Full sample code

/*
  Roboda verified Arduino sample 0009
  Feature: I2C Scan
  Generated for online build, classroom practice, and hardware upload testing.
*/

#include <Wire.h>

void setup() {
  Wire.begin();
  Serial.begin(9600);
}

void loop() {
  for (byte address = 1; address < 127; address++) {
    Wire.beginTransmission(address);
    if (Wire.endTransmission() == 0) {
      Serial.print("I2C device at 0x");
      Serial.println(address, HEX);
    }
  }
  delay(3000);
}

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.