Capacitor

Arduino library to measure capacitance from 0.2pF to over 100uF with no external hardware.

Introduction

This library allows capacitance to be measured between two pins. One pin must be an analog pin.

Usage

Declare a Capacitor object, e.g.:

Capacitor cap1(7, A2);

To measure the value of a capacitor (e.g. in the case above between pin D7 and A2) call the Measure() method, e.g.:

float val = cap1.Measure()

Returns the capacitance in picofarads, in this case in the variable val.
(note that 1nF = 1000pF and 1uF = 1000000pF)

What's New?

Version 1.1.0 introduces the CapacitorLite class. This uses much less program space* and guarantees a fast measurement. It only measures up to 655pF - any capacitors above this will return 65535 from the Measure() method. See the example code here.

* Capacitor uses about 3.5K of program space and 19 bytes of dynamic memory, CapacitorLite uses less than 1K of program space and 7 bytes of dynamic memory.

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I originally came up with this idea back in 2014. For some explanation of how it works please have a look at these links: https://hackaday.com/2014/01/22/capacitance-measurement-with-the-arduino-uno/#more-113173 http://wordpress.codewrite.co.uk/pic/2014/01/21/cap-meter-with-arduino-uno/ http://wordpress.codewrite.co.uk/pic/2014/01/25/capacitance-meter-mk-ii/
For more information about how to use the code and how it works, please see the WiKi.