Black/dark objects reflect less IR. The sensor will detect them only at 3-5cm, even after calibration. This is a physical limitation, not a defect.
void loop() // Read sensor output. LOW = obstacle detected sensorState = digitalRead(IR_SENSOR_PIN); Mh Sensor Series Flying Fish Ir Sensor Datasheet Fixed
if (sensorState == LOW) Serial.println("OBSTACLE DETECTED!"); digitalWrite(LED_BUILTIN, HIGH); else Serial.println("Clear path"); digitalWrite(LED_BUILTIN, LOW); Black/dark objects reflect less IR
But there is one annoying problem:
The following table summarizes the core operational parameters based on standard datasheets: Specification Operating Voltage 3.3V to 5V DC Detection Distance 2cm to 30cm (Adjustable) Detection Angle Approximately 35° LM393 Comparator Output Type Digital (0 or 1) / Active Low Current Consumption > 15mA driving capacity Dimensions ~3.2cm x 1.4cm Hardware Components InfraRed IR Obstacle Detector - Handson Technology if (sensorState == LOW) Serial.println("OBSTACLE DETECTED!")