Generate DAC samples using excel

[lowpowermcu]

Hi all,

I want to generate a sine wave using my Digital to Analog Converter so I think I should generate the samples using excel (sine wave at a 3 Hz and 320 samples) once done I add it as a constant array in my code.
Is there somebody who did somethink like that?

MCU Lüfter

 

[sky_123]

It's quite easy to write a quick 10-line C program to generate the correct table. Try this:

#include <stdio.h>
#include <math.h>

#define PI 3.14159

int
main(void)
{
  int range=127;
  int numsamp=320;
  
  int i;
  double s;
  double scaled;
  
  for (i=0; i<numsamp; i++)
  {
    s=sin(2*PI*(((double)i)/((double)numsamp)));
    scaled=s*((double)range);
    printf("%d,", (int)scaled);
  }
  
  return(0);
}

If you compile it and run it on you PC, it will print the sample values on the screen (or you could direct it into a file, e.g. by typing a.out > mysamples.txt, or just copy-and-paste the screen output directly into you code.
This was the output:

0,2,4,7,9,12,14,17,19,22,24,27,29,32,34,36,39,41,43,46,48,50,53,55,57,59,62,64,66,68,70,72,74,76,78,80,82,84,86,88,89,91,93,94,96,98,99,101,102,104,105,106,108,109,110,112,113,114,115,116,117,118,119,119,120,121,122,122,123,124,124,125,125,125,126,126,126,126,126,126,126,126,126,126,126,126,126,125,125,125,124,124,123,122,122,121,120,119,119,118,117,116,115,114,113,112,110,109,108,106,105,104,102,101,99,98,96,94,93,91,89,88,86,84,82,80,78,76,74,72,70,68,66,64,62,59,57,55,53,50,48,46,43,41,39,36,34,32,29,27,24,22,19,17,14,12,9,7,4,2,0,-2,-4,-7,-9,-12,-14,-17,-19,-22,-24,-27,-29,-32,-34,-36,-39,-41,-43,-46,-48,-50,-53,-55,-57,-59,-62,-64,-66,-68,-70,-72,-74,-76,-78,-80,-82,-84,-86,-88,-89,-91,-93,-94,-96,-98,-99,-101,-102,-104,-105,-106,-108,-109,-110,-112,-113,-114,-115,-116,-117,-118,-119,-119,-120,-121,-122,-122,-123,-124,-124,-125,-125,-125,-126,-126,-126,-126,-126,-126,-126,-126,-126,-126,-126,-126,-126,-125,-125,-125,-124,-124,-123,-122,-122,-121,-120,-119,-119,-118,-117,-116,-115,-114,-113,-112,-110,-109,-108,-106,-105,-104,-102,-101,-99,-98,-96,-94,-93,-91,-89,-88,-86,-84,-82,-80,-78,-76,-74,-72,-70,-68,-66,-64,-62,-59,-57,-55,-53,-50,-48,-46,-43,-41,-39,-36,-34,-32,-29,-27,-24,-22,-19,-17,-14,-12,-9,-7,-4,-2,

In Excel, this is what it looks like:

Note that you could just save a quarter sinewave, since it is symmetrical.