File content as of revision 7:604a8369b801:

#ifndef _H_SENSOR_H
#define _H_SENSOR_H

/// Base class for I2C-connected sensors. Defines functionality supported by all sensors.
class Sensor {
public:
    /// Base class for sensor data frame. Sensors may derive from this and add their own data fields.
    class Data {
    public:
        int16_t x; ///< x-axis sensor data
        int16_t y; ///< y-axis sensor data
        int16_t z; ///< z-axis sensor data
        int16_t reserved; ///< (reserved, do not use)
        float timestamp; ///< Timestamp in sec
    };
    
    /// Defines protocol used to send data back to owner. Derive from this class and use Sensor.setDelegate() to receive sensor updates.
    class Delegate {
    public:
        /// A new sensor data frame, might be called several (hundred) times a second.
        virtual void sensorUpdate(Sensor* source, Data frame) = 0;
    };
    
    virtual void setDelegate(Delegate &d) {
        _delegate = &d;
    }
    
    /// Power on a sensor and make it ready for use.
    /// @return true if power-up was successful, false otherwise.
    virtual bool powerOn() = 0;
    
    /// Power off a sensor. This will generally only put the sensor into deep sleep.
    virtual void powerOff() = 0;
    
    virtual void start() = 0; ///< Start continuous data capture. If a delegate is set, its sensorUpdate() method will be called for each data frame.
    virtual void stop() = 0; ///< Stop capturing data.
        
    virtual Data read() = 0; ///< Read and return instantaneous (current) sensor data. No need to start the sensor.
    
protected:
    /// Derived classes should use this method to pass sensor data to their owner. Delegate existence check is automatically done before dispatching.
    void sendData(Data frame) {
        if (_delegate)
            _delegate->sensorUpdate(this, frame);
    }
    Delegate * _delegate;
};

#endif//_H_SENSOR_H