From dc007bceb5c3ca56af2aad1c346033d3801d1c76 Mon Sep 17 00:00:00 2001
From: Mike Lynch <m.lynch@sydney.edu.au>
Date: Sun, 6 Oct 2024 16:01:04 +1100
Subject: [PATCH] Added 06

---
 06Degrading/06Degrading.ino | 116 ++++++++++++++++++++++++++++++++++++
 1 file changed, 116 insertions(+)
 create mode 100644 06Degrading/06Degrading.ino

diff --git a/06Degrading/06Degrading.ino b/06Degrading/06Degrading.ino
new file mode 100644
index 0000000..bbac5ff
--- /dev/null
+++ b/06Degrading/06Degrading.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 16
+#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 d = 0;
+
+float pattern[16];
+
+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)
+  OCR1A = 9000;;
+  // 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] = 220.0;
+  pattern[1] = 220.0 * 4.0 / 3.0;
+  pattern[2] = 220.0 * 3.0 / 2.0;
+  pattern[3] = 220.0 * 5.0 / 4.0;
+  
+  
+  for( int i = 0; i < 4; i++ ) {
+    pattern_inc[i] = pattern[i] * 975592.231884058;
+  }
+  randomSeed(analogRead(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;
+    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){
+  note += 1;
+  if( note == 4 ) {
+    note = 0;
+  }
+  int r = random(nsamp);
+  waveform[r] = random(dacmax);
+  phase_inc = pattern_inc[note];
+}
+ 
+
+
+void loop() {
+  phase += phase_inc;
+  int redphase = phase >> 27;
+  mcp.fastWrite(waveform[redphase] << 4, 0, 0, 0);
+}
+