VolumeControl.hpp

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/* ✔ */
 
#pragma once
 
#include <AH/Containers/Updatable.hpp>
#include <AH/Hardware/FilteredAnalog.hpp>
#include <Arduino.h>
#include <Audio.h>
#include <Def/Def.hpp>
 
BEGIN_CS_NAMESPACE
 
/** 
 * @brief   A class for controlling the volume of AudioMixer4 objects using a 
 *          potentiometer.
 * 
 * @tparam  N
 *          The number of mixers.
 * 
 * @ingroup Audio
 */
template <uint8_t N>
class VolumeControl : public AH::Updatable<Potentiometer> {
  public:
    /**
     * @brief   Create a new VolumeControl object.
     * 
     * @param   mixers
     *          An array of pointers to audio mixers.  
     *          Only the pointers are saved, so the mixers should outlive this
     *          object.
     * @param   analogPin
     *          The analog pin with the potentiometer connected.
     * @param   maxGain
     *          The maximum gain for the mixers.
     */
    VolumeControl(const Array<AudioMixer4 *, N> &mixers, pin_t analogPin,
                  float maxGain = 1.0)
        : mixers(mixers), filteredAnalog(analogPin), maxGain(maxGain) {}
 
    /**
     * @brief   Read the potentiometer value, and adjust the gain of the mixers.
     */
    void update() override {
        if (filteredAnalog.update()) {
            float gain = filteredAnalog.getFloatValue() * maxGain;
            for (AudioMixer4 *mixer : mixers)
                for (uint8_t ch = 0; ch < 4; ch++)
                    mixer->gain(ch, gain);
        }
    }
 
    /**
     * @brief   Initialize.
     */
    void begin() override {}
 
    /**
     * @brief   Specify a mapping function that is applied to the raw
     *          analog value before setting the volume.
     *
     * @param   fn
     *          A function pointer to the mapping function. This function
     *          should take the filtered analog value of @f$ 16 - 
     *          \mathrm{ANALOG\_FILTER\_SHIFT\_FACTOR} @f$ bits as a parameter, 
     *          and should return a value in the same range.
     * 
     * @see     FilteredAnalog::map
     */
    void map(MappingFunction fn) { filteredAnalog.map(fn); }
 
    /// Invert the analog value.
    void invert() { filteredAnalog.invert(); }
 
  private:
    Array<AudioMixer4 *, N> mixers;
    AH::FilteredAnalog<> filteredAnalog;
    const float maxGain;
};
 
END_CS_NAMESPACE