Tachometer Using A3144 Hall Effect Sensor & Arduino

Introduction

If you’re a hobbyist looking for an exciting project to tinker with, then building a tachometer using an A3144 Hall effect sensor and an Arduino is an excellent place to start. A tachometer is a device used to measure the rotational speed of a machine, and with this DIY project, you can build a reliable and accurate tachometer that’s easy to use and customize.

In this article, we’ll guide you through the process of building a tachometer using an A3144 Hall effect sensor and an Arduino. We’ll explain how the A3144 sensor works and how to interface it with an Arduino. We’ll also provide the complete code and a step-by-step guide to building the tachometer, so you can follow along even if you’re a beginner.

What is A3144 Hall Effect Sensor?

The A3144 Hall Effect Sensor is a small, low-cost, and reliable magnetic sensor that is widely used in electronic applications. It is based on the Hall Effect, which is a physical phenomenon that occurs when a current-carrying conductor is placed in a magnetic field. The sensor consists of a thin piece of semiconductor material, such as gallium arsenide, that is sensitive to magnetic fields. When a magnetic field is applied, the sensor generates a voltage that is proportional to the strength of the field.

Hardware Components

To build a Tachometer with Arduino, you’ll need the following hardware components to get started:

Components	Value	Qty
Arduino UNO	–	1
USB Cable Type A to B	–	1
DC Power for Arduino	–	1
Hall Effect Sensor	A3144	1
Resistor	1kΩ	1
Jumper Wires	–	1

A3144 Hall Effect Sensor Pinout

Pin Name	Pin Description
VCC	Used to power the hall sensor, typically VCC is used
Ground	Connect to the ground of the circuit
DAT	This pin goes high if a magnet is detected. The output voltage is equal to the Operating voltage.

Tachometer Arduino Circuit

Make connections according to the circuit diagram given below.

Wiring / Connections

Arduino	Hall Effect Sensor
5V	VCC
GND	GND
A0	OUT

Installing Arduino IDE

First, you need to install Arduino IDE Software from its official website Arduino. Here is a simple step-by-step guide on “How to install Arduino IDE“.

Code

Now copy the following code and upload it to Arduino IDE Software.

// Analog pin A0 is the hall pin, On the Uno the value of the A0 variable is 14
int hall_pin = 14;
// set number of hall trips for RPM reading (higher improves accuracy)
float hall_thresh = 100.0;
 
void setup() {
  // initialize serial communication at 9600 bits per second:
  Serial.begin(115200);
  // make the hall pin an input:
  pinMode(hall_pin, INPUT);
}
 
// the loop routine runs over and over again forever:
void loop() {
  // preallocate values for tach
  float hall_count = 1.0;
  float start = micros();
  bool on_state = false;
  // counting number of times the hall sensor is tripped
  // but without double counting during the same trip
  while (true) {
    if (digitalRead(hall_pin) == 0) {
      if (on_state == false) {
        on_state = true;
        hall_count += 1.0;
      }
    } else {
      on_state = false;
    }
 
    if (hall_count >= hall_thresh) {
      break;
    }
  }
 
  // print information about Time and RPM
  float end_time = micros();
  float time_passed = ((end_time - start) / 1000000.0);
  Serial.print("Time Passed: ");
  Serial.print(time_passed);
  Serial.println("s");
  float rpm_val = (hall_count / time_passed) * 60.0;
  Serial.print(rpm_val);
  Serial.println(" RPM");
  delay(1);        // delay in between reads for stability
}

Code Explanation

This Arduino code is used to measure the RPM (rotation per minute) of a motor or engine using an A3144 Hall Effect Sensor. The comments in the code explain the purpose of each line:

• The variable “hall_pin” is set to 14, which is the analog pin A0 on the Arduino Uno board that is connected to the Hall Effect Sensor.
• The “hall_thresh” variable is set to 100, which is the number of times the Hall Sensor needs to be triggered before a reading is taken. Increasing this value improves accuracy.
• In the “setup” function, the serial communication is initialized and the hall_pin is set as an input.
• In the “loop” function, the “hall_count” variable is initialized to 1, the “start” variable is set to the current time, and the “on_state” variable is set to false. Then a while loop starts that reads the value of the hall_pin, checks if it’s triggered, and increases the “hall_count” variable by 1 if it’s triggered. The “on_state” variable is used to ensure that the same trip is not double-counted.
• If the “hall_count” variable reaches the “hall_thresh” value, the while loop breaks.
• The “end_time” variable is set to the current time, the time_passed is calculated by subtracting the start time from the end time and dividing by 1,000,000 to convert to seconds.
• The RPM value is calculated by dividing the “hall_count” variable by the “time_passed” variable and multiplying by 60. The result is stored in the “rpm_val” variable.
• Finally, the “time_passed” and “rpm_val” variables are printed to the serial monitor, and a delay of 1 millisecond is added before the loop repeats.

Applications

Tachometer has a wide range of applications across different industries, including:

1. Automotive Industry: In the automotive industry, tachometers are commonly used to monitor the RPM (revolutions per minute) of the engine.
2. Manufacturing Industry: Tachometers are widely used in manufacturing industries to monitor the speed of production lines and machinery.
3. Aviation Industry: In aircraft, tachometers are used to monitor the speed of the engine and rotor blades.
4. Marine Industry: In marine applications, tachometers are used to monitor the speed of boat engines and propellers.
5. HVAC Industry: In the heating, ventilation, and air conditioning (HVAC) industry, tachometers are used to measure the speed of fans and blowers.

Conclusion

Building a tachometer using an A3144 Hall effect sensor and an Arduino is an exciting and rewarding project for hobbyists and DIY enthusiasts. With this project, you can measure the rotational speed of any machine, from a small hobby motor to a large industrial engine, and monitor its performance.

We hope this article has provided you with the necessary knowledge and tools to build your tachometer if you face any difficulty please comment below.