/*
SLdt 210308   (Disclaimer: None. Sue me.)

ATtiny2313: DDS 440 Hz Sinus

*/

#include <avr/io.h>
#include <avr/pgmspace.h>
#define F_CPU 10000000

#define ICR 256
#define PWM F_CPU/ICR
#define A4 440
#define A4_Phasendelta 738   // (A4/PWM*65536)

uint16_t Phase = 0;
const int8_t Sinus[256] PROGMEM = { 
   128,  131,  134,  137,  141,  144,  147,  150,  153,  156,  159,  162,  165,  168,  171,  174,
   177,  180,  183,  186,  188,  191,  194,  196,  199,  202,  204,  207,  209,  212,  214,  216,
   219,  221,  223,  225,  227,  229,  231,  233,  234,  236,  238,  239,  241,  242,  244,  245,
   246,  247,  249,  250,  250,  251,  252,  253,  254,  254,  255,  255,  255,  255,  255,  255,
   255,  255,  255,  255,  255,  255,  255,  254,  254,  253,  252,  251,  250,  250,  249,  247,
   246,  245,  244,  242,  241,  239,  238,  236,  234,  233,  231,  229,  227,  225,  223,  221,
   219,  216,  214,  212,  209,  207,  204,  202,  199,  196,  194,  191,  188,  186,  183,  180,
   177,  174,  171,  168,  165,  162,  159,  156,  153,  150,  147,  144,  141,  137,  134,  131,
   128,  125,  122,  119,  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,   44,   42,   40,
    37,   35,   33,   31,   29,   27,   25,   23,   22,   20,   18,   17,   15,   14,   12,   11,
    10,    9,    7,    6,    6,    5,    4,    3,    2,    2,    1,    1,    1,    0,    0,    0,
     0,    0,    0,    0,    1,    1,    1,    2,    2,    3,    4,    5,    6,    6,    7,    9,
    10,   11,   12,   14,   15,   17,   18,   20,   22,   23,   25,   27,   29,   31,   33,   35,
    37,   40,   42,   44,   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,  119,  122,  125};

/*
     0,    3,    6,    9,   13,   16,   19,   22,   25,   28,   31,   34,   37,   40,   43,   46,
    49,   52,   55,   58,   60,   63,   66,   68,   71,   74,   76,   79,   81,   84,   86,   88,
    91,   93,   95,   97,   99,  101,  103,  105,  106,  108,  110,  111,  113,  114,  116,  117,
   118,  119,  121,  122,  122,  123,  124,  125,  126,  126,  127,  127,  127,  127,  127,  127,
   127,  127,  127,  127,  127,  127,  127,  126,  126,  125,  124,  123,  122,  122,  121,  119,
   118,  117,  116,  114,  113,  111,  110,  108,  106,  105,  103,  101,   99,   97,   95,   93,
    91,   88,   86,   84,   81,   79,   76,   74,   71,   68,   66,   63,   60,   58,   55,   52,
    49,   46,   43,   40,   37,   34,   31,   28,   25,   22,   19,   16,   13,    9,    6,    3,
     0,   -3,   -6,   -9,  -13,  -16,  -19,  -22,  -25,  -28,  -31,  -34,  -37,  -40,  -43,  -46,
   -49,  -52,  -55,  -58,  -60,  -63,  -66,  -68,  -71,  -74,  -76,  -79,  -81,  -84,  -86,  -88,
   -91,  -93,  -95,  -97,  -99, -101, -103, -105, -106, -108, -110, -111, -113, -114, -116, -117,
  -118, -119, -121, -122, -122, -123, -124, -125, -126, -126, -127, -127, -127, -128, -128, -128,
  -128, -128, -128, -128, -127, -127, -127, -126, -126, -125, -124, -123, -122, -122, -121, -119,
  -118, -117, -116, -114, -113, -111, -110, -108, -106, -105, -103, -101,  -99,  -97,  -95,  -93,
   -91,  -88,  -86,  -84,  -81,  -79,  -76,  -74,  -71,  -68,  -66,  -63,  -60,  -58,  -55,  -52,
   -49,  -46,  -43,  -40,  -37,  -34,  -31,  -28,  -25,  -22,  -19,  -16,  -13,   -9,   -6,   -3 };
*/
   
int main(void) {
DDRB = (1<< DDB3);    
ICR1 = ICR -1;
TCCR1A = (1<<COM1A1)+(1<<COM1A0)+(1<<WGM11);
TCCR1B = (1<<WGM13)+(1<<WGM12)+(1<<CS10);

while (1) { 
Phase += A4_Phasendelta;
OCR1A = pgm_read_byte(&(Sinus[Phase>>8]));

while (!(TIFR & (1<<TOV1))) {};      // ohne jitter: sleep plus interrupt
TIFR |= (1<<TOV1);
};
}