Even more of a usable range!
This week I ordered an Arduino Due to speed up the project. It has 2 dedicated DACs, a 32 processor, and a 84mhz clock. It should be far more capable of outputting sounds between 0 and 44000 HZ. However, shipping takes time.
I spent some time working on the Uno again, trying to get it to go faster. My first goal was to eliminate PWM due to it's boundness to a clock that is also tied to analogue inputs. I followed the advice in
this tutorial to make an 8-bit resistor ladder. It has the same resolution as the PWM pins (0-255), but it allows for direct pin manipulation in a way the PWM did not. Prior to this change I was only able to get up to the 100HZ range, this allowed me to get to about 131HZ. A reasonable improvement.
I then wanted to see how much the analogue read was slowing me down. By cutting all calls to analogRead() and hard coding the frequency timing, I was able to get past 1.8MHz. Jeez. Goal number two, get rid of analogue reads.
Here is the new code:
/* Synth.ino
----------------------------------------------------------
Description:
A sketch to generate sound waves for audio processing
with an arduino uno.
State:
"in early developement" (AKA not functioning yet).
Something is slowing down the cycles to the point
where it just sounds like a speaker-pop. All
the coret values are beings processed, just not
quickly enough.
----------------------------------------------------------
References:
http://makezine.com/projects/make-35/advanced-arduino-sound-synthesis/
https://www.arduino.cc/en/Tutorial/SecretsOfArduinoPWM
http://www.instructables.com/id/Arduino-Audio-Output/?ALLSTEPS
http://www.microsmart.co.za/technical/2014/03/01/advanced-arduino-adc/
----------------------------------------------------------
Contact: ldavis@marlboro.edu
https://github.com/SafeCamp
https://safecamp.github.io/
Logan Davis | 2/18/16 | Arduino 1.6.7
*/
#include <avr/pgmspace.h>
//-----WAVE FORM NAMES-----//
#define TRIANGLE 0
#define SAW 1
#define SQUARE 2
#define WHITENOISE 3
#define SINE 4
//-----PIN NAMES------//
#define WAVESELECT A0
#define FREQ A1
#define AUDIO_PORT 11
/*------------------------WAVE FORMS------------------------------------*/
const PROGMEM byte saw_wave[256] = {0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20,
22, 24, 26, 28, 30, 32, 34, 36, 38, 40,
42, 44, 46, 48, 50, 52, 54, 56, 58, 60,
62, 64, 66, 68, 70, 72, 74, 76, 78, 80,
82, 84, 86, 88, 90, 92, 94, 96, 98, 100,
102, 104, 106, 108, 110, 112, 114, 116,
118, 120, 122, 124, 126, 128, 130, 132,
134, 136, 138, 140, 142, 144, 146, 148,
150, 152, 154, 156, 158, 160, 162, 164,
166, 168, 170, 172, 174, 176, 178, 180,
182, 184, 186, 188, 190, 192, 194, 196,
198, 200, 202, 204, 206, 208, 210, 212,
214, 216, 218, 220, 222, 224, 226, 228,
230, 232, 234, 236, 238, 240, 242, 244,
246, 248, 250, 252, 0, 2, 4, 6, 8, 10,
12, 14, 16, 18, 20, 22, 24, 26, 28, 30,
32, 34, 36, 38, 40, 42, 44, 46, 48, 50,
52, 54, 56, 58, 60, 62, 64, 66, 68, 70,
72, 74, 76, 78, 80, 82, 84, 86, 88, 90,
92, 94, 96, 98, 100, 102, 104, 106, 108,
110, 112, 114, 116, 118, 120, 122, 124,
126, 128, 130, 132, 134, 136, 138, 140,
142, 144, 146, 148, 150, 152, 154, 156,
158, 160, 162, 164, 166, 168, 170, 172,
174, 176, 178, 180, 182, 184, 186, 188,
190, 192, 194, 196, 198, 200, 202, 204,
206, 208, 210, 212, 214, 216, 218, 220,
222, 224, 226, 228, 230, 232, 234, 236,
238, 240, 242, 244, 246, 248, 250, 252,
254, 255};
const PROGMEM byte square_wave[256] = {255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
const PROGMEM byte triangle[256] = {0, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40,
44, 48, 52, 56, 60, 64, 68, 72, 76, 80,
84, 88, 92, 96, 100, 104, 108, 112, 116,
120, 124, 128, 132, 136, 140, 144, 148,
152, 156, 160, 164, 168, 172, 176, 180,
184, 188, 192, 196, 200, 204, 208, 212,
216, 220, 224, 228, 232, 236, 240, 244,
248, 252, 254, 255, 248, 244, 240, 236,
232, 228, 224, 220, 216, 212, 208, 204,
200, 196, 192, 188, 184, 180, 176, 172,
168, 164, 160, 156, 152, 148, 144, 140,
136, 132, 128, 124, 120, 116, 112, 108,
104, 100, 96, 92, 88, 84, 80, 76, 72,
68, 64, 60, 56, 52, 48, 44, 40, 36, 32,
28, 24, 20, 16, 12, 8, 40, 4, 8, 12, 16,
20, 24, 28, 32, 36, 40, 44, 48, 52, 56,
60, 64, 68, 72, 76, 80, 84, 88, 92, 96,
100, 104, 108, 112, 116, 120, 124, 128,
132, 136, 140, 144, 148, 152, 156, 160,
164, 168, 172, 176, 180, 184, 188, 192,
196, 200, 204, 208, 212, 216, 220, 224,
228, 232, 236, 240, 244, 248, 252, 254,
255, 248, 244, 240, 236, 232, 228, 224,
220, 216, 212, 208, 204, 200, 196, 192,
188, 184, 180, 176, 172, 168, 164, 160,
156, 152, 148, 144, 140, 136, 132, 128,
124, 120, 116, 112, 108, 104, 100, 96,
92, 88, 84, 80, 76, 72, 68, 64, 60, 56,
52, 48, 44, 40, 36, 32, 28, 24, 20, 16,
12, 8, 4};
const PROGMEM byte white_noise[256] = {104, 33, 220, 229, 128, 215, 44, 104,
212, 96, 63, 131, 36, 76, 27, 134, 138,
188, 67, 105, 149, 131, 116, 234, 175,
165, 198, 33, 2, 33, 240, 234, 16, 228,
135, 144, 80, 31, 240, 84, 190, 208, 101,
126, 137, 234, 155, 8, 0, 222, 55, 228,
219, 164, 3, 144, 233, 207, 13, 161, 198,
195, 241, 249, 219, 223, 33, 36, 223, 70,
119, 232, 32, 20, 219, 230, 16, 215, 63,
21, 163, 127, 54, 146, 133, 39, 237, 166,
78, 38, 199, 162, 167, 245, 207, 101, 195,
111, 21, 211, 224, 98, 11, 129, 254, 199,
29, 243, 144, 13, 253, 52, 223, 222, 10,
209, 251, 3, 146, 38, 41, 86, 39, 229, 88,
82, 5, 246, 156, 103, 21, 181, 67, 243, 193,
108, 85, 119, 176, 125, 114, 122, 116, 43,
104, 238, 136, 109, 139, 73, 120, 93, 35,
29, 97, 56, 141, 33, 123, 141, 56, 87, 167,
185, 195, 147, 40, 147, 135, 5, 124, 178,
150, 59, 163, 172, 223, 249, 95, 227, 57,
209, 156, 116, 219, 98, 226, 218, 100, 14,
246, 80, 140, 206, 43, 180, 45, 45, 34, 76,
61, 170, 216, 200, 97, 135, 150, 247, 82,
184, 50, 180, 199, 122, 23, 44, 74, 104,
14, 229, 213, 203, 1, 91, 220, 242, 171,
114, 60, 42, 2, 71, 161, 174, 153, 147, 67,
127, 189, 94, 83, 85, 62, 95, 22, 42, 153,
100, 180, 139, 165, 7, 136, 71, 74, 114};
const PROGMEM byte sine_wave[256] = {128, 131, 134, 137, 140, 143, 146, 149, 152,
155, 158, 161, 164, 167, 170, 173, 176, 179,
182, 185, 187, 190, 193, 195, 198, 201, 203,
206, 208, 210, 213, 215, 217, 219, 222, 224,
226, 228, 230, 231, 233, 235, 236, 238, 240,
241, 242, 244, 245, 246, 247, 248, 249, 250,
251, 251, 252, 253, 253, 254, 254, 254, 254,
254, 254, 254, 254, 254, 254, 254, 253, 253,
252, 251, 251, 250, 249, 248, 247, 246, 245,
244, 242, 241, 240, 238, 236, 235, 233, 231,
230, 228, 226, 224, 222, 219, 217, 215, 213,
210, 208, 206, 203, 201, 198, 195, 193, 190,
187, 185, 182, 179, 176, 173, 170, 167, 164,
161, 158, 155, 152, 149, 146, 143, 140, 137,
134, 131, 128, 124, 121, 118, 115, 112, 109,
106, 103, 100, 97, 94, 91, 88, 85, 82, 79,
76, 73, 70, 68, 65, 62, 60, 57, 54, 52, 49,
47, 45, 42, 40, 38, 36, 33, 31, 29, 27, 25,
24, 22, 20, 19, 17, 15, 14, 13, 11, 10, 9,
8, 7, 6, 5, 4, 4, 3, 2, 2, 1, 1, 1, 1, 0,
0, 0, 1, 1, 1, 1, 2, 2, 3, 4, 4, 5, 6, 7,
8, 9, 10, 11, 13, 14, 15, 17, 19, 20, 22,
24, 25, 27, 29, 31, 33, 36, 38, 40, 42, 45,
47, 49, 52, 54, 57, 60, 62, 65, 68, 70, 73,
76, 79, 82, 85, 88, 91, 94, 97, 100, 103,
106, 109, 112, 115, 118, 121, 124};
byte current_wave_form[256] = {0};
byte i = 0;
byte old_choice = 0;
byte current_choice = 0;
unsigned long int time_since_input = 0;
unsigned long int current_time_millis = 0;
// Define various ADC prescaler
const unsigned char PS_16 = (1 << ADPS2);
const unsigned char PS_32 = (1 << ADPS2) | (1 << ADPS0);
const unsigned char PS_64 = (1 << ADPS2) | (1 << ADPS1);
const unsigned char PS_128 = (1 << ADPS2) | (1 << ADPS1) | (1 << ADPS0);
void setup(){
/* Set PWM pin to OUTPUT */
pinMode(AUDIO_PORT, OUTPUT);
//set digital pins 0-7 as outputs
for (int i=0;i<8;i++){
pinMode(i,OUTPUT);
}
// set up the ADC
ADCSRA &= ~PS_128; // remove bits set by Arduino library
// you can choose a prescaler from above.
// PS_16, PS_32, PS_64 or PS_128
ADCSRA |= PS_16; // set our own prescaler to 64
}
void loop() {
/*check to see if the user wants a different wave
* if the selection is different, change waveforms.
* After that check, output waveform value and
* increase index.
*/
current_time_millis = millis();
if (current_time_millis - 100 >= time_since_input){
current_choice = map(analogRead(WAVESELECT),0,1024,0,5);
time_since_input = current_time_millis;
if(old_choice != current_choice){
old_choice = current_choice;
choose_wave(current_choice);
}
}
PORTD = current_wave_form[i];
i++;
delayMicroseconds(analogRead(FREQ));
}
void choose_wave(byte choice){
/* Check to see what wave the user is choosing
* then call swap_wave() on it.
*/
switch(choice){
case TRIANGLE:
swap_waves(triangle);
break;
case SAW:
swap_waves(saw_wave);
break;
case SQUARE:
swap_waves(square_wave);
break;
case WHITENOISE:
swap_waves(white_noise);
break;
case SINE:
swap_waves(sine_wave);
break;
}
}
void swap_waves(const byte stored_wave[]){
/* Read a given waveform from programmable
* memory into a global array stored in ram
*/
int i= 0;
for(i = 0;i < 256;i++){
current_wave_form[i] = pgm_read_word_near(&stored_wave[i]);
}
}
