Its measurement range is from a few hertz to 6.5 Megahertz. Three measurement time intervals are also available - 0.1, 1 and 10 seconds. If we measure only rectangular signals, then there is no need for a shaping amplifier and the signal is fed directly to the digital pin 5 from Arduino.
The code is very simple thanks to the "FreqCount" library which you can also download below.
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The device is very simple and consists of several components:
- Arduino Nano microcontroller
- Shaping amplifier board
- LCD display
- Input signal shape selector
- Input JACK
- and Time interval switch : we can choose three intervals 0.1 -1 -and 10 seconds .
As you can see in the video, the instrument is very precise in the whole range, and we can also calibrate the frequency meter with the simple procedure described below:
In 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.