Add EyeLights audio spectrum Arduino code (WIP)

EyeLights_Audio_Spectrum/EyeLights_Audio_Spectrum.ino

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+/*
+*/
+
+#include <Adafruit_IS31FL3741.h> // For LED driver
+#include <PDM.h>                 // For microphone
+#include <Adafruit_ZeroFFT.h>    // For math
+
+Adafruit_EyeLights_buffered glasses; // Buffered for smooth animation
+extern PDMClass             PDM;
+
+#define NUM_SAMPLES 512 // FFT size, MUST be a power of two
+short sampleBuffer[NUM_SAMPLES];  // buffer to read samples into, each sample is 16-bits
+volatile int samplesRead; // number of samples read (set in interrupt)
+
+#define SPECTRUM_SIZE (NUM_SAMPLES / 2) // Output spectrum is 1/2 of FFT result
+
+// Bottom of spectrum tends to be noisy, while top often exceeds musical
+// range and is just harmonics, so clip both ends off:
+//#define LOW_BIN  10  // Lowest bin of spectrum that contributes to graph
+//#define HIGH_BIN 75 // Highest bin "
+
+#define LOW_BIN  3   // Lowest bin of spectrum that contributes to graph
+#define HIGH_BIN 180 // Highest bin "
+
+// Crude error handler, prints message to Serial console, flashes LED
+void err(char *str, uint8_t hz) {
+  Serial.println(str);
+  pinMode(LED_BUILTIN, OUTPUT);
+  for (;;) digitalWrite(LED_BUILTIN, (millis() * hz / 500) & 1);
+}
+
+float data[SPECTRUM_SIZE];
+
+struct {
+  int      first_bin;
+  int      num_bins;
+  float   *bin_weights;
+  uint32_t color;
+  float    dot;
+  float    velocity;  
+} column_table[18];
+
+int frames;
+uint32_t start_time;
+
+void setup() { // Runs once at program start...
+
+  // Initialize hardware
+  Serial.begin(115200);
+//while(!Serial);
+  if (! glasses.begin()) err("IS3741 not found", 2);
+
+  uint8_t spectrum_bits = (int)log2f((float)SPECTRUM_SIZE);
+  float low_frac = log2f((float)LOW_BIN) / (float)spectrum_bits;
+  float frac_range = log2((float)HIGH_BIN) / (float)spectrum_bits - low_frac;
+Serial.printf("%d %f %f\n", spectrum_bits, low_frac, frac_range);
+
+  for (int column=0; column<18; column++) {
+    float lower = low_frac + frac_range * ((float)column / 18.0 * 0.95);
+    float upper = low_frac + frac_range * ((float)(column + 1) / 18.0);
+    float mid = (lower + upper) * 0.5;  // Center of lower-to-upper range
+    float half_width = (upper - lower) * 0.5 + 1e-2; // 1/2 of lower-to-upper range
+    // Map fractions back to spectrum bin indices that contribute to column
+    int first_bin = int(pow(2, (float)spectrum_bits * lower) + 1e-4);
+    int last_bin = int(pow(2, (float)spectrum_bits * upper) + 1e-4);
+    Serial.printf("%d %d %d\n", column, first_bin, last_bin);
+    float total_weight = 0.0;
+    int num_bins = last_bin - first_bin + 1;
+    column_table[column].bin_weights = (float *)malloc(num_bins * sizeof(float));
+    for (int bin_index = first_bin; bin_index <= last_bin; bin_index++) {
+      // Find distance from column's overall center to individual bin's
+      // center, expressed as 0.0 (bin at center) to 1.0 (bin at limit of
+      // lower-to-upper range).
+      float bin_center = log2f((float)bin_index + 0.5) / (float)spectrum_bits;
+      float dist = fabs(bin_center - mid) / half_width;
+      if (dist < 1.0) {  // Filter out a few math stragglers at either end
+        // Bin weights have a cubic falloff curve within range:
+        dist = 1.0 - dist; // Invert dist so 1.0 is at center
+        float bin_weight = (((3.0 - (dist * 2.0)) * dist) * dist);
+        column_table[column].bin_weights[bin_index - first_bin] = bin_weight;
+        total_weight += bin_weight;
+      }
+    }
+    Serial.println();
+    Serial.println(column);
+    for (int i=0; i<num_bins; i++) {
+      column_table[column].bin_weights[i] = column_table[column].bin_weights[i] / total_weight * (0.6 + (float)i / 18.0 * 1.8);
+      Serial.printf("  %f\n", column_table[column].bin_weights[i]);
+    }
+    column_table[column].first_bin = first_bin;
+    column_table[column].num_bins = num_bins;
+    column_table[column].color = glasses.color565(glasses.ColorHSV(57600UL * column / 18, 255, 255));
+    column_table[column].dot = 5.0;
+    column_table[column].velocity = 0.0;
+  }
+
+  for (int i=0; i<SPECTRUM_SIZE; i++) {
+    data[i] = 0.0;
+  }
+
+  // Configure glasses for max brightness, enable output
+  glasses.setLEDscaling(0xFF);
+  glasses.setGlobalCurrent(0xFF);
+  glasses.enable(true);
+
+  // Configure PDM mic, mono 16 KHz
+  PDM.onReceive(onPDMdata);
+  PDM.begin(1, 16000);
+
+  start_time = millis();
+}
+
+float dynamic_level = 6.0;
+
+volatile bool mic_on = false;
+
+void loop() { // Repeat forever...
+  int samplesRemaining = NUM_SAMPLES;
+  samplesRead = 0;
+  mic_on = true;
+  while (samplesRemaining) {
+    if(samplesRead) { // Set in onPDMdata()
+      samplesRemaining -= samplesRead;
+    }
+    yield();
+  }
+  mic_on = false;
+
+// To do: could record into alternating buffers
+
+  ZeroFFT(sampleBuffer, NUM_SAMPLES);
+
+
+
+  // Convert FFT output to spectrum
+  for(int i=0; i<SPECTRUM_SIZE; i++) {
+//    data[i] = (data[i] * 0.25) + ((float)sampleBuffer[i] * 0.75);
+    data[i] = (data[i] * 0.2) + ((sampleBuffer[i] ? log((float)sampleBuffer[i]) : 0.0) * 0.8);
+//    data[i] = (float)sampleBuffer[i];
+#if 0
+    uint32_t mag2 = fr[i] * fr[i] + fi[i] * fi[i];
+    if (mag2) {
+      data[i] = log(sqrt((float)mag2));
+//      data[i] = sqrt((float)mag2);
+    } else {
+      data[i] = 0.0;
+    }
+#endif
+  }
+
+  float lower = data[0], upper = data[0];
+  for (int i=1; i<SPECTRUM_SIZE; i++) {
+    if (data[i] < lower) lower = data[i];
+    if (data[i] > upper) upper = data[i];
+  }
+//  Serial.printf("%f %f\n", lower, upper);
+//  if (lower < 4) lower = 4;
+//  if (upper < 10) upper = 10;
+  if (upper < 4.5) upper = 4.5; // because log
+
+
+
+  if (upper > dynamic_level) {
+    // Got louder. Move level up quickly but allow initial "bump."
+    dynamic_level = upper * 0.5 + dynamic_level * 0.5;
+  } else {
+    // Got quieter. Ease level down, else too many bumps.
+    dynamic_level = dynamic_level * 0.7 + lower * 0.3;
+  }
+//  dynamic_level = 20.0;
+//dynamic_level = upper;
+
+  // Apply vertical scale to spectrum data. Results may exceed
+  // matrix height...that's OK, adds impact!
+  float scale = 10.0 / (dynamic_level - lower);
+  for (int i=0; i<SPECTRUM_SIZE; i++) {
+    data[i] = (data[i] - lower) * scale;
+  }
+
+  glasses.fill(0);
+  for(int column=0; column<18; column++) {
+    int first_bin = column_table[column].first_bin;
+    float column_top = 7.0;
+    for (int bin_offset=0; bin_offset<column_table[column].num_bins; bin_offset++) {
+      column_top -= data[first_bin + bin_offset] * column_table[column].bin_weights[bin_offset];
+    }
+    if(column_top < column_table[column].dot) {
+      column_table[column].dot = column_top - 0.5;
+      column_table[column].velocity = 0.0;
+    } else {
+      column_table[column].dot += column_table[column].velocity;
+      column_table[column].velocity += 0.01;
+    }
+
+    int itop = (int)column_top;
+    glasses.drawLine(column, itop, column, itop + 50, column_table[column].color);
+    glasses.drawPixel(column, (int)column_table[column].dot, 0xE410);
+  }
+
+  glasses.show();
+
+  frames += 1;
+  uint32_t elapsed = millis() - start_time;
+//  Serial.println(frames * 1000 / elapsed);
+}
+
+
+void onPDMdata() {
+  if (mic_on) {
+    // query the number of bytes available
+    int bytesAvailable = PDM.available();
+  
+    // read into the sample buffer
+    PDM.read(sampleBuffer, bytesAvailable);
+  
+    // 16-bit, 2 bytes per sample
+    samplesRead = bytesAvailable / 2;
+  }
+}