AudioSynthWaveform updated to add tone ramping when a tone starts and ends

PlayMidiTones example modified to work with ramping.

Audio.cpp

@@ -139,7 +139,21 @@ void AudioAnalyzeFFT256::update(void)
 
 
 /******************************************************************/
-
+// PAH - add ramp-up and ramp-down at the beginning and end of the wave
+// 
+void AudioSynthWaveform::set_ramp_length(uint16_t r_length)
+{
+	if(r_length < 0) {
+		ramp_length = 0;
+		return;
+	}
+	// Don't set the ramp length longer than about 4 milliseconds
+	if(r_length > 44*4) {
+		ramp_length = 44*4;
+		return;
+	}
+	ramp_length = r_length;
+}
 
 void AudioSynthWaveform::update(void)
 {
@@ -148,7 +162,7 @@ void AudioSynthWaveform::update(void)
 	int32_t val1, val2, val3;
 
 	//Serial.println("AudioSynthWaveform::update");
-	if (magnitude > 0 && (block = allocate()) != NULL) {
+	if (((magnitude > 0) || ramp_down) && (block = allocate()) != NULL) {
 		ph = phase;
 		inc = phase_increment;
 		for (i=0; i < AUDIO_BLOCK_SAMPLES; i++) {
@@ -159,7 +173,35 @@ void AudioSynthWaveform::update(void)
 			val2 *= scale;
 			val1 *= 0xFFFF - scale;
 			val3 = (val1 + val2) >> 16;
-			block->data[i] = (val3 * magnitude) >> 15;
+
+
+// The value of ramp_up is always initialized to RAMP_LENGTH and then is
+// decremented each time through here until it reaches zero.
+// The value of ramp_up is used to generate a Q15 fraction which varies
+// from [0 - 1), and multiplies this by the current sample
+			if(ramp_up) {
+				// ramp up to the new magnitude
+				// ramp_mag is the Q15 representation of the fraction
+				// Since ramp_up can't be zero, this cannot generate +1
+				ramp_mag = ((ramp_length-ramp_up)<<15)/ramp_length;
+				ramp_up--;
+				block->data[i] = (val3 * ((ramp_mag * magnitude)>>15)) >> 15;
+
+			} else if(ramp_down) {
+				// ramp down to zero from the last magnitude
+// The value of ramp_down is always initialized to RAMP_LENGTH and then is
+// decremented each time through here until it reaches zero.
+// The value of ramp_down is used to generate a Q15 fraction which varies
+// from (1 - 0], and multiplies this by the current sample
+				// avoid RAMP_LENGTH/RAMP_LENGTH because Q15 format
+				// cannot represent +1
+				ramp_mag = ((ramp_down - 1)<<15)/ramp_length;
+				ramp_down--;
+				block->data[i] = (val3 * ((ramp_mag * last_magnitude)>>15)) >> 15;
+			} else {			
+				block->data[i] = (val3 * magnitude) >> 15;
+			}
+
 			 //Serial.print(block->data[i]);
 			 //Serial.print(", ");
 			 //if ((i % 12) == 11) Serial.println();

Audio.h

@@ -73,7 +73,9 @@ class AudioSynthWaveform : public AudioStream
 {
 public:
 	AudioSynthWaveform(const int16_t *waveform)
-	  : AudioStream(0, NULL), wavetable(waveform), magnitude(0), phase(0) { }
+	  : AudioStream(0, NULL), wavetable(waveform), magnitude(0), phase(0)
+					, ramp_up(0), ramp_down(0), ramp_mag(0), ramp_length(0)
+	  				 { }
 	void frequency(float freq) {
 		if (freq > AUDIO_SAMPLE_RATE_EXACT / 2 || freq < 0.0) return;
 		phase_increment = (freq / AUDIO_SAMPLE_RATE_EXACT) * 4294967296.0f;
@@ -81,14 +83,32 @@ public:
 	void amplitude(float n) {        // 0 to 1.0
 		if (n < 0) n = 0;
 		else if (n > 1.0) n = 1.0;
+// Ramp code
+		if(magnitude && (n == 0)) {
+			ramp_down = ramp_length;
+			ramp_up = 0;
+			last_magnitude = magnitude;
+		}
+		else if((magnitude == 0) && n) {
+			ramp_up = ramp_length;
+			ramp_down = 0;
+		}
+// set new magnitude
 		magnitude = n * 32767.0;
 	}
 	virtual void update(void);
+	void set_ramp_length(uint16_t r_length);
+	
 private:
 	const int16_t *wavetable;
 	uint16_t magnitude;
+	uint16_t last_magnitude;
 	uint32_t phase;
 	uint32_t phase_increment;
+	uint32_t ramp_down;
+	uint32_t ramp_up;
+	uint32_t ramp_mag;
+	uint16_t ramp_length;
 };
 
 

examples/PlayMidiTones/MidiTones.ino

@@ -1,110 +0,0 @@
-#include <Audio.h>
-#include <Wire.h>
-//#include <WM8731.h>
-#include <SD.h>
-#include <SPI.h>
-
-
-//AudioInputI2S adc;
-//AudioInputAnalog ana(16);
-AudioSynthWaveform mysine(AudioWaveformSine);
-AudioSynthWaveform sine2(AudioWaveformSine);
-//AudioOutputPWM myout;
-//AudioPlaySDcardWAV wav;
-//AudioPlaySDcardRAW wav;
-//AudioMixer4 mix;
-AudioOutputI2S dac;
-
-
-//AudioControl_WM8731 codec;
-AudioControlSGTL5000 codec;
-
-AudioConnection c1(mysine, dac);
-
-//AudioConnection c1(wav, dac);
-//AudioConnection c2(wav, 1, dac, 1);
-
-
-int volume = 0;
-
-void setup() {
-  Serial1.begin(115200);
-  Serial1.println("***************");
-
-  while (!Serial) ;
-  delay(100);
-  
-  codec.enable();
-  
-  //while(1);
-  
-  
-  delay(200);
-  Serial.println("Begin AudioTest");
-  delay(50);
-
-  Serial1.print("B");
-
-  // Audio connections require memory to work.  For more
-  // detailed information, see the MemoryAndCpuUsage example
-  AudioMemory(15);
-
-
-  //mysine.connect(myout);
-  //mysine.connect(dac);
-  //mysine.connect(dac, 1, 0);
-  mysine.frequency(440);
-  
-  //wav.connect(dac);
-  //wav.connect(dac, 1, 0);
-  
-  //codec.inputLinein();
-  codec.volume(40);
-  
-  //adc.connect(dac);
-  //ana.connect(dac);
-  //ana.connect(dac, 1, 0);
-  
-/*
-  SPI.setMOSI(7);
-  SPI.setSCK(14);
-  if (SD.begin(10)) {
-    Serial.println("SD init ok");
-    //wav.play("01_16M.WAV");
-  }
-*/
-  Serial.println("setup done");
-  
-}
-
-
-
-
-void loop() {
-  /*
-  Serial.print("cpu: ");
-  Serial.print(AudioProcessorUsage());
-  Serial.print(", max: ");
-  Serial.print(AudioProcessorUsageMax());
-  Serial.print(", memory: ");
-  Serial.print(AudioMemoryUsage());
-  Serial.print(", max: ");
-  Serial.print(AudioMemoryUsageMax());
-  
-  Serial.println("");
-  */
-  
-  //int n;
-  //n = analogRead(15);
-  //Serial.println(n);
-  //if (n != volume) {
-    //volume = n;
-    //codec.volume((float)n / 10.23);
-  //}
-  //n = analogRead(16) / 8;
-  //Serial.println(n);
-  //mysine.frequency(200 + n * 4);
-  
-  //delay(5);
-  
-}

examples/PlayMidiTones/PlayMidiTones.h

@@ -0,0 +1,29 @@
+
+// Table of midi note frequencies * 2
+//   They are times 2 for greater accuracy, yet still fits in a word.
+//   Generated from Excel by =ROUND(2*440/32*(2^((x-9)/12)),0) for 0<x<128
+// The lowest notes might not work, depending on the Arduino clock frequency
+
+const unsigned int tune_frequencies2_PGM[128] =
+{
+    16,17,18,19,21,22,23,24,26,28,29,31,33,35,37,39,41,
+    44,46,49,52,55,58,62,65,69,73,78,82,87,92,98,104,110,
+    117,123,131,139,147,156,165,175,185,196,208,220,233,
+    247,262,277,294,311,330,349,370,392,415,440,466,494,
+    523,554,587,622,659,698,740,784,831,880,932,988,1047,
+    1109,1175,1245,1319,1397,1480,1568,1661,1760,1865,1976,
+    2093,2217,2349,2489,2637,2794,2960,3136,3322,3520,3729,
+    3951,4186,4435,4699,4978,5274,5588,5920,6272,6645,7040,
+    7459,7902,8372,8870,9397,9956,10548,11175,11840,12544,
+    13290,14080,14917,15804,16744,17740,18795,19912,21096,
+    22351,23680,25088
+};
+
+#define AMPLITUDE (0.4)
+#define CMD_PLAYNOTE	0x90	/* play a note: low nibble is generator #, note is next byte */
+#define CMD_STOPNOTE	0x80	/* stop a note: low nibble is generator # */
+#define CMD_RESTART	0xe0	/* restart the score from the beginning */
+#define CMD_STOP	0xf0	/* stop playing */
+
+// User must supply this score array
+extern unsigned char score[];

examples/PlayMidiTones/PlayMidiTones.ino

@@ -0,0 +1,145 @@
+#include <Audio.h>
+#include <Wire.h>
+//#include <WM8731.h>
+#include <SD.h>
+#include <SPI.h>
+
+#include "PlayMidiTones.h"
+
+unsigned char *sp = score;
+
+//AudioInputI2S adc;
+//AudioInputAnalog ana(16);
+AudioSynthWaveform sine0(AudioWaveformSine);
+AudioSynthWaveform sine1(AudioWaveformTriangle);
+AudioSynthWaveform sine2(AudioWaveformSquare);
+AudioSynthWaveform sine3(AudioWaveformSawtooth);
+AudioSynthWaveform sine4(AudioWaveformSine);
+AudioSynthWaveform sine5(AudioWaveformTriangle);
+AudioSynthWaveform sine6(AudioWaveformSquare);
+AudioSynthWaveform sine7(AudioWaveformSawtooth);
+AudioSynthWaveform *waves[8] = {
+  &sine0,
+  &sine1,
+  &sine2,
+  &sine3,
+  &sine4,
+  &sine5,
+  &sine6,
+  &sine7,
+};
+
+AudioMixer4              mixer1;
+AudioMixer4              mixer2;
+AudioOutputI2S audioOut;
+
+AudioConnection c0(sine0, 0, mixer1, 0);
+AudioConnection c1(sine1, 0, mixer1, 1);
+AudioConnection c2(sine2, 0, mixer1, 2);
+AudioConnection c3(sine3, 0, mixer1, 3);
+
+AudioConnection c4(sine4, 0, mixer2, 0);
+AudioConnection c5(sine5, 0, mixer2, 1);
+AudioConnection c6(sine6, 0, mixer2, 2);
+AudioConnection c7(sine7, 0, mixer2, 3);
+AudioConnection c11(mixer1, 0, audioOut, 0);
+AudioConnection c12(mixer2, 0, audioOut, 1);
+
+//AudioControl_WM8731 codec;
+AudioControlSGTL5000 codec;
+
+int volume = 50;
+
+void setup()
+{
+  Serial.begin(115200);
+  while (!Serial) ;
+  delay(3000);
+
+  // Audio connections require memory to work.  For more
+  // detailed information, see the MemoryAndCpuUsage example
+  AudioMemory(8);
+  
+  codec.enable();
+  codec.volume(volume);
+  // I want output on the line out too
+  codec.unmuteLineout();
+
+// Comment out this code to hear what it sounds like
+// when the tones aren't ramped. (or change 88 to 0)
+  // Set the ramp time for each wave
+  for(int i = 0; i < 8;i++) {
+    waves[i]->set_ramp_length(88);
+  }
+
+  
+  delay(200);
+  Serial.println("Begin PlayMidiTones");
+  delay(50);
+  Serial.println("setup done");
+AudioProcessorUsageMaxReset();
+AudioMemoryUsageMaxReset();
+}
+
+unsigned long last_time = millis();
+void loop()
+{
+  unsigned char c,opcode,chan;
+  unsigned long d_time;
+  
+if(0) {
+// For PlayMidiTones this produces:
+// Proc = 6 (12),  Mem = 2 (8)
+  if(millis() - last_time >= 5000) {
+    Serial.print("Proc = ");
+    Serial.print(AudioProcessorUsage());
+    Serial.print(" (");    
+    Serial.print(AudioProcessorUsageMax());
+    Serial.print("),  Mem = ");
+    Serial.print(AudioMemoryUsage());
+    Serial.print(" (");    
+    Serial.print(AudioMemoryUsageMax());
+    Serial.println(")");
+    last_time = millis();
+  }
+}
+
+  // Volume control
+  int n = analogRead(15);
+  if (n != volume) {
+    volume = n;
+    codec.volume((float)n / 10.23);
+  }
+  
+  c = *sp++;
+  opcode = c & 0xf0;
+  chan = c & 0x07;
+
+  if(c < 0x80) {
+    // Delay
+    d_time = (c << 8) | *sp++;
+    delay(d_time);
+    return;
+  }
+  if(*sp == CMD_STOP) {
+    Serial.println("DONE");
+    while(1);
+  }
+
+  // It is a command
+  if(opcode == CMD_STOPNOTE) {
+    waves[chan]->amplitude(0);
+    return;
+  }
+
+  if(opcode == CMD_PLAYNOTE) {
+    waves[chan]->frequency(tune_frequencies2_PGM[*sp++]);
+    waves[chan]->amplitude(AMPLITUDE);
+    return;
+  }
+
+  if(opcode == CMD_RESTART) {
+    sp = score;
+    return;
+  }
+}

examples/PlayMidiTones/william_tell_overture.c

@@ -1,7 +1,7 @@
 // Playtune bytestream for file "william_tell_overture.mid" created by MIDITONES V1.6 on Sat Oct 26 02:48:13 2013
 // command line: ./miditones -t10 william_tell_overture 
 #include "Arduino.h"
-const byte PROGMEM score [] = {
+const unsigned char score [] = {
 0x90,72, 0x91,72, 0x92,72, 0x93,72, 0x94,72, 1,169, 0x80, 0x81, 0x82, 0x83, 0x84, 0,183, 0x90,72, 
 0x91,72, 0x92,72, 0x93,72, 0x94,72, 0,41, 0x80, 0x81, 0x82, 0x83, 0x84, 0,58, 0x90,72, 0x91,72, 
 0x92,72, 0x93,72, 0x94,72, 0,41, 0x80, 0x81, 0x82, 0x83, 0x84, 0,58, 0x90,72, 0x91,72, 0x92,72,