// ✔️ https://wokwi.com/projects/368195060558294017  PWM duty issue AVR analogWrite
//    https://github.com/arduino/ArduinoCore-avr/blob/master/cores/arduino/wiring_analog.c

//   https://wokwi.com/projects/368197061730029569  PWM duty issue ESP32 analogWrite
//   https://github.com/espressif/arduino-esp32/blob/master/cores/esp32/esp32-hal-ledc.c

const int pwmPin = 11;
const int markPin = 10;
int dur = 20;

void mark() {
  digitalWrite(markPin, HIGH);
  digitalWrite(markPin, LOW);
}

void setup() {
  pinMode(markPin, OUTPUT);

  mark(); // start
  analogWrite(pwmPin, 0);
  delay (dur);
  mark();
  analogWrite(pwmPin, 1);
  delay (dur);
  mark();
  analogWrite(pwmPin, 254);
  delay (dur);
  mark();
  analogWrite(pwmPin, 255);
  delay (dur);
  mark();
  analogWrite(pwmPin, 256);
  delay (dur);
  mark();
  analogWrite(pwmPin, 257);
  delay (dur);
  mark();
  analogWrite(pwmPin, 0); // done
}

void loop() { }