lookup.ino

struct ForceLookup {
  uint16_t voltage;   //  millivolts (mV)
  uint16_t force;     //  grams (g)
 };

 ForceLookup table[FLT_SIZE] = {  {0, 0}, {900, 20}, {1400, 50}, {1750, 100}, {2250, 200}, {2500, 310},
                            {2800, 450}, {3000, 580}, {3200, 710}, {3400, 900}, {3450, 1000}   };

 float interpolate(uint16_t adc_mV) {
  //  Based on ADC voltage (mV), lookup the force (g) and interpolate between adjacent values if required.

  //  Constrain range to lookup table min and max
  adc_mV = constrain(adc_mV, 0, 3450);
  
  for (int i = 0; i < FLT_SIZE - 1; i++) {
        if (table[i].voltage <= adc_mV && table[i+1].voltage >= adc_mV) {
            float diffx = adc_mV - table[i].voltage;
            float diffn = table[i+1].voltage - table[i].voltage;

            return (table[i].force + (table[i+1].force - table[i].force) * diffx / diffn); 
        }
    }

    return -1.0f; // Not in Range
}