After a series of technical problems (something about the clock of the arduino's matching the computer when uploading code), I got some sound out of the thing. It is not optimal yet, but it is getting there. I spent most of my time (once the clock thing was solved) trying different versions of the loop function. This is the fastest so far. I think the need to handle comparisons of Long Ints on an 8-bit processor is the bottleneck (4 need to be read). I attempted to just divide the microsecond reading to get milliseconds, but the division results in an even greater slow down.

I looked a little as this link to some lower level methods, but it is a little too terse to be a single source. I will poke around and see what AVR tricks I can pull to speed the board up.

Also took inventory to avoid any surprise needs in the hardware department and started reading about using AVR ports.

Here is the code

/* Synth.ino ---------------------------------------------------------- Description: A sketch to generate sound waves for audio processing with an arduino uno. State: Sound is being produced, but not in a wide range of frequencies. Further optimization is needed. ----------------------------------- References: http://makezine.com/projects/make-35/advanced-arduino-sound-synthesis/ ---------------------------------------------------------- Contact: ldavis@marlboro.edu https://github.com/SafeCamp https://safecamp.github.io/ Logan Davis | 1/27/16 | 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 9 /*------------------------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; int frequency = 0; unsigned long int time_since_input = 0; unsigned long int time_since_sound = 0; unsigned long int current_time_micro = 0; unsigned long int current_time_millis = 0; void setup(){ /* Set PWM pin to OUTPUT */ pinMode(AUDIO_PORT, OUTPUT); } 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(); current_time_micro = micros(); 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); } } frequency = analogRead(FREQ); if (current_time_micro - frequency >= time_since_sound){ digitalWrite(AUDIO_PORT, current_wave_form[i]); i++; time_since_sound = current_time_micro; } } 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]); } }

http://cs.marlboro.edu/ courses/ spring2016/jims_tutorials/ ldavis/ February_5th
last modified Thursday February 4 2016 8:59 pm EST