SunFounder ESP32 Starter Kit
5.29 Line Tracking Module
• S: Usually low level, high level when the black line is detected.
• V+Power supply, 3.3v~5V
• G: Ground
This is a 1-channel Line Tracking module which, as the name suggests, tracks black lines on a white background or
white lines against a black background.
The module uses a TCRT500 infrared sensor, which consists of an infrared LED (blue) and a photosensitive triplet
(black).
• The blue infrared LED, when powered on, emits infrared light that is invisible to the human eye.
• The black phototransistor, which is used to receive infrared light, has an internal resistor whose resistance varies
with the infrared light received; the more infrared light received, the lower its resistance decreases and vice versa.
There is a LM393 comparator on the module, which is used to compare the voltage of the phototransistor with the set
voltage (adjusted by potentiometer), if it is greater than the set voltage, the output is 1; otherwise the output is 0.
Therefore, when the infrared emitter tube shines on a black surface, because the black will absorb light, the photosen-
sitive transistor receives less infrared light, its resistance will increase (voltage increase), after LM393 comparator, the
output high level.
Similarly, when it shines on a white surface, the reflected light will become more and the resistance of the photosensitive
transistor will decrease (voltage decreases); therefore, the comparator outputs a low level and the indicator LED lights
up.
• TCRT5000
Features
• Using infrared emission sensor TCRT5000
• Detection distance: 1-8mm, focal length of 2.5mm
• Comparator output signal clean, good waveform, driving capacity greater than 15mA
• Using potentiometer for sensitivity adjustment
748 Chapter 5. Learn about the Components in Your Kit
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