Braden Diotte== 's wiki page on Robert Twomey's website'Arduino Frequency Counter''' == http://interface.khm.de/index.php/lab/experiments/arduino-frequency-counter-library/ In many applications involving computers and radio electronics, it is necessary to have a "Frequency Counter" as a piece of test equipment amongst your arsenal of tools. A frequency counter counts the number of alternations a signal has during a short time period, and displays the frequency of the signal in a numerical format. With the proper scaling and conditioning, a frequency counter can be used to show the frequency of a radio transmitter, a note of a piano, the rotational speed of an engine, amongst many other things.For the sake of art projects, it might be necessary to count the number of "pulses" that a sensor receives, and have that number available inside of a computer for use by another program.My personal interest in this technology (with respect to my project) stems from a need to count the rotations of an engine in order to accurately control its speed.