Full sample code

/*
  Roboda verified Arduino sample 0004
  Feature: PWM Fade
  Generated for online build, classroom practice, and hardware upload testing.
*/

const byte pwmPin = 3;
int level = 0;
int stepSize = 1;

void setup() {
  pinMode(pwmPin, OUTPUT);
}

void loop() {
  analogWrite(pwmPin, level);
  level += stepSize;
  if (level <= 0 || level >= 255) {
    stepSize = -stepSize;
  }
  delay(16);
}

Teacher notes

• Compile the sample before changing wiring or constants.
• When changing boards, keep the code names the same and update only the pin number constants.
• For 3.3V boards, level-shift 5V sensors and modules before connecting signal pins.
• Use the first compiler error and the Roboda diagnostic suggestion before fixing later warnings.