, -1, BASS, -1, 0, 0, 0, 0, 0, 0, SNARE, 0, -1, 0, 0, 0, 0, 0
  },
  { // hi-hat
    HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, 
    HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, 
    HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1, HAT, -1
  },
  { // bass notes under bass drum
    SUB, -1, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, SUB, -1, SUB, -1, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, SUB, -1, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, SUB, -1, SUB, -1, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, SUB, -1, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, SUB, -1, SUB, -1, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, SUB, -1, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, SUB, -1, SUB, -1, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 
    SUB, -1, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, SUB, -1, SUB, -1, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, SUB, -1, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, SUB, -1, SUB, -1, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, SUB, -1, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, SUB, -1, SUB, -1, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, SUB, -1, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, SUB, -1, SUB, -1, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 
    SUB, -1, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, SUB, -1, SUB, -1, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, SUB, -1, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, SUB, -1, SUB, -1, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, SUB, -1, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, SUB, -1, SUB, -1, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, SUB, -1, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, SUB, -1, SUB, -1, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0
  }, 
};

void update_playback(void) {
  static uint16_t prev_beat = 1;
  static uint16_t beat = 0;

  absolute_time_t at = get_absolute_time();
  uint64_t tick_ms = to_us_since_boot(at) / 1000;

  beat = (tick_ms / 100) % SONG_LENGTH; // 100ms per beat

  if (beat == prev_beat) return;
  prev_beat = beat;

  for(uint8_t i = 0; i < 5; i++) {
    if(notes[i][beat] > 0) {
      channels[i].frequency = notes[i][beat];
      channels[i].trigger_attack();
    } else if (notes[i][beat] == -1) {
      channels[i].trigger_release();
    }
  }
}

int main() {
  stdio_init_all();
  struct audio_buffer_pool *ap = init_audio(synth::sample_rate, PICO_AUDIO_PACK_I2S_DATA, PICO_AUDIO_PACK_I2S_BCLK);

  // configure voices

  // melody track
  channels[0].waveforms   = Waveform::TRIANGLE | Waveform::SQUARE;
  channels[0].attack_ms   = 16;
  channels[0].decay_ms    = 168;
  channels[0].sustain     = 0xafff;
  channels[0].release_ms  = 168;
  channels[0].volume      = 10000;

  // rhythm track
  channels[1].waveforms   = Waveform::SINE | Waveform::SQUARE;
  channels[1].attack_ms   = 38;
  channels[1].decay_ms    = 300;
  channels[1].sustain     = 0;
  channels[1].release_ms  = 0;
  channels[1].volume      = 12000;

  // drum track
  channels[2].waveforms   = Waveform::NOISE;
  channels[2].attack_ms   = 5;
  channels[2].decay_ms    = 10;
  channels[2].sustain     = 16000;
  channels[2].release_ms  = 100;
  channels[2].volume      = 18000;

  // hi-hat track
  channels[3].waveforms   = Waveform::NOISE;
  channels[3].attack_ms   = 5;
  channels[3].decay_ms    = 5;
  channels[3].sustain     = 8000;
  channels[3].release_ms  = 40;
  channels[3].volume      = 8000;

  // bass track
  channels[4].waveforms   = Waveform::SQUARE;
  channels[4].attack_ms   = 10;
  channels[4].decay_ms    = 100;
  channels[4].sustain     = 0;
  channels[4].release_ms  = 500;
  channels[4].volume      = 12000;

  while (true) {
    update_playback();
    update_buffer(ap, get_audio_frame);
  }

  return 0;
}