This is a guitar tuner that tunes an electric guitar to Standard E tuning. It can be very easily modified for an acoustic guitar by adding a microphone and adjusting the gain with the potentiometer. Other tunings can also be programmed in if you know the frequency of the note.

The program uses the ADC library and a version of the Goertzel algorithm <1> which allows the mbed to check the magnitude of a specified frequency instead of outputting an entire Fourier transform. Currently it takes in a buffer and deconstructs the buffer; however, there is also more code <2> which does the calculations in real time which could be faster and allow this program to work on simpler hardware.

Parts:

• 1x Mbed;
  
• 1x Nokia LCD Display;
  
• 1x LM386 Audio Amplifier;
  
• 2x Potentiometer (10k);
  
• 1x 330nF Ceramic Capacitor;
  
• 1x 1/4" Mono/Stereo Jack;
  
• Wires

Picture:

Wiring Diagram:

Code:

Video: (Better Video Coming Soon)

References:
<1> Wikipedia on Goertzel's Algorithm: http://en.wikipedia.org/wiki/Goertzel_algorithm
<2> Goertzel Code From: http://netwerkt.wordpress.com/2011/08/25/goertzel-filter/