Generating waveforms with Arduino Uno

1/**************************************************************************************
2  ARDUINO UNO - WAVEFORM GENERATOR AND FILTER - JULIO CESAR - JCR - 09/21
3 **************************************************************************************/
4/*  Instructions: connect Arduino Uno to PC or Notebook via USB cable, choose one of  the functions to be plotted
5  (SAW, SQR, FILTER and SINE), load the sketch in  Arduino Uno, go to the Tools menu and open the Serial Plotter. */
6
7byte filter;
8byte  saw;
9byte sqr;
10int sine;
11int angle;
12
13void setup() {
14  Serial.begin(19200);
15}
16
17void  loop() {
18  delay(5);
19  saw_square_gen();
20  filter_lowpass();
21  sine_gen();
22
23  //Comment out one the below Serial.println() waveform you want to plot (one at  a time):
24  //Serial.println(saw);
25  //Serial.println(sqr);
26  //Serial.println(filter);
27  Serial.println(sine);
28}
29
30void saw_square_gen() {     //SAW & SQUARE WAVE  GEN
31  saw = saw + 1;
32  if (saw > 127 && saw < 256) sqr = 255; else sqr = 1;
33}
34
35void  sine_gen() {            //SINE WAVE GEN
36  angle = angle + 1;  if (angle > 360)  angle = 0;
37  //sine = 50 * sin((angle * PI / 180));
38  sine = 50 * sin(angle  * 0.0174532925);
39  //sine = abs(sine);
40}
41
42void filter_lowpass() {      //DIGITAL  FILTER
43  filter = filter * 0.9 + sqr * 0.1;
44}