#include <LiquidCrystal_I2C.h>
#include <Arduino.h>

// Define constants
const int shuntVoltagePinPositive = A0;  // Analog pin where the positive terminal voltage is connected
const int shuntVoltagePinNegative = A1;  // Analog pin where the negative terminal voltage is connected
const float voltageReference = 3.3;  // ESP32 voltage reference
const int adcMaxValue = 4095;  // Maximum ADC value for 12-bit resolution
const float shuntResistance = 1.0;  // Shunt resistor value in ohms
const float batteryCapacity = 10000.0;  // Battery capacity in milliampere-hours (mAh) 

// Variables for charge calculation and state of charge
float accumulatedCharge = 0.0;  // Accumulated charge in Coulombs
float accumulatedCapacity = 0.0;  // Accumulated capacity in milliampere-hours (mAh)
unsigned long lastTime = 0;  // Last time the charge was calculated
const int chargeInterval = 1000;  // Interval in milliseconds to calculate charge

void setup() {
  // Start serial communication
  Serial.begin(115200);
}

void loop() {
  // Read the voltage values from the positive and negative terminals of the shunt resistor
  int adcValuePositive = analogRead(shuntVoltagePinPositive);
  int adcValueNegative = analogRead(shuntVoltagePinNegative);

  // Convert ADC values to voltage
  float voltagePositive = (adcValuePositive / static_cast<float>(adcMaxValue)) * voltageReference;
  float voltageNegative = (adcValueNegative / static_cast<float>(adcMaxValue)) * voltageReference;

  // Calculate the voltage drop across the shunt resistor
  float voltageDrop = voltagePositive - voltageNegative;

  // Calculate the current using Ohm's Law (I = V/R)
  float current = voltageDrop / shuntResistance;

  // Calculate the time since the last charge calculation
  unsigned long currentTime = millis();
  unsigned long elapsedTime = currentTime - lastTime;

  // Update accumulated charge based on current and time
  accumulatedCharge += (current * elapsedTime) / 1000.0;  // Convert milliseconds to seconds

  // Calculate the state of charge (SoC)
  float soc = (accumulatedCharge / batteryCapacity) * 100.0;

  // Update accumulated capacity based on current and time
  accumulatedCapacity += (current * elapsedTime) / 3600000.0;  // Convert milliseconds to hours

  // Update the last time
  lastTime = currentTime;

  // Print the current, accumulated charge, and state of charge
  Serial.print("Current: ");
  Serial.print(current, 4);  // Print with 4 decimal places
  Serial.print(" A\tAccumulated Charge: ");
  Serial.print(accumulatedCharge, 4);  // Print with 4 decimal places
  Serial.print(" C\tState of Charge: ");
  Serial.print(soc, 2);  // Print with 2 decimal places
  Serial.println(" %");

  // Wait for the next charge calculation interval
  delay(chargeInterval);
}