130 lines
4.4 KiB
C++
130 lines
4.4 KiB
C++
/*
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Battery.h - Battery library
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Copyright (c) 2014 Roberto Lo Giacco.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation, either version 3 of the
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License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef BATTERY_H_
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#define BATTERY_H_
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#include <Arduino.h>
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typedef uint8_t(*mapFn_t)(uint16_t, uint16_t, uint16_t);
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class Battery {
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public:
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/**
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* Creates an instance to monitor battery voltage and level.
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* Initialization parameters depend on battery type and configuration.
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*
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* @param minVoltage is the voltage, expressed in millivolts, corresponding to an empty battery
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* @param maxVoltage is the voltage, expressed in millivolts, corresponding to a full battery
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* @param sensePin is the analog pin used for sensing the battery voltage
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*/
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Battery(uint16_t minVoltage, uint16_t maxVoltage, uint8_t sensePin);
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/**
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* Initializes the library by optionally setting additional parameters.
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* To obtain the best results use a calibrated reference using the VoltageReference library or equivalent.
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*
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* @param refVoltage is the board reference voltage, expressed in millivolts
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* @param dividerRatio is the multiplier used to obtain the real battery voltage
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* @param mapFunction is a pointer to the function used to map the battery voltage to the remaining capacity percentage (defaults to linear mapping)
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*/
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void begin(uint16_t refVoltage, float dividerRatio, mapFn_t = 0);
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/**
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* Enables on-demand activation of the sensing circuit to limit battery consumption.
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*
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* @param activationPin is the pin which will be turned HIGH or LOW before starting the battery sensing
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* @param activationMode is the optional value to set on the activationPin to enable battery sensing, defaults to LOW
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* useful when using a resistor divider to save on battery consumption, but it can be changed to HIGH in case
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* you are using a P-CH MOSFET or a PNP BJT
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*/
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void onDemand(uint8_t activationPin, uint8_t activationMode = LOW);
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/**
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* Activation pin value disabling the on-demand feature.
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*/
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static const uint8_t ON_DEMAND_DISABLE = 0xFF;
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/**
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* Returns the current battery level as a number between 0 and 100, with 0 indicating an empty battery and 100 a
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* full battery.
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*/
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uint8_t level();
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uint8_t level(uint16_t voltage);
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/**
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* Returns the current battery voltage in millivolts.
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*/
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uint16_t voltage();
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private:
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uint16_t refVoltage;
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uint16_t minVoltage;
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uint16_t maxVoltage;
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float dividerRatio;
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uint8_t sensePin;
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uint8_t activationPin;
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uint8_t activationMode;
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mapFn_t mapFunction;
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};
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//
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// Plots of the functions below available at
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// https://www.desmos.com/calculator/x0esk5bsrk
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//
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/**
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* Symmetric sigmoidal approximation
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* https://www.desmos.com/calculator/7m9lu26vpy
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*
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* c - c / (1 + k*x/v)^3
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*/
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static inline uint8_t sigmoidal(uint16_t voltage, uint16_t minVoltage, uint16_t maxVoltage) {
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// slow
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// uint8_t result = 110 - (110 / (1 + pow(1.468 * (voltage - minVoltage)/(maxVoltage - minVoltage), 6)));
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// steep
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// uint8_t result = 102 - (102 / (1 + pow(1.621 * (voltage - minVoltage)/(maxVoltage - minVoltage), 8.1)));
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// normal
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uint8_t result = 105 - (105 / (1 + pow(1.724 * (voltage - minVoltage)/(maxVoltage - minVoltage), 5.5)));
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return result >= 100 ? 100 : result;
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}
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/**
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* Asymmetric sigmoidal approximation
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* https://www.desmos.com/calculator/oyhpsu8jnw
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*
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* c - c / [1 + (k*x/v)^4.5]^3
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*/
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static inline uint8_t asigmoidal(uint16_t voltage, uint16_t minVoltage, uint16_t maxVoltage) {
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uint8_t result = 101 - (101 / pow(1 + pow(1.33 * (voltage - minVoltage)/(maxVoltage - minVoltage) ,4.5), 3));
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return result >= 100 ? 100 : result;
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}
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/**
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* Linear mapping
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* https://www.desmos.com/calculator/sowyhttjta
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*
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* x * 100 / v
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*/
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static inline uint8_t linear(uint16_t voltage, uint16_t minVoltage, uint16_t maxVoltage) {
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return (unsigned long)(voltage - minVoltage) * 100 / (maxVoltage - minVoltage);
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}
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#endif // BATTERY_H_
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