//
//    FILE: ML8511.cpp
//  AUTHOR: Rob.Tillaart@gmail.com
// VERSION: 0.1.4
// PURPOSE: ML8511 - UV sensor - library for Arduino
//
//  HISTORY:
//  0.1.0  2020-02-03  initial version
//  0.1.1  2020-02-17  added _voltPerStep() to support more boards
//  0.1.2  2020-06-21  refactor; add estimateDUVindex()
//  0.1.3  2021-01-01  arduino-ci + unit test
//  0.1.4  2021-04-23  fix for platformIO


#include "ML8511.h"


/////////////////////////////////////////////////////
//
// PUBLIC
//
ML8511::ML8511(uint8_t analogPin, uint8_t enablePin)
{
  _analogPin = analogPin;
  _voltsPerStep = 5.0/1023;
  _enablePin = enablePin;
  if (enablePin != 0xFF)
  {
    pinMode(_enablePin, OUTPUT);
    digitalWrite(_enablePin, LOW);
    _enabled = false;
    enable();
  }
  else 
  {
    _enabled = true;
  }
};


float ML8511::getUV(uint8_t energyMode)
{
  if (!_enabled)
  {
    enable();
    // datasheet page 5 states wait for max 1 millisecond
    uint32_t start = micros();
    while (micros() - start < 1000) yield();
  }

  float voltage = analogRead(_analogPin) * _voltsPerStep;
  if (energyMode == LOW)
  {
    disable();
  }

  // see datasheet - page 4
  // mW/cm2 @ 365 nm
  // @ 25 Celcius
  // formula estimated on graph
  if (voltage <= 1.0) 
  {
    return 0.0;
  }
  voltage -= 1.0;    // subtract for zero point.
  float mWcm2 = voltage * (15.0 / 1.8);
  return mWcm2;
}

// experimental estimate DUV index  (not calibrated, USE WITH CARE !!)
// input is power in mW per cm2
// weight is pretty high 
float ML8511::estimateDUVindex(float mWcm2)
{
  float weight = 1.0;   // this can be tuned to callibrate

  // convert to mW per m2
  float mWm2 = mWcm2 * 10000;
  // factor to normalize to an 0..10 scale see Wikipedia.
  float factor = 0.04;  // 1.0/25;  
  return mWm2 * weight * factor;
};

void  ML8511::setVoltsPerStep(float voltage, uint32_t steps)
{
  if (steps == 0) return;
  if (voltage > 0.0) _voltsPerStep = voltage / steps;
}


void ML8511::enable()
{
  if (_enablePin != 0xFF) digitalWrite(_enablePin, HIGH);
  _enabled = true;
};


void ML8511::disable()
{
  if (_enablePin != 0xFF) digitalWrite(_enablePin, LOW);
  _enabled = false;
};

// -- END OF FILE --