From 51c2f3bf8d188b717aa442c6e8691aa48202f2b2 Mon Sep 17 00:00:00 2001
From: Mike Lynch <m.lynch@sydney.edu.au>
Date: Fri, 5 Jan 2024 15:25:01 +1100
Subject: [PATCH] Wonderfully broken Karplus-Strong algorithm

---
 Karplus_Strong/Karplus_Strong.ino | 61 +++++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)
 create mode 100644 Karplus_Strong/Karplus_Strong.ino

diff --git a/Karplus_Strong/Karplus_Strong.ino b/Karplus_Strong/Karplus_Strong.ino
new file mode 100644
index 0000000..6de9abc
--- /dev/null
+++ b/Karplus_Strong/Karplus_Strong.ino
@@ -0,0 +1,61 @@
+//waveform generator
+
+// hacked from https://www.instructables.com/Arduino-Waveform-Generator-1/
+
+#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;
+
+  }
+}
+