Duty-Cycle control | Serial Monitor

Other Hardware LEDs and Multiplexing
1

Greetings, I'm trying to control the Duty-Cycle of a PWM by typing a number into the serial monitor. I'm having trouble trying to achieve this. Can anyone give me some advice, please? Here is the code:

void pwm_init1()
{
  int x = Serial.read();   // Read the number we received

  TIMSK1 = 0;
  TCNT1 = 0; 
  ICR1 = 780;
  OCR1A = x; // Duty - Cycle 
  DDRB |= (1 << DDB5); //  PB5 ( OC1A/PCINT5 ) | digital pin 11 (PWM) (https://www.arduino.cc/en/Hacking/PinMapping2560)
  TCCR1A = (1 << COM1A1) | (0 << COM1A0) | (1 << WGM11) | (0 << WGM10); // inverting PWM on OC1A, PWM Phase Correct, TOP = ICR1 
  TCCR1B = (1 << WGM13) | (1 << WGM12) | (1 << CS12) | (0 << CS11) | (1 << CS10);

}

int main() { 

  Serial.begin(115200);

  cli();

  sei();

  while (1)
  {
    if (Serial.available()) pwm_init1();  // Just loop looking for user input
  }
}

The reason I'm programming the PWM from the register is that it gives me easy control of the frequency.

Cheers,

Franco

2

Try running this sketch to make sure the data you are receiving is what you expect:

// Echos input from the serial monitor
void setup() {
  Serial.begin(115200);
  while (!Serial) {}
  Serial.println("hello");
}

void loop() {
  if (Serial.available() > 0) {
    Serial.print(Serial.read());
  }
}
3

Why do you want to control the duty cycle and the frequency?

4

Pert! Thank you for the suggestion! I will try it.

Paul, I want to control the DC and f because I want the user to be able to modify the PWM signal in order to adjust the LEDs that stimulate a sample during an experiment.

5

chiesadoc:
Paul, I want to control the DC and f because I want the user to be able to modify the PWM signal in order to adjust the LEDs that stimulate a sample during an experiment.

....and the frequency because....? ? ? ?

6

Paul. As it is configured in the register, the frequency right now is 20 Hz. Controlling the frequency will change the behavior of the LED. Maybe you didn't read it in the message before because I typed "f".

I think it's solved now, here is the code in case someone is lurking around:

long i;

// Echos input from the serial monitor
void setup() {
  Serial.begin(115200);

  while (!Serial) {}
  Serial.println("hello");

  Serial.setTimeout(10);
}

void loop() {
  if (Serial.available() > 0) {

    i = Serial.parseInt();

    Serial.print("i = ");
    Serial.println(i);
  }
}
7

chiesadoc:
Maybe you didn't read it in the message before because I typed "f".

Yep. Would it have worn your poor fingers to the bone to follow that "f" with "req"? It just looked like a typo.

8

I will take this into account for the next time.