Karplus_Strong/Karplus_Strong.ino

@@ -1,62 +0,0 @@
-// 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() {
-
-  Serial.begin(115200);
-
-  if (!mcp.begin(0x64)) {
-    while (1) {
-      delay(100);
-    }
-  }
-
-//  mcp.setSpeed(400000L);
-//  mcp.setSpeed(800000L);
-  mcp.setSpeed(800000L);
-
-  phase=0;
-  pluck();
-}
-
-byte waveform[nsamp];
-void pluck(){
-  Serial.println("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;
-    repeats += 1;
-  }
-  s2 = waveform[phase];
-  waveform[p0] = ( s1 & s2 ) + ((s1 ^ s2) >> 1);
-  mcp.fastWrite(s1 << 4, 0, 0, 0);
-  if( repeats > 100 ) {
-    pluck();
-    repeats = 0;
-
-  }
-}
-

waveforms/waveforms.ino

@@ -7,39 +7,44 @@
 
 Adafruit_MCP4728 mcp;
 
-#define nsamp 32
+#define nsamp 256
 #define dacmax 256
 
-const byte nclk = 200; // a guess
-long int freq; //frequency in Hz
+const byte nclk=42; //number of clock cycles of the loop
+long int freq; //frequency in mHz
 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
+ 
+  //Wire.setClock(1400000L); // wooooo
   Serial.begin(115200);
+  while (!Serial)
+    delay(10); // will pause Zero, Leonardo, etc until serial console opens
 
+
+  // Try to initialize!
   if (!mcp.begin(0x64)) {
+    Serial.println("Failed to find MCP4728 chip");
     while (1) {
-      delay(100);
+      delay(10);
     }
+  } else {
+    Serial.println("Adafruit MCP4728 initialised");
   }
 
-//  mcp.setSpeed(400000L);
-//  mcp.setSpeed(800000L);
-  mcp.setSpeed(800000L);
 
-  freq=440;
+  freq=660;
   phase=0;
   calc_phase_inc();
+  //phase_inc = 1;
 
   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;
@@ -47,10 +52,10 @@ void setwave(){
     int val=0;
 
     //saw
-  //val = dacmax * isamp / nsamp;
+    val = dacmax * isamp / nsamp;
     //val = ( isamp < nsamp / 2 ) ? 0 : dacmax - 1;
         //sine
-    val=(sin(phi)+1.0)*dacmax/2;
+    //val=(sin(phi)+1.0)*dacmax/2;
     //val=((sin(phi)+0.333*sin(3*phi))/0.943+1)*dacmax/2;
 
     val=max(val,0);
@@ -60,19 +65,19 @@ void setwave(){
 }
 
 
-//calculate the phase increment. 
+//calculate the phase increment. 2^32/16E6=268.435456
 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;
+  phase_inc=0.268435456*nclk*freq;
+  Serial.println("phase inc");
   Serial.println(phase_inc);
 }
 
-
-
+//regular running: generate waves
 void loop() {
-  phase += phase_inc;
-  int redphase = phase >> 27;
-  mcp.fastWrite(waveform[redphase] << 4, 0, 0, 0);
+  //phase+=900;
+  //int redphase = phase >> 24;
+  phase += analogRead(A0);
+  int redphase = phase % nsamp;
+  mcp.fastWrite(waveform[redphase] << 4, 0, 0,   0);
 }