Added 9, 10 and 11

097TET/097TET.ino

@@ -0,0 +1,104 @@
+// Basic demo for configuring the MCP4728 4-Channel 12-bit I2C DAC
+#include <Adafruit_MCP4728.h>
+#include <Wire.h>
+
+Adafruit_MCP4728 mcp;
+
+
+// 1 3 5 7 hexany log2
+float tuning[22];
+// bassline
+//int pitch[] = { 1,    2,     -1,    0, -1,    1,   -1, 0,    -1,     1,   -1 };
+//float dur[] = { 0.25, 0.25, 0.5, 0.25, 0.5, 0.25, 0.5, 0.25, 0.5, 0.25, 0.5  };
+// kick
+//int pitch[] = { 1,    -1,    1, -1, 1,    -1,    1, -1, 1  };
+//float dur[] = { 0.25, 0.75, 0.25, 0.75, 0.25, 0.75, 0.25, 0.75};
+int pitch[] = { 9,    7,     5,    3, 8,    6,   5, 3 };
+float dur[] = { 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5  };
+
+
+float gate = 0.25;
+int bpm = 140;
+int phrase = 8;
+float beat_s = 60.0 / (float)bpm;
+int beat_m = round(1000.0 * beat_s); 
+float voltrange = 4.85;  // measured this, probably not accurate
+float octave = 4096.0 / voltrange; // number of DAC steps in an octave
+float mod_b = 3.141592653589793 / 4.0;
+
+
+int s;
+bool noteon = false;
+long play_t;
+long release_t;
+long last_t;
+long init_t;
+
+
+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");
+  }
+
+  mcp.setChannelValue(MCP4728_CHANNEL_B, 0);
+
+  float n0 = 0;
+  for( int i = 0; i < 22; i++ ) {
+    tuning[i] = round(n0 + octave * (float)i / 7.0);
+  }
+
+  s = 0;
+  release_t = 0;
+  play_t = 0;
+  last_t = millis();
+  init_t = last_t;
+}
+
+
+
+void loop() {
+  long now = millis();
+  if( noteon ) {
+    if( now - last_t > release_t ) {
+      noteOff();
+      last_t = now;
+      play_t = round(beat_m * dur[s] * (1.0 - gate));
+      noteon = false;
+      s += 1;
+      if( s == phrase ) {
+        s = 0;
+      }
+    }
+  } else {
+    if( now - last_t > play_t ) {
+      noteOn(pitch[s]);
+      last_t = now;
+      release_t = round(beat_m * dur[s] * gate);
+      noteon = true;
+    }
+  }
+  // sychronise this better
+  long mod_t = (now - init_t);
+  float mod = 0.5 + 0.5 * sin(mod_b * (float)mod_t / (float)beat_m);
+  mcp.setChannelValue(MCP4728_CHANNEL_C, round(4095.0 * mod));
+}
+
+
+void noteOn(int note) {
+  if( note > -1 ) {
+    mcp.setChannelValue(MCP4728_CHANNEL_A, tuning[note]);
+    mcp.setChannelValue(MCP4728_CHANNEL_B, 4095);
+  }
+}
+
+void noteOff() {
+    mcp.setChannelValue(MCP4728_CHANNEL_B, 0);
+}

10MultiMod/10MultiMod.ino

@@ -0,0 +1,49 @@
+// Basic demo for configuring the MCP4728 4-Channel 12-bit I2C DAC
+#include <Adafruit_MCP4728.h>
+#include <Wire.h>
+
+Adafruit_MCP4728 mcp;
+
+
+int bpm = 98;
+float beat_s = 60.0 / (float)bpm;
+int beat_m = round(1000.0 * beat_s); 
+long init_t;
+
+float pi = 3.141592653589793;
+float mod_a = pi;
+float mod_b = pi / 4.0;
+float mod_c = pi / 3.0;
+float mod_d = pi / 5.0;
+
+
+
+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");
+  }
+
+  init_t = millis();
+  mcp.setChannelValue(MCP4728_CHANNEL_B, 0);
+
+}
+
+
+void loop() {
+  long now = millis();
+  long mod_t = (now - init_t);
+  float tf = (float)mod_t / (float)beat_m;
+  uint16_t a = round(4095.0 * (0.5 + 0.5 * sin(mod_a * tf)));
+  uint16_t b = round(4095.0 * (0.5 + 0.5 * sin(mod_b * tf)));
+  uint16_t c = round(4095.0 * (0.5 + 0.5 * sin(mod_c * tf)));
+  uint16_t d = round(4095.0 * (0.5 + 0.5 * sin(mod_d * tf)));
+  mcp.fastWrite(a, b, c, d);
+}

11KarplusStrongAgain/11KarplusStrongAgain.ino

@@ -0,0 +1,93 @@
+// Very basic Karplus-Strong 
+
+// based on this explanation http://sites.music.columbia.edu/cmc/MusicAndComputers/chapter4/04_09.php
+
+
+#include <Adafruit_MCP4728.h>
+#include <Wire.h>
+
+Adafruit_MCP4728 mcp;
+
+#define nsamp 256
+#define dacmax 256
+
+unsigned int phase;
+unsigned int length;
+unsigned int repeats;
+int note = 0;
+int freqs[] = { 256, 112, 102, 96, 84, 76, 64, 56, 50, 48, 42, 38, 34, 32 };
+int tune2[] = { 0, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 1, -1, -1, -1   };
+
+byte waveform[nsamp];
+
+int pd = 30;
+
+void setup() {
+
+  cli();
+
+//set timer1 interrupt at 1Hz
+  TCCR1A = 0;// set entire TCCR1A register to 0
+  TCCR1B = 0;// same for TCCR1B
+  TCNT1  = 0;//initialize counter value to 0
+  // set compare match register for 1hz increments
+  //OCR1A = 15624;// = (16*10^6) / (1*1024) - 1 (must be <65536)
+  //OCR1A = 7812;// = (16*10^6) / (1*1024) - 1 (must be <65536)
+  OCR1A = 800;
+  // turn on CTC mode
+  TCCR1B |= (1 << WGM12);
+  // Set CS10 and CS12 bits for 1024 escaler
+  TCCR1B |= (1 << CS12) | (1 << CS10);  
+  // enable timer compare interrupt
+  TIMSK1 |= (1 << OCIE1A);
+
+  sei();
+
+
+
+  if (!mcp.begin(0x64)) {
+    while (1) {
+      delay(100);
+    }
+  }
+
+  randomSeed(analogRead(A0));
+  mcp.setSpeed(800000L);
+
+  phase=0;
+  note=0;
+}
+
+ISR(TIMER1_COMPA_vect){//timer1
+  if( tune2[note] > -1 ) {
+    length=freqs[tune2[note]];
+    for (int i=0; i<nsamp; ++i){  
+      waveform[i]=random(256);
+    }
+  }
+  note++;
+  if( note > 15 ) {
+    note = 0;
+  }
+  pd = analogRead(A0) >> 4;
+}
+
+
+
+void loop() {
+  byte s1, s2;
+  int p0 = phase;
+  int p1 = phase - pd;
+  if( p1 < 0 ) {
+    p1 += length;
+  } 
+  phase += 1;
+  if( phase >= length ) {
+    phase = 0;
+  }
+  s1 = waveform[p1];
+  s2 = waveform[p0];
+  waveform[p0] =   ( s1 & s2 ) + ((s1 ^ s2) >> 1);
+  mcp.fastWrite(s1 << 4, 0, 0, 0);
+}
+

TODO.md

@@ -2,10 +2,10 @@
 
 Sunday 6 October
 
-6 - Wavetable updates
+s 6 - Wavetable updates
-7 - Change a sequence while it's playing
+m 7 - Change a sequence while it's playing
-8 - Sound clouds
+t 8 - Sound clouds
-9 - 7TET groove
+w 9 - 7TET groove
-10 - Drum pattern
+t 10 - Drum pattern
-11 - FM
+f 11 - FM
-12 - Karplus-Strong
+s 12 - Karplus-Strong