108 lines
3.1 KiB
C++
108 lines
3.1 KiB
C++
#include <mutex>
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#include "AudioThread.h"
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#include "SharedState.h"
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#include <I2S.h>
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#include <math.h>
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#include "synth_engine.h"
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// I2S Pin definitions
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// You may need to change these to match your hardware setup (e.g., for a specific DAC).
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const int I2S_BCLK_PIN = 9; // Bit Clock (GP9)
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const int I2S_LRC_PIN = 10; // Left-Right Clock (GP10)
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const int I2S_DOUT_PIN = 11; // Data Out (GP11)
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// Audio parameters
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const int SAMPLE_RATE = 44100 / 2;
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const int16_t AMPLITUDE = 16383 / 2; // Use a lower amplitude to avoid clipping (max is 32767 for 16-bit)
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// Create an I2S output object
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I2S i2s(OUTPUT);
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extern SynthEngine* globalSynth;
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// --- Synthesizer State ---
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float currentFrequency = 440.0f;
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double phase = 0.0;
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unsigned long lastNoteChangeTime = 0;
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// ---
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void setupAudio() {
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// Configure I2S pins
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i2s.setBCLK(I2S_BCLK_PIN);
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i2s.setDATA(I2S_DOUT_PIN);
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// Set the sample rate and start I2S communication
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i2s.setFrequency(SAMPLE_RATE);
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if (!i2s.begin()) {
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Serial.println("Failed to initialize I2S!");
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while (1); // Halt on error
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}
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// Seed the random number generator from an unconnected analog pin
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randomSeed(analogRead(A0));
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// Initialize the portable synth engine
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globalSynth = new SynthEngine(SAMPLE_RATE);
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globalSynth->loadPreset(2);
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}
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void loopAudio() {
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unsigned long now = millis();
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// Every 500ms, pick a new random note to play
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if (now - lastNoteChangeTime > 500) {
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lastNoteChangeTime = now;
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int noteIndex = random(0, SCALES[currentScaleIndex].numNotes + 2);
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bool rest = noteIndex >= SCALES[currentScaleIndex].numNotes;
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if (!rest) {
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// Calculate frequency based on key, scale, and octave
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const float baseFrequency = 261.63f; // C4
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float keyFrequency = baseFrequency * pow(2.0f, currentKeyIndex / 12.0f);
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int semitoneOffset = SCALES[currentScaleIndex].semitones[noteIndex];
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currentFrequency = keyFrequency * pow(2.0f, semitoneOffset / 12.0f);
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} else {
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currentFrequency = 0;
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}
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if (globalSynth) {
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globalSynth->setFrequency(currentFrequency > 0 ? currentFrequency : 440.0f);
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globalSynth->setGate(!rest); // Trigger envelope
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}
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}
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const int BATCH_SIZE = 16;
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// Ensure we don't generate samples faster than the I2S can consume them.
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// We write 2 samples (Left + Right) for every 1 synth sample.
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if (i2s.availableForWrite() < BATCH_SIZE * 2) {
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return;
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}
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// Process a small batch of samples
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static int16_t samples[BATCH_SIZE];
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// Generate sound samples
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if (globalSynth) {
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// using synth engine
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globalSynth->process(samples, BATCH_SIZE);
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} else {
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// using fallback sawtooth
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for (int i = 0; i < BATCH_SIZE; ++i) {
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if (currentFrequency > 0) {
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//samples[i] = (int16_t)(sin(phase) * AMPLITUDE);
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phase += 2.0 * M_PI * currentFrequency / SAMPLE_RATE;
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if (phase >= 2.0 * M_PI) phase -= 2.0 * M_PI;
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samples[i] = phase * 0.1f * AMPLITUDE;
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} else {
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samples[i] = 0;
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}
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}
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}
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// write out stereo samples
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for (int i = 0; i < BATCH_SIZE; ++i) {
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i2s.write(samples[i]);
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i2s.write(samples[i]);
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}
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} |