initial commit

projekte/soundz/karplus_strong_totally_borken/karplus_strong_totally_borken.pde

@@ -0,0 +1,104 @@
+#include "avr/delay.h"
+
+void setup() {
+  pinMode(11, OUTPUT);
+ 
+  // Set up Timer 2 to do pulse width modulation on the speaker
+  // pin.
+
+  // Use internal clock (datasheet p.160)
+  ASSR &= ~(_BV(EXCLK) | _BV(AS2));
+
+  // Set fast PWM mode  (p.157)
+  TCCR2A |= _BV(WGM21) | _BV(WGM20);
+  TCCR2B &= ~_BV(WGM22);
+
+  // Do non-inverting PWM on pin OC2A (p.155)
+  // On the Arduino this is pin 11.
+  TCCR2A = (TCCR2A | _BV(COM2A1)) & ~_BV(COM2A0);
+  TCCR2A &= ~(_BV(COM2B1) | _BV(COM2B0));
+
+  // No prescaler (p.158)
+  TCCR2B = (TCCR2B & ~(_BV(CS12) | _BV(CS11))) | _BV(CS10);
+
+  // Set initial pulse width to the first sample.
+  OCR2A = 0;
+}
+
+
+int play (uint16_t f, uint8_t T) {
+  sendKarplusStrongSound(f, T);
+}
+  
+  
+// http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1249193795
+int sendKarplusStrongSound(const uint16_t f /*Hz*/, const uint8_t T /*sec*/) {
+   const uint8_t N = 32;
+   const uint32_t sr = f * N; // sample rate: 800(25Hz)..47619(1488Hz)
+
+   int16_t buf[N];
+   for (uint8_t i=0; i<N; i++)
+     buf[i] = (int16_t) random(-32768,32767);
+   uint8_t bh = 0;
+
+   const int Tloop = 60; // or is it more?
+   const int dt = 16000000/sr - Tloop;
+   
+   for (uint32_t i=sr*T/2; i>0; i--) {
+	const int8_t v = (int8_t) (buf[bh] >> 8);
+
+	OCR2A = v;
+        _delay_us(dt); // or do something else for <dt> usecs
+        
+	uint8_t nbh = bh!=N-1 ? bh+1 : 0;
+	int32_t avg = buf[bh] + (int32_t)buf[nbh];
+	//avg = (avg << 10) - avg; // subtract avg more than once to get faster volume decrease
+        avg = (avg << 10) - avg -avg;
+	buf[bh] = avg >> 11; // no division, just shift
+	bh = nbh;
+   }
+} 
+
+// Frequencies (in Hz) of notes
+#define FSH_4 370
+#define A_4 440
+#define B_4 494
+#define E_4 330
+#define CSH_5 554
+#define D_5 587
+#define FSH_5 740
+#define CSH_4 277
+#define GSH_4 415
+
+#define REST 0
+
+void loop() {
+    // Axel F
+    play(FSH_4, 2);
+    play(REST, 2);
+    play(A_4, 3);
+    play(FSH_4, 2);
+    play(FSH_4, 1);
+    play(B_4, 2);
+    play(FSH_4, 2);
+    play(E_4, 2);
+    play(FSH_4, 2);
+    play(REST, 2);
+    play(CSH_5, 3);
+    play(FSH_4, 2);
+    play(FSH_4, 1);
+    play(D_5, 2);
+    play(CSH_5, 2);
+    play(A_4, 2);
+    play(FSH_4, 2);
+    play(CSH_5, 2);
+    play(FSH_5, 2);
+    play(FSH_4, 1);
+    play(E_4, 2);
+    play(E_4, 1);
+    play(CSH_4, 2);
+    play(GSH_4, 2);
+    play(FSH_4, 6);
+    play(REST, 12);
+    delay(100);
+}