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2WD Speed Measurement Module – Smart Tracking Car Counter, Dual-Channel Motor Speed Sensor (Red)

SKU: FA3016-4
Module Type

Dual-channel photoelectric speed sensor
Number of Channels

2 independent channels
Sensor Type

Photoelectric interrupt (IR emitter + receiver)
Operating Voltage

3.3V – 5V DC
Output Type

Digital pulse (square wave)
Response Time

Fast (suitable for high-speed motors)
Pin Count

5–6 pins (VCC, GND, OUT1, OUT2)
Module Dimensions

Compact PCB with mounting holes

The 2WD Speed Measurement Module is a compact, dual-channel motor speed sensor designed for smart tracking cars, robotics projects, and DIY electronics. It uses photoelectric interrupt technology to measure the rotational speed of two motors simultaneously, providing precise speed and distance data for your microcontroller. This makes it an ideal solution for line-following robots, odometry tracking, PID speed control, and any application requiring accurate motor feedback.

At the heart of the module are two independent photoelectric interrupt sensors, each consisting of an infrared emitter and receiver pair. The sensor detects the rotation of a slotted encoder disc (typically attached to the motor shaft) by counting the interruptions in the infrared beam as the disc rotates. Each interruption generates a digital pulse, which the microcontroller can count to determine the motor’s speed and direction.

The module features dual-channel outputs (typically labeled OUT1 and OUT2 or A and B), one for each motor. Each channel provides a digital square wave whose frequency is proportional to the motor’s rotational speed. By counting the pulses over a fixed time period, you can calculate the RPM (revolutions per minute) and, using the wheel diameter, the linear speed and distance traveled. This makes the module essential for odometry and dead reckoning in autonomous robots.

The module operates from a 3.3V to 5V DC supply, making it compatible with Arduino, ESP32, STM32, and other microcontrollers. The compact PCB design with mounting holes allows easy integration into robot chassis and custom enclosures. The red PCB color provides easy identification in your project.

The photoelectric interrupt principle offers several advantages over mechanical encoders: no contact wear, high reliability, fast response time, and long lifespan. The module is widely used in line-following robots, smart cars, obstacle avoidance robots, PID speed control systems, odometry tracking, motor testing, and educational STEM projects.

Important Note: The module requires a slotted encoder disc (not included) to be attached to the motor shaft for operation. The sensor detects the interruptions in the infrared beam as the disc rotates. Ensure the disc is properly aligned with the sensor’s slot for reliable counting. The module is not waterproof and should be kept dry.

Whether you are building a line-following robot, a smart car, or a PID-controlled motor system, the 2WD Speed Measurement Module provides a reliable, affordable solution for dual-channel motor speed sensing. It is suitable for individual makers, students, and businesses purchasing in bulk for product development or educational programs.

Features

  • Dual-channel speed sensing — Measures two motors simultaneously

  • Photoelectric interrupt technology — Non-contact, wear-free operation

  • Digital pulse output — Frequency proportional to motor speed

  • Wide voltage range — 3.3V to 5V DC, compatible with Arduino, ESP32, STM32

  • Fast response time — Suitable for high-speed motor applications

  • Long lifespan — No mechanical wear, unlike mechanical encoders

  • Compact PCB design — With mounting holes for easy integration

  • Red PCB color — Easy identification in your project

  • Wide application range — Line-following robots, smart cars, odometry, PID control

  • Cost-effective — Affordable solution for motor speed sensing in volume production

Technical Specifications 

# Parameter Specification
1 Module Type Dual-channel photoelectric speed sensor
2 Number of Channels 2 independent channels
3 Sensor Type Photoelectric interrupt (IR emitter + receiver)
4 Operating Voltage 3.3V – 5V DC
5 Output Type Digital pulse (square wave)
6 Response Time Fast (suitable for high-speed motors)
7 Pin Count 5–6 pins (VCC, GND, OUT1, OUT2)
8 Module Dimensions Compact PCB with mounting holes

Usage

Getting Started

  1. Mount the encoder discs — Attach a slotted encoder disc (not included) to each motor shaft. Ensure the disc passes through the sensor’s slot as it rotates.

  2. Connect power — Supply 3.3V or 5V DC to the VCC pin and GND to ground.

  3. Connect the outputs — Connect the two output pins (OUT1 and OUT2) to digital input pins on your microcontroller:

    • Arduino: D2 and D3 (interrupt-capable pins recommended)

    • ESP32: Any available GPIO pins

  4. Upload a test sketch — Use interrupt counting or polling to count the pulses from each channel. Calculate RPM or speed based on the pulse count.

  5. Implement speed control — Use the pulse count as feedback for PID control to maintain consistent motor speed.

Pin Connections

Module Pin Function
VCC Power (3.3V–5V)
GND Ground
OUT1 Channel 1 digital pulse output
OUT2 Channel 2 digital pulse output

Example Arduino Code (Interrupt-Based Counting)

cpp
volatile int count1 = 0;
volatile int count2 = 0;

void setup() {
  Serial.begin(9600);
  pinMode(2, INPUT_PULLUP);
  pinMode(3, INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(2), countPulse1, FALLING);
  attachInterrupt(digitalPinToInterrupt(3), countPulse2, FALLING);
}

void countPulse1() { count1++; }
void countPulse2() { count2++; }

void loop() {
  count1 = 0;
  count2 = 0;
  delay(1000);
  Serial.print("Motor 1: "); Serial.print(count1); Serial.println(" pulses/sec");
  Serial.print("Motor 2: "); Serial.print(count2); Serial.println(" pulses/sec");
}

Speed Calculation

Parameter Formula
RPM (Pulses per second / Slots per disc) × 60
Linear Speed RPM × Wheel Circumference / 60
Distance Total Pulses / Slots per disc × Wheel Circumference

Typical Applications

  • Line-following robots — Precise speed control for smooth tracking

  • Smart cars — Odometry and distance measurement

  • Obstacle avoidance robots — Speed feedback for navigation

  • PID speed control — Maintain consistent motor speed under varying loads

  • Odometry tracking — Calculate position and distance traveled

  • Motor testing — Measure RPM and performance characteristics

  • Educational STEM projects — Teaching speed sensing and control principles

Notes for Business Buyers

  • Dual-channel capability — One module measures two motors simultaneously.

  • Non-contact sensing — Photoelectric principle eliminates mechanical wear.

  • Simple interface — Digital pulse outputs connect directly to MCU interrupt pins.

  • Suitable for bulk purchasing — Ideal for robotics kit manufacturers, smart car makers, and educational institutions.

Q: What is the 2WD Speed Measurement Module used for?

It is a dual-channel motor speed sensor for smart tracking cars, robots, and DIY electronics, used for speed measurement, odometry, and PID control.

Q: How does the module measure motor speed?

It uses a photoelectric interrupt sensor to detect the rotation of a slotted encoder disc attached to the motor shaft. Each slot passing through the sensor generates a digital pulse, which the microcontroller counts to calculate speed.

Q: What is included with the module?

The module includes the dual-channel photoelectric sensor board. The encoder discs are not included and must be sourced separately or attached to your motor shafts.

Q: What voltage does the module require?

It operates from 3.3V to 5V DC, making it compatible with Arduino, ESP32, STM32, and other microcontrollers.

Q: How many channels does the module have?

It has two independent channels, allowing you to measure the speed of two motors simultaneously.

Q: What is the output signal?

Each channel outputs a digital square wave whose frequency is proportional to the motor’s rotational speed.

Q: How do I calculate RPM?

Use the formula: RPM = (Pulses per second / Slots per disc) × 60.

Q: Does the module need an encoder disc?

Yes. A slotted encoder disc must be attached to each motor shaft for the sensor to detect rotation. The discs are not included.

Q: Is the module waterproof?

No. The module is not waterproof and should be kept dry.

Q: Can I purchase in bulk for a product development project?

Yes. This module is suitable for both individual users and business purchasing, including robotics kit manufacturers, smart car makers, and educational institutions.

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