peterkevindavis.com

I have recieved my board in the mail and after a few hours testing the code out i almost have it working as i would like. You can see the updated code below, hopefully it is cleaner, tried to tidy it up as much as possible. Also now use a pointer in the output (table) rather than testing the shape of the wave every time a sample is outputted, this should speed up the Timer_ISR quite a lot

Read more for code

/*
COMAND STRUCTURE
Single byte commands are received by the arduino

byte structure: xxyy zzzz

: xx bits – octave
: yy bits – wave shape
: zz bits – note

*/
#include “TimerOne.h”
#include <avr/pgmspace.h>

prog_uchar SINE_TABLE[] PROGMEM=
{
0×80,0×83,0×86,0×89,0x8c,0x8f,0×92,0×95,0×98,0x9c,0x9f,0xa2,0xa5,0xa8,0xab,0xae,
0xb0,0xb3,0xb6,0xb9,0xbc,0xbf,0xc1,0xc4,0xc7,0xc9,0xcc,0xce,0xd1,0xd3,0xd5,0xd8,
0xda,0xdc,0xde,0xe0,0xe2,0xe4,0xe6,0xe8,0xea,0xec,0xed,0xef,0xf0,0xf2,0xf3,0xf5,
0xf6,0xf7,0xf8,0xf9,0xfa,0xfb,0xfc,0xfc,0xfd,0xfe,0xfe,0xff,0xff,0xff,0xff,0xff,
0xff,0xff,0xff,0xff,0xff,0xff,0xfe,0xfe,0xfd,0xfc,0xfc,0xfb,0xfa,0xf9,0xf8,0xf7,
0xf6,0xf5,0xf3,0xf2,0xf0,0xef,0xed,0xec,0xea,0xe8,0xe6,0xe4,0xe2,0xe0,0xde,0xdc,
0xda,0xd8,0xd5,0xd3,0xd1,0xce,0xcc,0xc9,0xc7,0xc4,0xc1,0xbf,0xbc,0xb9,0xb6,0xb3,
0xb0,0xae,0xab,0xa8,0xa5,0xa2,0x9f,0x9c,0×98,0×95,0×92,0x8f,0x8c,0×89,0×86,0×83,
0×80,0x7c,0×79,0×76,0×73,0×70,0x6d,0x6a,0×67,0×63,0×60,0x5d,0x5a,0×57,0×54,0×51,
0x4f,0x4c,0×49,0×46,0×43,0×40,0x3e,0x3b,0×38,0×36,0×33,0×31,0x2e,0x2c,0x2a,0×27,
0×25,0×23,0×21,0x1f,0x1d,0x1b,0×19,0×17,0×15,0×13,0×12,0×10,0x0f,0x0d,0x0c,0x0a,
0×09,0×08,0×07,0×06,0×05,0×04,0×03,0×03,0×02,0×01,0×01,0×00,0×00,0×00,0×00,0×00,
0×00,0×00,0×00,0×00,0×00,0×00,0×01,0×01,0×02,0×03,0×03,0×04,0×05,0×06,0×07,0×08,
0×09,0x0a,0x0c,0x0d,0x0f,0×10,0×12,0×13,0×15,0×17,0×19,0x1b,0x1d,0x1f,0×21,0×23,
0×25,0×27,0x2a,0x2c,0x2e,0×31,0×33,0×36,0×38,0x3b,0x3e,0×40,0×43,0×46,0×49,0x4c,
0x4f,0×51,0×54,0×57,0x5a,0x5d,0×60,0×63,0×67,0x6a,0x6d,0×70,0×73,0×76,0×79,0x7c
};

prog_uchar SAW_TABLE[] PROGMEM=
{
0×00,0×01,0×02,0×03,0×04,0×05,0×06,0×07,0×08,0×09,0x0a,0x0b,0x0c,0x0d,0x0e,0x0f,
0×10,0×11,0×12,0×13,0×14,0×15,0×16,0×17,0×18,0×19,0x1a,0x1b,0x1c,0x1d,0x1e,0x1f,
0×20,0×21,0×22,0×23,0×24,0×25,0×26,0×27,0×28,0×29,0x2a,0x2b,0x2c,0x2d,0x2e,0x2f,
0×30,0×31,0×32,0×33,0×34,0×35,0×36,0×37,0×38,0×39,0x3a,0x3b,0x3c,0x3d,0x3e,0x3f,
0×40,0×41,0×42,0×43,0×44,0×45,0×46,0×47,0×48,0×49,0x4a,0x4b,0x4c,0x4d,0x4e,0x4f,
0×50,0×51,0×52,0×53,0×54,0×55,0×56,0×57,0×58,0×59,0x5a,0x5b,0x5c,0x5d,0x5e,0x5f,
0×60,0×61,0×62,0×63,0×64,0×65,0×66,0×67,0×68,0×69,0x6a,0x6b,0x6c,0x6d,0x6e,0x6f,
0×70,0×71,0×72,0×73,0×74,0×75,0×76,0×77,0×78,0×79,0x7a,0x7b,0x7c,0x7d,0x7e,0x7f,
0×80,0×81,0×82,0×83,0×84,0×85,0×86,0×87,0×88,0×89,0x8a,0x8b,0x8c,0x8d,0x8e,0x8f,
0×90,0×91,0×92,0×93,0×94,0×95,0×96,0×97,0×98,0×99,0x9a,0x9b,0x9c,0x9d,0x9e,0x9f,
0xa0,0xa1,0xa2,0xa3,0xa4,0xa5,0xa6,0xa7,0xa8,0xa9,0xaa,0xab,0xac,0xad,0xae,0xaf,
0xb0,0xb1,0xb2,0xb3,0xb4,0xb5,0xb6,0xb7,0xb8,0xb9,0xba,0xbb,0xbc,0xbd,0xbe,0xbf,
0xc0,0xc1,0xc2,0xc3,0xc4,0xc5,0xc6,0xc7,0xc8,0xc9,0xca,0xcb,0xcc,0xcd,0xce,0xcf,
0xd0,0xd1,0xd2,0xd3,0xd4,0xd5,0xd6,0xd7,0xd8,0xd9,0xda,0xdb,0xdc,0xdd,0xde,0xdf,
0xe0,0xe1,0xe2,0xe3,0xe4,0xe5,0xe6,0xe7,0xe8,0xe9,0xea,0xeb,0xec,0xed,0xee,0xef,
0xf0,0xf1,0xf2,0xf3,0xf4,0xf5,0xf6,0xf7,0xf8,0xf9,0xfa,0xfb,0xfc,0xfd,0xfe,0xff
};

prog_uchar SQUARE_TABLE[] PROGMEM=
{
0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,
0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,
0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,
0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,
0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,
0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,
0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,
0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,0×00,
0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff
};

prog_uchar TRIANGLE_TABLE[] PROGMEM=
{
0×00,0×02,0×04,0×06,0×08,0x0a,0x0c,0x0e,0×10,0×12,0×14,0×16,0×18,0x1a,0x1c,0x1e,
0×20,0×22,0×24,0×26,0×28,0x2a,0x2c,0x2e,0×30,0×32,0×34,0×36,0×38,0x3a,0x3c,0x3e,
0×40,0×42,0×44,0×46,0×48,0x4a,0x4c,0x4e,0×50,0×52,0×54,0×56,0×58,0x5a,0x5c,0x5e,
0×60,0×62,0×64,0×66,0×68,0x6a,0x6c,0x6e,0×70,0×72,0×74,0×76,0×78,0x7a,0x7c,0x7e,
0×80,0×82,0×84,0×86,0×88,0x8a,0x8c,0x8e,0×90,0×92,0×94,0×96,0×98,0x9a,0x9c,0x9e,
0xa0,0xa2,0xa4,0xa6,0xa8,0xaa,0xac,0xae,0xb0,0xb2,0xb4,0xb6,0xb8,0xba,0xbc,0xbe,
0xc0,0xc2,0xc4,0xc6,0xc8,0xca,0xcc,0xce,0xd0,0xd2,0xd4,0xd6,0xd8,0xda,0xdc,0xde,
0xe0,0xe2,0xe4,0xe6,0xe8,0xea,0xec,0xee,0xf0,0xf2,0xf4,0xf6,0xf8,0xfa,0xfc,0xfe,
0xff,0xfd,0xfb,0xf9,0xf7,0xf5,0xf3,0xf1,0xef,0xef,0xeb,0xe9,0xe7,0xe5,0xe3,0xe1,
0xdf,0xdd,0xdb,0xd9,0xd7,0xd5,0xd3,0xd1,0xcf,0xcf,0xcb,0xc9,0xc7,0xc5,0xc3,0xc1,
0xbf,0xbd,0xbb,0xb9,0xb7,0xb5,0xb3,0xb1,0xaf,0xaf,0xab,0xa9,0xa7,0xa5,0xa3,0xa1,
0x9f,0x9d,0x9b,0×99,0×97,0×95,0×93,0×91,0x8f,0x8f,0x8b,0×89,0×87,0×85,0×83,0×81,
0x7f,0x7d,0x7b,0×79,0×77,0×75,0×73,0×71,0x6f,0x6f,0x6b,0×69,0×67,0×65,0×63,0×61,
0x5f,0x5d,0x5b,0×59,0×57,0×55,0×53,0×51,0x4f,0x4f,0x4b,0×49,0×47,0×45,0×43,0×41,
0x3f,0x3d,0x3b,0×39,0×37,0×35,0×33,0×31,0x2f,0x2f,0x2b,0×29,0×27,0×25,0×23,0×21,
0x1f,0x1d,0x1b,0×19,0×17,0×15,0×13,0×11,0x0f,0x0f,0x0b,0×09,0×07,0×05,0×03,0×01
};

byte *table;
byte key;
byte x1;
//byte y0;
//byte y1;
//byte m;
volatile unsigned int phase;
volatile unsigned int phaseDelta;
//unsigned int note[] = {
// 0, 264,275,293.33,309.37,330,352,366.67,396,412.5,440.00,469.34,495};
unsigned int note[] = {
0, 131, 139, 147, 156, 165, 175, 185, 196, 208, 220, 233, 247 };

void setup()
{
//setup

//portd (dac) setup
//portd uses digital pins 0 – 7
DDRD = DDRD | B11111100; //bits 2 – 7
DDRB = DDRB | B00000011; //bits 0 and 1

//timer setup for 16.384khz (61us)
Timer1.initialize(61);
Timer1.attachInterrupt(Timer_ISR);

//serial setup
Serial.begin(9600);
}

void loop()
{
byte xx;
byte yy;
byte zzzz;
//main loop

if (Serial.available() > 0)
{
key = Serial.read(); //get byte
Serial.print(key,DEC); //acknowledge byte

zzzz = key & 0x0F; //break byte into command
key >>= 4; //and its params
yy = key & 0×03;
key >>= 2;
xx = key & 0×03;
key = 0;

//delta = (SAMP / FREQ) * note
//SAMP/FREQ = 4 which is the same as shift left 2 bits
phaseDelta = (note[zzzz] << 2) << xx;

if (yy == 0) //sine wave
{
table = SINE_TABLE;
}
else if (yy == 1) //saw tooth
{
table = SAW_TABLE;
}
else if (yy == 2) //square
{
table = SQUARE_TABLE;
}
else if (yy == 3) //triangle
{
table = TRIANGLE_TABLE;
}
}
}

void Timer_ISR()
{
//
phase += phaseDelta;

x1 = pgm_read_byte_near(table+(phase>>8));

PORTD &= 0×03;
PORTD |= x1 & 0xFC;
PORTB &= 0xFC;
PORTB |= x1 & 0×03;
}