Two more experiments

BeepBox/BeepBox.ino

@@ -0,0 +1,116 @@
+//waveform generator
+
+// hacked from https://www.instructables.com/Arduino-Waveform-Generator-1/
+
+#include <Adafruit_MCP4728.h>
+#include <Wire.h>
+
+Adafruit_MCP4728 mcp;
+
+#define nsamp 32
+#define dacmax 256
+
+const byte nclk = 200; // a guess
+long int freq; //frequency in Hz
+long unsigned int phase;
+long unsigned int phase_inc;
+
+int note = 0;
+int gate;
+int decay = 2;
+
+float pattern[4];
+
+long unsigned int pattern_inc[4];
+
+void setup() {
+  TIMSK0 &= ~_BV(TOIE0); // disable timer0 overflow interrupt
+
+  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 = 3905;// = (16*10^6) / (1*1024) - 1 (must be <65536)
+  // turn on CTC mode
+  TCCR1B |= (1 << WGM12);
+  // Set CS10 and CS12 bits for 1024 prescaler
+  TCCR1B |= (1 << CS12) | (1 << CS10);  
+  // enable timer compare interrupt
+  TIMSK1 |= (1 << OCIE1A);
+
+  sei();
+
+
+  Serial.begin(115200);
+
+  if (!mcp.begin(0x64)) {
+    while (1) {
+      delay(100);
+    }
+  }
+
+//  mcp.setSpeed(400000L);
+//  mcp.setSpeed(800000L);
+  mcp.setSpeed(800000L);
+
+  freq=440;
+  phase=0;
+  pattern[0] = 110.0;
+  pattern[1] = 82.40688922821751;
+  pattern[2] = 97.99885899543737;
+  pattern[3] = 82.40688922821751;
+
+  for( int i = 0; i < 4; i++ ) {
+    pattern_inc[i] = pattern[i] * 975592.231884058;
+  }
+
+  setwave();
+}
+
+const float pi=3.14159265;
+byte waveform[nsamp];
+byte phaseb = 0;
+void setwave(){
+  for (int isamp=0; isamp<nsamp; ++isamp){
+    float phip=(isamp+0.5)/nsamp;
+    float phi=2*pi*phip;
+    int val=0;
+
+    //saw
+    val = dacmax * isamp / nsamp;
+    //val = ( isamp < nsamp / 2 ) ? 0 : dacmax - 1;
+        //sine
+    //val=(sin(phi)+1.0)*dacmax/2;
+    //val=((sin(phi)+0.333*sin(3*phi))/0.943+1)*dacmax/2;
+
+    val=max(val,0);
+    val=min(val,dacmax-1);
+    waveform[isamp]=val;
+  }
+}
+
+
+
+ISR(TIMER1_COMPA_vect){//timer1 interrupt 1Hz 
+  note += 1;
+  if( note > 3 ) {
+    note = 0;
+  }
+  phase_inc = pattern_inc[note];
+  gate = 4095;
+}
+ 
+
+
+void loop() {
+  phase += phase_inc;
+  int redphase = phase >> 27;
+  mcp.fastWrite(waveform[redphase] << 4, gate, 0, 0);
+  if( gate > 0 ) {
+    gate -= decay;
+  }
+}
+

Karplus_Strong/Karplus_Strong.ino

@@ -8,14 +8,44 @@
 
 Adafruit_MCP4728 mcp;
 
-#define nsamp 128
+#define nsamp 256
 #define dacmax 256
 
 unsigned int phase;
+unsigned int length;
 unsigned int repeats;
+int note = 0;
+//int freqs[] = { 256, 228, 205, 192, 171, 154, 137, 128, 114, 102, 96, 85, 77, 68, 64 };
+//int freqs[] = { 128, 114, 102, 96, 85, 77, 68, 64, 56, 51, 48, 42, 38, 34, 32 };
+int freqs[] = { 64, 56, 51, 48, 42, 38, 34, 32, 28, 25, 24, 21, 19, 17, 16  };
+int tune[] = { 0, 4, 3, 5, -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 = 10000;
+  // turn on CTC mode
+  TCCR1B |= (1 << WGM12);
+  // Set CS10 and CS12 bits for 1024 prescaler
+  TCCR1B |= (1 << CS12) | (1 << CS10);  
+  // enable timer compare interrupt
+  TIMSK1 |= (1 << OCIE1A);
+
+  sei();
+
+
   Serial.begin(115200);
 
   if (!mcp.begin(0x64)) {
@@ -28,32 +58,40 @@ void setup() {
   mcp.setSpeed(800000L);
 
   phase=0;
+  note=0;
 }
 
-byte waveform[nsamp];
+ISR(TIMER1_COMPA_vect){//timer1
-
+  if( tune[note] > -1 ) {
-
+    length=freqs[tune[note]];
-void pluck(){
     for (int i=0; i<nsamp; ++i){  
       waveform[i]=random(256);
     }
   }
+  note++;
+  if( note > 7 ) {
+    note = 0;
+  }
+  pd = analogRead(A0) >> 4;
+  Serial.println(pd);
+}
+
+
 
 void loop() {
   byte s1, s2;
   int p0 = phase;
-  s1 = waveform[phase];
+  int p1 = phase - pd;
-  phase += 1;
+  if( p1 < 0 ) {
-  if( phase >= nsamp ) {
+    p1 += length;
-    phase = 0;
-    repeats += 1;
   } 
-  s2 = waveform[phase];
+  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);
-  if( repeats > 100 ) {
-     pluck();
-     repeats = 0;
-  }
 }
 

Noisemakers/Noisemakers.ino

@@ -0,0 +1,81 @@
+// 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 128
+#define dacmax 256
+
+unsigned int phase;
+unsigned int repeats;
+
+
+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 = 1952;
+  // turn on CTC mode
+  TCCR1B |= (1 << WGM12);
+  // Set CS10 and CS12 bits for 1024 prescaler
+  TCCR1B |= (1 << CS12) | (1 << CS10);  
+  // enable timer compare interrupt
+  TIMSK1 |= (1 << OCIE1A);
+
+  sei();
+
+
+  Serial.begin(115200);
+
+  if (!mcp.begin(0x64)) {
+    while (1) {
+      delay(100);
+    }
+  }
+
+//  mcp.setSpeed(400000L);
+//  mcp.setSpeed(800000L);
+  mcp.setSpeed(800000L);
+
+  randomSeed(analogRead(A0));
+
+  phase=0;
+}
+
+byte waveform[nsamp];
+void pluck(){
+  for (int i=0; i<nsamp; ++i){
+    waveform[i]=random(256);
+  }
+}
+
+void loop() {
+  byte s1, s2;
+  int p0 = phase;
+  s1 = waveform[phase];
+  phase += 1;
+  if( phase > nsamp ) {
+    phase = 0;
+  }
+  s2 = waveform[phase];
+  waveform[p0] = ( s1 & s2 ) + ((s1 ^ s2) >> 1);
+  mcp.fastWrite(s1 << 4, 0, 0, 0);
+}
+
+ISR(TIMER1_COMPA_vect){//timer1 interrupt 1Hz 
+    pluck();
+}
+

waveforms/waveforms.ino

@@ -16,7 +16,25 @@ long unsigned int phase;
 long unsigned int phase_inc;
 
 void setup() {
-//  TIMSK0 &= ~_BV(TOIE0); // disable timer0 overflow interrupt
+  TIMSK0 &= ~_BV(TOIE0); // disable timer0 overflow interrupt
+
+//  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)
+//   // turn on CTC mode
+//   TCCR1B |= (1 << WGM12);
+//   // Set CS10 and CS12 bits for 1024 prescaler
+//   TCCR1B |= (1 << CS12) | (1 << CS10);  
+//   // enable timer compare interrupt
+//   TIMSK1 |= (1 << OCIE1A);
+
+//   sei();
+
 
   Serial.begin(115200);
 
@@ -52,9 +70,8 @@ void setwave(){
         //sine
     val=(sin(phi)+1.0)*dacmax/2;
     //val=((sin(phi)+0.333*sin(3*phi))/0.943+1)*dacmax/2;
-
+    // val=max(val,0);
-    val=max(val,0);
+    // val=min(val,dacmax-1);
-    val=min(val,dacmax-1);
     waveform[isamp]=val;
   }
 }
@@ -65,14 +82,21 @@ void calc_phase_inc(){
   // by measurement, 2^27 is about 138Hz (C below middle C)
   // 2^27 / 138 = 972592.231884058
   phase_inc = freq * 975592.231884058;
-  Serial.println(phase_inc);
 }
 
+// ISR(TIMER1_COMPA_vect){//timer1 interrupt 1Hz 
+//   freq = 55 + 1760.0 * analogRead(A0) / 1024.0;
+//   Serial.println(freq);
+//   calc_phase_inc();
+// }
+ 
 
 
 void loop() {
   phase += phase_inc;
   int redphase = phase >> 27;
+  freq = 55 + 1760.0 * analogRead(A0) / 1024.0;
+  calc_phase_inc();
   mcp.fastWrite(waveform[redphase] << 4, 0, 0, 0);
 }