lowpass_filter.cpp

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#include "lowpass_filter.h"
 
LowPassFilter::LowPassFilter(float time_constant)
    : Tf(time_constant)
    , y_prev(0.0f)
{
    timestamp_prev = _micros();
}
 
 
float LowPassFilter::operator() (float x)
{
    unsigned long timestamp = _micros();
    float dt = (timestamp - timestamp_prev)*1e-6f;
 
    if (dt < 0.0f || dt > 0.5f)
        dt = 1e-3f;
 
    float alpha = Tf/(Tf + dt);
    float y = alpha*y_prev + (1.0f - alpha)*x;
 
    y_prev = y;
    timestamp_prev = timestamp;
    return y;
}