[NEW] Calculate Battery SoC

[AlexanderTonn]

 🚀 Please describe your feature request

• calculate the battery SoC of LiFePo4 Accu

 ✏️ Describe the solution you'd like

• take the battery voltage and calculate the SoC. You have to consider that the voltage is under load divergent against the voltage without load
• use interpolation for calculating the values between the support values
• the support values (the known percentage at a specific voltage) will be stored in a Array

Linear Interpolation

• In MyArduinoSnippets Repo i created a function for calculating a linear interpolation based on two Array Datasets.

• the function needs the std::array implementation of janelia-arduino

  
  template <size_t T>
  auto fLinInterpolation (float fx, const Array<float, T>& aX, const Array<float, T>& aY) -> float
  {
  static auto n = sizeof(aX) / 4;
  auto x1 = 0.0F, x2 = 0.0F; 
  auto y1 = 0.0F, y2 = 0.0F; 
  bool xLowRec = false, xUpperRec = false; // true, if lower/upper value was received
  
  // getting x1 && y1
  for (auto i = n; i > 0 && !xLowRec; i--)
  {
  if(fx >= aX[i])
  {
    x1 = aX[i];
    y1 = aY[i];
    xLowRec = true;
  }
  }
  // getting x2 && y2
  for (auto i = 0; i < n && !xUpperRec; i++)
  {
  if(fx <= aX[i])
  {
    x2 = aX[i];
    y2 = aY[i];
    xUpperRec = true;
  }
  }
  
  // All necesssary values collected, now calculate
  auto fResult = 0.0F;
  if(xLowRec && xUpperRec)
  {
  auto term1 = (fx - x1)/(x2 - x1);
  auto term2 = (y2 - y1);
  fResult = y1+term1*term2;
  }
  return fResult;
  }

##  📌 Describe alternatives you've considered

# Additional context

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