TwoPointAnalogLoadCell.h

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/* Copyright (c) 2024 Skyward Experimental Rocketry
 * Author: Davide Mor, Niccolò Betto
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
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 * THE SOFTWARE.
 */
 
#pragma once
 
#include <sensors/Sensor.h>
#include <sensors/SensorData.h>
 
#include <atomic>
#include <functional>
 
namespace Boardcore
{
 
class TwoPointAnalogLoadCell : public Sensor<LoadCellData>
{
public:
    TwoPointAnalogLoadCell(std::function<VoltageData()> getVoltage,
                           float p0Voltage, float p0Mass, float p1Voltage,
                           float p1Mass)
        : getVoltage{std::move(getVoltage)},
          staticScale{(p1Mass - p0Mass) / (p1Voltage - p0Voltage)},
          staticOffset{p0Mass - staticScale * p0Voltage}
    {
    }
 
    TwoPointAnalogLoadCell(TwoPointAnalogLoadCell&& other)
        : getVoltage{std::move(other.getVoltage)},
          dynamicOffset{other.dynamicOffset.load()},
          staticScale{other.staticScale}, staticOffset{other.staticOffset}
    {
    }
 
    bool init() override { return true; }
 
    bool selfTest() override { return true; }
 
    void setOffset(float value) { dynamicOffset = value; }
 
    void updateOffset(float value)
    {
        float currentOffset = 0.0f;
        // Compare/exchange loop because operator+= on atomic floats is only
        // supported since C++20
        do
        {
            currentOffset = dynamicOffset.load();
        } while (!dynamicOffset.compare_exchange_weak(currentOffset,
                                                      currentOffset + value));
    }
 
    float getOffset() { return dynamicOffset; }
 
protected:
    LoadCellData sampleImpl() override
    {
        auto voltage = getVoltage();
        auto mass    = voltage.voltage * staticScale + staticOffset;
 
        return {voltage.voltageTimestamp, mass - dynamicOffset};
    }
 
private:
    std::function<VoltageData()> getVoltage;
 
    std::atomic<float> dynamicOffset{0.0f};
 
    const float staticScale;
    const float staticOffset;
};
 
}  // namespace Boardcore