Arduino Workshop: Infrared Line Tracking Sensor

Experiment: TCRT5000 infrared reflective photoelectric switch tracking sensor module

The reflex photoelectric switch, which falls under the category of infrared invisible light devices, is a compact photoelectric component designed to detect variations in the intensity of received light. Originally employed for sensing the presence or absence of objects, this switch combines an infrared emitter with an infrared receiver. The emitter operates within a wavelength range of 780nm to 1mm and includes a calibration lens to direct the light towards the receiver. The receiver then transmits the signal via a cable to a vacuum tube amplifier. Detection occurs between the emitter and detector within the gap of the slotted switch along the optical path when an object enters this space. As the object nears the detection zone, some of the light collected by the receiver is reflected onto the photoelectric element. By leveraging the object's ability to obstruct or reflect the infrared light beam, the synchronous circuit is triggered, indicating the presence of the object. This system can detect not only metallic objects but also any object capable of reflecting light.

The TCRT5000 operates on the same principle as general infrared sensors.The system is composed of an infrared emitter and receiver. When the emitter sends out an infrared signal, and this signal is reflected back to the receiver, the receiver's resistance changes. This change usually appears as a voltage variation within the circuit. The final output result is processed through ADC conversion or by shaping circuits such as the LM324. The change in resistance depends on the intensity of the infrared signal received, which is often affected by both the color of the reflecting surface and the distance between the surface and the receiver.

Work Environment

+: Connect to positive pole of DC 5V

-: Connect to negative pole of DC 5V

S: Signal output terminal, the phototransistor is saturated. At this time, the output terminal of the module is at a high level, indicating that the diode is illuminated.

Operating voltage: DC 3V~5.5V, recommended operating voltage is 5V

Detection distance: Suitable for 1mm~8mm, with a focal distance of 2.5mm

The TCRT5000's infrared emitting diode continuously emits infrared light. If the emitted light is not reflected back, or if it returns with insufficient intensity, the photosensitive transistor stays off. During this state, the module's output remains at a low level, indicating that the diode is inactive. However, when an object enters the detection range and the reflected infrared light is sufficiently strong, the photosensitive transistor becomes saturated. This causes the module's output to switch to a high level, signifying that the diode is activated.

Several application circuits for TCRT5000 sensor.

TCRT5000 Infrared Reflective Optoelectronic Switch Tracking Sensor Module

Utilizes TCRT5000 infrared reflective sensor.
Detects reflection distance of 1mm to 25mm.
Comparator output with clean signal, good waveform, and strong driving capability exceeding 15mA.
Equipped with multi-turn adjustable precision potentiometer for sensitivity adjustment.
Operating voltage: 3.3V-5V.
Output form: digital switch quantity output (0 and 1).
Features fixed bolt holes for easy installation.
Small PCB size: 3.2cm x 1.4cm.
Uses wide voltage LM393 comparator.

Module Description

This sensor module is highly adaptable to varying ambient light conditions and consists of an infrared emitter-receiver pair. The emitting tube sends out infrared rays at a specific frequency, and when these rays encounter an obstacle (a reflective surface) in the detection path, they are reflected back to the receiving tube. Once processed by a comparator circuit, the green indicator light turns on, and simultaneously, the signal output interface delivers a digital signal (low-level). The detection distance can be adjusted using a potentiometer, with an effective range from 2 to 30 cm. The module operates within a voltage range of 3.3V to 5V. Key features include adjustable detection distance via a potentiometer, low susceptibility to interference, easy assembly, and user-friendly operation. This sensor is versatile and can be used in various applications like pulse data sampling for electricity meters, paper detection in fax machines and shredders, counting on assembly lines, obstacle avoidance for robots and vehicles, and black-and-white line tracking, among many other uses.

Module Wiring Instructions

VCC: Connect to positive terminal of power supply (3-5V).
GND: Connect to negative terminal of power supply.
DO: TTL switch signal output.
AO: Analog signal output (output different voltages depending on the distance, this pin can generally be left unconnected).

Experimental open-source simulation programming

Tag：TCRT5000; Vishay Intertechnology ; Electronic components