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Infrared Speed Sensor Module

Introduction

The Infrared Speed Sensor Module is an IR counter that has an IR transmitter and receiver. If any obstacle is placed between these sensors, a signal is sent to the microcontroller. The module can be used in association with a microcontroller for motor speed detection, pulse count, position limit, etc.

Principle

The speed sensor module is mainly used to detect changes in rotational speed or velocity. When an object passes by the H2010 sensor, it generates a pulse signal. The integrated LM393 comparator inside the module compares this pulse signal with a preset threshold, producing a stable high-level output signal.

The Infrared Speed Sensor Module has 1 H2010 photocell, which consists of a phototransistor and an infrared light emitter packaged in a 10 cm wide black plastic housing.

When operating, the infrared light-emitting diode continuously emits infrared light (invisible light), and the photosensitive triode will conduct if it receives it.

Module Schematic Diagram

Usage

Hardware components

• Arduino Uno R4 or R3 board * 1

• Infrared Speed Sensor Module * 1

• Jumper Wires

Circuit Assembly

Code

Code explanation

1. Setting up the pins and initializing variables. Here, we define the pins for the motor and the speed sensor. We also initialize variables that will be used to measure and calculate the speed of the motor.

   // Define the sensor and motor pins
   const int sensorPin = 11;
   const int motorB_1A = 9;
   const int motorB_2A = 10;
   
   // Define variables for measuring speed
   unsigned long start_time = 0;
   unsigned long end_time = 0;
   int steps = 0;
   float steps_old = 0;
   float temp = 0;
   float rps = 0;
   

2. Initialization in the setup() function. This section sets up the serial communication, configures the pins’ modes, and sets the initial motor speed.

   void setup() {
     Serial.begin(9600);
     pinMode(sensorPin, INPUT);
     pinMode(motorB_1A, OUTPUT);
     pinMode(motorB_2A, OUTPUT);
     analogWrite(motorB_1A, 160);
     analogWrite(motorB_2A, 0);
   }
   

3. Measuring the motor’s speed in the loop() function. In this segment, the motor’s steps are measured for a duration of 1 second. These steps are then used to calculate the revolutions per second (rps), which is then printed to the serial monitor.

   millis() returns the number of milliseconds passed since the Arduino board began running the current program.

   void loop() {
     start_time = millis();
     end_time = start_time + 1000;
     while (millis() < end_time) {
       if (digitalRead(sensorPin)) {
         steps = steps + 1;
         while (digitalRead(sensorPin))
           ;
       }
     }
     temp = steps - steps_old;
     steps_old = steps;
     rps = (temp / 20);
     Serial.print("rps:");
     Serial.println(rps);
   }
   

Additional Ideas

• Display the rps on an LCD screen for a more user-friendly interface.