[sdiy] sine wave floating point conversion issue

[Jay Schwichtenberg]

Dan,

Try:
	sine_int = (int) ((((sine_float + 1.0) * 256.0) - 1.0) / 2.0);

Jay S.

-----Original Message-----
From: synth-diy-bounces at dropmix.xs4all.nl
[mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of dan snazelle
Sent: Sunday, December 31, 2000 4:52 PM
To: synthdiy diy
Subject: [sdiy] sine wave floating point conversion issue

If I have a value in my program that is putting out floating point values
(to make a sine wave) between 0.0 and 1.0

I would like to get these values into an integer value of between 0 and 255
for my dac routine.

i tried changing the type and multiplying the value and then dividing it,
but then i ended up with negative and positive values....


here is the routine which MAKES the sine

	

void loop () {
  int FREQUENCY=25+analogRead(0);
  float sample;
   int j; 

	for(j = 0; j < NUM_SAMPLES; j++) {

		

  		sample = sin(2 * PI * FREQUENCY * j / SAMPLING_RATE);


sample is the value which is a float and puts out the number I want to
transform into something usable for the dacOutput function.


This has shown me I need to get better and basic type conversion, etc


thanks



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