Currently, the following filters are supported:
Filters a digital input such as a button. Prevent spurious changes in state due to button "bouncing", rapid changes when the button is pressed or released. Also provides rising and falling edges.
Filters an analog input using an exponential moving average filer.
An exponential moving average filter. This uses only integer (32-bit) math. This supports up to 24-bit inputs.
An exponential moving average filter is defined as: average = input_value * alpha + previous_average * (1 - alpha) This filter takes an alpha from 0 to 255, with 255 corresponding to 1 on a typical floating-point based filter.
An alpha of 255 means that the filter returns the current value of the input. An alpha of 0 means the filtered value changes very slowly.
Keeps a buffer of recent inputs, and returns the median of those values.
This filter has been written to be relatively fast, without sacrificing too much readability for speed. In the typical case (once the buffer is full), it iterates through the buffer at most once.
For even sizes, this returns the lower median.
If you're using PlatformIO, add ademuri/smart-input-filter@^0.3.1 to your lib_deps.
If you're using the Arduino IDE, install this library by placing a copy of it in your Arduino/libraries folder.
If you're on a platform that doesn't have some of the C++ STL libraries (e.g. the Arduino Uno), install the ArduinoSTL library through the Arduino library manager.
See the examples directory for how to use the filters.
Generally, call the Run function periodically. Then, call GetFilteredValue to get the output of the filter.
Call SetLogToSerial(true) on your filter to enable debug logging. Values are logged to Serial in the form . These values can be graphed using the Arduino serial plotter. Both input and output are converted before logging.
By default, the filter will not convert the output (beyond filtering it). You can optionally pass a conversion function into the filter constructors to convert the output before returning it. For example, you could do this to convert an analogRead value (on most platforms, a 10-bit unsigned int) to a float voltage.
The filters can use digitalRead and analogRead as inputs by passing filter_functions::ForDigitalRead or filter_functions::ForAnalogRead. If you want to use these filters with a different kind of input device, pass in a different ReadFromSensor function to the constructor. See the debounce example for how to do this.
To check that all code builds for Arduino, run build_arduino.sh. To run the unit tests, run test.sh.
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sudo -H pip install platformio -
CMake
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gcc for your platform
I'm using this library in several of my projects, and adding features as needed.
All filters have pretty good unit test coverage. Check build_arduino.sh for the Arduino platforms that this is compiled against.