Arudino PWM control AnkerMake M5

README.md

Arudino programs to test running a 4 wire PWM fan

https://www.youtube.com/watch?v=YBNEXWp-gf0

arduino-fan-pwm-25k.ino

// https://www.facebook.com/page/107323940927534/search/?q=fan

const int fan_control_pin = 9; //Blue Wire on Fan (about 25kHz PWM)
int count = 0;
unsigned long start_time;
int rpm;
void setup() {
  TCCR1A = 0; // undo the configuration done by...
  TCCR1B = 0; // ...the Arduino core library
  TCNT1 = 0; // reset timer
  TCCR1A = _BV(COM1A1) | _BV(COM1B1) | _BV(WGM11); //Undo default timers
  TCCR1B = _BV(WGM13) | _BV(CS10); //for pins 9 & 10
  ICR1 = 320; // PWM will be 0 to 320 instead of 0 to 255
  pinMode( fan_control_pin, OUTPUT);
  OCR1A = 0;  //set pwm to 0 out of 320 on pin 9
  OCR1B = 0;  //set pwm to 0 out of 320 on pin 10
  Serial.begin(9600);
  attachInterrupt(digitalPinToInterrupt(2), counter, RISING); //Yello Wire with 5V pullup
}
void loop() {
  for(int pwm = 0; pwm <= 320; pwm += 64){
    OCR1A = pwm;
    delay(5000);
    start_time = millis();
    count = 0;
    while((millis() - start_time) < 1000){
    }
   rpm = count * 30;  //60/2
    Serial.print("PWM = ");
    Serial.print(map(pwm, 0, 320, 0, 100));
    Serial.print("% , Speed = ");
    Serial.print(rpm);
    Serial.println(" rpm");
  }
}
void counter() {
  count++;
}

arduino-fan-pwm.ino

// Standard PWM
// 490hz 

int fanPin = 9; // digital pin 19 (analog pin 5) connected to the fan
int speed = 0; // variable to store the desired fan speed
unsigned long previousMillis = 0; // variable to store the previous time
const long interval = 5000; // interval in milliseconds for changing the fan speed
int ledPin = 13; // built-in LED pin

void setup() {
  pinMode(fanPin, OUTPUT);
  analogWrite(fanPin, 0); // set the initial fan speed to 0%
  pinMode(ledPin, OUTPUT); // set the LED pin as an output
}

void loop() {
  unsigned long currentMillis = millis();
  
  // check if the interval has elapsed
  if (currentMillis - previousMillis >= interval) {
    // update the previous time
    previousMillis = currentMillis;
    
    // switch the fan speed between 0%, 30%, 60%, and 100%
    if (speed == 0) {
      speed = 76; // 30% duty cycle
      blinkLED(1); // blink the LED once
    } else if (speed == 76) {
      speed = 153; // 60% duty cycle
      blinkLED(2); // blink the LED twice
    } else if (speed == 153) {
      speed = 255; // 100% duty cycle
      blinkLED(3); // blink the LED three times
    } else {
      speed = 0; // 0% duty cycle
      blinkLED(4); // blink the LED four times
    }
  }
  
  // set the fan speed using the PWM signal
  analogWrite(fanPin, speed);
  
  delay(100); // add a small delay to avoid rapid changes in fan speed
}

void blinkLED(int numBlinks) {
  for (int i = 0; i < numBlinks; i++) {
    digitalWrite(ledPin, HIGH);
    delay(250);
    digitalWrite(ledPin, LOW);
    delay(250);
  }
}

Photo credit Cisien

Speculated that P is pulse, S is sense

The fan runs at a 20kHz frequency.
It starts at 87% duty cycle then slows to 50% duty cycle at idle)

ankermake/AnkerMake-Marlin#3