Finished version of We Wish You a Merry Christmas

for what this sounds like

Xmas/Xmas.ino

@@ -0,0 +1,168 @@
+// Basic demo for configuring the MCP4728 4-Channel 12-bit I2C DAC
+#include <Adafruit_MCP4728.h>
+#include <Wire.h>
+
+Adafruit_MCP4728 mcp;
+
+
+float tuning[16];
+// 0 = A, 8 = F (tonic)
+
+int m1[] =   { 3, 8, 8, 10, 8,  7,  5,  5,  5, 10, 10, 12, 10,  8,  7,  3,  7, 12, 12, 13, 12, 10,  8,  5, 3,  3,  5,  10,  7,  8,  3, 8,   8,  8,  7,  7,  8,  7,  5,  3, 10, 12, 10, 10, 8, 8,   15, 3,   3,  3, 5, 10, 7, 8  };
+int s1[] =   { 0, 2, 4,  5, 6,  7,  8, 10, 12, 14, 16, 17, 18, 19, 20, 22, 24, 26, 28, 29, 30, 31, 32, 34, 36, 37, 38, 40, 42, 44, 48, 50, 52, 54, 56, 60, 62, 64, 66, 68, 72, 74, 76, 77, 78, 79, 80, 82, 84, 85, 86, 88, 90, 92 };  
+float d1[] = { 2, 1, 1,  1, 1,  1,  2,  1,  2,  1,  1,  1,  1,  1,  2,  1,  2,  1, 1,  1,   1,  1,  2,  2, 1,  1,  2,   2,  2,  4,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2, 1,   1,  1,  1,  1, 1,   1,  1, 2, 2, 2, 4  };
+
+int m2[] =   {    8,                1,          2,                  3,          4,                  5,     0,      1,       3,  8,     8,           3,      5,          7,      8,                  7,      0,     1,      3,   8  };
+int s2[] =   {    2,                8,         14,                 20,         26,                 32,     36,     38,     42, 44,    50,          56,      62,        68,     74,                 80,     84,    86,     90, 92 };
+float d2[] =   {  6,                6,          6,                  6,          6,                  4,      2,      4,      2,  6,     6,           6,       6,         6,      6,                  4,      2,     4,      2,  4  };
+
+
+
+// int m1[] =     { 0,    2,    4,   5,     7,   9,  11, 12 };
+// int s1[] =     { 0,    2,    4,   6,    8,  10,  12,  14 };
+// float d1[] =   { 1.0, 0.5, 1.0, 0.5,  1.0, 0.5, 1.0, 0.5  };
+// int m2[] =     { 0,    4,    7,  12, 0,    4,    7,  12, 0,    4,    7,  12, 0,    4,    7,  12 };
+// int s2[] =     { 0, 1 ,    2,    3,   4,    5,  6,  7, 8, 9, 10, 11, 12, 13, 14, 15 };
+// float d2[] =   { 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5 };
+
+
+float gate = 0.5;
+int bpm = 320;
+float beat_s = 60.0 / (float)bpm;
+int beat = round(1000.0 * beat_s); 
+
+// count_in = number of beats since t0 to wait before we startt playing
+// repeat = number of beats to repeat - could be computed from the sequence data
+
+// From here on, all times are in milliseconds to head off floating point errors
+
+long count_in = 4 * beat;
+int repeat = 96;
+
+
+float voltrange = 5.0; 
+float octave = 4096.0 / voltrange; // number of DAC steps in an octave
+float mod_b = 3.141592653589793 / 4.0;
+
+typedef struct {
+  int s = -1;
+  bool playing = false;
+  bool looped = false;
+  long play = 0;
+  long rel = 0;
+  long last = 0;
+  long init = 0;
+  int *melody;
+  int *start;
+  float *duration;
+  int len = 0;
+  MCP4728_channel_t pitch;
+  MCP4728_channel_t gate;
+} sequencer;
+
+sequencer seq1, seq2;
+long start_time;
+
+void setup(void) {
+  Serial.begin(115200);
+  while (!Serial)
+    delay(10); // will pause Zero, Leonardo, etc until serial console opens
+
+  if (!mcp.begin(0x64)) {
+    Serial.println("Failed to find MCP4728 chip");
+    while (1) {
+      delay(10);
+    }
+    Serial.println("MCP4728 initialised");
+  }
+
+
+  float n0 = 0;
+  for( int i = 0; i < 16; i++ ) {
+      tuning[i] = round(n0 + octave * (float)i / 12.0);
+  }
+  long now = millis();
+  start_time = now;
+  seq1.last = now;
+  seq1.pitch = MCP4728_CHANNEL_A;
+  seq1.gate = MCP4728_CHANNEL_B;
+  seq1.melody = m1;
+  seq1.start = s1;
+  seq1.duration = d1;
+  seq1.len = sizeof(m1) / sizeof(m1[0]);
+
+  times_to_ms(seq1);
+
+  seq2.last = now;
+  seq2.pitch = MCP4728_CHANNEL_C;
+  seq2.gate = MCP4728_CHANNEL_D;
+  seq2.melody = m2;
+  seq2.duration = d2;
+  seq2.start = s2;
+  seq2.len = sizeof(m2) / sizeof(m2[0]);
+
+  times_to_ms(seq2);
+
+}
+
+void times_to_ms(sequencer& seq) {
+  for( int i = 0; i < seq.len; i++ ) {
+    seq.start[i] *= beat;
+    seq.duration[i] = (float)beat * seq.duration[i] * 0.8;
+  }
+}
+
+
+
+void loop() {
+  long now = millis();
+  long t = now - start_time;
+  long beats = -1;
+  if( t >= count_in ) {
+    beats = (t - count_in) % (beat * repeat);
+    runSequencer(seq1, t, beats);
+    runSequencer(seq2, t, beats);
+  }
+}
+
+void runSequencer(sequencer& seq, long now, long beats) {
+  int next = seq.s + 1;
+  int start;
+
+  if( seq.playing ) {
+    if( now > seq.rel ) {
+      mcp.setChannelValue(seq.gate, 0);
+      seq.playing = false;
+    }
+  }
+
+  if( next > seq.len - 1 ) {
+    seq.s = -1;
+    seq.looped = true;
+    return; // don't start the loop yet
+  } else {
+    start = seq.start[next];
+  }
+
+  if( seq.looped ) { // reached the end and waiting for the start of the bar
+    if( beats < seq.last ) {
+      seq.looped = false; // bar has restarted, start waiting
+      seq.s = -1;
+      next = 0;
+    } else {
+      return;
+    }
+  }
+  seq.last = beats;
+
+  if( beats >= start ) {
+    seq.s = next;
+    seq.rel = now + seq.duration[seq.s];
+    if( seq.melody[seq.s] > -1 ) {
+      mcp.setChannelValue(seq.pitch, tuning[seq.melody[seq.s]]);
+      mcp.setChannelValue(seq.gate, 4095);
+    }
+    seq.playing = true;
+  }
+}
+