DIY 6.5MHz Arduino Frequency Meter With MAX7219 7segment Led Module

Introduction: DIY 6.5MHz Arduino Frequency Meter With MAX7219 7segment Led Module

A frequency meter is an instrument that displays the frequency of a periodic electrical signal. The video shows such an instrument where the value of the frequency is displayed on a 7-segment LED display in retro style, which is also very noticeable.

Step 1: Deascription

It can measure the frequency of signals with rectangular, sinusoidal and triangular shapes. Its measurement range is from a few hertz to 6.5 Megahertz. The code is simple thanks to "FreqCount" and "LedControl" libraries. The device consists of several components:

- Arduinio Nano microcontroller

- Shaping amplifier board

- 8 Digit 7 Seg Display

- and input jack

Step 2: Building , Schematic and Code

If we measure the frequency only on rectangular signals, then the input circuit (shaping amplifier) can be omitted, in which case we carry the signal directly to the D5 pin of the Arduino. The instrument is very precise in the whole range, and we can also calibrate the frequency meter with the simple procedure described below:

I n the Arduino libraries folder find the FreqCount library, in the FreqCount.cpp file find the lines:

#if defined (TIMER_USE_TIMER2) && F_CPU == 12000000L float correct = count_output * 0.996155; and replace them with:

#if defined (TIMER_USE_TIMER2) && F_CPU == 16000000L float correct = count_output * 1.000000;

where 1.000000 is your correction factor, the correction must be carried out by applying 1 MHz to the input of the frequency meter. After changing the file, upload a new sketch to the Arduino board. Finally, the frequency meter is built into a suitable plastic box and is another useful instrument in the electronic laboratory.

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    3 Comments

    0
    teoamigo31
    teoamigo31

    1 year ago

    Hi,
    I builded this frequency counter, and I need to activate DP for the 3 and 6 digits.
    Can you send me the code for this? Thanks.

    0
    robroy060
    robroy060

    Question 1 year ago on Introduction

    Hi,
    Could you give me the resistor and transistor values please.
    Thanks

    0
    FatlyCatly
    FatlyCatly

    1 year ago

    I think my favourite part of this is actually the box! Is it painted?