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Building a Simple Pulse Frequency Counter Circuit with Arduino

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A pulse frequency counter, which calculates a signals frequency in hertz (Hz), is a crucial instrument in electronics.

The development of microcontrollers such as the Arduino has made the process of creating a frequency counter more readily available and economical.

This article describes how to use an Arduino Uno and a few other parts to make a pulse frequency counter.

An IC 555 for pulse production, an IC 7809 for voltage regulation, and a basic LED indication will be part of the setup.

Code with Explanation:

[Arduino]          [IC 555]          [IC 7809]
   Pin 2 <------- Pin 3
 
volatile unsigned long pulseCount = 0;
unsigned long frequency = 0;

void setup() {
    Serial.begin(9600);
    pinMode(2, INPUT); // Pin connected to IC 555 output
        attachInterrupt(digitalPinToInterrupt(2), countPulse, RISING);
}

void loop() {
    pulseCount = 0; // Reset pulse count
    interrupts(); // Enable interrupts
    delay(1000); // Count pulses for 1 second
    noInterrupts(); // Disable interrupts

    frequency = pulseCount; // Store the frequency count
    Serial.print("Frequency: ");
    Serial.print(frequency);
    Serial.println(" Hz");
    digitalWrite(13, frequency > 0 ? HIGH : LOW); // Turn LED on if frequency > 0
}

void countPulse() {
    pulseCount++; // Increment pulse count
}

Explanation:

Circuit Working:

Parts List:

ComponentValueQuantityRemarks
Resistor1k11/4 watt
Resistor220Ω11/4 watt
Potentiometer100k1
CapacitorElectrolytic 1μF 25V1
CapacitorCeramic 0.01μF1
ArduinoUno Board1
IC7809 1Voltage Regulator
IC555 Timer1For pulse generation
LED Red5mm 20mA1Any color

The pulse frequency counter projects dependability is greatly dependent on the IC 7809.

The Arduino Uno and the IC 555 in the circuit normally need a steady power source.

A greater input voltage, such as 12V, can be controlled by the IC 7809 to provide a steady 9 volt output.

The Arduino, which detects the pulse frequency, and the IC 555, which produces the pulse signal, both depend on this controlled voltage to operate correctly.

The potentiometer is used to regulate the frequency of a continuous square wave signal produced by the astable mode of operation of the IC 555.

The Arduino can count the number of pulses in a second by detecting the rising edges of the square wave through an interrupt.

The Arduino uses the detected frequency to drive the LED and shows the frequency count on the serial monitor.

Formulas:

The formula to calculate frequency from pulse duration is:

Frequency (Hz) = Total Pulse Duration (s)1​×106

This is the span of time when a pulse is present.

It is measurable in seconds (s).

For instance, 0.001 seconds would be the duration of a pulse lasting one millisecond (ms).

This is frequently the total amount of time that a series of pulses take inside a specific amount of time.

The frequency of an event is measured in hertz (Hz), which is the number of times it occurs in a given amount of time.

It represents the number of pulses that occur in a second within the context of a pulse signal.

The duration of the pulse is converted from microseconds (μs) to seconds using the 106 factor.

This is important when working with microcontroller timing functions that commonly operate in microseconds.

How to Build:

For Building a Simple Pulse Frequency Counter Circuit with Arduino follow the below steps:

Conclusion:

An easy and instructive project that offers insights into frequency measurement and signal processing is building an Arduino pulse frequency counter.

An Arduino may be used for counting and an IC 555 for creating pulses to build a flexible instrument that can be used for testing circuits and detecting signal frequencies, among other things.

This project gives users a hands-on introduction to fundamental electronic components while showcasing the versatility of Arduino in addressing electronic chores.

References:

Pulse counter – using internal comparator?

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