![]() But after biasing the input, +2.5V will read 1023 and -2.5V will read zero. The Arduino's ADC is 10-bits, which means it reads a maximum of 1023 with +5V applied. You'll need to bias the Arduino's input at 2.5VDC so the analog-to-digital converter can read positive and negative values. ![]() (So, you just have to pick-out the fundamental.) It's advanced university-level engineering math, but there are software libraries so you don't have to program it yourself.Īs you probably know, audio signals are AC so they swing positive and negative. It will give you the fundamental frequency and its amplitude, as well as the amplitudes for the harmonics & overtones. The second approach is using something called FFT, which converts the normal time-domain "waveform" into its frequency components. I really don't know, but I suspect that inexpensive electronic guitar tuners use zero-crossing. ![]() There might be a way of doing it by finding the peaks and the zero-crossings and maybe with some filtering & averaging and some simple logic to throw-out "wrong" information, etc. This is super-simple and it works with pure sine waves, but with multiple frequencies you can get un-even zero-crossings caused by the harmonics & overtones. You can time the zero-crossings of the wave. The lowest frequency (the fundsmental) is what our brain associates with pitch and usually this is the strongest frequency, but sometimes the 1st harmonic is stronger. A guitar has certain harmonics and overtones that make it sound different from a piano, saxophone, or human voice. It's has been done before so you might want to search for Arduino Guitar Tuner.Īs you may know, real-world sounds are not pure sine waves. It seems simple but it's not quite a simple as it seems.
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