Use the Hall sensor to measure the speed

Introduction
Hall 3144 is a unipolar Hall switch circuit. When the N pole of a magnet approaches to its print surface, the switch outputs Low; when the N pole moves away, the switch outputs High. In this section, we will use the Hall sensor to measure the DC motor speed. DC motor is a device that converts electrical energy into mechanical one. It is usually used in fan, electronic toy, shaver, etc. considering it is easy to control.
Components
– 2 * Adeept Arduino UNO R3 Board
– 1 * Hall Sensor Module
– 1 * DC motor Module
– 1 * Magnet(N/S)
– 1 * 3D printing material
– 2 * USB Cable
– 1 * 3-Pin Wires
– 1 * 4-Pin Wires

Experimental Principle 
The Fritzing image:

Pin definition:

The schematic diagram:

The Fritzing image:

Pin definition:

The schematic diagram:

Experimental Procedures
Step 1: Build the circuit

Step 2: Use the 3D printer to print the keypad to secure the platform
3D Module download link:3Dmodule

Step 3: Program  HallSensorModule.ino

/***********************************************************
File name: HallSensorModule.ino
Description:  Use the Hall sensor to measure the speed
             you will see the data in the serial monitor 
Website: www.adeept.com
E-mail: support@adeept.com
Author: Tom
Date: 2016/12/23 
***********************************************************/
int hallsensorPin=2;             //Set the digital 2 to hall sensor module interface 

unsigned long duration;  //Define the duration variable as an unsigned long integer variable
void setup()
{
  Serial.begin(9600);  //The serial baud rate is 9600
  pinMode(hallsensorPin, INPUT); //Set the pin to input mode
} 
void loop()
{
 //Read the high pulse on the pin, the maximum
 //pulse time interval of 60 seconds, and the results assigned to the duration variable
  duration = pulseIn(hallsensorPin, HIGH,60000000);
  Serial.print(60000000/duration); //The duration variable is output through the serial port
  Serial.println(" r/min");
}

Step 4: Compile and download the sketch to the UNO R3 board.