This project discusses the creation of a digital frequency meter using Arduino Uno to determine the sinusoidal frequency signal in the range of 20 Hz to 5 kHz. The frequency range covered by the meter is 20 Hz to 5 kHz. In order to follow the reasoning, you will need to count the total number of pulses that occur each second at a digital pin on Arduino. Circuit and the working Fig.1 presents the schematic representation of the digital frequency meter's internal workings. In addition to a few other components, it has an Arduino Uno board, an optocoupler MCT2E (IC1), a 16x2 LCD, and a few more. In accordance with what is depicted in Figure 3, the sinusoidal signal whose frequency is going to be measured is fed into the signal input terminals (CON1). In order for this frequency meter to function properly, the signal being tested must be one that alternates, and its amplitude must not be more than the maximum forward diode current rating of the optocoupler

for a given value of series resistance. (The series resistance that we chose was 1k in this instance.) Fig. 2: Circuit diagram of digital frequency meter The alternating signal is then passed via a bridge rectifier, which transforms it into a completely rectified pulsing direct current signal. On the side of the optocoupler that contains the diode, this pulsating DC signal is applied. This signal has been entirely rectified. The optocoupler is responsible for the production of spikes in the signal. The spikes have a frequency that is twice as high as the test signal input. These spikes are then applied to digital I/O pin 5 of the Arduino, and the program that is running in the CPU of the microcontroller (MCU) then calculates the frequency of the test signal and displays it on the 16x2 LCD as well as on the serial monitor of the personal computer.

The Arduino Uno is a development board that is based on the AVR ATmega328P MCU and has 14 digital I/O pins in addition to six analogue input pins. The MCU

contains 32 kilobytes of ISP flash memory, 2 kilobytes of RAM, and 1 kilobyte of EEPROM. The capability of serial communication can be achieved on the board through the use of UART, SPI, and I2C. The clock frequency of the MCU is capable of reaching up to 16 MHz. For the purposes of this endeavor, the digital I/O pin 5 of the Arduino Uno board has been repurposed as a pulse input pin, and the digital I/O pins 7, 8, 9, 10, 11, and 12 have been used to connect with the LCD. Bridge rectifier In order to convert the alternating input signal to pulsing DC, the bridge rectifier (BR1) is put into operation. Optocoupler The pulsating DC waveform is fed into the optocoupler so that spikes can be generated from it.

Displaying the frequency on the 16x2 LCD is possible thanks to its size. For the purpose of showing data, it has sixteen columns and two rows. This particular LCD has a backlight built into it. It communicates in 4-bit mode with Arduino, which is its interface. LCD pins RS, EN, D4, D5, D6, and D7 are each linked to the relevant digital I/O pins 12, 11, 7, 8, 9, and 10 on an Arduino. Software Programming an Arduino Uno requires the use of the Arduino IDE. After opening the source code or sketch for the Freq meter 1.ino file in the Arduino IDE, navigate to the Tools menu to choose the COM port and board. The source code should then be uploaded to the board when the appropriate COM port and board have been selected.