implement a new version to read battery pack

lib/Battery/battery.cpp

@@ -0,0 +1,72 @@
+/**
+ * @file battery.cpp
+ * @author Alexander Klein (alex@kleiax.de)
+ * @brief 
+ * @version 0.1
+ * @date 2022-02-05
+ * 
+ * @copyright Copyright (c) 2022
+ * 
+ */
+
+#include "battery.h"
+
+Battery::Battery(uint8_t pin, uint32_t r1, uint32_t r2) {
+    this->pin = pin;
+    this->r1 = r1;
+    this->r2 = r2;
+    this->calculateBatteryVoltage();
+}
+
+void Battery::loop() {
+    if (millis() - this->lastMillis < this->delay)
+        return;
+
+    this->calculateBatteryVoltage();
+    this->calculateBatteryPercent();
+
+    this->lastMillis = millis();
+}
+
+double Battery::getBatteryVoltage() {
+    return this->batteryVoltage;
+}
+
+uint8_t Battery::getBatteryPercent() {
+    return this->batteryPercent;
+}
+
+double Battery::readInputVoltage() {
+    // Reference voltage is 3v3 so maximum reading is 3v3 = 4095 in range 0 to 4095
+    double reading = analogRead(this->pin);
+    if(reading < 1 || reading > 4095) return 0;
+    return  - 0.000000000000016 * pow(reading,4)
+            + 0.000000000118171 * pow(reading,3)
+            - 0.000000301211691 * pow(reading,2)
+            + 0.001109019271794 * reading
+            + 0.034143524634089;
+}
+
+void Battery::calculateBatteryVoltage() {
+    this->batteryVoltage = (readInputVoltage() * (double) (this->r1 + this->r2)) / (double) this->r2;
+}
+
+void Battery::calculateBatteryPercent() {
+    int8_t size = sizeof(this->capacityVoltages) / sizeof(this->capacityVoltages);
+    uint8_t i;
+    for (i = 0; i < size; i++) {
+        if (this->batteryVoltage <= this->capacityVoltages[i])
+            break;
+    }
+    if (i == 0) {
+        std::cout << "Critical low battery!" << std::endl;
+    } else if (i == size - 1) {
+
+    } else {
+        double diffToLowerVal = this->batteryVoltage - this->capacityVoltages[i - 1];
+        double diffToHigherVal = this->capacityVoltages[i] - this->batteryVoltage;
+        if (diffToLowerVal > diffToHigherVal)
+            i--;
+    }
+    this->batteryPercent = i * (100 / (size - 1));
+}

lib/Battery/battery.h

@@ -0,0 +1,97 @@
+/**
+ * @file battery.h
+ * @author Alexander Klein (alex@kleiax.de)
+ * @brief Contains a class for battery monitoring
+ * @version 0.1
+ * @date 2022-02-05
+ * 
+ * @copyright Copyright (c) 2022
+ * 
+ */
+
+#ifndef AKKU_H
+#define AKKU_H
+
+#include <stdint.h>
+#include <iostream>
+#include <math.h>
+#include <Arduino.h>
+
+/**
+ * @brief A class for battery monitoring
+ * 
+ * This class reads the voltage from an analog pin to calculate the
+ * charge level of a 3 Cell Li-Poly battery pack. The battery pack have
+ * to be after a voltage diveder, so that maximum voltage for the
+ * microcontroller is 3.3 Volt.
+ */
+class Battery {
+    public:
+        /**
+         * @brief Construct a new Battery object
+         * 
+         * The voltage devider have to be calculated, so that the input
+         * voltage from 3.3 Volt is never exceeded. It is assumed that
+         * the microcontroller is connected to the second resistor.
+         * 
+         * @param pin The analog to read from.
+         * @param r1 First resistor of the voltage devider.
+         * @param r2 Second resistor of the voltage devider.
+         */
+        Battery(uint8_t pin, uint32_t r1, uint32_t r2);
+
+        /**
+         * @brief Read new values if the delay is reached. 
+         */
+        void loop();
+
+        /**
+         * @brief Set the delay to wait befor new values are read
+         * 
+         * @param delay in milliseconds
+         */
+        void setDelay(uint16_t delay) {this->delay = delay;        }
+
+        /**
+         * @brief Get the delay to wait befor new values are read
+         * 
+         * @return uint16_t delay in milliseconds
+         */
+        uint16_t getDelay()           {return this->delay;         }
+
+        /**
+         * @brief Get the battery voltage
+         * 
+         * @return double in Volt
+         */
+        double getBatteryVoltage()    {return this->batteryVoltage;}
+
+        /**
+         * @brief Get the charge level of the battery
+         * 
+         * @return uint8_t charge level in percent
+         */
+        uint8_t getBatteryPercent()   {return this->batteryPercent;}
+
+    private:
+        double readInputVoltage();
+        void calculateBatteryVoltage();
+        void calculateBatteryPercent();
+
+        uint8_t pin;
+        uint8_t batteryPercent;
+        uint16_t delay = 5000;
+        uint32_t r1;
+        uint32_t r2;
+        uint64_t lastMillis = 0;
+        double batteryVoltage;
+
+        const float capacityVoltages[21] = {9.82, 10.83, 11.06, 11.12,
+                                            11.18, 11.24, 11.3, 11.36,
+                                            11.39, 11.45, 11.51, 11.56,
+                                            11.62, 11.74, 11.86, 11.95,
+                                            12.07, 12.25, 12.33, 12.45,
+                                            12.6 };
+};
+
+#endif // AKKU_H