White Line Sensors

Overview

White Line Sensors in AlphaBot V2 detect contrasting surfaces (typically a white line on a dark surface or vice versa) to enable line-following capabilities.

Key Feature

• Sensor Arrangement
  • Typically 5 sensors in a line across the front
• Line Following Logic
  • Stay centered on a line
  • Detect turns or intersections
  • Correct its position if drifting off course
• Typical Values
  • lesser than 800 for white surfaces (Low reflection)
  • Greater than 800 for white surfaces (high reflection)

Working

• Each sensor contains an IR LED and phototransistor
• The IR LED emits infrared light
• The phototransistor detects reflected light
• On dark surfaces: More light is absorbed → less reflection → Lesser sensor value
• On light surfaces: More light is reflected → Higher sensor value
• Hardware Setup
  • Clock (pin 13) - Synchronizes data transfer
  • Addr (pin 12) - Address selection
  • DO (pin 11) - Data output (with internal pull-up)
  • CS (pin 10) - Chip select (active low)