zvonler / debouncedldr

Arduino library working with Light-Dependent Resistors

DebouncedLDR

This library implements a class that applies quantization and hysteresis to the analog readings of a Light Dependent Resistor (LDR) so that applications can work with logical light levels instead of physical light readings. Using this library, applications can easily avoid the flickering effects that can happen with simple thresholding.

Theory of operation

The DebouncedLDR class does not do any of the actual GPIO manipulation. The client application is expected to call DebouncedLDR::update frequently (i.e. every few milliseconds) with the latest reading from the analog pin. The update method returns the current logical light level.

The light level value returned by update represents a logical light level between zero and the maximum level passed to the instance's constructor. The noise parameter to the constructor is used to define "meaningful" changes in the LDR reading, a higher noise value requires a larger change in the readings to cause a change in the reported light level, and a noise value of zero will do no debouncing of the readings.

Testing

This library includes unit tests that can be run on a host system (not on the Arduino) using CMake. From the top-level of the library repo, these commands should run the tests:

cd tests
cmake -S . -B build
cmake --build build && (cd build; ctest --output-on-failure)

The first cmake command above only needs to be run once, the second command can be run each time the source is changed to check the test status.