float x=0;
int y=0;
double OK=false;
void setup() {
Serial.begin(9600);
}
// the loop function runs over and over again forever
void loop() {
y=x*250; // calculate duty cycle(250 not 255 because will help to turn off transistors)
delay(100);
//because the maximum duty cycle is 250 means that maximum value for x is 1
// for a 100Hz signal we have 1/314=0.0031 increasing step
if(x<0.5 &&OK==false){
x=x+0.0031;// increase the angle on the half of the signal
}
if(x>0.5){//middle of the signal
OK=true;
}
if(OK==true){
x=x-0.0031;// decrease the angle on the other half of the signal
}
Serial.println(y);// on the serial monitor will appear duty cycles between 0 and 90 deg
}
The program for the triangle waves is:
int i=0;// position in mypwm vector
int m; // takes values from vector
int mypwm[]={0,1,2,3,3,4,5,6,6,7,8,9,10,11,12,13,14,15,16,17,17,18,19,20,20,21,22,23,24,25,26,27,27,28,29,30,31,31,32,
33,34,34,35,36,37,37,38,39,40,41,41,42,43,44,44,45,46,47,48,48,49,50,51,51,52,53,54,55,55,56,57,58,58,59,60,61,61,
62,63,64,65,65,66,67,68,68,69,70,71,72,72,73,74,75,75,76,77,78,79,79,80,81,82,82,83,84,85,86,86,87,88,89,89,90,91,
92,93,93,94,95,96,96,97,98,99,99,100,101,102,103,103,104,105,106,106,107,108,109,110,111,112,113,113,114,115,116,
117,117,118,119,120,120,121,122,123,124,124,124,124,123,122,121,120,120,119,118,117,117,116,115,114,113,113,112,111,
110,110,109,108,107,106,106,105,104,103,103,102,101,100,99,99,98,97,96,96,95,94,93,93,92,91,90,89,89,88,87,86,86,85,
84,83,82,82,81,80,79,79,78,77,76,75,75,74,73,72,72,71,70,69,68,68,67,66,65,65,64,63,62,61,61,60,59,58,58,57,56,55,55,
54,53,52,51,51,50,49,48,48,47,46,45,44,44,43,42,41,41,40,39,38,37,37,36,35,34,34,33,32,31,31,30,29,28,27,27,26,25,24,
24,23,22,21,20,20,19,18,17,17,16,15,14,13,13,12,11,10,10,9,8,7,6,6,5,4,3,3,2,1,0};
// mypwm vector contains duty cycle values
void setup() {
Serial.begin(9600);
pinMode(5, OUTPUT);
cli();// stop interrupts
TCCR0A=0;
TCCR0B=0;
TCNT0=0;
TCCR0A=0b10100001;// |= (1 << WGM00);//phase correct pwm mode
TCCR0B=0b00000001;// |= (1<< CS00);// //no prescaling
TCCR1A=0;
TCCR1B=0;
TCNT1=0;
OCR1A=510;// here we have sincronized both timers (0 and 1)
//0b allow me to write bits in binary
TCCR1B=0b00001001;// |=(1 << WGM12);
//TCCR1B |= (1 << CS10);//0b00001010;// fara prescaler
TIMSK1 |=(1 << OCIE1A);
sei();
}
ISR(TIMER1_COMPA_vect){
if(i>(312)){// is n-1 because the vector is zero indexed
i=0; // we have only 313 elements in the array because in this way we have
// exactly 100.00Hz oscilloscope
}
m=mypwm[i];// the variable m takes values from vector
i=i+1; // increase the position in vector
OCR0B=m;// pin 5 on pwm with duty cycle from vector
}
void loop() {
}
