Battery.h

/*
 Battery.h - Battery library
 Copyright (c) 2014 Roberto Lo Giacco.
 
 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU Lesser General Public License as 
 published by the Free Software Foundation, either version 3 of the 
 License, or (at your option) any later version.
 
 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.
 
 You should have received a copy of the GNU General Public License
 along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
#ifndef BATTERY_H_
#define BATTERY_H_
 
#include <Arduino.h>
 
typedef uint8_t(*mapFn_t)(uint16_t, uint16_t, uint16_t);
 
class Battery {
    public:
        Battery(uint16_t minVoltage, uint16_t maxVoltage, uint8_t sensePin, uint8_t adcBits = 10);
 
        void begin(uint16_t refVoltage, float dividerRatio, mapFn_t = 0);
 
        void onDemand(uint8_t activationPin, uint8_t activationMode = LOW);
 
        static const uint8_t ON_DEMAND_DISABLE = 0xFF;
 
        uint8_t level();
        uint8_t level(uint16_t voltage);
 
        uint16_t voltage(uint8_t delay = 2);
 
    private:
        uint16_t refVoltage;
        uint16_t minVoltage;
        uint16_t maxVoltage;
        float dividerRatio;
        uint8_t sensePin;
        uint8_t activationPin;
        uint8_t activationMode;
        mapFn_t mapFunction;
 
        const uint16_t adc;
};
 
//
// Plots of the functions below available at
// https://www.desmos.com/calculator/x0esk5bsrk
//
 
static inline uint8_t sigmoidal(uint16_t voltage, uint16_t minVoltage, uint16_t maxVoltage) {
    // slow
    // uint8_t result = 110 - (110 / (1 + pow(1.468 * (voltage - minVoltage)/(maxVoltage - minVoltage), 6)));
 
    // steep
    // uint8_t result = 102 - (102 / (1 + pow(1.621 * (voltage - minVoltage)/(maxVoltage - minVoltage), 8.1)));
 
    // normal
    uint8_t result = 105 - (105 / (1 + pow(1.724 * (voltage - minVoltage)/(maxVoltage - minVoltage), 5.5)));
    return result >= 100 ? 100 : result;
}
 
static inline uint8_t asigmoidal(uint16_t voltage, uint16_t minVoltage, uint16_t maxVoltage) {
    uint8_t result = 101 - (101 / pow(1 + pow(1.33 * (voltage - minVoltage)/(maxVoltage - minVoltage) ,4.5), 3));
    return result >= 100 ? 100 : result;
}
 
static inline uint8_t linear(uint16_t voltage, uint16_t minVoltage, uint16_t maxVoltage) {
    return (unsigned long)(voltage - minVoltage) * 100 / (maxVoltage - minVoltage);
}
#endif // BATTERY_H_