Low PWM freqency

Projects General Guidance
1

Hello,
is there a way to generate 1.5 or 2.5 Hz pwm signal without changing timers?

2

No they won't go that slow, due to the limit of the prescaller divider circuit.

3

Possibly something like below as a guideline

void loop()
{
  while(1)
  {
    digitalWrite(yourPin, HIGH);
    delay(200);
    digitalWrite(yourPin, LOW);
    delay(200);
   }
 }
4

Hello
Yes you can.
Take the example BLINKWITHOUTDELAY from the IDE and modify the blinkrate to you requirements.

5

This is a duty cycle program I wrote for Nano / UNO, might give you some ideas, type h in the serial monitor plus a number for Hertz or a p and number for duty cycle, sorry, whole numbers only.
Example: h3,p25 [ENTER] for 3Hz and 25% duty cycle.

unsigned long cycleStart,
          onTime,              
          cycleTime,
          hz;
int val;              
const byte powerPin = LED_BUILTIN;
byte percent = 50;
void setup()
{
  Serial.begin(9600);
  Serial.println(" Hz = 5  Duty Cycle = 50%");
  hz = 5;
  cycleTime = 1000000UL / hz;
  onTime = cycleTime / 2;  
  pinMode(powerPin,OUTPUT);
}
void loop()
{
  bitWrite(PORTB,5,micros() - cycleStart < onTime);  
  if(micros() - cycleStart > cycleTime)
cycleStart += cycleTime;
  // if there's any serial available, read it:
  if(Serial.available() > 0)
  {
 val = Serial.read();
if(val == 'h' || val == 'H')
  hz = Serial.parseInt();
else if(val == 'p' || val == 'P')
{
  percent = Serial.parseInt();   
}
else
  while(Serial.available() > 0)
    Serial.read();  
cycleTime = 1000000UL / hz;
percent = constrain(percent, 0, 100);
onTime = cycleTime * 0.01 * percent;
cycleStart = micros();
Serial.print(" Hz = ");

Serial.print(hz);
Serial.print("  Duty Cycle = ");
Serial.print(percent);
Serial.println("%");
  }
}
6

2.5 Hz is REALLY slow for a microcontroller. Any reason you can't bit-bang it?

7

Curious: Why are the timers off limits?

8

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