This code is an evolution of the Frequency Detector Code:
www.electrosmash.com/forum/arduino-audio...o-frequency-detector

It shows 2 rows of numbers and a letter on the screen:

• The first row indicates the Note and Ideal frequency you want to tune your string against, let's say this is the reference value
• The second row indicates the actual frequency of your string, you have to adjust it until the first and second rows are equal

This code has many similarities with the Frequency detector:

• If the read is not accurate, try using the Gain potentiometer (if the signal is too big or too small the program will misbehave)
• Make sure that you have a good power supply. I have found that sometimes does not work properly if running on USB power. I guess that you can create some ground loops that make the system unstable
• There is a "counter" variable in the code that can make the code work differently

  if (counter==20)

  . It delays the display representation, you can experiment changing it to a different value

  if (counter==50)

  or

  if (counter==10)

  etc
• The detected frequency can be also read in the serial monitor

Hope you like it!